perf trace: Support tracepoint dynamic char arrays
Things like:
# grep __data_loc /sys/kernel/debug/tracing/events/sched/sched_process_exec/format
field:__data_loc char[] filename; offset:8; size:4; signed:1;
#
That, at that offset (8) and with that size(8) have an integer that
contains the real length and offset for the contents of that array.
Now this works:
# perf trace --max-events 1 -e sched:*exec -a
0.000 sed/19441 sched:sched_process_exec(filename: "/usr/bin/sync", pid: 19441 (sync), old_pid: 19441 (sync))
#
As when using the libtraceevent based beautifier:
# perf trace --libtraceevent --max-events 1 -e sched:*exec -a
0.000 sync/19463 sched:sched_process_exec(filename=/usr/bin/sync pid=19463 old_pid=19463)
#
I.e. that 'filename' is implemented as a dynamic char array.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-950p0m842fe6n7sxsdwqj5i2@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index cdee22d..907eaf3 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -563,7 +563,7 @@ static size_t syscall_arg__scnprintf_char_array(char *bf, size_t size, struct sy
// XXX Hey, maybe for sched:sched_switch prev/next comm fields we can
// fill missing comms using thread__set_comm()...
// here or in a special syscall_arg__scnprintf_pid_sched_tp...
- return scnprintf(bf, size, "\"%-.*s\"", arg->fmt->nr_entries, arg->val);
+ return scnprintf(bf, size, "\"%-.*s\"", arg->fmt->nr_entries ?: arg->len, arg->val);
}
#define SCA_CHAR_ARRAY syscall_arg__scnprintf_char_array
@@ -1559,7 +1559,7 @@ syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format_field
arg->scnprintf = SCA_PID;
else if (strcmp(field->type, "umode_t") == 0)
arg->scnprintf = SCA_MODE_T;
- else if ((field->flags & TEP_FIELD_IS_ARRAY) && strstarts(field->type, "char")) {
+ else if ((field->flags & TEP_FIELD_IS_ARRAY) && strstr(field->type, "char")) {
arg->scnprintf = SCA_CHAR_ARRAY;
arg->nr_entries = field->arraylen;
} else if ((strcmp(field->type, "int") == 0 ||
@@ -2523,10 +2523,19 @@ static size_t trace__fprintf_tp_fields(struct trace *trace, struct evsel *evsel,
if (syscall_arg.mask & bit)
continue;
+ syscall_arg.len = 0;
syscall_arg.fmt = arg;
- if (field->flags & TEP_FIELD_IS_ARRAY)
- val = (uintptr_t)(sample->raw_data + field->offset);
- else
+ if (field->flags & TEP_FIELD_IS_ARRAY) {
+ int offset = field->offset;
+
+ if (field->flags & TEP_FIELD_IS_DYNAMIC) {
+ offset = format_field__intval(field, sample, evsel->needs_swap);
+ syscall_arg.len = offset >> 16;
+ offset &= 0xffff;
+ }
+
+ val = (uintptr_t)(sample->raw_data + offset);
+ } else
val = format_field__intval(field, sample, evsel->needs_swap);
/*
* Some syscall args need some mask, most don't and
