Hey-
It appears that when the i386 arch traps on a machine check, the code in
entry.S loads the vector pointed to by the machine_check_vector kernel varialbe.
Since this happens before the switch to the kernel context in error_code, the
result is an oops, if the reverenced address is unmapped, or silent memory
corruption if the address is mapped. This patch corrects that, by jumping
instead to a statically allocated kernel function instead, allowing us to load a
static value, rather than the contents of a memory address before the switch to
kernel context, like all of our other entry points do.
Thanks & Regards
Neil
Signed-off-by: Neil Horman <[email protected]>
cpu/mcheck/mce.c | 5 +++++
cpu/mcheck/mce.h | 1 +
entry.S | 2 +-
3 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/i386/kernel/cpu/mcheck/mce.c b/arch/i386/kernel/cpu/mcheck/mce.c
index d555bec..a8e8e80 100644
--- a/arch/i386/kernel/cpu/mcheck/mce.c
+++ b/arch/i386/kernel/cpu/mcheck/mce.c
@@ -29,6 +29,11 @@ static fastcall void unexpected_machine_
/* Call the installed machine check handler for this CPU setup. */
void fastcall (*machine_check_vector)(struct pt_regs *, long error_code) = unexpected_machine_check;
+asmlinkage void do_machine_check(struct pt_regs *regs, long error_code)
+{
+ machine_check_vector(regs, error_code);
+}
+
/* This has to be run for each processor */
void mcheck_init(struct cpuinfo_x86 *c)
{
diff --git a/arch/i386/kernel/cpu/mcheck/mce.h b/arch/i386/kernel/cpu/mcheck/mce.h
index 84fd4cf..0e7003f 100644
--- a/arch/i386/kernel/cpu/mcheck/mce.h
+++ b/arch/i386/kernel/cpu/mcheck/mce.h
@@ -8,6 +8,7 @@ void winchip_mcheck_init(struct cpuinfo_
/* Call the installed machine check handler for this CPU setup. */
extern fastcall void (*machine_check_vector)(struct pt_regs *, long error_code);
+extern asmlinkage void do_machine_check(struct pt_regs *, long error_code);
extern int mce_disabled;
extern int nr_mce_banks;
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index 5a63d6f..19a2929 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -928,7 +928,7 @@ ENTRY(machine_check)
RING0_INT_FRAME
pushl $0
CFI_ADJUST_CFA_OFFSET 4
- pushl machine_check_vector
+ pushl $do_machine_check
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
--
/***************************************************
*Neil Horman
*Software Engineer
*gpg keyid: 1024D / 0x92A74FA1 - http://pgp.mit.edu
***************************************************/
-
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