| Message ID | 1d7ca935857f93bd09c82a2ff57a53e373211b7e.1501496603.git.panand@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Jul 31, 2017 at 04:10:29PM +0530, Pratyush Anand wrote: > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index 24a635887f28..7da951f94b47 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -233,6 +233,12 @@ struct hw_perf_event { > */ > u64 freq_time_stamp; > u64 freq_count_stamp; > + /* > + * A HW breakpoint user can either have it's own step handling > + * mechanism or it can use default step handling meachanism defined > + * by arch code. Set step_needed to use default mechanism. > + */ > + int step_needed; You'll note that there is an anonymous structure inside the anonymous union specifically dedicated to hardware breakpoint state. Why not put it there? > #endif > }; > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 6c4e523dc1e2..66ce5574e778 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -9444,9 +9444,11 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, > } else if (is_write_backward(event)){ > event->overflow_handler = perf_event_output_backward; > event->overflow_handler_context = NULL; > + event->hw.step_needed = 1; > } else { > event->overflow_handler = perf_event_output_forward; > event->overflow_handler_context = NULL; > + event->hw.step_needed = 1; > } These here need a comment, because even if I'd know now why the heck we need that = 1 here, I'd sure as hell won't know tomorrow.
diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h index 0464c85e63fd..b9ac9629bf74 100644 --- a/include/linux/hw_breakpoint.h +++ b/include/linux/hw_breakpoint.h @@ -38,6 +38,12 @@ static inline int hw_breakpoint_type(struct perf_event *bp) return bp->attr.bp_type; } +static inline bool +hw_breakpoint_needs_single_step(struct perf_event *bp) +{ + return bp->hw.step_needed; +} + static inline unsigned long hw_breakpoint_len(struct perf_event *bp) { return bp->attr.bp_len; diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 24a635887f28..7da951f94b47 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -233,6 +233,12 @@ struct hw_perf_event { */ u64 freq_time_stamp; u64 freq_count_stamp; + /* + * A HW breakpoint user can either have it's own step handling + * mechanism or it can use default step handling meachanism defined + * by arch code. Set step_needed to use default mechanism. + */ + int step_needed; #endif }; diff --git a/kernel/events/core.c b/kernel/events/core.c index 6c4e523dc1e2..66ce5574e778 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9444,9 +9444,11 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, } else if (is_write_backward(event)){ event->overflow_handler = perf_event_output_backward; event->overflow_handler_context = NULL; + event->hw.step_needed = 1; } else { event->overflow_handler = perf_event_output_forward; event->overflow_handler_context = NULL; + event->hw.step_needed = 1; } perf_event__state_init(event);
Architecture like ARM64 currently allows to use default hw breakpoint single step handler only to perf. However, some other users like few systemtap tests or kernel test in samples/hw_breakpoint/data_breakpoint.c can also work with default step handler implementation. Therefore, this patch introduces a flag 'step_needed' in struct hw_perf_event, so that arch specific code(specially on arm64) can make a decision to enable single stepping. Any architecture which is not using this field will not have any side effect. Signed-off-by: Pratyush Anand <panand@redhat.com> --- include/linux/hw_breakpoint.h | 6 ++++++ include/linux/perf_event.h | 6 ++++++ kernel/events/core.c | 2 ++ 3 files changed, 14 insertions(+)