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linux-next/arch/x86/lib/memcpy_64.S
Tony Luck cbf8b5a2b6 x86/mm, x86/mce: Fix return type/value for memcpy_mcsafe() 
Returning a 'bool' was very unpopular. Doubly so because the
code was just wrong (returning zero for true, one for false;
great for shell programming, not so good for C).

Change return type to "int". Keep zero as the success indicator
because it matches other similar code and people may be more
comfortable writing:

	if (memcpy_mcsafe(to, from, count)) {
		printk("Sad panda, copy failed\n");
		...
	}

Make the failure return value -EFAULT for now.

Reported by: Mika Penttilä <mika.penttila@nextfour.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: mika.penttila@nextfour.com
Fixes: 92b0729c34 ("x86/mm, x86/mce: Add memcpy_mcsafe()")
Link: http://lkml.kernel.org/r/695f14233fa7a54fcac4406c706d7fec228e3f4c.1457993040.git.tony.luck@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-16 09:02:18 +01:00

298 lines
6.0 KiB
ArmAsm
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/* Copyright 2002 Andi Kleen */
#include <linux/linkage.h>
#include <asm/errno.h>
#include <asm/cpufeatures.h>
#include <asm/alternative-asm.h>
/*
* We build a jump to memcpy_orig by default which gets NOPped out on
* the majority of x86 CPUs which set REP_GOOD. In addition, CPUs which
* have the enhanced REP MOVSB/STOSB feature (ERMS), change those NOPs
* to a jmp to memcpy_erms which does the REP; MOVSB mem copy.
*/
.weak memcpy
/*
* memcpy - Copy a memory block.
*
* Input:
* rdi destination
* rsi source
* rdx count
*
* Output:
* rax original destination
*/
ENTRY(__memcpy)
ENTRY(memcpy)
ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \
"jmp memcpy_erms", X86_FEATURE_ERMS
movq %rdi, %rax
movq %rdx, %rcx
shrq $3, %rcx
andl $7, %edx
rep movsq
movl %edx, %ecx
rep movsb
ret
ENDPROC(memcpy)
ENDPROC(__memcpy)
/*
* memcpy_erms() - enhanced fast string memcpy. This is faster and
* simpler than memcpy. Use memcpy_erms when possible.
*/
ENTRY(memcpy_erms)
movq %rdi, %rax
movq %rdx, %rcx
rep movsb
ret
ENDPROC(memcpy_erms)
ENTRY(memcpy_orig)
movq %rdi, %rax
cmpq $0x20, %rdx
jb .Lhandle_tail
/*
* We check whether memory false dependence could occur,
* then jump to corresponding copy mode.
*/
cmp %dil, %sil
jl .Lcopy_backward
subq $0x20, %rdx
.Lcopy_forward_loop:
subq $0x20, %rdx
/*
* Move in blocks of 4x8 bytes:
*/
movq 0*8(%rsi), %r8
movq 1*8(%rsi), %r9
movq 2*8(%rsi), %r10
movq 3*8(%rsi), %r11
leaq 4*8(%rsi), %rsi
movq %r8, 0*8(%rdi)
movq %r9, 1*8(%rdi)
movq %r10, 2*8(%rdi)
movq %r11, 3*8(%rdi)
leaq 4*8(%rdi), %rdi
jae .Lcopy_forward_loop
addl $0x20, %edx
jmp .Lhandle_tail
.Lcopy_backward:
/*
* Calculate copy position to tail.
*/
addq %rdx, %rsi
addq %rdx, %rdi
subq $0x20, %rdx
/*
* At most 3 ALU operations in one cycle,
* so append NOPS in the same 16 bytes trunk.
*/
.p2align 4
.Lcopy_backward_loop:
subq $0x20, %rdx
movq -1*8(%rsi), %r8
movq -2*8(%rsi), %r9
movq -3*8(%rsi), %r10
movq -4*8(%rsi), %r11
leaq -4*8(%rsi), %rsi
movq %r8, -1*8(%rdi)
movq %r9, -2*8(%rdi)
movq %r10, -3*8(%rdi)
movq %r11, -4*8(%rdi)
leaq -4*8(%rdi), %rdi
jae .Lcopy_backward_loop
/*
* Calculate copy position to head.
*/
addl $0x20, %edx
subq %rdx, %rsi
subq %rdx, %rdi
.Lhandle_tail:
cmpl $16, %edx
jb .Lless_16bytes
/*
* Move data from 16 bytes to 31 bytes.
*/
movq 0*8(%rsi), %r8
movq 1*8(%rsi), %r9
movq -2*8(%rsi, %rdx), %r10
movq -1*8(%rsi, %rdx), %r11
movq %r8, 0*8(%rdi)
movq %r9, 1*8(%rdi)
movq %r10, -2*8(%rdi, %rdx)
movq %r11, -1*8(%rdi, %rdx)
retq
.p2align 4
.Lless_16bytes:
cmpl $8, %edx
jb .Lless_8bytes
/*
* Move data from 8 bytes to 15 bytes.
*/
movq 0*8(%rsi), %r8
movq -1*8(%rsi, %rdx), %r9
movq %r8, 0*8(%rdi)
movq %r9, -1*8(%rdi, %rdx)
retq
.p2align 4
.Lless_8bytes:
cmpl $4, %edx
jb .Lless_3bytes
/*
* Move data from 4 bytes to 7 bytes.
*/
movl (%rsi), %ecx
movl -4(%rsi, %rdx), %r8d
movl %ecx, (%rdi)
movl %r8d, -4(%rdi, %rdx)
retq
.p2align 4
.Lless_3bytes:
subl $1, %edx
jb .Lend
/*
* Move data from 1 bytes to 3 bytes.
*/
movzbl (%rsi), %ecx
jz .Lstore_1byte
movzbq 1(%rsi), %r8
movzbq (%rsi, %rdx), %r9
movb %r8b, 1(%rdi)
movb %r9b, (%rdi, %rdx)
.Lstore_1byte:
movb %cl, (%rdi)
.Lend:
retq
ENDPROC(memcpy_orig)
#ifndef CONFIG_UML
/*
* memcpy_mcsafe - memory copy with machine check exception handling
* Note that we only catch machine checks when reading the source addresses.
* Writes to target are posted and don't generate machine checks.
*/
ENTRY(memcpy_mcsafe)
cmpl $8, %edx
/* Less than 8 bytes? Go to byte copy loop */
jb .L_no_whole_words
/* Check for bad alignment of source */
testl $7, %esi
/* Already aligned */
jz .L_8byte_aligned
/* Copy one byte at a time until source is 8-byte aligned */
movl %esi, %ecx
andl $7, %ecx
subl $8, %ecx
negl %ecx
subl %ecx, %edx
.L_copy_leading_bytes:
movb (%rsi), %al
movb %al, (%rdi)
incq %rsi
incq %rdi
decl %ecx
jnz .L_copy_leading_bytes
.L_8byte_aligned:
/* Figure out how many whole cache lines (64-bytes) to copy */
movl %edx, %ecx
andl $63, %edx
shrl $6, %ecx
jz .L_no_whole_cache_lines
/* Loop copying whole cache lines */
.L_cache_w0: movq (%rsi), %r8
.L_cache_w1: movq 1*8(%rsi), %r9
.L_cache_w2: movq 2*8(%rsi), %r10
.L_cache_w3: movq 3*8(%rsi), %r11
movq %r8, (%rdi)
movq %r9, 1*8(%rdi)
movq %r10, 2*8(%rdi)
movq %r11, 3*8(%rdi)
.L_cache_w4: movq 4*8(%rsi), %r8
.L_cache_w5: movq 5*8(%rsi), %r9
.L_cache_w6: movq 6*8(%rsi), %r10
.L_cache_w7: movq 7*8(%rsi), %r11
movq %r8, 4*8(%rdi)
movq %r9, 5*8(%rdi)
movq %r10, 6*8(%rdi)
movq %r11, 7*8(%rdi)
leaq 64(%rsi), %rsi
leaq 64(%rdi), %rdi
decl %ecx
jnz .L_cache_w0
/* Are there any trailing 8-byte words? */
.L_no_whole_cache_lines:
movl %edx, %ecx
andl $7, %edx
shrl $3, %ecx
jz .L_no_whole_words
/* Copy trailing words */
.L_copy_trailing_words:
movq (%rsi), %r8
mov %r8, (%rdi)
leaq 8(%rsi), %rsi
leaq 8(%rdi), %rdi
decl %ecx
jnz .L_copy_trailing_words
/* Any trailing bytes? */
.L_no_whole_words:
andl %edx, %edx
jz .L_done_memcpy_trap
/* Copy trailing bytes */
movl %edx, %ecx
.L_copy_trailing_bytes:
movb (%rsi), %al
movb %al, (%rdi)
incq %rsi
incq %rdi
decl %ecx
jnz .L_copy_trailing_bytes
/* Copy successful. Return zero */
.L_done_memcpy_trap:
xorq %rax, %rax
ret
ENDPROC(memcpy_mcsafe)
.section .fixup, "ax"
/* Return -EFAULT for any failure */
.L_memcpy_mcsafe_fail:
mov $-EFAULT, %rax
ret
.previous
_ASM_EXTABLE_FAULT(.L_copy_leading_bytes, .L_memcpy_mcsafe_fail)
_ASM_EXTABLE_FAULT(.L_cache_w0, .L_memcpy_mcsafe_fail)
_ASM_EXTABLE_FAULT(.L_cache_w1, .L_memcpy_mcsafe_fail)
_ASM_EXTABLE_FAULT(.L_cache_w3, .L_memcpy_mcsafe_fail)
_ASM_EXTABLE_FAULT(.L_cache_w3, .L_memcpy_mcsafe_fail)
_ASM_EXTABLE_FAULT(.L_cache_w4, .L_memcpy_mcsafe_fail)
_ASM_EXTABLE_FAULT(.L_cache_w5, .L_memcpy_mcsafe_fail)
_ASM_EXTABLE_FAULT(.L_cache_w6, .L_memcpy_mcsafe_fail)
_ASM_EXTABLE_FAULT(.L_cache_w7, .L_memcpy_mcsafe_fail)
_ASM_EXTABLE_FAULT(.L_copy_trailing_words, .L_memcpy_mcsafe_fail)
_ASM_EXTABLE_FAULT(.L_copy_trailing_bytes, .L_memcpy_mcsafe_fail)
#endif
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