x86: EDAC: MCE: Fix MCE decoding callback logic

Make decoding of MCEs happen only on AMD hardware by registering a
non-default callback only on CPU families which support it.

While looking at the interaction of decode_mce() with the other MCE
code i also noticed a few other things and made the following
cleanups/fixes:

 - Fixed the mce_decode() weak alias - a weak alias is really not
   good here, it should be a proper callback. A weak alias will be
   overriden if a piece of code is built into the kernel - not
   good, obviously.

 - The patch initializes the callback on AMD family 10h and 11h.

 - Added the more correct fallback printk of:

	No support for human readable MCE decoding on this CPU type.
	Transcribe the message and run it through 'mcelog --ascii' to decode.

   On CPUs that dont have a decoder.

 - Made the surrounding code more readable.

Note that the callback allows us to have a default fallback -
without having to check the CPU versions during the printout
itself. When an EDAC module registers itself, it can install the
decode-print function.

(there's no unregister needed as this is core code.)

version -v2 by Borislav Petkov:

 - add K8 to the set of supported CPUs

 - always build in edac_mce_amd since we use an early_initcall now

 - fix checkpatch warnings

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>
LKML-Reference: <20091001141432.GA11410@aftab>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
index b608a64c581..f1363b72364 100644
--- a/arch/x86/include/asm/mce.h
+++ b/arch/x86/include/asm/mce.h
@@ -133,6 +133,8 @@ static inline void winchip_mcheck_init(struct cpuinfo_x86 *c) {}
 static inline void enable_p5_mce(void) {}
 #endif
 
+extern void (*x86_mce_decode_callback)(struct mce *m);
+
 void mce_setup(struct mce *m);
 void mce_log(struct mce *m);
 DECLARE_PER_CPU(struct sys_device, mce_dev);