Commit 8a2462df authored by Linus Torvalds's avatar Linus Torvalds Committed by Borislav Petkov (AMD)
Browse files

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



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

No functional changes.

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/CAHk-=whYb2L_atsRk9pBiFiVLGe5wNZLHhRinA69yu6FiKvDsw@mail.gmail.com
parent 6ba59ff4

arch/x86/lib/getuser.S

+20 −49
Original line number Diff line number Diff line
@@ -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