| /* SPDX-License-Identifier: GPL-2.0-only */ |
| /* Copyright 2002 Andi Kleen */ |
| |
| #include <linux/export.h> |
| #include <linux/linkage.h> |
| #include <asm/errno.h> |
| #include <asm/cpufeatures.h> |
| #include <asm/alternative.h> |
| |
| .section .noinstr.text, "ax" |
| |
| /* |
| * memcpy - Copy a memory block. |
| * |
| * Input: |
| * rdi destination |
| * rsi source |
| * rdx count |
| * |
| * Output: |
| * rax original destination |
| * |
| * The FSRM alternative should be done inline (avoiding the call and |
| * the disgusting return handling), but that would require some help |
| * from the compiler for better calling conventions. |
| * |
| * The 'rep movsb' itself is small enough to replace the call, but the |
| * two register moves blow up the code. And one of them is "needed" |
| * only for the return value that is the same as the source input, |
| * which the compiler could/should do much better anyway. |
| */ |
| SYM_TYPED_FUNC_START(__memcpy) |
| ALTERNATIVE "jmp memcpy_orig", "", X86_FEATURE_FSRM |
| |
| movq %rdi, %rax |
| movq %rdx, %rcx |
| rep movsb |
| RET |
| SYM_FUNC_END(__memcpy) |
| EXPORT_SYMBOL(__memcpy) |
| |
| SYM_FUNC_ALIAS_MEMFUNC(memcpy, __memcpy) |
| EXPORT_SYMBOL(memcpy) |
| |
| SYM_FUNC_START_LOCAL(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) |
| RET |
| .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) |
| RET |
| .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) |
| RET |
| .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: |
| RET |
| SYM_FUNC_END(memcpy_orig) |
| |
