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| /* SPDX-License-Identifier: GPL-2.0-only */
| /* Copyright 2002 Andi Kleen */
|
| #include <linux/linkage.h>
| #include <asm/errno.h>
| #include <asm/cpufeatures.h>
| #include <asm/alternative.h>
| #include <asm/export.h>
|
| .pushsection .noinstr.text, "ax"
|
| /*
| * 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.
| */
|
| /*
| * memcpy - Copy a memory block.
| *
| * Input:
| * rdi destination
| * rsi source
| * rdx count
| *
| * Output:
| * rax original destination
| */
| SYM_FUNC_START_ALIAS(__memcpy)
| SYM_FUNC_START_WEAK(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
| SYM_FUNC_END(memcpy)
| SYM_FUNC_END_ALIAS(__memcpy)
| EXPORT_SYMBOL(memcpy)
| EXPORT_SYMBOL(__memcpy)
|
| /*
| * memcpy_erms() - enhanced fast string memcpy. This is faster and
| * simpler than memcpy. Use memcpy_erms when possible.
| */
| SYM_FUNC_START_LOCAL(memcpy_erms)
| movq %rdi, %rax
| movq %rdx, %rcx
| rep movsb
| RET
| SYM_FUNC_END(memcpy_erms)
|
| 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)
|
| .popsection
|
|
