Commit 82e844a6 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Thomas Gleixner
Browse files

x86/uaccess: Remove redundant CLACs in getuser/putuser error paths 



The same getuser/putuser error paths are used regardless of whether AC
is set.  In non-exception failure cases, this results in an unnecessary
CLAC.

Fixes the following warnings:

  arch/x86/lib/getuser.o: warning: objtool: .altinstr_replacement+0x18: redundant UACCESS disable
  arch/x86/lib/putuser.o: warning: objtool: .altinstr_replacement+0x18: redundant UACCESS disable

Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/bc14ded2755ae75bd9010c446079e113dbddb74b.1563413318.git.jpoimboe@redhat.com
parent 5e307a6b

arch/x86/lib/getuser.S

+10 −10
Original line number Diff line number Diff line
@@ -115,29 +115,29 @@ ENDPROC(__get_user_8) 
EXPORT_SYMBOL(__get_user_8)





bad_get_user_clac:

	ASM_CLAC

bad_get_user:

	xor %edx,%edx

	mov $(-EFAULT),%_ASM_AX

	ASM_CLAC

	ret

END(bad_get_user)



#ifdef CONFIG_X86_32

bad_get_user_8_clac:

	ASM_CLAC

bad_get_user_8:

	xor %edx,%edx

	xor %ecx,%ecx

	mov $(-EFAULT),%_ASM_AX

	ASM_CLAC

	ret

END(bad_get_user_8)

#endif



	_ASM_EXTABLE_UA(1b, bad_get_user)

	_ASM_EXTABLE_UA(2b, bad_get_user)

	_ASM_EXTABLE_UA(3b, bad_get_user)

	_ASM_EXTABLE_UA(1b, bad_get_user_clac)

	_ASM_EXTABLE_UA(2b, bad_get_user_clac)

	_ASM_EXTABLE_UA(3b, bad_get_user_clac)

#ifdef CONFIG_X86_64

	_ASM_EXTABLE_UA(4b, bad_get_user)

	_ASM_EXTABLE_UA(4b, bad_get_user_clac)

#else

	_ASM_EXTABLE_UA(4b, bad_get_user_8)

	_ASM_EXTABLE_UA(5b, bad_get_user_8)

	_ASM_EXTABLE_UA(4b, bad_get_user_8_clac)

	_ASM_EXTABLE_UA(5b, bad_get_user_8_clac)

#endif

arch/x86/lib/putuser.S

+16 −13
Original line number Diff line number Diff line
@@ -32,8 +32,6 @@ 
 */



#define ENTER	mov PER_CPU_VAR(current_task), %_ASM_BX

#define EXIT	ASM_CLAC ;	\

		ret



.text

ENTRY(__put_user_1)
@@ -43,7 +41,8 @@ ENTRY(__put_user_1) 
	ASM_STAC

1:	movb %al,(%_ASM_CX)

	xor %eax,%eax

	EXIT

	ASM_CLAC

	ret

ENDPROC(__put_user_1)

EXPORT_SYMBOL(__put_user_1)
@@ -56,7 +55,8 @@ ENTRY(__put_user_2) 
	ASM_STAC

2:	movw %ax,(%_ASM_CX)

	xor %eax,%eax

	EXIT

	ASM_CLAC

	ret

ENDPROC(__put_user_2)

EXPORT_SYMBOL(__put_user_2)
@@ -69,7 +69,8 @@ ENTRY(__put_user_4) 
	ASM_STAC

3:	movl %eax,(%_ASM_CX)

	xor %eax,%eax

	EXIT

	ASM_CLAC

	ret

ENDPROC(__put_user_4)

EXPORT_SYMBOL(__put_user_4)
@@ -85,19 +86,21 @@ ENTRY(__put_user_8) 
5:	movl %edx,4(%_ASM_CX)

#endif

	xor %eax,%eax

	EXIT

	ASM_CLAC

	RET

ENDPROC(__put_user_8)

EXPORT_SYMBOL(__put_user_8)



bad_put_user_clac:

	ASM_CLAC

bad_put_user:

	movl $-EFAULT,%eax

	EXIT

END(bad_put_user)

	RET



	_ASM_EXTABLE_UA(1b, bad_put_user)

	_ASM_EXTABLE_UA(2b, bad_put_user)

	_ASM_EXTABLE_UA(3b, bad_put_user)

	_ASM_EXTABLE_UA(4b, bad_put_user)

	_ASM_EXTABLE_UA(1b, bad_put_user_clac)

	_ASM_EXTABLE_UA(2b, bad_put_user_clac)

	_ASM_EXTABLE_UA(3b, bad_put_user_clac)

	_ASM_EXTABLE_UA(4b, bad_put_user_clac)

#ifdef CONFIG_X86_32

	_ASM_EXTABLE_UA(5b, bad_put_user)

	_ASM_EXTABLE_UA(5b, bad_put_user_clac)

#endif

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