[PATCH v3 4/8] perf trace: Pretty print struct data

Howard Chu
2024-08-24T16:33:29Z

Change the arg->augmented.args to arg->augmented.args->value to skip the
header for customized pretty printers, since we collect data in BPF
using the general augment_sys_enter(), which always adds the header.

Use btf_dump API to pretty print augmented struct pointer.

Prefer existed pretty-printer than btf general pretty-printer.

set compact = true and skip_names = true, so that no newline character
and argument name are printed.

Committer notes:

Simplified the btf_dump_snprintf callback to avoid using multiple
buffers, as discussed in the thread accessible via the Link tag below.

Signed-off-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240815013626.935097-7-howardchu95@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-trace.c | 65 +++++++++++++++++++++--
tools/perf/trace/beauty/perf_event_open.c | 2 +-
tools/perf/trace/beauty/sockaddr.c | 2 +-
tools/perf/trace/beauty/timespec.c | 2 +-
4 files changed, 63 insertions(+), 8 deletions(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 43b1f63415b4..048bcb92624c 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -990,6 +990,54 @@ static size_t btf_enum_scnprintf(const struct btf_type *type, struct btf *btf, c
return 0;
}

+struct trace_btf_dump_snprintf_ctx {
+ char *bf;
+ size_t printed, size;
+};
+
+static void trace__btf_dump_snprintf(void *vctx, const char *fmt, va_list args)
+{
+ struct trace_btf_dump_snprintf_ctx *ctx = vctx;
+
+ ctx->printed += vscnprintf(ctx->bf + ctx->printed, ctx->size - ctx->printed, fmt, args);
+}
+
+static size_t btf_struct_scnprintf(const struct btf_type *type, struct btf *btf, char *bf, size_t size, struct syscall_arg *arg)
+{
+ struct trace_btf_dump_snprintf_ctx ctx = {
+ .bf = bf,
+ .size = size,
+ };
+ struct augmented_arg *augmented_arg = arg->augmented.args;
+ int type_id = arg->fmt->type_id, consumed;
+ struct btf_dump *btf_dump;
+
+ LIBBPF_OPTS(btf_dump_opts, dump_opts);
+ LIBBPF_OPTS(btf_dump_type_data_opts, dump_data_opts);
+
+ if (arg == NULL || arg->augmented.args == NULL)
+ return 0;
+
+ dump_data_opts.compact = true;
+ dump_data_opts.skip_names = true;
+
+ btf_dump = btf_dump__new(btf, trace__btf_dump_snprintf, &ctx, &dump_opts);
+ if (btf_dump == NULL)
+ return 0;
+
+ /* pretty print the struct data here */
+ if (btf_dump__dump_type_data(btf_dump, type_id, arg->augmented.args->value, type->size, &dump_data_opts) == 0)
+ return 0;
+
+ consumed = sizeof(*augmented_arg) + augmented_arg->size;
+ arg->augmented.args = ((void *)arg->augmented.args) + consumed;
+ arg->augmented.size -= consumed;
+
+ btf_dump__free(btf_dump);
+
+ return ctx.printed;
+}
+
static size_t trace__btf_scnprintf(struct trace *trace, struct syscall_arg *arg, char *bf,
size_t size, int val, char *type)
{
@@ -1009,6 +1057,8 @@ static size_t trace__btf_scnprintf(struct trace *trace, struct syscall_arg *arg,

if (btf_is_enum(arg_fmt->type))
return btf_enum_scnprintf(arg_fmt->type, trace->btf, bf, size, val);
+ else if (btf_is_struct(arg_fmt->type))
+ return btf_struct_scnprintf(arg_fmt->type, trace->btf, bf, size, arg);

return 0;
}
@@ -2222,6 +2272,7 @@ static size_t syscall__scnprintf_args(struct syscall *sc, char *bf, size_t size,
.show_string_prefix = trace->show_string_prefix,
};
struct thread_trace *ttrace = thread__priv(thread);
+ void *default_scnprintf;

/*
* Things like fcntl will set this in its 'cmd' formatter to pick the
@@ -2263,11 +2314,15 @@ static size_t syscall__scnprintf_args(struct syscall *sc, char *bf, size_t size,
if (trace->show_arg_names)
printed += scnprintf(bf + printed, size - printed, "%s: ", field->name);

- btf_printed = trace__btf_scnprintf(trace, &arg, bf + printed,
- size - printed, val, field->type);
- if (btf_printed) {
- printed += btf_printed;
- continue;
+ default_scnprintf = sc->arg_fmt[arg.idx].scnprintf;
+
+ if (default_scnprintf == NULL || default_scnprintf == SCA_PTR) {
+ btf_printed = trace__btf_scnprintf(trace, &arg, bf + printed,
+ size - printed, val, field->type);
+ if (btf_printed) {
+ printed += btf_printed;
+ continue;
+ }
}

printed += syscall_arg_fmt__scnprintf_val(&sc->arg_fmt[arg.idx],
diff --git a/tools/perf/trace/beauty/perf_event_open.c b/tools/perf/trace/beauty/perf_event_open.c
index 01ee15fe9d0c..632237128640 100644
--- a/tools/perf/trace/beauty/perf_event_open.c
+++ b/tools/perf/trace/beauty/perf_event_open.c
@@ -76,7 +76,7 @@ static size_t perf_event_attr___scnprintf(struct perf_event_attr *attr, char *bf

static size_t syscall_arg__scnprintf_augmented_perf_event_attr(struct syscall_arg *arg, char *bf, size_t size)
{
- return perf_event_attr___scnprintf((void *)arg->augmented.args, bf, size, arg->trace->show_zeros);
+ return perf_event_attr___scnprintf((void *)arg->augmented.args->value, bf, size, arg->trace->show_zeros);
}

static size_t syscall_arg__scnprintf_perf_event_attr(char *bf, size_t size, struct syscall_arg *arg)
diff --git a/tools/perf/trace/beauty/sockaddr.c b/tools/perf/trace/beauty/sockaddr.c
index 2e0e867c0c1b..6ecebf776899 100644
--- a/tools/perf/trace/beauty/sockaddr.c
+++ b/tools/perf/trace/beauty/sockaddr.c
@@ -47,7 +47,7 @@ static size_t (*af_scnprintfs[])(struct sockaddr *sa, char *bf, size_t size) = {

static size_t syscall_arg__scnprintf_augmented_sockaddr(struct syscall_arg *arg, char *bf, size_t size)
{
- struct sockaddr *sa = (struct sockaddr *)arg->augmented.args;
+ struct sockaddr *sa = (struct sockaddr *)arg->augmented.args->value;
char family[32];
size_t printed;

diff --git a/tools/perf/trace/beauty/timespec.c b/tools/perf/trace/beauty/timespec.c
index e1a61f092aad..b14ab72a2738 100644
--- a/tools/perf/trace/beauty/timespec.c
+++ b/tools/perf/trace/beauty/timespec.c
@@ -7,7 +7,7 @@

static size_t syscall_arg__scnprintf_augmented_timespec(struct syscall_arg *arg, char *bf, size_t size)
{
- struct timespec *ts = (struct timespec *)arg->augmented.args;
+ struct timespec *ts = (struct timespec *)arg->augmented.args->value;

return scnprintf(bf, size, "{ .tv_sec: %" PRIu64 ", .tv_nsec: %" PRIu64 " }", ts->tv_sec, ts->tv_nsec);
}
--
2.45.2