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linux/arch/x86/lib/copy_user_64.S
Josh Poimboeuf 02041b3225 x86/uaccess: Don't jump between functions 
For unwinding sanity, a function shouldn't jump to the middle of another
function.  Move the short string user copy code out to a separate
non-function code snippet.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/9519e4853148b765e047967708f2b61e56c93186.1649718562.git.jpoimboe@redhat.com
2022-04-19 21:58:53 +02:00

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9.3 KiB
ArmAsm
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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright 2008 Vitaly Mayatskikh <vmayatsk@redhat.com>
* Copyright 2002 Andi Kleen, SuSE Labs.
*
* Functions to copy from and to user space.
*/
#include <linux/linkage.h>
#include <asm/current.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/cpufeatures.h>
#include <asm/alternative.h>
#include <asm/asm.h>
#include <asm/smap.h>
#include <asm/export.h>
#include <asm/trapnr.h>
.macro ALIGN_DESTINATION
/* check for bad alignment of destination */
movl %edi,%ecx
andl $7,%ecx
jz 102f /* already aligned */
subl $8,%ecx
negl %ecx
subl %ecx,%edx
100: movb (%rsi),%al
101: movb %al,(%rdi)
incq %rsi
incq %rdi
decl %ecx
jnz 100b
102:
_ASM_EXTABLE_CPY(100b, .Lcopy_user_handle_align)
_ASM_EXTABLE_CPY(101b, .Lcopy_user_handle_align)
.endm
/*
* copy_user_generic_unrolled - memory copy with exception handling.
* This version is for CPUs like P4 that don't have efficient micro
* code for rep movsq
*
* Input:
* rdi destination
* rsi source
* rdx count
*
* Output:
* eax uncopied bytes or 0 if successful.
*/
SYM_FUNC_START(copy_user_generic_unrolled)
ASM_STAC
cmpl $8,%edx
jb .Lcopy_user_short_string_bytes
ALIGN_DESTINATION
movl %edx,%ecx
andl $63,%edx
shrl $6,%ecx
jz copy_user_short_string
1: movq (%rsi),%r8
2: movq 1*8(%rsi),%r9
3: movq 2*8(%rsi),%r10
4: movq 3*8(%rsi),%r11
5: movq %r8,(%rdi)
6: movq %r9,1*8(%rdi)
7: movq %r10,2*8(%rdi)
8: movq %r11,3*8(%rdi)
9: movq 4*8(%rsi),%r8
10: movq 5*8(%rsi),%r9
11: movq 6*8(%rsi),%r10
12: movq 7*8(%rsi),%r11
13: movq %r8,4*8(%rdi)
14: movq %r9,5*8(%rdi)
15: movq %r10,6*8(%rdi)
16: movq %r11,7*8(%rdi)
leaq 64(%rsi),%rsi
leaq 64(%rdi),%rdi
decl %ecx
jnz 1b
jmp copy_user_short_string
30: shll $6,%ecx
addl %ecx,%edx
jmp .Lcopy_user_handle_tail
_ASM_EXTABLE_CPY(1b, 30b)
_ASM_EXTABLE_CPY(2b, 30b)
_ASM_EXTABLE_CPY(3b, 30b)
_ASM_EXTABLE_CPY(4b, 30b)
_ASM_EXTABLE_CPY(5b, 30b)
_ASM_EXTABLE_CPY(6b, 30b)
_ASM_EXTABLE_CPY(7b, 30b)
_ASM_EXTABLE_CPY(8b, 30b)
_ASM_EXTABLE_CPY(9b, 30b)
_ASM_EXTABLE_CPY(10b, 30b)
_ASM_EXTABLE_CPY(11b, 30b)
_ASM_EXTABLE_CPY(12b, 30b)
_ASM_EXTABLE_CPY(13b, 30b)
_ASM_EXTABLE_CPY(14b, 30b)
_ASM_EXTABLE_CPY(15b, 30b)
_ASM_EXTABLE_CPY(16b, 30b)
SYM_FUNC_END(copy_user_generic_unrolled)
EXPORT_SYMBOL(copy_user_generic_unrolled)
/* Some CPUs run faster using the string copy instructions.
* This is also a lot simpler. Use them when possible.
*
* Only 4GB of copy is supported. This shouldn't be a problem
* because the kernel normally only writes from/to page sized chunks
* even if user space passed a longer buffer.
* And more would be dangerous because both Intel and AMD have
* errata with rep movsq > 4GB. If someone feels the need to fix
* this please consider this.
*
* Input:
* rdi destination
* rsi source
* rdx count
*
* Output:
* eax uncopied bytes or 0 if successful.
*/
SYM_FUNC_START(copy_user_generic_string)
ASM_STAC
cmpl $8,%edx
jb 2f /* less than 8 bytes, go to byte copy loop */
ALIGN_DESTINATION
movl %edx,%ecx
shrl $3,%ecx
andl $7,%edx
1: rep movsq
2: movl %edx,%ecx
3: rep movsb
xorl %eax,%eax
ASM_CLAC
RET
11: leal (%rdx,%rcx,8),%ecx
12: movl %ecx,%edx /* ecx is zerorest also */
jmp .Lcopy_user_handle_tail
_ASM_EXTABLE_CPY(1b, 11b)
_ASM_EXTABLE_CPY(3b, 12b)
SYM_FUNC_END(copy_user_generic_string)
EXPORT_SYMBOL(copy_user_generic_string)
/*
* Some CPUs are adding enhanced REP MOVSB/STOSB instructions.
* It's recommended to use enhanced REP MOVSB/STOSB if it's enabled.
*
* Input:
* rdi destination
* rsi source
* rdx count
*
* Output:
* eax uncopied bytes or 0 if successful.
*/
SYM_FUNC_START(copy_user_enhanced_fast_string)
ASM_STAC
/* CPUs without FSRM should avoid rep movsb for short copies */
ALTERNATIVE "cmpl $64, %edx; jb copy_user_short_string", "", X86_FEATURE_FSRM
movl %edx,%ecx
1: rep movsb
xorl %eax,%eax
ASM_CLAC
RET
12: movl %ecx,%edx /* ecx is zerorest also */
jmp .Lcopy_user_handle_tail
_ASM_EXTABLE_CPY(1b, 12b)
SYM_FUNC_END(copy_user_enhanced_fast_string)
EXPORT_SYMBOL(copy_user_enhanced_fast_string)
/*
* Try to copy last bytes and clear the rest if needed.
* Since protection fault in copy_from/to_user is not a normal situation,
* it is not necessary to optimize tail handling.
* Don't try to copy the tail if machine check happened
*
* Input:
* eax trap number written by ex_handler_copy()
* rdi destination
* rsi source
* rdx count
*
* Output:
* eax uncopied bytes or 0 if successful.
*/
SYM_CODE_START_LOCAL(.Lcopy_user_handle_tail)
cmp $X86_TRAP_MC,%eax
je 3f
movl %edx,%ecx
1: rep movsb
2: mov %ecx,%eax
ASM_CLAC
RET
3:
movl %edx,%eax
ASM_CLAC
RET
_ASM_EXTABLE_CPY(1b, 2b)
.Lcopy_user_handle_align:
addl %ecx,%edx /* ecx is zerorest also */
jmp .Lcopy_user_handle_tail
SYM_CODE_END(.Lcopy_user_handle_tail)
/*
* Finish memcpy of less than 64 bytes. #AC should already be set.
*
* Input:
* rdi destination
* rsi source
* rdx count (< 64)
*
* Output:
* eax uncopied bytes or 0 if successful.
*/
SYM_CODE_START_LOCAL(copy_user_short_string)
movl %edx,%ecx
andl $7,%edx
shrl $3,%ecx
jz .Lcopy_user_short_string_bytes
18: movq (%rsi),%r8
19: movq %r8,(%rdi)
leaq 8(%rsi),%rsi
leaq 8(%rdi),%rdi
decl %ecx
jnz 18b
.Lcopy_user_short_string_bytes:
andl %edx,%edx
jz 23f
movl %edx,%ecx
21: movb (%rsi),%al
22: movb %al,(%rdi)
incq %rsi
incq %rdi
decl %ecx
jnz 21b
23: xor %eax,%eax
ASM_CLAC
RET
40: leal (%rdx,%rcx,8),%edx
jmp 60f
50: movl %ecx,%edx /* ecx is zerorest also */
60: jmp .Lcopy_user_handle_tail
_ASM_EXTABLE_CPY(18b, 40b)
_ASM_EXTABLE_CPY(19b, 40b)
_ASM_EXTABLE_CPY(21b, 50b)
_ASM_EXTABLE_CPY(22b, 50b)
SYM_CODE_END(copy_user_short_string)
/*
* copy_user_nocache - Uncached memory copy with exception handling
* This will force destination out of cache for more performance.
*
* Note: Cached memory copy is used when destination or size is not
* naturally aligned. That is:
* - Require 8-byte alignment when size is 8 bytes or larger.
* - Require 4-byte alignment when size is 4 bytes.
*/
SYM_FUNC_START(__copy_user_nocache)
ASM_STAC
/* If size is less than 8 bytes, go to 4-byte copy */
cmpl $8,%edx
jb .L_4b_nocache_copy_entry
/* If destination is not 8-byte aligned, "cache" copy to align it */
ALIGN_DESTINATION
/* Set 4x8-byte copy count and remainder */
movl %edx,%ecx
andl $63,%edx
shrl $6,%ecx
jz .L_8b_nocache_copy_entry /* jump if count is 0 */
/* Perform 4x8-byte nocache loop-copy */
.L_4x8b_nocache_copy_loop:
1: movq (%rsi),%r8
2: movq 1*8(%rsi),%r9
3: movq 2*8(%rsi),%r10
4: movq 3*8(%rsi),%r11
5: movnti %r8,(%rdi)
6: movnti %r9,1*8(%rdi)
7: movnti %r10,2*8(%rdi)
8: movnti %r11,3*8(%rdi)
9: movq 4*8(%rsi),%r8
10: movq 5*8(%rsi),%r9
11: movq 6*8(%rsi),%r10
12: movq 7*8(%rsi),%r11
13: movnti %r8,4*8(%rdi)
14: movnti %r9,5*8(%rdi)
15: movnti %r10,6*8(%rdi)
16: movnti %r11,7*8(%rdi)
leaq 64(%rsi),%rsi
leaq 64(%rdi),%rdi
decl %ecx
jnz .L_4x8b_nocache_copy_loop
/* Set 8-byte copy count and remainder */
.L_8b_nocache_copy_entry:
movl %edx,%ecx
andl $7,%edx
shrl $3,%ecx
jz .L_4b_nocache_copy_entry /* jump if count is 0 */
/* Perform 8-byte nocache loop-copy */
.L_8b_nocache_copy_loop:
20: movq (%rsi),%r8
21: movnti %r8,(%rdi)
leaq 8(%rsi),%rsi
leaq 8(%rdi),%rdi
decl %ecx
jnz .L_8b_nocache_copy_loop
/* If no byte left, we're done */
.L_4b_nocache_copy_entry:
andl %edx,%edx
jz .L_finish_copy
/* If destination is not 4-byte aligned, go to byte copy: */
movl %edi,%ecx
andl $3,%ecx
jnz .L_1b_cache_copy_entry
/* Set 4-byte copy count (1 or 0) and remainder */
movl %edx,%ecx
andl $3,%edx
shrl $2,%ecx
jz .L_1b_cache_copy_entry /* jump if count is 0 */
/* Perform 4-byte nocache copy: */
30: movl (%rsi),%r8d
31: movnti %r8d,(%rdi)
leaq 4(%rsi),%rsi
leaq 4(%rdi),%rdi
/* If no bytes left, we're done: */
andl %edx,%edx
jz .L_finish_copy
/* Perform byte "cache" loop-copy for the remainder */
.L_1b_cache_copy_entry:
movl %edx,%ecx
.L_1b_cache_copy_loop:
40: movb (%rsi),%al
41: movb %al,(%rdi)
incq %rsi
incq %rdi
decl %ecx
jnz .L_1b_cache_copy_loop
/* Finished copying; fence the prior stores */
.L_finish_copy:
xorl %eax,%eax
ASM_CLAC
sfence
RET
.L_fixup_4x8b_copy:
shll $6,%ecx
addl %ecx,%edx
jmp .L_fixup_handle_tail
.L_fixup_8b_copy:
lea (%rdx,%rcx,8),%rdx
jmp .L_fixup_handle_tail
.L_fixup_4b_copy:
lea (%rdx,%rcx,4),%rdx
jmp .L_fixup_handle_tail
.L_fixup_1b_copy:
movl %ecx,%edx
.L_fixup_handle_tail:
sfence
jmp .Lcopy_user_handle_tail
_ASM_EXTABLE_CPY(1b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(2b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(3b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(4b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(5b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(6b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(7b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(8b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(9b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(10b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(11b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(12b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(13b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(14b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(15b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(16b, .L_fixup_4x8b_copy)
_ASM_EXTABLE_CPY(20b, .L_fixup_8b_copy)
_ASM_EXTABLE_CPY(21b, .L_fixup_8b_copy)
_ASM_EXTABLE_CPY(30b, .L_fixup_4b_copy)
_ASM_EXTABLE_CPY(31b, .L_fixup_4b_copy)
_ASM_EXTABLE_CPY(40b, .L_fixup_1b_copy)
_ASM_EXTABLE_CPY(41b, .L_fixup_1b_copy)
SYM_FUNC_END(__copy_user_nocache)
EXPORT_SYMBOL(__copy_user_nocache)
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