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

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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: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/bc14ded2755ae75bd9010c446079e113dbddb74b.1563413318.git.jpoimboe@redhat.com
This commit is contained in:
Josh Poimboeuf 2019-07-17 20:36:44 -05:00 committed by Thomas Gleixner
parent 5e307a6bc7
commit 82e844a653
2 changed files with 26 additions and 23 deletions
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20
arch/x86/lib/getuser.S
View File

@ -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

29
arch/x86/lib/putuser.S
View File

@ -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