Currently the code skips the first field with the expectation that it is
'nr'. But older kernels do not have the 'nr' field:
field:int nr; offset:8; size:4; signed:1;
Change perf-trace to drop the field if it exists after parsing the format
file.
This fixes the off-by-one problem with older kernels (e.g., RHEL6). e.g,
perf-trace shows this for write:
1.515 ( 0.006 ms): dd/4245 write(buf: 2</dev/pts/0>, count: 140733837536224
) = 26
where 2 is really the fd, the huge number is really the buf address, etc.
With this patch you get the more appropriate:
1.813 ( 0.003 ms): dd/6330 write(fd: 2</dev/pts/0>, buf: 0x7fff22fc81f0,
count: 25 ) = 25
Signed-off-by: David Ahern <[email protected]>
---
tools/lib/traceevent/event-parse.c | 11 ++++++++---
tools/lib/traceevent/event-parse.h | 1 +
tools/perf/builtin-trace.c | 16 +++++++++++++---
3 files changed, 22 insertions(+), 6 deletions(-)
diff --git a/tools/lib/traceevent/event-parse.c
b/tools/lib/traceevent/event-parse.c
index afe20ed9fac8..e8a29e730dfb 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -6228,15 +6228,20 @@ void pevent_ref(struct pevent *pevent)
pevent->ref_count++;
}
+void free_format_field(struct format_field *field)
+{
+ free(field->type);
+ free(field->name);
+ free(field);
+}
+
static void free_format_fields(struct format_field *field)
{
struct format_field *next;
while (field) {
next = field->next;
- free(field->type);
- free(field->name);
- free(field);
+ free_format_field(field);
field = next;
}
}
diff --git a/tools/lib/traceevent/event-parse.h
b/tools/lib/traceevent/event-parse.h
index 5b4efc062320..a548fac646f6 100644
--- a/tools/lib/traceevent/event-parse.h
+++ b/tools/lib/traceevent/event-parse.h
@@ -619,6 +619,7 @@ enum pevent_errno pevent_parse_format(struct pevent *pevent,
const char *buf,
unsigned long size, const char *sys);
void pevent_free_format(struct event_format *event);
+void free_format_field(struct format_field *field);
void *pevent_get_field_raw(struct trace_seq *s, struct event_format *event,
const char *name, struct pevent_record *record,
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index dcd950ef2fd7..5caeefeda48a 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1442,14 +1442,24 @@ static int syscall__set_arg_fmts(struct syscall *sc)
struct format_field *field;
int idx = 0;
- sc->arg_scnprintf = calloc(sc->tp_format->format.nr_fields - 1,
sizeof(void *));
+ field = sc->tp_format->format.fields;
+ /* drop nr field - not relevant here; does not exist on older kernels */
+ if (field && strcmp(field->name, "nr") == 0) {
+ struct format_field *next = field->next;
+
+ free_format_field(field);
+ sc->tp_format->format.fields = next;
+ sc->tp_format->format.nr_fields--;
+ }
+
+ sc->arg_scnprintf = calloc(sc->tp_format->format.nr_fields, sizeof(void
*));
if (sc->arg_scnprintf == NULL)
return -1;
if (sc->fmt)
sc->arg_parm = sc->fmt->arg_parm;
- for (field = sc->tp_format->format.fields->next; field; field =
field->next) {
+ for (field = sc->tp_format->format.fields; field; field = field->next) {
if (sc->fmt && sc->fmt->arg_scnprintf[idx])
sc->arg_scnprintf[idx] = sc->fmt->arg_scnprintf[idx];
else if (field->flags & FIELD_IS_POINTER)
@@ -1547,7 +1557,7 @@ static size_t syscall__scnprintf_args(struct syscall *sc,
char *bf, size_t size,
.thread = thread,
};
- for (field = sc->tp_format->format.fields->next; field;
+ for (field = sc->tp_format->format.fields; field;
field = field->next, ++arg.idx, bit <<= 1) {
if (arg.mask & bit)
continue;
--
2.2.1
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