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| /* SPDX-License-Identifier: GPL-2.0 */
| /*
| * Normally compiler builtins are used, but sometimes the compiler calls out
| * of line code. Based on asm-i386/string.h.
| *
| * This assembly file is re-written from memmove_64.c file.
| * - Copyright 2011 Fenghua Yu <fenghua.yu@intel.com>
| */
| #include <linux/linkage.h>
| #include <asm/cpufeatures.h>
| #include <asm/alternative.h>
| #include <asm/export.h>
|
| #undef memmove
|
| /*
| * Implement memmove(). This can handle overlap between src and dst.
| *
| * Input:
| * rdi: dest
| * rsi: src
| * rdx: count
| *
| * Output:
| * rax: dest
| */
| SYM_FUNC_START_WEAK(memmove)
| SYM_FUNC_START(__memmove)
|
| mov %rdi, %rax
|
| /* Decide forward/backward copy mode */
| cmp %rdi, %rsi
| jge .Lmemmove_begin_forward
| mov %rsi, %r8
| add %rdx, %r8
| cmp %rdi, %r8
| jg 2f
|
| /* FSRM implies ERMS => no length checks, do the copy directly */
| .Lmemmove_begin_forward:
| ALTERNATIVE "cmp $0x20, %rdx; jb 1f", "", X86_FEATURE_FSRM
| ALTERNATIVE "", "jmp .Lmemmove_erms", X86_FEATURE_ERMS
|
| /*
| * movsq instruction have many startup latency
| * so we handle small size by general register.
| */
| cmp $680, %rdx
| jb 3f
| /*
| * movsq instruction is only good for aligned case.
| */
|
| cmpb %dil, %sil
| je 4f
| 3:
| sub $0x20, %rdx
| /*
| * We gobble 32 bytes forward in each loop.
| */
| 5:
| sub $0x20, %rdx
| movq 0*8(%rsi), %r11
| movq 1*8(%rsi), %r10
| movq 2*8(%rsi), %r9
| movq 3*8(%rsi), %r8
| leaq 4*8(%rsi), %rsi
|
| movq %r11, 0*8(%rdi)
| movq %r10, 1*8(%rdi)
| movq %r9, 2*8(%rdi)
| movq %r8, 3*8(%rdi)
| leaq 4*8(%rdi), %rdi
| jae 5b
| addq $0x20, %rdx
| jmp 1f
| /*
| * Handle data forward by movsq.
| */
| .p2align 4
| 4:
| movq %rdx, %rcx
| movq -8(%rsi, %rdx), %r11
| lea -8(%rdi, %rdx), %r10
| shrq $3, %rcx
| rep movsq
| movq %r11, (%r10)
| jmp 13f
| .Lmemmove_end_forward:
|
| /*
| * Handle data backward by movsq.
| */
| .p2align 4
| 7:
| movq %rdx, %rcx
| movq (%rsi), %r11
| movq %rdi, %r10
| leaq -8(%rsi, %rdx), %rsi
| leaq -8(%rdi, %rdx), %rdi
| shrq $3, %rcx
| std
| rep movsq
| cld
| movq %r11, (%r10)
| jmp 13f
|
| /*
| * Start to prepare for backward copy.
| */
| .p2align 4
| 2:
| cmp $0x20, %rdx
| jb 1f
| cmp $680, %rdx
| jb 6f
| cmp %dil, %sil
| je 7b
| 6:
| /*
| * Calculate copy position to tail.
| */
| addq %rdx, %rsi
| addq %rdx, %rdi
| subq $0x20, %rdx
| /*
| * We gobble 32 bytes backward in each loop.
| */
| 8:
| subq $0x20, %rdx
| movq -1*8(%rsi), %r11
| movq -2*8(%rsi), %r10
| movq -3*8(%rsi), %r9
| movq -4*8(%rsi), %r8
| leaq -4*8(%rsi), %rsi
|
| movq %r11, -1*8(%rdi)
| movq %r10, -2*8(%rdi)
| movq %r9, -3*8(%rdi)
| movq %r8, -4*8(%rdi)
| leaq -4*8(%rdi), %rdi
| jae 8b
| /*
| * Calculate copy position to head.
| */
| addq $0x20, %rdx
| subq %rdx, %rsi
| subq %rdx, %rdi
| 1:
| cmpq $16, %rdx
| jb 9f
| /*
| * Move data from 16 bytes to 31 bytes.
| */
| movq 0*8(%rsi), %r11
| movq 1*8(%rsi), %r10
| movq -2*8(%rsi, %rdx), %r9
| movq -1*8(%rsi, %rdx), %r8
| movq %r11, 0*8(%rdi)
| movq %r10, 1*8(%rdi)
| movq %r9, -2*8(%rdi, %rdx)
| movq %r8, -1*8(%rdi, %rdx)
| jmp 13f
| .p2align 4
| 9:
| cmpq $8, %rdx
| jb 10f
| /*
| * Move data from 8 bytes to 15 bytes.
| */
| movq 0*8(%rsi), %r11
| movq -1*8(%rsi, %rdx), %r10
| movq %r11, 0*8(%rdi)
| movq %r10, -1*8(%rdi, %rdx)
| jmp 13f
| 10:
| cmpq $4, %rdx
| jb 11f
| /*
| * Move data from 4 bytes to 7 bytes.
| */
| movl (%rsi), %r11d
| movl -4(%rsi, %rdx), %r10d
| movl %r11d, (%rdi)
| movl %r10d, -4(%rdi, %rdx)
| jmp 13f
| 11:
| cmp $2, %rdx
| jb 12f
| /*
| * Move data from 2 bytes to 3 bytes.
| */
| movw (%rsi), %r11w
| movw -2(%rsi, %rdx), %r10w
| movw %r11w, (%rdi)
| movw %r10w, -2(%rdi, %rdx)
| jmp 13f
| 12:
| cmp $1, %rdx
| jb 13f
| /*
| * Move data for 1 byte.
| */
| movb (%rsi), %r11b
| movb %r11b, (%rdi)
| 13:
| RET
|
| .Lmemmove_erms:
| movq %rdx, %rcx
| rep movsb
| RET
| SYM_FUNC_END(__memmove)
| SYM_FUNC_END_ALIAS(memmove)
| EXPORT_SYMBOL(__memmove)
| EXPORT_SYMBOL(memmove)
|
|
