From: Stephane Eranian Date: Fri, 15 Mar 2013 13:26:07 +0000 (+0100) Subject: perf,x86: fix kernel crash with PEBS/BTS after suspend/resume X-Git-Tag: v3.0.70~19 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=87a42f27adef5e88b8907edbc168de1380e7129e;p=karo-tx-linux.git perf,x86: fix kernel crash with PEBS/BTS after suspend/resume commit 1d9d8639c063caf6efc2447f5f26aa637f844ff6 upstream. This patch fixes a kernel crash when using precise sampling (PEBS) after a suspend/resume. Turns out the CPU notifier code is not invoked on CPU0 (BP). Therefore, the DS_AREA (used by PEBS) is not restored properly by the kernel and keeps it power-on/resume value of 0 causing any PEBS measurement to crash when running on CPU0. The workaround is to add a hook in the actual resume code to restore the DS Area MSR value. It is invoked for all CPUS. So for all but CPU0, the DS_AREA will be restored twice but this is harmless. Reported-by: Linus Torvalds Signed-off-by: Stephane Eranian Signed-off-by: Linus Torvalds Signed-off-by: Shuah Khan Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c index d812fe2d02be..cf82ee55ef4b 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c @@ -754,6 +754,14 @@ static void intel_ds_init(void) } } +void perf_restore_debug_store(void) +{ + if (!x86_pmu.bts && !x86_pmu.pebs) + return; + + init_debug_store_on_cpu(smp_processor_id()); +} + #else /* CONFIG_CPU_SUP_INTEL */ static void reserve_ds_buffers(void) diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c index 87bb35e34ef1..0ea8bd233def 100644 --- a/arch/x86/power/cpu.c +++ b/arch/x86/power/cpu.c @@ -10,6 +10,7 @@ #include #include +#include #include #include @@ -224,6 +225,7 @@ static void __restore_processor_state(struct saved_context *ctxt) do_fpu_end(); mtrr_bp_restore(); + perf_restore_debug_store(); } /* Needed by apm.c */ diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index effadd668aca..038ad4af336e 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1153,6 +1153,7 @@ extern void perf_swevent_put_recursion_context(int rctx); extern void perf_event_enable(struct perf_event *event); extern void perf_event_disable(struct perf_event *event); extern void perf_event_task_tick(void); +extern void perf_restore_debug_store(void); #else static inline void perf_event_task_sched_in(struct task_struct *task) { } @@ -1187,6 +1188,7 @@ static inline void perf_swevent_put_recursion_context(int rctx) { } static inline void perf_event_enable(struct perf_event *event) { } static inline void perf_event_disable(struct perf_event *event) { } static inline void perf_event_task_tick(void) { } +static inline void perf_restore_debug_store(void) { } #endif #define perf_output_put(handle, x) perf_output_copy((handle), &(x), sizeof(x))