[PATCH] i386: inline asm cleanup

i386 Inline asm cleanup.  Use cr/dr accessor functions.

Also, a potential bugfix.  Also, some CR accessors really should be volatile.
Reads from CR0 (numeric state may change in an exception handler), writes to
CR4 (flipping CR4.TSD) and reads from CR2 (page fault) prevent instruction
re-ordering.  I did not add memory clobber to CR3 / CR4 / CR0 updates, as it
was not there to begin with, and in no case should kernel memory be clobbered,
except when doing a TLB flush, which already has memory clobber.

I noticed that page invalidation does not have a memory clobber.  I can't find
a bug as a result, but there is definitely a potential for a bug here:

#define __flush_tlb_single(addr) \
	__asm__ __volatile__("invlpg %0": :"m" (*(char *) addr))

Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 5 deletions

diff --git a/arch/i386/kernel/cpu/cyrix.c b/arch/i386/kernel/cpu/cyrix.c
index ba4b01138c8f..ff87cc22b323 100644
--- a/arch/i386/kernel/cpu/cyrix.c
+++ b/arch/i386/kernel/cpu/cyrix.c
@@ -132,11 +132,7 @@ static void __init set_cx86_memwb(void)
         setCx86(CX86_CCR2, getCx86(CX86_CCR2) & ~0x04);
         /* set 'Not Write-through' */
         cr0 = 0x20000000;
-        __asm__("movl %%cr0,%%eax\n\t"
-                "orl %0,%%eax\n\t"
-                "movl %%eax,%%cr0\n"
-                : : "r" (cr0)
-                :"ax");
+        write_cr0(read_cr0() | cr0);
         /* CCR2 bit 2: lock NW bit and set WT1 */
         setCx86(CX86_CCR2, getCx86(CX86_CCR2) | 0x14 );
 }