diff mbox series

[v2,3/6] x86/uaccess: Rearrange putuser.S

Message ID 7818233ecd726628a3eb9cbb5ed0ba831e69af4b.1729201904.git.jpoimboe@kernel.org (mailing list archive)
State New
Headers show
Series x86/uaccess: Avoid barrier_nospec() | expand

Commit Message

Josh Poimboeuf Oct. 17, 2024, 9:55 p.m. UTC 
Separate __put_user_*() from __put_user_nocheck_*() to make the layout
similar to getuser.S.  This will also make it easier to do a subsequent
change.  No functional changes.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 arch/x86/lib/putuser.S | 67 ++++++++++++++++++++++--------------------
 1 file changed, 35 insertions(+), 32 deletions(-)

Comments

Kirill A . Shutemov Oct. 18, 2024, 8:51 a.m. UTC | #1 
On Thu, Oct 17, 2024 at 02:55:22PM -0700, Josh Poimboeuf wrote:
>  SYM_FUNC_START(__put_user_2)
>  	check_range size=2
>  	ASM_STAC
> -3:	movw %ax,(%_ASM_CX)
> +2:	movw %ax,(%_ASM_CX)
>  	xor %ecx,%ecx
>  	ASM_CLAC
>  	RET
>  SYM_FUNC_END(__put_user_2)
>  EXPORT_SYMBOL(__put_user_2)

This patch provides an opportunity to give these labels more meaningful
names, so that future rearrangements do not require as much boilerplate.

For example, we can rename this label 2: to .Luser_2 or something similar.
Josh Poimboeuf Oct. 18, 2024, 3:55 p.m. UTC | #2 
On Fri, Oct 18, 2024 at 11:51:06AM +0300, Kirill A . Shutemov wrote:
> On Thu, Oct 17, 2024 at 02:55:22PM -0700, Josh Poimboeuf wrote:
> >  SYM_FUNC_START(__put_user_2)
> >  	check_range size=2
> >  	ASM_STAC
> > -3:	movw %ax,(%_ASM_CX)
> > +2:	movw %ax,(%_ASM_CX)
> >  	xor %ecx,%ecx
> >  	ASM_CLAC
> >  	RET
> >  SYM_FUNC_END(__put_user_2)
> >  EXPORT_SYMBOL(__put_user_2)
> 
> This patch provides an opportunity to give these labels more meaningful
> names, so that future rearrangements do not require as much boilerplate.

Yeah, I can add a patch like Linus' patch to getuser.S which
encapsulates it all in a macro:

.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
	UACCESS movzbl (%_ASM_AX),%edx
	xor %eax,%eax
	ASM_CLAC
	RET
SYM_FUNC_END(__get_user_1)
EXPORT_SYMBOL(__get_user_1)
diff mbox series

Patch

diff --git a/arch/x86/lib/putuser.S b/arch/x86/lib/putuser.S
index 09b7e37934ab..cb137e0286be 100644
--- a/arch/x86/lib/putuser.S
+++ b/arch/x86/lib/putuser.S
@@ -54,59 +54,32 @@  SYM_FUNC_START(__put_user_1)
 SYM_FUNC_END(__put_user_1)
 EXPORT_SYMBOL(__put_user_1)
 
-SYM_FUNC_START(__put_user_nocheck_1)
-	ASM_STAC
-2:	movb %al,(%_ASM_CX)
-	xor %ecx,%ecx
-	ASM_CLAC
-	RET
-SYM_FUNC_END(__put_user_nocheck_1)
-EXPORT_SYMBOL(__put_user_nocheck_1)
-
 SYM_FUNC_START(__put_user_2)
 	check_range size=2
 	ASM_STAC
-3:	movw %ax,(%_ASM_CX)
+2:	movw %ax,(%_ASM_CX)
 	xor %ecx,%ecx
 	ASM_CLAC
 	RET
 SYM_FUNC_END(__put_user_2)
 EXPORT_SYMBOL(__put_user_2)
 
-SYM_FUNC_START(__put_user_nocheck_2)
-	ASM_STAC
-4:	movw %ax,(%_ASM_CX)
-	xor %ecx,%ecx
-	ASM_CLAC
-	RET
-SYM_FUNC_END(__put_user_nocheck_2)
-EXPORT_SYMBOL(__put_user_nocheck_2)
-
 SYM_FUNC_START(__put_user_4)
 	check_range size=4
 	ASM_STAC
-5:	movl %eax,(%_ASM_CX)
+3:	movl %eax,(%_ASM_CX)
 	xor %ecx,%ecx
 	ASM_CLAC
 	RET
 SYM_FUNC_END(__put_user_4)
 EXPORT_SYMBOL(__put_user_4)
 
-SYM_FUNC_START(__put_user_nocheck_4)
-	ASM_STAC
-6:	movl %eax,(%_ASM_CX)
-	xor %ecx,%ecx
-	ASM_CLAC
-	RET
-SYM_FUNC_END(__put_user_nocheck_4)
-EXPORT_SYMBOL(__put_user_nocheck_4)
-
 SYM_FUNC_START(__put_user_8)
 	check_range size=8
 	ASM_STAC
-7:	mov %_ASM_AX,(%_ASM_CX)
+4:	mov %_ASM_AX,(%_ASM_CX)
 #ifdef CONFIG_X86_32
-8:	movl %edx,4(%_ASM_CX)
+5:	movl %edx,4(%_ASM_CX)
 #endif
 	xor %ecx,%ecx
 	ASM_CLAC
@@ -114,6 +87,34 @@  SYM_FUNC_START(__put_user_8)
 SYM_FUNC_END(__put_user_8)
 EXPORT_SYMBOL(__put_user_8)
 
+/* .. and the same for __put_user, just without the range checks */
+SYM_FUNC_START(__put_user_nocheck_1)
+	ASM_STAC
+6:	movb %al,(%_ASM_CX)
+	xor %ecx,%ecx
+	ASM_CLAC
+	RET
+SYM_FUNC_END(__put_user_nocheck_1)
+EXPORT_SYMBOL(__put_user_nocheck_1)
+
+SYM_FUNC_START(__put_user_nocheck_2)
+	ASM_STAC
+7:	movw %ax,(%_ASM_CX)
+	xor %ecx,%ecx
+	ASM_CLAC
+	RET
+SYM_FUNC_END(__put_user_nocheck_2)
+EXPORT_SYMBOL(__put_user_nocheck_2)
+
+SYM_FUNC_START(__put_user_nocheck_4)
+	ASM_STAC
+8:	movl %eax,(%_ASM_CX)
+	xor %ecx,%ecx
+	ASM_CLAC
+	RET
+SYM_FUNC_END(__put_user_nocheck_4)
+EXPORT_SYMBOL(__put_user_nocheck_4)
+
 SYM_FUNC_START(__put_user_nocheck_8)
 	ASM_STAC
 9:	mov %_ASM_AX,(%_ASM_CX)
@@ -137,11 +138,13 @@  SYM_CODE_END(__put_user_handle_exception)
 	_ASM_EXTABLE_UA(2b, __put_user_handle_exception)
 	_ASM_EXTABLE_UA(3b, __put_user_handle_exception)
 	_ASM_EXTABLE_UA(4b, __put_user_handle_exception)
+#ifdef CONFIG_X86_32
 	_ASM_EXTABLE_UA(5b, __put_user_handle_exception)
+#endif
 	_ASM_EXTABLE_UA(6b, __put_user_handle_exception)
 	_ASM_EXTABLE_UA(7b, __put_user_handle_exception)
+	_ASM_EXTABLE_UA(8b, __put_user_handle_exception)
 	_ASM_EXTABLE_UA(9b, __put_user_handle_exception)
 #ifdef CONFIG_X86_32
-	_ASM_EXTABLE_UA(8b, __put_user_handle_exception)
 	_ASM_EXTABLE_UA(10b, __put_user_handle_exception)
 #endif