x86: don't clobber r8 nor use rcx.

There's really no reason to clobber r8 or pass the address in rcx.
We can safely use only two registers (which we already have to touch anyway)
to do the job.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 2 deletions

diff --git a/include/asm-x86/uaccess_64.h b/include/asm-x86/uaccess_64.h
index b8a2f4339903..a2d49078e19c 100644
--- a/include/asm-x86/uaccess_64.h
+++ b/include/asm-x86/uaccess_64.h
@@ -90,8 +90,7 @@ extern int fixup_exception(struct pt_regs *regs);
 #define __get_user_x(size, ret, x, ptr)               \
         asm volatile("call __get_user_" #size         \
                      : "=a" (ret),"=d" (x)            \
-                     : "c" (ptr)                      \
-                     : "r8")
+                     : "0" (ptr))                     \
 
 /* Careful: we have to cast the result to the type of the pointer
  * for sign reasons */