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linux/arch/arm/lib/copy_template.S

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treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 Based on 2 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation # extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 4122 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Enrico Weigelt <info@metux.net> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-04 16:11:33 +08:00
/* SPDX-License-Identifier: GPL-2.0-only */
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
/*
* linux/arch/arm/lib/copy_template.s
*
* Code template for optimized memory copy functions
*
* Author: Nicolas Pitre
* Created: Sep 28, 2005
* Copyright: MontaVista Software, Inc.
*/
/*
* Theory of operation
* -------------------
*
* This file provides the core code for a forward memory copy used in
* the implementation of memcopy(), copy_to_user() and copy_from_user().
*
* The including file must define the following accessor macros
* according to the need of the given function:
*
* ldr1w ptr reg abort
*
* This loads one word from 'ptr', stores it in 'reg' and increments
* 'ptr' to the next word. The 'abort' argument is used for fixup tables.
*
* ldr4w ptr reg1 reg2 reg3 reg4 abort
* ldr8w ptr, reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort
*
* This loads four or eight words starting from 'ptr', stores them
* in provided registers and increments 'ptr' past those words.
* The'abort' argument is used for fixup tables.
*
* ldr1b ptr reg cond abort
*
* Similar to ldr1w, but it loads a byte and increments 'ptr' one byte.
* It also must apply the condition code if provided, otherwise the
* "al" condition is assumed by default.
*
* str1w ptr reg abort
* str8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort
* str1b ptr reg cond abort
*
* Same as their ldr* counterparts, but data is stored to 'ptr' location
* rather than being loaded.
*
* enter reg1 reg2
*
* Preserve the provided registers on the stack plus any additional
* data as needed by the implementation including this code. Called
* upon code entry.
*
ARM: 8225/1: Add unwinding support for memory copy functions The memory copy functions(memcpy, __copy_from_user, __copy_to_user) never had unwinding annotations added. Currently, when accessing invalid pointer by these functions occurs the backtrace shown will stop at these functions or some completely unrelated function. Add unwinding annotations in hopes of getting a more useful backtrace in following cases: 1. die on accessing invalid pointer by these functions 2. kprobe trapped at any instruction within these functions 3. interrupted at any instruction within these functions Signed-off-by: Lin Yongting <linyongting@gmail.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-11-26 21:38:33 +08:00
* usave reg1 reg2
*
* Unwind annotation macro is corresponding for 'enter' macro.
* It tell unwinder that preserved some provided registers on the stack
* and additional data by a prior 'enter' macro.
*
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
* exit reg1 reg2
*
* Restore registers with the values previously saved with the
* 'preserv' macro. Called upon code termination.
Thumb-2: Implement the unified arch/arm/lib functions This patch adds the ARM/Thumb-2 unified support for the arch/arm/lib/* files. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-24 19:32:57 +08:00
*
* LDR1W_SHIFT
* STR1W_SHIFT
*
* Correction to be applied to the "ip" register when branching into
* the ldr1w or str1w instructions (some of these macros may expand to
* than one 32bit instruction in Thumb-2)
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
*/
ARM: 8225/1: Add unwinding support for memory copy functions The memory copy functions(memcpy, __copy_from_user, __copy_to_user) never had unwinding annotations added. Currently, when accessing invalid pointer by these functions occurs the backtrace shown will stop at these functions or some completely unrelated function. Add unwinding annotations in hopes of getting a more useful backtrace in following cases: 1. die on accessing invalid pointer by these functions 2. kprobe trapped at any instruction within these functions 3. interrupted at any instruction within these functions Signed-off-by: Lin Yongting <linyongting@gmail.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-11-26 21:38:33 +08:00
UNWIND( .fnstart )
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
enter r4, UNWIND(fpreg,) lr
UNWIND( .setfp fpreg, sp )
UNWIND( mov fpreg, sp )
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
subs r2, r2, #4
blt 8f
ands ip, r0, #3
PLD( pld [r1, #0] )
bne 9f
ands ip, r1, #3
bne 10f
1: subs r2, r2, #(28)
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
stmfd sp!, {r5, r6, r8, r9}
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
blt 5f
[ARM] cache align destination pointer when copying memory for some processors The implementation for memory copy functions on ARM had a (disabled) provision for aligning the source pointer before loading registers with data. Turns out that aligning the _destination_ pointer is much more useful, as the read side is already sufficiently helped with the use of preload. So this changes the definition of the CALGN() macro to target the destination pointer instead, and turns it on for Feroceon processors where the gain is very noticeable. Signed-off-by: Nicolas Pitre <nico@marvell.com> Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
2008-04-01 00:38:31 +08:00
CALGN( ands ip, r0, #31 )
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
CALGN( rsb r3, ip, #32 )
ARM: 8844/1: use unified assembler in assembly files Use unified assembler syntax (UAL) in assembly files. Divided syntax is considered deprecated. This will also allow to build the kernel using LLVM's integrated assembler. Signed-off-by: Stefan Agner <stefan@agner.ch> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2019-02-18 07:57:38 +08:00
CALGN( sbcsne r4, r3, r2 ) @ C is always set here
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
CALGN( bcs 2f )
CALGN( adr r4, 6f )
CALGN( subs r2, r2, r3 ) @ C gets set
CALGN( add pc, r4, ip )
PLD( pld [r1, #0] )
2: PLD( subs r2, r2, #96 )
PLD( pld [r1, #28] )
PLD( blt 4f )
PLD( pld [r1, #60] )
PLD( pld [r1, #92] )
3: PLD( pld [r1, #124] )
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
4: ldr8w r1, r3, r4, r5, r6, r8, r9, ip, lr, abort=20f
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
subs r2, r2, #32
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
str8w r0, r3, r4, r5, r6, r8, r9, ip, lr, abort=20f
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
bge 3b
PLD( cmn r2, #96 )
PLD( bge 4b )
5: ands ip, r2, #28
rsb ip, ip, #32
Thumb-2: Implement the unified arch/arm/lib functions This patch adds the ARM/Thumb-2 unified support for the arch/arm/lib/* files. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-24 19:32:57 +08:00
#if LDR1W_SHIFT > 0
lsl ip, ip, #LDR1W_SHIFT
#endif
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
addne pc, pc, ip @ C is always clear here
b 7f
Thumb-2: Implement the unified arch/arm/lib functions This patch adds the ARM/Thumb-2 unified support for the arch/arm/lib/* files. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-24 19:32:57 +08:00
6:
.rept (1 << LDR1W_SHIFT)
W(nop)
.endr
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
ldr1w r1, r3, abort=20f
ldr1w r1, r4, abort=20f
ldr1w r1, r5, abort=20f
ldr1w r1, r6, abort=20f
ldr1w r1, r8, abort=20f
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
ldr1w r1, r9, abort=20f
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
ldr1w r1, lr, abort=20f
Thumb-2: Implement the unified arch/arm/lib functions This patch adds the ARM/Thumb-2 unified support for the arch/arm/lib/* files. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-24 19:32:57 +08:00
#if LDR1W_SHIFT < STR1W_SHIFT
lsl ip, ip, #STR1W_SHIFT - LDR1W_SHIFT
#elif LDR1W_SHIFT > STR1W_SHIFT
lsr ip, ip, #LDR1W_SHIFT - STR1W_SHIFT
#endif
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
add pc, pc, ip
nop
Thumb-2: Implement the unified arch/arm/lib functions This patch adds the ARM/Thumb-2 unified support for the arch/arm/lib/* files. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-24 19:32:57 +08:00
.rept (1 << STR1W_SHIFT)
W(nop)
.endr
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
str1w r0, r3, abort=20f
str1w r0, r4, abort=20f
str1w r0, r5, abort=20f
str1w r0, r6, abort=20f
str1w r0, r8, abort=20f
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
str1w r0, r9, abort=20f
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
str1w r0, lr, abort=20f
CALGN( bcs 2b )
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
7: ldmfd sp!, {r5, r6, r8, r9}
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
8: movs r2, r2, lsl #31
ldr1b r1, r3, ne, abort=21f
ldr1b r1, r4, cs, abort=21f
ldr1b r1, ip, cs, abort=21f
str1b r0, r3, ne, abort=21f
str1b r0, r4, cs, abort=21f
str1b r0, ip, cs, abort=21f
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
exit r4, UNWIND(fpreg,) pc
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
9: rsb ip, ip, #4
cmp ip, #2
ldr1b r1, r3, gt, abort=21f
ldr1b r1, r4, ge, abort=21f
ldr1b r1, lr, abort=21f
str1b r0, r3, gt, abort=21f
str1b r0, r4, ge, abort=21f
subs r2, r2, ip
str1b r0, lr, abort=21f
blt 8b
ands ip, r1, #3
beq 1b
10: bic r1, r1, #3
cmp ip, #2
ldr1w r1, lr, abort=21f
beq 17f
bgt 18f
.macro forward_copy_shift pull push
subs r2, r2, #28
blt 14f
[ARM] cache align destination pointer when copying memory for some processors The implementation for memory copy functions on ARM had a (disabled) provision for aligning the source pointer before loading registers with data. Turns out that aligning the _destination_ pointer is much more useful, as the read side is already sufficiently helped with the use of preload. So this changes the definition of the CALGN() macro to target the destination pointer instead, and turns it on for Feroceon processors where the gain is very noticeable. Signed-off-by: Nicolas Pitre <nico@marvell.com> Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
2008-04-01 00:38:31 +08:00
CALGN( ands ip, r0, #31 )
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
CALGN( rsb ip, ip, #32 )
ARM: 8844/1: use unified assembler in assembly files Use unified assembler syntax (UAL) in assembly files. Divided syntax is considered deprecated. This will also allow to build the kernel using LLVM's integrated assembler. Signed-off-by: Stefan Agner <stefan@agner.ch> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2019-02-18 07:57:38 +08:00
CALGN( sbcsne r4, ip, r2 ) @ C is always set here
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
CALGN( subcc r2, r2, ip )
CALGN( bcc 15f )
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
11: stmfd sp!, {r5, r6, r8 - r10}
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
PLD( pld [r1, #0] )
PLD( subs r2, r2, #96 )
PLD( pld [r1, #28] )
PLD( blt 13f )
PLD( pld [r1, #60] )
PLD( pld [r1, #92] )
12: PLD( pld [r1, #124] )
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
13: ldr4w r1, r4, r5, r6, r8, abort=19f
ARM: 7990/1: asm: rename logical shift macros push pull into lspush lspull Renames logical shift macros, 'push' and 'pull', defined in arch/arm/include/asm/assembler.h, into 'lspush' and 'lspull'. That eliminates name conflict between 'push' logical shift macro and 'push' instruction mnemonic. That allows assembler.h to be included in .S files that use 'push' instruction. Suggested-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-02-25 15:41:09 +08:00
mov r3, lr, lspull #\pull
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
subs r2, r2, #32
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
ldr4w r1, r9, r10, ip, lr, abort=19f
ARM: 7990/1: asm: rename logical shift macros push pull into lspush lspull Renames logical shift macros, 'push' and 'pull', defined in arch/arm/include/asm/assembler.h, into 'lspush' and 'lspull'. That eliminates name conflict between 'push' logical shift macro and 'push' instruction mnemonic. That allows assembler.h to be included in .S files that use 'push' instruction. Suggested-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-02-25 15:41:09 +08:00
orr r3, r3, r4, lspush #\push
mov r4, r4, lspull #\pull
orr r4, r4, r5, lspush #\push
mov r5, r5, lspull #\pull
orr r5, r5, r6, lspush #\push
mov r6, r6, lspull #\pull
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
orr r6, r6, r8, lspush #\push
ARM: 7990/1: asm: rename logical shift macros push pull into lspush lspull Renames logical shift macros, 'push' and 'pull', defined in arch/arm/include/asm/assembler.h, into 'lspush' and 'lspull'. That eliminates name conflict between 'push' logical shift macro and 'push' instruction mnemonic. That allows assembler.h to be included in .S files that use 'push' instruction. Suggested-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-02-25 15:41:09 +08:00
mov r8, r8, lspull #\pull
orr r8, r8, r9, lspush #\push
mov r9, r9, lspull #\pull
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
orr r9, r9, r10, lspush #\push
mov r10, r10, lspull #\pull
orr r10, r10, ip, lspush #\push
ARM: 7990/1: asm: rename logical shift macros push pull into lspush lspull Renames logical shift macros, 'push' and 'pull', defined in arch/arm/include/asm/assembler.h, into 'lspush' and 'lspull'. That eliminates name conflict between 'push' logical shift macro and 'push' instruction mnemonic. That allows assembler.h to be included in .S files that use 'push' instruction. Suggested-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-02-25 15:41:09 +08:00
mov ip, ip, lspull #\pull
orr ip, ip, lr, lspush #\push
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
str8w r0, r3, r4, r5, r6, r8, r9, r10, ip, abort=19f
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
bge 12b
PLD( cmn r2, #96 )
PLD( bge 13b )
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
ldmfd sp!, {r5, r6, r8 - r10}
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
14: ands ip, r2, #28
beq 16f
ARM: 7990/1: asm: rename logical shift macros push pull into lspush lspull Renames logical shift macros, 'push' and 'pull', defined in arch/arm/include/asm/assembler.h, into 'lspush' and 'lspull'. That eliminates name conflict between 'push' logical shift macro and 'push' instruction mnemonic. That allows assembler.h to be included in .S files that use 'push' instruction. Suggested-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-02-25 15:41:09 +08:00
15: mov r3, lr, lspull #\pull
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
ldr1w r1, lr, abort=21f
subs ip, ip, #4
ARM: 7990/1: asm: rename logical shift macros push pull into lspush lspull Renames logical shift macros, 'push' and 'pull', defined in arch/arm/include/asm/assembler.h, into 'lspush' and 'lspull'. That eliminates name conflict between 'push' logical shift macro and 'push' instruction mnemonic. That allows assembler.h to be included in .S files that use 'push' instruction. Suggested-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-02-25 15:41:09 +08:00
orr r3, r3, lr, lspush #\push
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
str1w r0, r3, abort=21f
bgt 15b
CALGN( cmp r2, #0 )
CALGN( bge 11b )
16: sub r1, r1, #(\push / 8)
b 8b
.endm
forward_copy_shift pull=8 push=24
17: forward_copy_shift pull=16 push=16
18: forward_copy_shift pull=24 push=8
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
UNWIND( .fnend )
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
/*
[PATCH] Typo fixes Fix a lot of typos. Eyeballed by jmc@ in OpenBSD. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-28 17:56:53 +08:00
* Abort preamble and completion macros.
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
* If a fixup handler is required then those macros must surround it.
* It is assumed that the fixup code will handle the private part of
* the exit macro.
*/
.macro copy_abort_preamble
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
19: ldmfd sp!, {r5, r6, r8 - r10}
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
b 21f
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
20: ldmfd sp!, {r5, r6, r8, r9}
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
21:
.endm
.macro copy_abort_end
ARM: memcpy: use frame pointer as unwind anchor The memcpy template is a bit unusual in the way it manages the stack pointer: depending on the execution path through the function, the SP assumes different values as different subsets of the register file are preserved and restored again. This is problematic when it comes to EHABI unwind info, as it is not instruction accurate, and does not allow tracking the SP value as it changes. Commit 279f487e0b471 ("ARM: 8225/1: Add unwinding support for memory copy functions") addressed this by carving up the function in different chunks as far as the unwinder is concerned, and keeping a set of unwind directives for each of them, each corresponding with the state of the stack pointer during execution of the chunk in question. This not only duplicates unwind info unnecessarily, but it also complicates unwinding the stack upon overflow. Instead, let's do what the compiler does when the SP is updated halfway through a function, which is to use a frame pointer and emit the appropriate unwind directives to communicate this to the unwinder. Note that Thumb-2 uses R7 for this, while ARM uses R11 aka FP. So let's avoid touching R7 in the body of the template, so that Thumb-2 can use it as the frame pointer. R11 was not modified in the first place. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
2021-10-04 01:05:53 +08:00
ldmfd sp!, {r4, UNWIND(fpreg,) pc}
[ARM] 2947/1: copy template with new memcpy/memmove Patch from Nicolas Pitre This patch provides a new implementation for optimized memory copy functions on ARM. It is made of two levels: a template that consists of the core copy code and separate files that define macros to be used with the core code depending on the type of copy needed. This allows for best performances while sharing the same core for implementing memcpy(), copy_from_user() and copy_to_user() for instance. Two reasons for this work: 1) the current copy_to_user/copy_from_user implementation assumes no task switch will ever occur in the middle of each copied page making it completely unsafe with CONFIG_PREEMPT=y. 2) current copy implementations are measurably suboptimal and optimizing different implementations separately is a pain and more opportunities for bugs. The reason for (1) is the fact that copy inside user pages are performed with the ldm instruction which has no mean for testing user protections and could possibly race with process preemption bypassing the COW mechanism for example. This is a longstanding issue that we said ought to be fixed for about two years now. The solution is to substitute those ldm insns with a series of ldrt or strt insns to enforce user memory protection. At least on StrongARM and XScale cores the ldm is not faster than the equivalent ldr/str insns with a warm i-cache so there is no measurable performance degradation with that change. The fact that the copy code is a template makes it pretty easy to reuse the same core code as for memcpy and benefit from the same performance optimizations. Now (2) is best demonstrated with actual throughput measurements. First, here is a summary of memcopy tests performed on a StrongARM core: PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 59.73 107.43 unaligned 32 61.31 74.72 aligned 100 132.47 136.15 unaligned 100 103.84 123.76 aligned 4096 130.67 130.80 unaligned 4096 130.68 130.64 aligned 1048576 68.03 68.18 unaligned 1048576 68.03 68.18 The buffer size is in bytes and the measured speed in MB/s. The copy was performed repeatedly with given buffer and throughput averaged over 3 seconds. Here we can see that the current kernel version has a higher entry cost that shows up with small buffers. As buffer size grows both implementation converge to the same throughput. Now here's the exact same test performed on an XScale core (PXA255): PTR alignment buffer size kernel version this version ------------------------------------------------------------ aligned 32 46.99 77.58 unaligned 32 53.61 59.59 aligned 100 107.19 136.59 unaligned 100 83.61 97.58 aligned 4096 129.13 129.98 unaligned 4096 128.36 128.53 aligned 1048576 53.76 59.41 unaligned 1048576 33.67 56.96 Again we can see the entry setup cost being higher for the current kernel before getting to the main copy loop. Then throughput results converge as long as the buffer remains in the cache. Then the 1MB case shows more differences probably due to better pld placement and/or less instruction interlocks in this proposed implementation. Disclaimer: The PXA system was running with slower clocks than the StrongARM system so trying to infer any conclusion by comparing those separate sets of results side by side would be completely inappropriate. So... What this patch does is to replace both memcpy and memmove with an implementation based on the provided copy code template. The memmove code is kept separate since it is used only if the memory areas involved do overlap in which case the code is a transposition of the template but with the copy occurring in the opposite direction (trying to fit that mode into the template turned it into a mess not worth it for memmove alone). And obviously both memcpy and memmove were tested with all kinds of pointer alignments and buffer sizes to exercise all code paths for correctness. The next patch will provide the now trivial replacement implementation copy_to_user and copy_from_user. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-02 03:52:23 +08:00
.endm
Reference in New Issue Copy Permalink