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Date: Wed, 17 Jul 2019 20:36:44 -0500
From: Josh Poimboeuf <jpoimboe@...hat.com>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Arnd Bergmann <arnd@...db.de>, Jann Horn <jannh@...gle.com>,
Randy Dunlap <rdunlap@...radead.org>
Subject: [PATCH v2 09/22] 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: Josh Poimboeuf <jpoimboe@...hat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
arch/x86/lib/getuser.S | 20 ++++++++++----------
arch/x86/lib/putuser.S | 29 ++++++++++++++++-------------
2 files changed, 26 insertions(+), 23 deletions(-)
diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S
index 74fdff968ea3..304f958c27b2 100644
--- a/arch/x86/lib/getuser.S
+++ b/arch/x86/lib/getuser.S
@@ -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
diff --git a/arch/x86/lib/putuser.S b/arch/x86/lib/putuser.S
index d2e5c9c39601..14bf78341d3c 100644
--- a/arch/x86/lib/putuser.S
+++ b/arch/x86/lib/putuser.S
@@ -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
--
2.20.1
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