From: Tony Luck Date: Wed, 23 May 2012 21:14:22 +0000 (-0700) Subject: x86/mce: Fix check for processor context when machine check was taken. X-Git-Tag: v3.3.8~15 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=fd1a48fe1d6813c141c890541951fcb54b0f20d7;p=karo-tx-linux.git x86/mce: Fix check for processor context when machine check was taken. commit 875e26648cf9b6db9d8dc07b7959d7c61fb3f49c upstream. Linus pointed out that there was no value is checking whether m->ip was zero - because zero is a legimate value. If we have a reliable (or faked in the VM86 case) "m->cs" we can use it to tell whether we were in user mode or kernelwhen the machine check hit. Reported-by: Linus Torvalds Signed-off-by: Tony Luck Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/x86/kernel/cpu/mcheck/mce-severity.c b/arch/x86/kernel/cpu/mcheck/mce-severity.c index 7395d5f4272d..c9c9cfe2adf4 100644 --- a/arch/x86/kernel/cpu/mcheck/mce-severity.c +++ b/arch/x86/kernel/cpu/mcheck/mce-severity.c @@ -145,15 +145,19 @@ static struct severity { }; /* - * If the EIPV bit is set, it means the saved IP is the - * instruction which caused the MCE. + * If mcgstatus indicated that ip/cs on the stack were + * no good, then "m->cs" will be zero and we will have + * to assume the worst case (IN_KERNEL) as we actually + * have no idea what we were executing when the machine + * check hit. + * If we do have a good "m->cs" (or a faked one in the + * case we were executing in VM86 mode) we can use it to + * distinguish an exception taken in user from from one + * taken in the kernel. */ static int error_context(struct mce *m) { - if (m->mcgstatus & MCG_STATUS_EIPV) - return (m->ip && (m->cs & 3) == 3) ? IN_USER : IN_KERNEL; - /* Unknown, assume kernel */ - return IN_KERNEL; + return ((m->cs & 3) == 3) ? IN_USER : IN_KERNEL; } int mce_severity(struct mce *m, int tolerant, char **msg)