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