[PATCH 16/86] perf trace: Allow syscall_arg beautifiers to set a different return formatter

Arnaldo Carvalho de Melo
2017-07-19T14:31:41Z

From: Arnaldo Carvalho de Melo <acme@redhat.com>

Things like fcntl will use this to set the right formatter based on its
'cmd' argument.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-4ea3wplb8b4j7aymj0d5uo0h@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-trace.c | 27 ++++++++++++++++++++++++++-
tools/perf/trace/beauty/beauty.h | 3 +++
2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 1f070bc43742..d48981c36b70 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -908,6 +908,8 @@ static size_t fprintf_duration(unsigned long t, bool calculated, FILE *fp)
* filename.ptr: The filename char pointer that will be vfs_getname'd
* filename.entry_str_pos: Where to insert the string translated from
* filename.ptr by the vfs_getname tracepoint/kprobe.
+ * ret_scnprintf: syscall args may set this to a different syscall return
+ * formatter, for instance, fcntl may return fds, file flags, etc.
*/
struct thread_trace {
u64 entry_time;
@@ -916,6 +918,7 @@ struct thread_trace {
unsigned long pfmaj, pfmin;
char *entry_str;
double runtime_ms;
+ size_t (*ret_scnprintf)(unsigned long value, char *bf, size_t size);
struct {
unsigned long ptr;
short int entry_str_pos;
@@ -966,6 +969,15 @@ static struct thread_trace *thread__trace(struct thread *thread, FILE *fp)
return NULL;
}

+
+void syscall_arg__set_ret_scnprintf(struct syscall_arg *arg,
+ size_t (*ret_scnprintf)(unsigned long val, char *bf, size_t size))
+{
+ struct thread_trace *ttrace = thread__priv(arg->thread);
+
+ ttrace->ret_scnprintf = ret_scnprintf;
+}
+
#define TRACE_PFMAJ (1 << 0)
#define TRACE_PFMIN (1 << 1)

@@ -1390,6 +1402,14 @@ static size_t syscall__scnprintf_args(struct syscall *sc, char *bf, size_t size,
{
size_t printed = 0;
unsigned long val;
+ struct thread_trace *ttrace = thread__priv(thread);
+
+ /*
+ * Things like fcntl will set this in its 'cmd' formatter to pick the
+ * right formatter for the return value (an fd? file flags?), which is
+ * not needed for syscalls that always return a given type, say an fd.
+ */
+ ttrace->ret_scnprintf = NULL;

if (sc->args != NULL) {
struct format_field *field;
@@ -1704,7 +1724,12 @@ static int trace__sys_exit(struct trace *trace, struct perf_evsel *evsel,
fprintf(trace->output, ") = -1 %s %s", e, emsg);
} else if (ret == 0 && sc->fmt->timeout)
fprintf(trace->output, ") = 0 Timeout");
- else if (sc->fmt->hexret)
+ else if (ttrace->ret_scnprintf) {
+ char bf[1024];
+ ttrace->ret_scnprintf(ret, bf, sizeof(bf));
+ ttrace->ret_scnprintf = NULL;
+ fprintf(trace->output, ") = %s", bf);
+ } else if (sc->fmt->hexret)
fprintf(trace->output, ") = %#lx", ret);
else if (sc->fmt->errpid) {
struct thread *child = machine__find_thread(trace->host, ret, ret);
diff --git a/tools/perf/trace/beauty/beauty.h b/tools/perf/trace/beauty/beauty.h
index c05bb2ecf502..a9613d2e6cfe 100644
--- a/tools/perf/trace/beauty/beauty.h
+++ b/tools/perf/trace/beauty/beauty.h
@@ -54,4 +54,7 @@ size_t syscall_arg__scnprintf_statx_mask(char *bf, size_t size, struct syscall_a

size_t open__scnprintf_flags(unsigned long flags, char *bf, size_t size);

+void syscall_arg__set_ret_scnprintf(struct syscall_arg *arg,
+ size_t (*ret_scnprintf)(unsigned long val, char *bf, size_t size));
+
#endif /* _PERF_TRACE_BEAUTY_H */
--
2.9.4