382 lines
8.4 KiB
ArmAsm
382 lines
8.4 KiB
ArmAsm
/*
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* Copyright 2008 Vitaly Mayatskikh <vmayatsk@redhat.com>
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* Copyright 2002 Andi Kleen, SuSE Labs.
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* Subject to the GNU Public License v2.
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*
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* Functions to copy from and to user space.
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*/
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#include <linux/linkage.h>
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#include <asm/current.h>
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#include <asm/asm-offsets.h>
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#include <asm/thread_info.h>
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#include <asm/cpufeatures.h>
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#include <asm/alternative-asm.h>
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#include <asm/asm.h>
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#include <asm/smap.h>
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/* Standard copy_to_user with segment limit checking */
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ENTRY(_copy_to_user)
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GET_THREAD_INFO(%rax)
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movq %rdi,%rcx
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addq %rdx,%rcx
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jc bad_to_user
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cmpq TI_addr_limit(%rax),%rcx
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ja bad_to_user
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ALTERNATIVE_2 "jmp copy_user_generic_unrolled", \
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"jmp copy_user_generic_string", \
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X86_FEATURE_REP_GOOD, \
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"jmp copy_user_enhanced_fast_string", \
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X86_FEATURE_ERMS
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ENDPROC(_copy_to_user)
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/* Standard copy_from_user with segment limit checking */
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ENTRY(_copy_from_user)
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GET_THREAD_INFO(%rax)
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movq %rsi,%rcx
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addq %rdx,%rcx
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jc bad_from_user
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cmpq TI_addr_limit(%rax),%rcx
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ja bad_from_user
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ALTERNATIVE_2 "jmp copy_user_generic_unrolled", \
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"jmp copy_user_generic_string", \
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X86_FEATURE_REP_GOOD, \
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"jmp copy_user_enhanced_fast_string", \
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X86_FEATURE_ERMS
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ENDPROC(_copy_from_user)
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.section .fixup,"ax"
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/* must zero dest */
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ENTRY(bad_from_user)
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bad_from_user:
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movl %edx,%ecx
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xorl %eax,%eax
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rep
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stosb
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bad_to_user:
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movl %edx,%eax
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ret
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ENDPROC(bad_from_user)
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.previous
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/*
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* copy_user_generic_unrolled - memory copy with exception handling.
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* This version is for CPUs like P4 that don't have efficient micro
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* code for rep movsq
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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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* eax uncopied bytes or 0 if successful.
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*/
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ENTRY(copy_user_generic_unrolled)
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ASM_STAC
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cmpl $8,%edx
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jb 20f /* less then 8 bytes, go to byte copy loop */
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ALIGN_DESTINATION
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movl %edx,%ecx
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andl $63,%edx
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shrl $6,%ecx
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jz 17f
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1: movq (%rsi),%r8
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2: movq 1*8(%rsi),%r9
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3: movq 2*8(%rsi),%r10
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4: movq 3*8(%rsi),%r11
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5: movq %r8,(%rdi)
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6: movq %r9,1*8(%rdi)
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7: movq %r10,2*8(%rdi)
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8: movq %r11,3*8(%rdi)
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9: movq 4*8(%rsi),%r8
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10: movq 5*8(%rsi),%r9
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11: movq 6*8(%rsi),%r10
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12: movq 7*8(%rsi),%r11
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13: movq %r8,4*8(%rdi)
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14: movq %r9,5*8(%rdi)
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15: movq %r10,6*8(%rdi)
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16: movq %r11,7*8(%rdi)
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leaq 64(%rsi),%rsi
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leaq 64(%rdi),%rdi
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decl %ecx
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jnz 1b
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17: movl %edx,%ecx
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andl $7,%edx
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shrl $3,%ecx
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jz 20f
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18: movq (%rsi),%r8
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19: movq %r8,(%rdi)
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leaq 8(%rsi),%rsi
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leaq 8(%rdi),%rdi
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decl %ecx
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jnz 18b
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20: andl %edx,%edx
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jz 23f
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movl %edx,%ecx
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21: movb (%rsi),%al
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22: movb %al,(%rdi)
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incq %rsi
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incq %rdi
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decl %ecx
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jnz 21b
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23: xor %eax,%eax
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ASM_CLAC
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ret
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.section .fixup,"ax"
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30: shll $6,%ecx
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addl %ecx,%edx
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jmp 60f
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40: leal (%rdx,%rcx,8),%edx
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jmp 60f
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50: movl %ecx,%edx
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60: jmp copy_user_handle_tail /* ecx is zerorest also */
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.previous
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_ASM_EXTABLE(1b,30b)
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_ASM_EXTABLE(2b,30b)
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_ASM_EXTABLE(3b,30b)
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_ASM_EXTABLE(4b,30b)
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_ASM_EXTABLE(5b,30b)
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_ASM_EXTABLE(6b,30b)
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_ASM_EXTABLE(7b,30b)
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_ASM_EXTABLE(8b,30b)
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_ASM_EXTABLE(9b,30b)
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_ASM_EXTABLE(10b,30b)
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_ASM_EXTABLE(11b,30b)
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_ASM_EXTABLE(12b,30b)
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_ASM_EXTABLE(13b,30b)
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_ASM_EXTABLE(14b,30b)
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_ASM_EXTABLE(15b,30b)
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_ASM_EXTABLE(16b,30b)
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_ASM_EXTABLE(18b,40b)
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_ASM_EXTABLE(19b,40b)
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_ASM_EXTABLE(21b,50b)
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_ASM_EXTABLE(22b,50b)
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ENDPROC(copy_user_generic_unrolled)
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/* Some CPUs run faster using the string copy instructions.
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* This is also a lot simpler. Use them when possible.
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*
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* Only 4GB of copy is supported. This shouldn't be a problem
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* because the kernel normally only writes from/to page sized chunks
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* even if user space passed a longer buffer.
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* And more would be dangerous because both Intel and AMD have
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* errata with rep movsq > 4GB. If someone feels the need to fix
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* this please consider this.
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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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* eax uncopied bytes or 0 if successful.
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*/
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ENTRY(copy_user_generic_string)
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ASM_STAC
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cmpl $8,%edx
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jb 2f /* less than 8 bytes, go to byte copy loop */
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ALIGN_DESTINATION
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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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1: rep
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movsq
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2: movl %edx,%ecx
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3: rep
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movsb
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xorl %eax,%eax
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ASM_CLAC
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ret
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.section .fixup,"ax"
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11: leal (%rdx,%rcx,8),%ecx
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12: movl %ecx,%edx /* ecx is zerorest also */
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jmp copy_user_handle_tail
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.previous
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_ASM_EXTABLE(1b,11b)
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_ASM_EXTABLE(3b,12b)
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ENDPROC(copy_user_generic_string)
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/*
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* Some CPUs are adding enhanced REP MOVSB/STOSB instructions.
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* It's recommended to use enhanced REP MOVSB/STOSB if it's enabled.
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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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* eax uncopied bytes or 0 if successful.
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*/
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ENTRY(copy_user_enhanced_fast_string)
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ASM_STAC
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movl %edx,%ecx
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1: rep
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movsb
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xorl %eax,%eax
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ASM_CLAC
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ret
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.section .fixup,"ax"
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12: movl %ecx,%edx /* ecx is zerorest also */
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jmp copy_user_handle_tail
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.previous
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_ASM_EXTABLE(1b,12b)
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ENDPROC(copy_user_enhanced_fast_string)
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/*
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* copy_user_nocache - Uncached memory copy with exception handling
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* This will force destination out of cache for more performance.
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*
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* Note: Cached memory copy is used when destination or size is not
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* naturally aligned. That is:
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* - Require 8-byte alignment when size is 8 bytes or larger.
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* - Require 4-byte alignment when size is 4 bytes.
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*/
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ENTRY(__copy_user_nocache)
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ASM_STAC
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/* If size is less than 8 bytes, go to 4-byte copy */
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cmpl $8,%edx
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jb .L_4b_nocache_copy_entry
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/* If destination is not 8-byte aligned, "cache" copy to align it */
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ALIGN_DESTINATION
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/* Set 4x8-byte copy count and remainder */
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movl %edx,%ecx
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andl $63,%edx
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shrl $6,%ecx
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jz .L_8b_nocache_copy_entry /* jump if count is 0 */
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/* Perform 4x8-byte nocache loop-copy */
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.L_4x8b_nocache_copy_loop:
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1: movq (%rsi),%r8
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2: movq 1*8(%rsi),%r9
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3: movq 2*8(%rsi),%r10
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4: movq 3*8(%rsi),%r11
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5: movnti %r8,(%rdi)
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6: movnti %r9,1*8(%rdi)
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7: movnti %r10,2*8(%rdi)
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8: movnti %r11,3*8(%rdi)
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9: movq 4*8(%rsi),%r8
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10: movq 5*8(%rsi),%r9
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11: movq 6*8(%rsi),%r10
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12: movq 7*8(%rsi),%r11
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13: movnti %r8,4*8(%rdi)
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14: movnti %r9,5*8(%rdi)
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15: movnti %r10,6*8(%rdi)
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16: movnti %r11,7*8(%rdi)
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leaq 64(%rsi),%rsi
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leaq 64(%rdi),%rdi
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decl %ecx
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jnz .L_4x8b_nocache_copy_loop
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/* Set 8-byte copy count and remainder */
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.L_8b_nocache_copy_entry:
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movl %edx,%ecx
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andl $7,%edx
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shrl $3,%ecx
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jz .L_4b_nocache_copy_entry /* jump if count is 0 */
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/* Perform 8-byte nocache loop-copy */
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.L_8b_nocache_copy_loop:
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20: movq (%rsi),%r8
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21: movnti %r8,(%rdi)
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leaq 8(%rsi),%rsi
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leaq 8(%rdi),%rdi
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decl %ecx
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jnz .L_8b_nocache_copy_loop
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/* If no byte left, we're done */
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.L_4b_nocache_copy_entry:
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andl %edx,%edx
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jz .L_finish_copy
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/* If destination is not 4-byte aligned, go to byte copy: */
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movl %edi,%ecx
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andl $3,%ecx
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jnz .L_1b_cache_copy_entry
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/* Set 4-byte copy count (1 or 0) and remainder */
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movl %edx,%ecx
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andl $3,%edx
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shrl $2,%ecx
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jz .L_1b_cache_copy_entry /* jump if count is 0 */
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/* Perform 4-byte nocache copy: */
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30: movl (%rsi),%r8d
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31: movnti %r8d,(%rdi)
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leaq 4(%rsi),%rsi
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leaq 4(%rdi),%rdi
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/* If no bytes left, we're done: */
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andl %edx,%edx
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jz .L_finish_copy
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/* Perform byte "cache" loop-copy for the remainder */
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.L_1b_cache_copy_entry:
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movl %edx,%ecx
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.L_1b_cache_copy_loop:
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40: movb (%rsi),%al
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41: movb %al,(%rdi)
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incq %rsi
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incq %rdi
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decl %ecx
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jnz .L_1b_cache_copy_loop
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/* Finished copying; fence the prior stores */
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.L_finish_copy:
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xorl %eax,%eax
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ASM_CLAC
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sfence
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ret
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.section .fixup,"ax"
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.L_fixup_4x8b_copy:
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shll $6,%ecx
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addl %ecx,%edx
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jmp .L_fixup_handle_tail
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.L_fixup_8b_copy:
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lea (%rdx,%rcx,8),%rdx
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jmp .L_fixup_handle_tail
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.L_fixup_4b_copy:
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lea (%rdx,%rcx,4),%rdx
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jmp .L_fixup_handle_tail
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.L_fixup_1b_copy:
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movl %ecx,%edx
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.L_fixup_handle_tail:
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sfence
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jmp copy_user_handle_tail
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.previous
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_ASM_EXTABLE(1b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(2b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(3b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(4b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(5b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(6b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(7b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(8b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(9b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(10b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(11b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(12b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(13b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(14b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(15b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(16b,.L_fixup_4x8b_copy)
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_ASM_EXTABLE(20b,.L_fixup_8b_copy)
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_ASM_EXTABLE(21b,.L_fixup_8b_copy)
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_ASM_EXTABLE(30b,.L_fixup_4b_copy)
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_ASM_EXTABLE(31b,.L_fixup_4b_copy)
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_ASM_EXTABLE(40b,.L_fixup_1b_copy)
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_ASM_EXTABLE(41b,.L_fixup_1b_copy)
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ENDPROC(__copy_user_nocache)
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