[PATCH] [7/98] i8k: Tell gcc that *regs gets clobbered

Andi Kleen
2011-07-27T00:35:06Z

From: Jim Bos <jim876@xs4all.nl>

[ upstream commit 6b4e81db2552bad04100e7d5ddeed7e848f53b48 ]

More recent GCC caused the i8k driver to stop working, on Slackware
compiler was upgraded from gcc-4.4.4 to gcc-4.5.1 after which it didn't
work anymore, meaning the driver didn't load or gave total nonsensical
output.

As it turned out the asm(..) statement forgot to mention it modifies the
*regs variable.

Credits to Andi Kleen and Andreas Schwab for providing the fix.

Signed-off-by: Jim Bos <jim876@xs4all.nl>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Index: linux-2.6.35.y/drivers/char/i8k.c
===================================================================
--- linux-2.6.35.y.orig/drivers/char/i8k.c
+++ linux-2.6.35.y/drivers/char/i8k.c
@@ -141,7 +141,7 @@ static int i8k_smm(struct smm_regs *regs
"lahf\n\t"
"shrl $8,%%eax\n\t"
"andl $1,%%eax\n"
- :"=a"(rc)
+ :"=a"(rc), "+m" (*regs)
: "a"(regs)
: "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory");
#else
@@ -166,7 +166,8 @@ static int i8k_smm(struct smm_regs *regs
"movl %%edx,0(%%eax)\n\t"
"lahf\n\t"
"shrl $8,%%eax\n\t"
- "andl $1,%%eax\n":"=a"(rc)
+ "andl $1,%%eax\n"
+ :"=a"(rc), "+m" (*regs)
: "a"(regs)
: "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory");
#endif