From: Andi Kleen <ak@suse.de>

Fix more bad issues in the x86-64 machine check handler. 

- Actually test status after reading it from the register, not before.

- Check the UC bit instead of the PCC bit to detect the bank which caused
  the exception.

- Add tolerant==3 level for easier testing. This will avoid any panics.

- Don't threat bank overflows as fatal - they must have come from a non
  fatal exception, which should not cause a panic.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>