From 11868a2dc4f5e4f2f652bfd259e1360193fcee62 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Wed, 23 Sep 2009 17:49:55 +0200 Subject: [PATCH] x86: mce: Use safer ways to access MCE registers Use rdmsrl_safe() when accessing MCE registers. While in theory we always 'know' which ones are safe to access from the capability bits, there's a lot of hardware variations and reality might differ from theory, as it did in this case: http://bugzilla.kernel.org/show_bug.cgi?id=14204 [ 0.010016] mce: CPU supports 5 MCE banks [ 0.011029] general protection fault: 0000 [#1] [ 0.011998] last sysfs file: [ 0.011998] Modules linked in: [ 0.011998] [ 0.011998] Pid: 0, comm: swapper Not tainted (2.6.31_router #1) HP Vectra [ 0.011998] EIP: 0060:[] EFLAGS: 00010246 CPU: 0 [ 0.011998] EIP is at mce_rdmsrl+0x19/0x60 [ 0.011998] EAX: 00000000 EBX: 00000001 ECX: 00000407 EDX: 08000000 [ 0.011998] ESI: 00000000 EDI: 8c000000 EBP: 00000405 ESP: c17d5eac So WARN_ONCE() instead of crashing the box. ( also fix a number of stylistic inconsistencies in the code. ) Note, we might still crash in wrmsrl() if we get that far, but we shouldnt if the registers are truly inaccessible. Reported-by: GNUtoo Cc: Hidetoshi Seto Cc: Huang Ying Cc: Andi Kleen LKML-Reference: Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/mcheck/mce.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index 2f5aab26320e..4b2af86e3e8d 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -305,13 +305,25 @@ static int msr_to_offset(u32 msr) static u64 mce_rdmsrl(u32 msr) { u64 v; + if (__get_cpu_var(injectm).finished) { int offset = msr_to_offset(msr); + if (offset < 0) return 0; return *(u64 *)((char *)&__get_cpu_var(injectm) + offset); } - rdmsrl(msr, v); + + if (rdmsrl_safe(msr, &v)) { + WARN_ONCE(1, "mce: Unable to read msr %d!\n", msr); + /* + * Return zero in case the access faulted. This should + * not happen normally but can happen if the CPU does + * something weird, or if the code is buggy. + */ + v = 0; + } + return v; } @@ -319,6 +331,7 @@ static void mce_wrmsrl(u32 msr, u64 v) { if (__get_cpu_var(injectm).finished) { int offset = msr_to_offset(msr); + if (offset >= 0) *(u64 *)((char *)&__get_cpu_var(injectm) + offset) = v; return; @@ -415,7 +428,7 @@ static inline void mce_get_rip(struct mce *m, struct pt_regs *regs) m->ip = mce_rdmsrl(rip_msr); } -#ifdef CONFIG_X86_LOCAL_APIC +#ifdef CONFIG_X86_LOCAL_APIC /* * Called after interrupts have been reenabled again * when a MCE happened during an interrupts off region @@ -1172,6 +1185,7 @@ static int mce_banks_init(void) return -ENOMEM; for (i = 0; i < banks; i++) { struct mce_bank *b = &mce_banks[i]; + b->ctl = -1ULL; b->init = 1; } @@ -1203,6 +1217,7 @@ static int __cpuinit mce_cap_init(void) banks = b; if (!mce_banks) { int err = mce_banks_init(); + if (err) return err; } @@ -1237,6 +1252,7 @@ static void mce_init(void) for (i = 0; i < banks; i++) { struct mce_bank *b = &mce_banks[i]; + if (!b->init) continue; wrmsrl(MSR_IA32_MCx_CTL(i), b->ctl); @@ -1626,6 +1642,7 @@ static int mce_disable(void) for (i = 0; i < banks; i++) { struct mce_bank *b = &mce_banks[i]; + if (b->init) wrmsrl(MSR_IA32_MCx_CTL(i), 0); } @@ -1911,6 +1928,7 @@ static void mce_disable_cpu(void *h) cmci_clear(); for (i = 0; i < banks; i++) { struct mce_bank *b = &mce_banks[i]; + if (b->init) wrmsrl(MSR_IA32_MCx_CTL(i), 0); } @@ -1928,6 +1946,7 @@ static void mce_reenable_cpu(void *h) cmci_reenable(); for (i = 0; i < banks; i++) { struct mce_bank *b = &mce_banks[i]; + if (b->init) wrmsrl(MSR_IA32_MCx_CTL(i), b->ctl); }