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 <[email protected]> --- include/linux/hw_breakpoint.h | 6 ++++++ include/linux/perf_event.h | 6 ++++++ kernel/events/core.c | 2 ++ 3 files changed, 14 insertions(+) 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); -- 2.9.4
