Commit-ID: 9b3614ccfa5492f57f743f3856253f285b10a702
Gitweb: http://git.kernel.org/tip/9b3614ccfa5492f57f743f3856253f285b10a702
Author: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
AuthorDate: Wed, 29 Jan 2014 12:01:37 +0000
Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
CommitDate: Wed, 29 Jan 2014 09:09:40 -0800
x86, boot: Fix word-size assumptions in has_eflag() inline asm
Commit dd78b97367bd575918204cc89107c1479d3fc1a7 ("x86, boot: Move CPU
flags out of cpucheck") introduced ambiguous inline asm in the
has_eflag() function. We want the instruction to be 'pushfl', but we
just say 'pushf' and hope the compiler does what we wanted.
When building with 'clang -m16', it won't, because clang doesn't use
the horrid '.code16gcc' hack that even 'gcc -m16' uses internally.
Say what we mean and don't make the compiler make assumptions.
[ hpa: we use plain "pushf" in the equivalent code elsewhere which may
be compiled as either 32- or 64-bit code. In those cases we want
the assembler to pick the appropriate size for us. However, this is
*16-bit* code and we still need these to be 32-bit operations. ]
Signed-off-by: David Woodhouse <David.Woodhouse@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1390996897.20153.123.camel@xxxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
---
arch/x86/boot/cpuflags.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/x86/boot/cpuflags.c b/arch/x86/boot/cpuflags.c
index a9fcb7c..168dd25 100644
--- a/arch/x86/boot/cpuflags.c
+++ b/arch/x86/boot/cpuflags.c
@@ -32,16 +32,16 @@ int has_eflag(unsigned long mask)
{
unsigned long f0, f1;
- asm volatile("pushf \n\t"
- "pushf \n\t"
+ asm volatile("pushfl \n\t"
+ "pushfl \n\t"
"pop %0 \n\t"
"mov %0,%1 \n\t"
"xor %2,%1 \n\t"
"push %1 \n\t"
- "popf \n\t"
- "pushf \n\t"
+ "popfl \n\t"
+ "pushfl \n\t"
"pop %1 \n\t"
- "popf"
+ "popfl"
: "=&r" (f0), "=&r" (f1)
: "ri" (mask));
--
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