Commit-ID: bdfc017eead9bc17cd23317ff42eb7297cb9468a
Gitweb: http://git.kernel.org/tip/bdfc017eead9bc17cd23317ff42eb7297cb9468a
Author: Jan-Simon Möller <dl9pf@xxxxxx>
AuthorDate: Thu, 29 Aug 2013 21:13:05 +0200
Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
CommitDate: Thu, 29 Aug 2013 13:26:33 -0700
x86, asm: Fix a compilation issue with clang
Clang does not support the "shortcut" we're taking here for gcc (see below).
The patch uses the macro _ASM_DX to do the job.
>From arch/x86/include/asm/uaccess.h:
/*
* Careful: we have to cast the result to the type of the pointer
* for sign reasons.
*
* The use of %edx as the register specifier is a bit of a
* simplification, as gcc only cares about it as the starting point
* and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
* (%ecx being the next register in gcc's x86 register sequence), and
* %rdx on 64 bits.
*/
[ hpa: I consider this a compatibility bug in clang as this reflects a
bit of a misunderstanding about how register strings are used by
gcc, but the workaround is straightforward and there is no
particular reason to not do it. ]
Signed-off-by: Jan-Simon Möller <dl9pf@xxxxxx>
Link: http://lkml.kernel.org/r/1377803585-5913-3-git-send-email-dl9pf@xxxxxx
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/uaccess.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 5ee2687..f715fee 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -162,7 +162,7 @@ __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
#define get_user(x, ptr) \
({ \
int __ret_gu; \
- register __inttype(*(ptr)) __val_gu asm("%edx"); \
+ register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \
__chk_user_ptr(ptr); \
might_fault(); \
asm volatile("call __get_user_%P3" \
--
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