forked from rrcarlosr/Jetpack
57 lines
997 B
ArmAsm
57 lines
997 B
ArmAsm
#include <linux/linkage.h>
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#include <asm/cpufeatures.h>
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#include <asm/alternative-asm.h>
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#include <asm/export.h>
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/*
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* Most CPUs support enhanced REP MOVSB/STOSB instructions. It is
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* recommended to use this when possible and we do use them by default.
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* If enhanced REP MOVSB/STOSB is not available, try to use fast string.
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* Otherwise, use original.
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*/
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/*
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* Zero a page.
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* %rdi - page
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*/
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ENTRY(clear_page)
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ALTERNATIVE_2 "jmp clear_page_orig", "", X86_FEATURE_REP_GOOD, \
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"jmp clear_page_c_e", X86_FEATURE_ERMS
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movl $4096/8,%ecx
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xorl %eax,%eax
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rep stosq
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ret
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ENDPROC(clear_page)
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EXPORT_SYMBOL(clear_page)
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ENTRY(clear_page_orig)
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xorl %eax,%eax
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movl $4096/64,%ecx
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.p2align 4
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.Lloop:
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decl %ecx
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#define PUT(x) movq %rax,x*8(%rdi)
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movq %rax,(%rdi)
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PUT(1)
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PUT(2)
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PUT(3)
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PUT(4)
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PUT(5)
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PUT(6)
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PUT(7)
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leaq 64(%rdi),%rdi
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jnz .Lloop
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nop
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ret
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ENDPROC(clear_page_orig)
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ENTRY(clear_page_c_e)
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movl $4096,%ecx
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xorl %eax,%eax
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rep stosb
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ret
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ENDPROC(clear_page_c_e)
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