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linux-next/arch/x86/include/asm/qspinlock.h

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 22:07:57 +08:00
/* SPDX-License-Identifier: GPL-2.0 */
locking/qspinlock, x86: Enable x86-64 to use queued spinlocks This patch makes the necessary changes at the x86 architecture specific layer to enable the use of queued spinlocks for x86-64. As x86-32 machines are typically not multi-socket. The benefit of queue spinlock may not be apparent. So queued spinlocks are not enabled. Currently, there is some incompatibilities between the para-virtualized spinlock code (which hard-codes the use of ticket spinlock) and the queued spinlocks. Therefore, the use of queued spinlocks is disabled when the para-virtualized spinlock is enabled. The arch/x86/include/asm/qspinlock.h header file includes some x86 specific optimization which will make the queueds spinlock code perform better than the generic implementation. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Daniel J Blueman <daniel@numascale.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paolo Bonzini <paolo.bonzini@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-3-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-25 02:56:31 +08:00
#ifndef _ASM_X86_QSPINLOCK_H
#define _ASM_X86_QSPINLOCK_H
#include <linux/jump_label.h>
#include <asm/cpufeature.h>
locking/qspinlock, x86: Enable x86-64 to use queued spinlocks This patch makes the necessary changes at the x86 architecture specific layer to enable the use of queued spinlocks for x86-64. As x86-32 machines are typically not multi-socket. The benefit of queue spinlock may not be apparent. So queued spinlocks are not enabled. Currently, there is some incompatibilities between the para-virtualized spinlock code (which hard-codes the use of ticket spinlock) and the queued spinlocks. Therefore, the use of queued spinlocks is disabled when the para-virtualized spinlock is enabled. The arch/x86/include/asm/qspinlock.h header file includes some x86 specific optimization which will make the queueds spinlock code perform better than the generic implementation. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Daniel J Blueman <daniel@numascale.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paolo Bonzini <paolo.bonzini@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-3-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-25 02:56:31 +08:00
#include <asm-generic/qspinlock_types.h>
locking/pvqspinlock, x86: Implement the paravirt qspinlock call patching We use the regular paravirt call patching to switch between: native_queued_spin_lock_slowpath() __pv_queued_spin_lock_slowpath() native_queued_spin_unlock() __pv_queued_spin_unlock() We use a callee saved call for the unlock function which reduces the i-cache footprint and allows 'inlining' of SPIN_UNLOCK functions again. We further optimize the unlock path by patching the direct call with a "movb $0,%arg1" if we are indeed using the native unlock code. This makes the unlock code almost as fast as the !PARAVIRT case. This significantly lowers the overhead of having CONFIG_PARAVIRT_SPINLOCKS enabled, even for native code. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Daniel J Blueman <daniel@numascale.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paolo Bonzini <paolo.bonzini@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-10-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-25 02:56:38 +08:00
#include <asm/paravirt.h>
locking/qspinlock, x86: Provide liveness guarantee On x86 we cannot do fetch_or() with a single instruction and thus end up using a cmpxchg loop, this reduces determinism. Replace the fetch_or() with a composite operation: tas-pending + load. Using two instructions of course opens a window we previously did not have. Consider the scenario: CPU0 CPU1 CPU2 1) lock trylock -> (0,0,1) 2) lock trylock /* fail */ 3) unlock -> (0,0,0) 4) lock trylock -> (0,0,1) 5) tas-pending -> (0,1,1) load-val <- (0,1,0) from 3 6) clear-pending-set-locked -> (0,0,1) FAIL: _2_ owners where 5) is our new composite operation. When we consider each part of the qspinlock state as a separate variable (as we can when _Q_PENDING_BITS == 8) then the above is entirely possible, because tas-pending will only RmW the pending byte, so the later load is able to observe prior tail and lock state (but not earlier than its own trylock, which operates on the whole word, due to coherence). To avoid this we need 2 things: - the load must come after the tas-pending (obviously, otherwise it can trivially observe prior state). - the tas-pending must be a full word RmW instruction, it cannot be an XCHGB for example, such that we cannot observe other state prior to setting pending. On x86 we can realize this by using "LOCK BTS m32, r32" for tas-pending followed by a regular load. Note that observing later state is not a problem: - if we fail to observe a later unlock, we'll simply spin-wait for that store to become visible. - if we observe a later xchg_tail(), there is no difference from that xchg_tail() having taken place before the tas-pending. Suggested-by: Will Deacon <will.deacon@arm.com> Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Will Deacon <will.deacon@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: andrea.parri@amarulasolutions.com Cc: longman@redhat.com Fixes: 59fb586b4a07 ("locking/qspinlock: Remove unbounded cmpxchg() loop from locking slowpath") Link: https://lkml.kernel.org/r/20181003130957.183726335@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-09-26 19:01:20 +08:00
#include <asm/rmwcc.h>
locking/qspinlock, x86: Enable x86-64 to use queued spinlocks This patch makes the necessary changes at the x86 architecture specific layer to enable the use of queued spinlocks for x86-64. As x86-32 machines are typically not multi-socket. The benefit of queue spinlock may not be apparent. So queued spinlocks are not enabled. Currently, there is some incompatibilities between the para-virtualized spinlock code (which hard-codes the use of ticket spinlock) and the queued spinlocks. Therefore, the use of queued spinlocks is disabled when the para-virtualized spinlock is enabled. The arch/x86/include/asm/qspinlock.h header file includes some x86 specific optimization which will make the queueds spinlock code perform better than the generic implementation. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Daniel J Blueman <daniel@numascale.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paolo Bonzini <paolo.bonzini@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-3-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-25 02:56:31 +08:00
#define _Q_PENDING_LOOPS (1 << 9)
locking/qspinlock, x86: Provide liveness guarantee On x86 we cannot do fetch_or() with a single instruction and thus end up using a cmpxchg loop, this reduces determinism. Replace the fetch_or() with a composite operation: tas-pending + load. Using two instructions of course opens a window we previously did not have. Consider the scenario: CPU0 CPU1 CPU2 1) lock trylock -> (0,0,1) 2) lock trylock /* fail */ 3) unlock -> (0,0,0) 4) lock trylock -> (0,0,1) 5) tas-pending -> (0,1,1) load-val <- (0,1,0) from 3 6) clear-pending-set-locked -> (0,0,1) FAIL: _2_ owners where 5) is our new composite operation. When we consider each part of the qspinlock state as a separate variable (as we can when _Q_PENDING_BITS == 8) then the above is entirely possible, because tas-pending will only RmW the pending byte, so the later load is able to observe prior tail and lock state (but not earlier than its own trylock, which operates on the whole word, due to coherence). To avoid this we need 2 things: - the load must come after the tas-pending (obviously, otherwise it can trivially observe prior state). - the tas-pending must be a full word RmW instruction, it cannot be an XCHGB for example, such that we cannot observe other state prior to setting pending. On x86 we can realize this by using "LOCK BTS m32, r32" for tas-pending followed by a regular load. Note that observing later state is not a problem: - if we fail to observe a later unlock, we'll simply spin-wait for that store to become visible. - if we observe a later xchg_tail(), there is no difference from that xchg_tail() having taken place before the tas-pending. Suggested-by: Will Deacon <will.deacon@arm.com> Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Will Deacon <will.deacon@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: andrea.parri@amarulasolutions.com Cc: longman@redhat.com Fixes: 59fb586b4a07 ("locking/qspinlock: Remove unbounded cmpxchg() loop from locking slowpath") Link: https://lkml.kernel.org/r/20181003130957.183726335@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-09-26 19:01:20 +08:00
#define queued_fetch_set_pending_acquire queued_fetch_set_pending_acquire
static __always_inline u32 queued_fetch_set_pending_acquire(struct qspinlock *lock)
{
u32 val;
/*
* We can't use GEN_BINARY_RMWcc() inside an if() stmt because asm goto
* and CONFIG_PROFILE_ALL_BRANCHES=y results in a label inside a
* statement expression, which GCC doesn't like.
*/
val = GEN_BINARY_RMWcc(LOCK_PREFIX "btsl", lock->val.counter, c,
"I", _Q_PENDING_OFFSET) * _Q_PENDING_VAL;
locking/qspinlock, x86: Provide liveness guarantee On x86 we cannot do fetch_or() with a single instruction and thus end up using a cmpxchg loop, this reduces determinism. Replace the fetch_or() with a composite operation: tas-pending + load. Using two instructions of course opens a window we previously did not have. Consider the scenario: CPU0 CPU1 CPU2 1) lock trylock -> (0,0,1) 2) lock trylock /* fail */ 3) unlock -> (0,0,0) 4) lock trylock -> (0,0,1) 5) tas-pending -> (0,1,1) load-val <- (0,1,0) from 3 6) clear-pending-set-locked -> (0,0,1) FAIL: _2_ owners where 5) is our new composite operation. When we consider each part of the qspinlock state as a separate variable (as we can when _Q_PENDING_BITS == 8) then the above is entirely possible, because tas-pending will only RmW the pending byte, so the later load is able to observe prior tail and lock state (but not earlier than its own trylock, which operates on the whole word, due to coherence). To avoid this we need 2 things: - the load must come after the tas-pending (obviously, otherwise it can trivially observe prior state). - the tas-pending must be a full word RmW instruction, it cannot be an XCHGB for example, such that we cannot observe other state prior to setting pending. On x86 we can realize this by using "LOCK BTS m32, r32" for tas-pending followed by a regular load. Note that observing later state is not a problem: - if we fail to observe a later unlock, we'll simply spin-wait for that store to become visible. - if we observe a later xchg_tail(), there is no difference from that xchg_tail() having taken place before the tas-pending. Suggested-by: Will Deacon <will.deacon@arm.com> Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Will Deacon <will.deacon@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: andrea.parri@amarulasolutions.com Cc: longman@redhat.com Fixes: 59fb586b4a07 ("locking/qspinlock: Remove unbounded cmpxchg() loop from locking slowpath") Link: https://lkml.kernel.org/r/20181003130957.183726335@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-09-26 19:01:20 +08:00
val |= atomic_read(&lock->val) & ~_Q_PENDING_MASK;
return val;
}
#ifdef CONFIG_PARAVIRT_SPINLOCKS
extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
extern void __pv_init_lock_hash(void);
extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock);
extern bool nopvspin;
locking/qspinlock, x86: Enable x86-64 to use queued spinlocks This patch makes the necessary changes at the x86 architecture specific layer to enable the use of queued spinlocks for x86-64. As x86-32 machines are typically not multi-socket. The benefit of queue spinlock may not be apparent. So queued spinlocks are not enabled. Currently, there is some incompatibilities between the para-virtualized spinlock code (which hard-codes the use of ticket spinlock) and the queued spinlocks. Therefore, the use of queued spinlocks is disabled when the para-virtualized spinlock is enabled. The arch/x86/include/asm/qspinlock.h header file includes some x86 specific optimization which will make the queueds spinlock code perform better than the generic implementation. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Daniel J Blueman <daniel@numascale.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paolo Bonzini <paolo.bonzini@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-3-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-25 02:56:31 +08:00
#define queued_spin_unlock queued_spin_unlock
/**
* queued_spin_unlock - release a queued spinlock
* @lock : Pointer to queued spinlock structure
*
* A smp_store_release() on the least-significant byte.
*/
locking/pvqspinlock, x86: Implement the paravirt qspinlock call patching We use the regular paravirt call patching to switch between: native_queued_spin_lock_slowpath() __pv_queued_spin_lock_slowpath() native_queued_spin_unlock() __pv_queued_spin_unlock() We use a callee saved call for the unlock function which reduces the i-cache footprint and allows 'inlining' of SPIN_UNLOCK functions again. We further optimize the unlock path by patching the direct call with a "movb $0,%arg1" if we are indeed using the native unlock code. This makes the unlock code almost as fast as the !PARAVIRT case. This significantly lowers the overhead of having CONFIG_PARAVIRT_SPINLOCKS enabled, even for native code. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Daniel J Blueman <daniel@numascale.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paolo Bonzini <paolo.bonzini@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-10-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-25 02:56:38 +08:00
static inline void native_queued_spin_unlock(struct qspinlock *lock)
locking/qspinlock, x86: Enable x86-64 to use queued spinlocks This patch makes the necessary changes at the x86 architecture specific layer to enable the use of queued spinlocks for x86-64. As x86-32 machines are typically not multi-socket. The benefit of queue spinlock may not be apparent. So queued spinlocks are not enabled. Currently, there is some incompatibilities between the para-virtualized spinlock code (which hard-codes the use of ticket spinlock) and the queued spinlocks. Therefore, the use of queued spinlocks is disabled when the para-virtualized spinlock is enabled. The arch/x86/include/asm/qspinlock.h header file includes some x86 specific optimization which will make the queueds spinlock code perform better than the generic implementation. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Daniel J Blueman <daniel@numascale.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paolo Bonzini <paolo.bonzini@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-3-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-25 02:56:31 +08:00
{
smp_store_release(&lock->locked, 0);
locking/qspinlock, x86: Enable x86-64 to use queued spinlocks This patch makes the necessary changes at the x86 architecture specific layer to enable the use of queued spinlocks for x86-64. As x86-32 machines are typically not multi-socket. The benefit of queue spinlock may not be apparent. So queued spinlocks are not enabled. Currently, there is some incompatibilities between the para-virtualized spinlock code (which hard-codes the use of ticket spinlock) and the queued spinlocks. Therefore, the use of queued spinlocks is disabled when the para-virtualized spinlock is enabled. The arch/x86/include/asm/qspinlock.h header file includes some x86 specific optimization which will make the queueds spinlock code perform better than the generic implementation. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Daniel J Blueman <daniel@numascale.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paolo Bonzini <paolo.bonzini@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-3-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-25 02:56:31 +08:00
}
locking/pvqspinlock, x86: Implement the paravirt qspinlock call patching We use the regular paravirt call patching to switch between: native_queued_spin_lock_slowpath() __pv_queued_spin_lock_slowpath() native_queued_spin_unlock() __pv_queued_spin_unlock() We use a callee saved call for the unlock function which reduces the i-cache footprint and allows 'inlining' of SPIN_UNLOCK functions again. We further optimize the unlock path by patching the direct call with a "movb $0,%arg1" if we are indeed using the native unlock code. This makes the unlock code almost as fast as the !PARAVIRT case. This significantly lowers the overhead of having CONFIG_PARAVIRT_SPINLOCKS enabled, even for native code. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Daniel J Blueman <daniel@numascale.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paolo Bonzini <paolo.bonzini@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-10-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-25 02:56:38 +08:00
static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
{
pv_queued_spin_lock_slowpath(lock, val);
}
static inline void queued_spin_unlock(struct qspinlock *lock)
{
pv_queued_spin_unlock(lock);
}
#define vcpu_is_preempted vcpu_is_preempted
static inline bool vcpu_is_preempted(long cpu)
{
return pv_vcpu_is_preempted(cpu);
}
locking/pvqspinlock, x86: Implement the paravirt qspinlock call patching We use the regular paravirt call patching to switch between: native_queued_spin_lock_slowpath() __pv_queued_spin_lock_slowpath() native_queued_spin_unlock() __pv_queued_spin_unlock() We use a callee saved call for the unlock function which reduces the i-cache footprint and allows 'inlining' of SPIN_UNLOCK functions again. We further optimize the unlock path by patching the direct call with a "movb $0,%arg1" if we are indeed using the native unlock code. This makes the unlock code almost as fast as the !PARAVIRT case. This significantly lowers the overhead of having CONFIG_PARAVIRT_SPINLOCKS enabled, even for native code. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Daniel J Blueman <daniel@numascale.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paolo Bonzini <paolo.bonzini@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-10-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-25 02:56:38 +08:00
#endif
#ifdef CONFIG_PARAVIRT
/*
* virt_spin_lock_key - enables (by default) the virt_spin_lock() hijack.
*
* Native (and PV wanting native due to vCPU pinning) should disable this key.
* It is done in this backwards fashion to only have a single direction change,
* which removes ordering between native_pv_spin_init() and HV setup.
*/
DECLARE_STATIC_KEY_TRUE(virt_spin_lock_key);
void native_pv_lock_init(void) __init;
/*
* Shortcut for the queued_spin_lock_slowpath() function that allows
* virt to hijack it.
*
* Returns:
* true - lock has been negotiated, all done;
* false - queued_spin_lock_slowpath() will do its thing.
*/
#define virt_spin_lock virt_spin_lock
static inline bool virt_spin_lock(struct qspinlock *lock)
{
if (!static_branch_likely(&virt_spin_lock_key))
return false;
/*
* On hypervisors without PARAVIRT_SPINLOCKS support we fall
* back to a Test-and-Set spinlock, because fair locks have
* horrible lock 'holder' preemption issues.
*/
do {
while (atomic_read(&lock->val) != 0)
cpu_relax();
} while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0);
return true;
}
#else
static inline void native_pv_lock_init(void)
{
}
#endif /* CONFIG_PARAVIRT */
locking/qspinlock, x86: Enable x86-64 to use queued spinlocks This patch makes the necessary changes at the x86 architecture specific layer to enable the use of queued spinlocks for x86-64. As x86-32 machines are typically not multi-socket. The benefit of queue spinlock may not be apparent. So queued spinlocks are not enabled. Currently, there is some incompatibilities between the para-virtualized spinlock code (which hard-codes the use of ticket spinlock) and the queued spinlocks. Therefore, the use of queued spinlocks is disabled when the para-virtualized spinlock is enabled. The arch/x86/include/asm/qspinlock.h header file includes some x86 specific optimization which will make the queueds spinlock code perform better than the generic implementation. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Daniel J Blueman <daniel@numascale.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paolo Bonzini <paolo.bonzini@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-3-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-25 02:56:31 +08:00
#include <asm-generic/qspinlock.h>
#endif /* _ASM_X86_QSPINLOCK_H */