Add a map to the rtla-timerlat BPF program that holds a file descriptor of another BPF program, to be executed on threshold overflow.
timerlat_bpf_set_action() is added as an interface to set the program. Signed-off-by: Tomas Glozar <[email protected]> --- tools/tracing/rtla/src/timerlat.bpf.c | 25 +++++++++++++++++++++---- tools/tracing/rtla/src/timerlat_bpf.c | 13 +++++++++++++ tools/tracing/rtla/src/timerlat_bpf.h | 1 + 3 files changed, 35 insertions(+), 4 deletions(-) diff --git a/tools/tracing/rtla/src/timerlat.bpf.c b/tools/tracing/rtla/src/timerlat.bpf.c index e2265b5d6491..549d2d2191d2 100644 --- a/tools/tracing/rtla/src/timerlat.bpf.c +++ b/tools/tracing/rtla/src/timerlat.bpf.c @@ -40,6 +40,17 @@ struct { __uint(max_entries, 1); } signal_stop_tracing SEC(".maps"); +struct { + __uint(type, BPF_MAP_TYPE_PROG_ARRAY); + __uint(key_size, sizeof(unsigned int)); + __uint(max_entries, 1); + __array(values, unsigned int (void *)); +} bpf_action SEC(".maps") = { + .values = { + [0] = 0 + }, +}; + /* Params to be set by rtla */ const volatile int bucket_size = 1; const volatile int output_divisor = 1000; @@ -109,7 +120,7 @@ nosubprog void update_summary(void *map, map_set(map, SUMMARY_SUM, map_get(map, SUMMARY_SUM) + latency); } -nosubprog void set_stop_tracing(void) +nosubprog void set_stop_tracing(struct trace_event_raw_timerlat_sample *tp_args) { int value = 0; @@ -118,6 +129,12 @@ nosubprog void set_stop_tracing(void) /* Signal to userspace */ bpf_ringbuf_output(&signal_stop_tracing, &value, sizeof(value), 0); + + /* + * Call into BPF action program, if attached. + * Otherwise, just silently fail. + */ + bpf_tail_call(tp_args, &bpf_action, 0); } SEC("tp/osnoise/timerlat_sample") @@ -138,19 +155,19 @@ int handle_timerlat_sample(struct trace_event_raw_timerlat_sample *tp_args) update_summary(&summary_irq, latency, bucket); if (irq_threshold != 0 && latency_us >= irq_threshold) - set_stop_tracing(); + set_stop_tracing(tp_args); } else if (tp_args->context == 1) { update_main_hist(&hist_thread, bucket); update_summary(&summary_thread, latency, bucket); if (thread_threshold != 0 && latency_us >= thread_threshold) - set_stop_tracing(); + set_stop_tracing(tp_args); } else { update_main_hist(&hist_user, bucket); update_summary(&summary_user, latency, bucket); if (thread_threshold != 0 && latency_us >= thread_threshold) - set_stop_tracing(); + set_stop_tracing(tp_args); } return 0; diff --git a/tools/tracing/rtla/src/timerlat_bpf.c b/tools/tracing/rtla/src/timerlat_bpf.c index e97d16646bcd..1d619e502c65 100644 --- a/tools/tracing/rtla/src/timerlat_bpf.c +++ b/tools/tracing/rtla/src/timerlat_bpf.c @@ -59,6 +59,19 @@ int timerlat_bpf_init(struct timerlat_params *params) return 0; } +/* + * timerlat_bpf_set_action - set action on threshold executed on BPF side + */ +static int timerlat_bpf_set_action(struct bpf_program *prog) +{ + unsigned int key = 0, value = bpf_program__fd(prog); + + return bpf_map__update_elem(bpf->maps.bpf_action, + &key, sizeof(key), + &value, sizeof(value), + BPF_ANY); +} + /* * timerlat_bpf_attach - attach BPF program to collect timerlat data */ diff --git a/tools/tracing/rtla/src/timerlat_bpf.h b/tools/tracing/rtla/src/timerlat_bpf.h index 118487436d30..b5009092c7a3 100644 --- a/tools/tracing/rtla/src/timerlat_bpf.h +++ b/tools/tracing/rtla/src/timerlat_bpf.h @@ -12,6 +12,7 @@ enum summary_field { }; #ifndef __bpf__ +#include <bpf/libbpf.h> #ifdef HAVE_BPF_SKEL int timerlat_bpf_init(struct timerlat_params *params); int timerlat_bpf_attach(void); -- 2.51.1
