Re: [ 29/75] perf,x86: fix kernel crash with PEBS/BTS after suspend/resume

Stephane Eranian
2013-03-18T21:11:41Z

On Mon, Mar 18, 2013 at 10:06 PM, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
> 3.8-stable review patch. If anyone has any objections, please let me know.
>
Greg, you also need to pick David Rientjes patch to fix compilation on
non X86 architectures.
Thanks.
> ------------------
>
> From: Stephane Eranian <eranian@google.com>
>
> 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 <torvalds@linux-foundation.org>
> Signed-off-by: Stephane Eranian <eranian@google.com>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> ---
> arch/x86/kernel/cpu/perf_event_intel_ds.c | 8 ++++++++
> arch/x86/power/cpu.c | 2 ++
> include/linux/perf_event.h | 2 ++
> 3 files changed, 12 insertions(+)
>
> --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
> @@ -729,3 +729,11 @@ 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());
> +}
> --- a/arch/x86/power/cpu.c
> +++ b/arch/x86/power/cpu.c
> @@ -11,6 +11,7 @@
> #include <linux/suspend.h>
> #include <linux/export.h>
> #include <linux/smp.h>
> +#include <linux/perf_event.h>
>
> #include <asm/pgtable.h>
> #include <asm/proto.h>
> @@ -228,6 +229,7 @@ static void __restore_processor_state(st
> do_fpu_end();
> x86_platform.restore_sched_clock_state();
> mtrr_bp_restore();
> + perf_restore_debug_store();
> }
>
> /* Needed by apm.c */
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -753,6 +753,7 @@ extern void perf_event_enable(struct per
> extern void perf_event_disable(struct perf_event *event);
> extern int __perf_event_disable(void *info);
> 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 *prev,
> @@ -792,6 +793,7 @@ static inline void perf_event_enable(str
> static inline void perf_event_disable(struct perf_event *event) { }
> static inline int __perf_event_disable(void *info) { return -1; }
> 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))
>
>