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x86/uaccess: Improve the 8-byte getuser() case

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Streamline the 8-byte case and drop the special handling. Use a macro
which hides the exception handling.

No functional changes.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/CAHk-=whYb2L_atsRk9pBiFiVLGe5wNZLHhRinA69yu6FiKvDsw@mail.gmail.com
This commit is contained in:
Linus Torvalds 2024-06-19 14:54:23 +02:00 committed by Borislav Petkov (AMD)
parent 6ba59ff422
commit 8a2462df15
1 changed files with 20 additions and 49 deletions
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69
arch/x86/lib/getuser.S
View File

@ -44,21 +44,23 @@
or %rdx, %rax
.else
cmp $TASK_SIZE_MAX-\size+1, %eax
.if \size != 8
jae .Lbad_get_user
.else
jae .Lbad_get_user_8
.endif
sbb %edx, %edx /* array_index_mask_nospec() */
and %edx, %eax
.endif
.endm
.macro UACCESS op src dst
1: \op \src,\dst
_ASM_EXTABLE_UA(1b, __get_user_handle_exception)
.endm
.text
SYM_FUNC_START(__get_user_1)
check_range size=1
ASM_STAC
1: movzbl (%_ASM_AX),%edx
UACCESS movzbl (%_ASM_AX),%edx
xor %eax,%eax
ASM_CLAC
RET
@ -68,7 +70,7 @@ EXPORT_SYMBOL(__get_user_1)
SYM_FUNC_START(__get_user_2)
check_range size=2
ASM_STAC
2: movzwl (%_ASM_AX),%edx
UACCESS movzwl (%_ASM_AX),%edx
xor %eax,%eax
ASM_CLAC
RET
@ -78,7 +80,7 @@ EXPORT_SYMBOL(__get_user_2)
SYM_FUNC_START(__get_user_4)
check_range size=4
ASM_STAC
3: movl (%_ASM_AX),%edx
UACCESS movl (%_ASM_AX),%edx
xor %eax,%eax
ASM_CLAC
RET
@ -89,10 +91,11 @@ SYM_FUNC_START(__get_user_8)
check_range size=8
ASM_STAC
#ifdef CONFIG_X86_64
4: movq (%_ASM_AX),%rdx
UACCESS movq (%_ASM_AX),%rdx
#else
4: movl (%_ASM_AX),%edx
5: movl 4(%_ASM_AX),%ecx
xor %ecx,%ecx
UACCESS movl (%_ASM_AX),%edx
UACCESS movl 4(%_ASM_AX),%ecx
#endif
xor %eax,%eax
ASM_CLAC
@ -104,7 +107,7 @@ EXPORT_SYMBOL(__get_user_8)
SYM_FUNC_START(__get_user_nocheck_1)
ASM_STAC
ASM_BARRIER_NOSPEC
6: movzbl (%_ASM_AX),%edx
UACCESS movzbl (%_ASM_AX),%edx
xor %eax,%eax
ASM_CLAC
RET
@ -114,7 +117,7 @@ EXPORT_SYMBOL(__get_user_nocheck_1)
SYM_FUNC_START(__get_user_nocheck_2)
ASM_STAC
ASM_BARRIER_NOSPEC
7: movzwl (%_ASM_AX),%edx
UACCESS movzwl (%_ASM_AX),%edx
xor %eax,%eax
ASM_CLAC
RET
@ -124,7 +127,7 @@ EXPORT_SYMBOL(__get_user_nocheck_2)
SYM_FUNC_START(__get_user_nocheck_4)
ASM_STAC
ASM_BARRIER_NOSPEC
8: movl (%_ASM_AX),%edx
UACCESS movl (%_ASM_AX),%edx
xor %eax,%eax
ASM_CLAC
RET
@ -135,10 +138,11 @@ SYM_FUNC_START(__get_user_nocheck_8)
ASM_STAC
ASM_BARRIER_NOSPEC
#ifdef CONFIG_X86_64
9: movq (%_ASM_AX),%rdx
UACCESS movq (%_ASM_AX),%rdx
#else
9: movl (%_ASM_AX),%edx
10: movl 4(%_ASM_AX),%ecx
xor %ecx,%ecx
UACCESS movl (%_ASM_AX),%edx
UACCESS movl 4(%_ASM_AX),%ecx
#endif
xor %eax,%eax
ASM_CLAC
@ -154,36 +158,3 @@ SYM_CODE_START_LOCAL(__get_user_handle_exception)
mov $(-EFAULT),%_ASM_AX
RET
SYM_CODE_END(__get_user_handle_exception)
#ifdef CONFIG_X86_32
SYM_CODE_START_LOCAL(__get_user_8_handle_exception)
ASM_CLAC
.Lbad_get_user_8:
xor %edx,%edx
xor %ecx,%ecx
mov $(-EFAULT),%_ASM_AX
RET
SYM_CODE_END(__get_user_8_handle_exception)
#endif
/* get_user */
_ASM_EXTABLE_UA(1b, __get_user_handle_exception)
_ASM_EXTABLE_UA(2b, __get_user_handle_exception)
_ASM_EXTABLE_UA(3b, __get_user_handle_exception)
#ifdef CONFIG_X86_64
_ASM_EXTABLE_UA(4b, __get_user_handle_exception)
#else
_ASM_EXTABLE_UA(4b, __get_user_8_handle_exception)
_ASM_EXTABLE_UA(5b, __get_user_8_handle_exception)
#endif
/* __get_user */
_ASM_EXTABLE_UA(6b, __get_user_handle_exception)
_ASM_EXTABLE_UA(7b, __get_user_handle_exception)
_ASM_EXTABLE_UA(8b, __get_user_handle_exception)
#ifdef CONFIG_X86_64
_ASM_EXTABLE_UA(9b, __get_user_handle_exception)
#else
_ASM_EXTABLE_UA(9b, __get_user_8_handle_exception)
_ASM_EXTABLE_UA(10b, __get_user_8_handle_exception)
#endif