258 lines
5.0 KiB
ArmAsm
258 lines
5.0 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/dwarf2.h>
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#define FIX_ALIGNMENT 1
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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/cpufeature.h>
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.macro ALTERNATIVE_JUMP feature,orig,alt
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0:
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.byte 0xe9 /* 32bit jump */
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.long \orig-1f /* by default jump to orig */
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1:
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.section .altinstr_replacement,"ax"
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2: .byte 0xe9 /* near jump with 32bit immediate */
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.long \alt-1b /* offset */ /* or alternatively to alt */
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.previous
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.section .altinstructions,"a"
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.align 8
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.quad 0b
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.quad 2b
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.word \feature /* when feature is set */
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.byte 5
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.byte 5
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.previous
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.endm
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.macro ALIGN_DESTINATION
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#ifdef FIX_ALIGNMENT
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/* check for bad alignment of destination */
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movl %edi,%ecx
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andl $7,%ecx
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jz 102f /* already aligned */
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subl $8,%ecx
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negl %ecx
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subl %ecx,%edx
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100: movb (%rsi),%al
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101: 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 100b
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102:
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.section .fixup,"ax"
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103: addl %ecx,%edx /* ecx is zerorest also */
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jmp copy_user_handle_tail
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.previous
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.section __ex_table,"a"
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.align 8
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.quad 100b,103b
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.quad 101b,103b
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.previous
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#endif
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.endm
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/* Standard copy_to_user with segment limit checking */
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ENTRY(_copy_to_user)
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CFI_STARTPROC
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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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jae bad_to_user
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ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,copy_user_generic_unrolled,copy_user_generic_string
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CFI_ENDPROC
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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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CFI_STARTPROC
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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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jae bad_from_user
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ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,copy_user_generic_unrolled,copy_user_generic_string
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CFI_ENDPROC
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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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CFI_STARTPROC
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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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CFI_ENDPROC
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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 successfull.
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*/
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ENTRY(copy_user_generic_unrolled)
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CFI_STARTPROC
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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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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: lea (%rdx,%rcx,8),%rdx
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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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.section __ex_table,"a"
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.align 8
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.quad 1b,30b
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.quad 2b,30b
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.quad 3b,30b
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.quad 4b,30b
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.quad 5b,30b
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.quad 6b,30b
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.quad 7b,30b
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.quad 8b,30b
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.quad 9b,30b
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.quad 10b,30b
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.quad 11b,30b
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.quad 12b,30b
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.quad 13b,30b
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.quad 14b,30b
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.quad 15b,30b
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.quad 16b,30b
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.quad 18b,40b
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.quad 19b,40b
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.quad 21b,50b
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.quad 22b,50b
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.previous
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CFI_ENDPROC
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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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CFI_STARTPROC
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andl %edx,%edx
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jz 4f
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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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4: xorl %eax,%eax
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ret
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.section .fixup,"ax"
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11: lea (%rdx,%rcx,8),%rcx
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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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.section __ex_table,"a"
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.align 8
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.quad 1b,11b
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.quad 3b,12b
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.previous
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CFI_ENDPROC
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ENDPROC(copy_user_generic_string)
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