132 строки
2.0 KiB
ArmAsm
132 строки
2.0 KiB
ArmAsm
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/* Copyright 2002 Andi Kleen */
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#include <linux/linkage.h>
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#include <asm/dwarf2.h>
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#include <asm/cpufeature.h>
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/*
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* memcpy - Copy a memory block.
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*
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* Input:
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* rdi destination
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* rsi source
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* rdx count
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*
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* Output:
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* rax original destination
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*/
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ALIGN
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memcpy_c:
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CFI_STARTPROC
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movq %rdi,%rax
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movl %edx,%ecx
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shrl $3,%ecx
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andl $7,%edx
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rep movsq
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movl %edx,%ecx
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rep movsb
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ret
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CFI_ENDPROC
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ENDPROC(memcpy_c)
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ENTRY(__memcpy)
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ENTRY(memcpy)
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CFI_STARTPROC
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pushq %rbx
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CFI_ADJUST_CFA_OFFSET 8
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CFI_REL_OFFSET rbx, 0
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movq %rdi,%rax
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movl %edx,%ecx
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shrl $6,%ecx
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jz .Lhandle_tail
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.p2align 4
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.Lloop_64:
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decl %ecx
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movq (%rsi),%r11
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movq 8(%rsi),%r8
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movq %r11,(%rdi)
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movq %r8,1*8(%rdi)
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movq 2*8(%rsi),%r9
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movq 3*8(%rsi),%r10
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movq %r9,2*8(%rdi)
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movq %r10,3*8(%rdi)
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movq 4*8(%rsi),%r11
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movq 5*8(%rsi),%r8
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movq %r11,4*8(%rdi)
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movq %r8,5*8(%rdi)
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movq 6*8(%rsi),%r9
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movq 7*8(%rsi),%r10
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movq %r9,6*8(%rdi)
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movq %r10,7*8(%rdi)
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leaq 64(%rsi),%rsi
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leaq 64(%rdi),%rdi
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jnz .Lloop_64
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.Lhandle_tail:
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movl %edx,%ecx
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andl $63,%ecx
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shrl $3,%ecx
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jz .Lhandle_7
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.p2align 4
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.Lloop_8:
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decl %ecx
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movq (%rsi),%r8
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movq %r8,(%rdi)
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leaq 8(%rdi),%rdi
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leaq 8(%rsi),%rsi
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jnz .Lloop_8
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.Lhandle_7:
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movl %edx,%ecx
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andl $7,%ecx
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jz .Lende
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.p2align 4
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.Lloop_1:
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movb (%rsi),%r8b
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movb %r8b,(%rdi)
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incq %rdi
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incq %rsi
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decl %ecx
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jnz .Lloop_1
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.Lende:
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popq %rbx
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CFI_ADJUST_CFA_OFFSET -8
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CFI_RESTORE rbx
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ret
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.Lfinal:
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CFI_ENDPROC
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ENDPROC(memcpy)
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ENDPROC(__memcpy)
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/* Some CPUs run faster using the string copy instructions.
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It is also a lot simpler. Use this when possible */
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.section .altinstr_replacement,"ax"
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1: .byte 0xeb /* jmp <disp8> */
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.byte (memcpy_c - memcpy) - (2f - 1b) /* offset */
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2:
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.previous
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.section .altinstructions,"a"
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.align 8
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.quad memcpy
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.quad 1b
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.byte X86_FEATURE_REP_GOOD
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/* Replace only beginning, memcpy is used to apply alternatives, so it
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* is silly to overwrite itself with nops - reboot is only outcome... */
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.byte 2b - 1b
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.byte 2b - 1b
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.previous
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