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/* SPDX-License-Identifier: GPL-2.0-only */
/* Copyright(c) 2016-2020 Intel Corporation. All rights reserved. */
#include <linux/linkage.h>
#include <asm/asm.h>
#ifndef CONFIG_UML
#ifdef CONFIG_X86_MCE
/*
* copy_mc_fragile - copy memory with indication if an exception / fault happened
*
* The 'fragile' version is opted into by platform quirks and takes
* pains to avoid unrecoverable corner cases like 'fast-string'
* instruction sequences, and consuming poison across a cacheline
* boundary. The non-fragile version is equivalent to memcpy()
* regardless of CPU machine-check-recovery capability.
*/
SYM_FUNC_START(copy_mc_fragile)
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_read_leading_bytes:
movb (%rsi), %al
.L_write_leading_bytes:
movb %al, (%rdi)
incq %rsi
incq %rdi
decl %ecx
jnz .L_read_leading_bytes
.L_8byte_aligned:
movl %edx, %ecx
andl $7, %edx
shrl $3, %ecx
jz .L_no_whole_words
.L_read_words:
movq (%rsi), %r8
.L_write_words:
movq %r8, (%rdi)
addq $8, %rsi
addq $8, %rdi
decl %ecx
jnz .L_read_words
/* Any trailing bytes? */
.L_no_whole_words:
andl %edx, %edx
jz .L_done_memcpy_trap
/* Copy trailing bytes */
movl %edx, %ecx
.L_read_trailing_bytes:
movb (%rsi), %al
.L_write_trailing_bytes:
movb %al, (%rdi)
incq %rsi
incq %rdi
decl %ecx
jnz .L_read_trailing_bytes
/* Copy successful. Return zero */
.L_done_memcpy_trap:
xorl %eax, %eax
.L_done:
ret
SYM_FUNC_END(copy_mc_fragile)
.section .fixup, "ax"
/*
* Return number of bytes not copied for any failure. Note that
* there is no "tail" handling since the source buffer is 8-byte
* aligned and poison is cacheline aligned.
*/
.E_read_words:
shll $3, %ecx
.E_leading_bytes:
addl %edx, %ecx
.E_trailing_bytes:
mov %ecx, %eax
jmp .L_done
/*
* For write fault handling, given the destination is unaligned,
* we handle faults on multi-byte writes with a byte-by-byte
* copy up to the write-protected page.
*/
.E_write_words:
shll $3, %ecx
addl %edx, %ecx
movl %ecx, %edx
jmp copy_mc_fragile_handle_tail
.previous
_ASM_EXTABLE_FAULT(.L_read_leading_bytes, .E_leading_bytes)
_ASM_EXTABLE_FAULT(.L_read_words, .E_read_words)
_ASM_EXTABLE_FAULT(.L_read_trailing_bytes, .E_trailing_bytes)
_ASM_EXTABLE(.L_write_leading_bytes, .E_leading_bytes)
_ASM_EXTABLE(.L_write_words, .E_write_words)
_ASM_EXTABLE(.L_write_trailing_bytes, .E_trailing_bytes)
#endif /* CONFIG_X86_MCE */
/*
* copy_mc_enhanced_fast_string - memory copy with exception handling
*
* Fast string copy + fault / exception handling. If the CPU does
* support machine check exception recovery, but does not support
* recovering from fast-string exceptions then this CPU needs to be
* added to the copy_mc_fragile_key set of quirks. Otherwise, absent any
* machine check recovery support this version should be no slower than
* standard memcpy.
*/
SYM_FUNC_START(copy_mc_enhanced_fast_string)
movq %rdi, %rax
movq %rdx, %rcx
.L_copy:
rep movsb
/* Copy successful. Return zero */
xorl %eax, %eax
ret
SYM_FUNC_END(copy_mc_enhanced_fast_string)
.section .fixup, "ax"
.E_copy:
/*
* On fault %rcx is updated such that the copy instruction could
* optionally be restarted at the fault position, i.e. it
* contains 'bytes remaining'. A non-zero return indicates error
* to copy_mc_generic() users, or indicate short transfers to
* user-copy routines.
*/
movq %rcx, %rax
ret
.previous
_ASM_EXTABLE_FAULT(.L_copy, .E_copy)
#endif /* !CONFIG_UML */
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