[PATCH 22/69] perf trace: Add array of chars scnprintf beautifier

From: Arnaldo Carvalho de Melo
Date: Fri Oct 11 2019 - 16:08:30 EST


From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

Needed for sched's traceoints prev/next comm, where, unlike with
syscalls, we are not dealing with an integer or pointer, but an array
straight out from the ring buffer.

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Luis ClÃudio GonÃalves <lclaudio@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Link: https://lkml.kernel.org/n/tip-rlll7tmcqe1g4odtaifil5re@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/builtin-trace.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index f30296c72415..b3fb208cbd30 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -91,6 +91,7 @@ struct syscall_arg_fmt {
unsigned long (*mask_val)(struct syscall_arg *arg, unsigned long val);
void *parm;
const char *name;
+ u16 nr_entries; // for arrays
bool show_zero;
};

@@ -522,6 +523,16 @@ size_t syscall_arg__scnprintf_long(char *bf, size_t size, struct syscall_arg *ar
return scnprintf(bf, size, "%ld", arg->val);
}

+static size_t syscall_arg__scnprintf_char_array(char *bf, size_t size, struct syscall_arg *arg)
+{
+ // 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);
+}
+
+#define SCA_CHAR_ARRAY syscall_arg__scnprintf_char_array
+
static const char *bpf_cmd[] = {
"MAP_CREATE", "MAP_LOOKUP_ELEM", "MAP_UPDATE_ELEM", "MAP_DELETE_ELEM",
"MAP_GET_NEXT_KEY", "PROG_LOAD",
@@ -1491,7 +1502,10 @@ 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 ((strcmp(field->type, "int") == 0 ||
+ else if ((field->flags & TEP_FIELD_IS_ARRAY) && strstarts(field->type, "char")) {
+ arg->scnprintf = SCA_CHAR_ARRAY;
+ arg->nr_entries = field->arraylen;
+ } else if ((strcmp(field->type, "int") == 0 ||
strcmp(field->type, "unsigned int") == 0 ||
strcmp(field->type, "long") == 0) &&
len >= 2 && strcmp(field->name + len - 2, "fd") == 0) {
--
2.21.0