x86: check for and defend against BIOS memory corruption

Some BIOSes have been observed to corrupt memory in the low 64k.  This
change:
 - Reserves all memory which does not have to be in that area, to
   prevent it from being used as general memory by the kernel.  Things
   like the SMP trampoline are still in the memory, however.
 - Clears the reserved memory so we can observe changes to it.
 - Adds a function check_for_bios_corruption() which checks and reports on
   memory becoming unexpectedly non-zero.  Currently it's called in the
   x86 fault handler, and the powermanagement debug output.

Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ed92864d1325..1bb52e2ca02e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -201,6 +201,9 @@ config X86_TRAMPOLINE
         depends on X86_SMP || (X86_VOYAGER && SMP) || (64BIT && ACPI_SLEEP)
         default y
 
+config X86_CHECK_BIOS_CORRUPTION
+        def_bool y
+
 config KTIME_SCALAR
         def_bool X86_32
 source "init/Kconfig"