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278b917f8c
_ASM_EXTABLE_UA is a general exception entry to record the exception fixup for all exception spots between kernel and user space access. To enable recovery from machine checks while coping data from user addresses it is necessary to be able to distinguish the places that are looping copying data from those that copy a single byte/word/etc. Add a new macro _ASM_EXTABLE_CPY and use it in place of _ASM_EXTABLE_UA in the copy functions. Record the exception reason number to regs->ax at ex_handler_uaccess which is used to check MCE triggered. The new fixup routine ex_handler_copy() is almost an exact copy of ex_handler_uaccess() The difference is that it sets regs->ax to the trap number. Following patches use this to avoid trying to copy remaining bytes from the tail of the copy and possibly hitting the poison again. New mce.kflags bit MCE_IN_KERNEL_COPYIN will be used by mce_severity() calculation to indicate that a machine check is recoverable because the kernel was copying from user space. Signed-off-by: Youquan Song <youquan.song@intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20201006210910.21062-4-tony.luck@intel.com
393 lines
8.9 KiB
ArmAsm
393 lines
8.9 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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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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*
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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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#include <asm/export.h>
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.macro ALIGN_DESTINATION
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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 .Lcopy_user_handle_tail
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.previous
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_ASM_EXTABLE_CPY(100b, 103b)
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_ASM_EXTABLE_CPY(101b, 103b)
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.endm
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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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SYM_FUNC_START(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 .L_copy_short_string
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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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.L_copy_short_string:
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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 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 .Lcopy_user_handle_tail /* ecx is zerorest also */
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.previous
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_ASM_EXTABLE_CPY(1b, 30b)
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_ASM_EXTABLE_CPY(2b, 30b)
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_ASM_EXTABLE_CPY(3b, 30b)
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_ASM_EXTABLE_CPY(4b, 30b)
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_ASM_EXTABLE_CPY(5b, 30b)
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_ASM_EXTABLE_CPY(6b, 30b)
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_ASM_EXTABLE_CPY(7b, 30b)
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_ASM_EXTABLE_CPY(8b, 30b)
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_ASM_EXTABLE_CPY(9b, 30b)
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_ASM_EXTABLE_CPY(10b, 30b)
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_ASM_EXTABLE_CPY(11b, 30b)
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_ASM_EXTABLE_CPY(12b, 30b)
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_ASM_EXTABLE_CPY(13b, 30b)
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_ASM_EXTABLE_CPY(14b, 30b)
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_ASM_EXTABLE_CPY(15b, 30b)
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_ASM_EXTABLE_CPY(16b, 30b)
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_ASM_EXTABLE_CPY(18b, 40b)
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_ASM_EXTABLE_CPY(19b, 40b)
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_ASM_EXTABLE_CPY(21b, 50b)
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_ASM_EXTABLE_CPY(22b, 50b)
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SYM_FUNC_END(copy_user_generic_unrolled)
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EXPORT_SYMBOL(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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SYM_FUNC_START(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 .Lcopy_user_handle_tail
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.previous
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_ASM_EXTABLE_CPY(1b, 11b)
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_ASM_EXTABLE_CPY(3b, 12b)
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SYM_FUNC_END(copy_user_generic_string)
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EXPORT_SYMBOL(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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SYM_FUNC_START(copy_user_enhanced_fast_string)
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ASM_STAC
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cmpl $64,%edx
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jb .L_copy_short_string /* less then 64 bytes, avoid the costly 'rep' */
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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 .Lcopy_user_handle_tail
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.previous
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_ASM_EXTABLE_CPY(1b, 12b)
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SYM_FUNC_END(copy_user_enhanced_fast_string)
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EXPORT_SYMBOL(copy_user_enhanced_fast_string)
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/*
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* Try to copy last bytes and clear the rest if needed.
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* Since protection fault in copy_from/to_user is not a normal situation,
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* it is not necessary to optimize tail handling.
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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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SYM_CODE_START_LOCAL(.Lcopy_user_handle_tail)
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movl %edx,%ecx
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1: rep movsb
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2: mov %ecx,%eax
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ASM_CLAC
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ret
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_ASM_EXTABLE_CPY(1b, 2b)
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SYM_CODE_END(.Lcopy_user_handle_tail)
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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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SYM_FUNC_START(__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 .Lcopy_user_handle_tail
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.previous
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_ASM_EXTABLE_CPY(1b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(2b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(3b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(4b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(5b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(6b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(7b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(8b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(9b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(10b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(11b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(12b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(13b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(14b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(15b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(16b, .L_fixup_4x8b_copy)
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_ASM_EXTABLE_CPY(20b, .L_fixup_8b_copy)
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_ASM_EXTABLE_CPY(21b, .L_fixup_8b_copy)
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_ASM_EXTABLE_CPY(30b, .L_fixup_4b_copy)
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_ASM_EXTABLE_CPY(31b, .L_fixup_4b_copy)
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_ASM_EXTABLE_CPY(40b, .L_fixup_1b_copy)
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_ASM_EXTABLE_CPY(41b, .L_fixup_1b_copy)
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SYM_FUNC_END(__copy_user_nocache)
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EXPORT_SYMBOL(__copy_user_nocache)
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