Commit aa616f5a authored by Leo Yan's avatar Leo Yan Committed by Arnaldo Carvalho de Melo
Browse files

perf jit: Let convert_timestamp() to be backwards-compatible 



Commit d110162c ("perf tsc: Support cap_user_time_short for
event TIME_CONV") supports the extended parameters for event TIME_CONV,
but it broke the backwards compatibility, so any perf data file with old
event format fails to convert timestamp.

This patch introduces a helper event_contains() to check if an event
contains a specific member or not.  For the backwards-compatibility, if
the event size confirms the extended parameters are supported in the
event TIME_CONV, then copies these parameters.

Committer notes:

To make this compiler backwards compatible add this patch:

  -       struct perf_tsc_conversion tc = { 0 };
  +       struct perf_tsc_conversion tc = { .time_shift = 0, };

Fixes: d110162c ("perf tsc: Support cap_user_time_short for event TIME_CONV")
Signed-off-by: default avatarLeo Yan <leo.yan@linaro.org>
Acked-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve MacLean <Steve.MacLean@Microsoft.com>
Cc: Yonatan Goldschmidt <yonatan.goldschmidt@granulate.io>
Link: https://lore.kernel.org/r/20210428120915.7123-3-leo.yan@linaro.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent e1d380ea

tools/lib/perf/include/perf/event.h

+2 −0
Original line number Diff line number Diff line
@@ -8,6 +8,8 @@ 
#include <linux/bpf.h>

#include <sys/types.h> /* pid_t */



#define event_contains(obj, mem) ((obj).header.size > offsetof(typeof(obj), mem))



struct perf_record_mmap {

	struct perf_event_header header;

	__u32			 pid, tid;

tools/perf/util/jitdump.c

+20 −10
Original line number Diff line number Diff line
@@ -396,21 +396,31 @@ static pid_t jr_entry_tid(struct jit_buf_desc *jd, union jr_entry *jr) 


static uint64_t convert_timestamp(struct jit_buf_desc *jd, uint64_t timestamp)

{

	struct perf_tsc_conversion tc;

	struct perf_tsc_conversion tc = { .time_shift = 0, };

	struct perf_record_time_conv *time_conv = &jd->session->time_conv;



	if (!jd->use_arch_timestamp)

		return timestamp;



	tc.time_shift	       = jd->session->time_conv.time_shift;

	tc.time_mult	       = jd->session->time_conv.time_mult;

	tc.time_zero	       = jd->session->time_conv.time_zero;

	tc.time_cycles	       = jd->session->time_conv.time_cycles;

	tc.time_mask	       = jd->session->time_conv.time_mask;

	tc.cap_user_time_zero  = jd->session->time_conv.cap_user_time_zero;

	tc.cap_user_time_short = jd->session->time_conv.cap_user_time_short;

	tc.time_shift = time_conv->time_shift;

	tc.time_mult  = time_conv->time_mult;

	tc.time_zero  = time_conv->time_zero;



	/*

	 * The event TIME_CONV was extended for the fields from "time_cycles"

	 * when supported cap_user_time_short, for backward compatibility,

	 * checks the event size and assigns these extended fields if these

	 * fields are contained in the event.

	 */

	if (event_contains(*time_conv, time_cycles)) {

		tc.time_cycles	       = time_conv->time_cycles;

		tc.time_mask	       = time_conv->time_mask;

		tc.cap_user_time_zero  = time_conv->cap_user_time_zero;

		tc.cap_user_time_short = time_conv->cap_user_time_short;



		if (!tc.cap_user_time_zero)

			return 0;

	}



	return tsc_to_perf_time(timestamp, &tc);

}