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perf trace: Handle legacy syscalls tracepoints

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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

Based-on-a-patch-by: David Ahern <dsahern@gmail.com>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-gvpdave4u2yq2jnzbcdznpvf@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2015-03-20 17:46:53 -03:00
parent e6c76d6203
commit f208bd8df0
1 changed files with 14 additions and 4 deletions
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18
tools/perf/builtin-trace.c
View file

@ -1135,6 +1135,8 @@ static struct syscall_fmt *syscall_fmt__find(const char *name)
struct syscall { struct syscall {
struct event_format *tp_format; struct event_format *tp_format;
int nr_args;
struct format_field *args;
const char *name; const char *name;
bool filtered; bool filtered;
bool is_exit; bool is_exit;
@ -1442,14 +1444,14 @@ static int syscall__set_arg_fmts(struct syscall *sc)
struct format_field *field; struct format_field *field;
int idx = 0; int idx = 0;
sc->arg_scnprintf = calloc(sc->tp_format->format.nr_fields - 1, sizeof(void *)); sc->arg_scnprintf = calloc(sc->nr_args, sizeof(void *));
if (sc->arg_scnprintf == NULL) if (sc->arg_scnprintf == NULL)
return -1; return -1;
if (sc->fmt) if (sc->fmt)
sc->arg_parm = sc->fmt->arg_parm; sc->arg_parm = sc->fmt->arg_parm;
for (field = sc->tp_format->format.fields->next; field; field = field->next) { for (field = sc->args; field; field = field->next) {
if (sc->fmt && sc->fmt->arg_scnprintf[idx]) if (sc->fmt && sc->fmt->arg_scnprintf[idx])
sc->arg_scnprintf[idx] = sc->fmt->arg_scnprintf[idx]; sc->arg_scnprintf[idx] = sc->fmt->arg_scnprintf[idx];
else if (field->flags & FIELD_IS_POINTER) else if (field->flags & FIELD_IS_POINTER)
@ -1515,6 +1517,14 @@ static int trace__read_syscall_info(struct trace *trace, int id)
if (sc->tp_format == NULL) if (sc->tp_format == NULL)
return -1; return -1;
sc->args = sc->tp_format->format.fields;
sc->nr_args = sc->tp_format->format.nr_fields;
/* drop nr field - not relevant here; does not exist on older kernels */
if (sc->args && strcmp(sc->args->name, "nr") == 0) {
sc->args = sc->args->next;
--sc->nr_args;
}
sc->is_exit = !strcmp(name, "exit_group") || !strcmp(name, "exit"); sc->is_exit = !strcmp(name, "exit_group") || !strcmp(name, "exit");
return syscall__set_arg_fmts(sc); return syscall__set_arg_fmts(sc);
@ -1537,7 +1547,7 @@ static size_t syscall__scnprintf_args(struct syscall *sc, char *bf, size_t size,
unsigned char *p; unsigned char *p;
unsigned long val; unsigned long val;
if (sc->tp_format != NULL) { if (sc->args != NULL) {
struct format_field *field; struct format_field *field;
u8 bit = 1; u8 bit = 1;
struct syscall_arg arg = { struct syscall_arg arg = {
@ -1547,7 +1557,7 @@ static size_t syscall__scnprintf_args(struct syscall *sc, char *bf, size_t size,
.thread = thread, .thread = thread,
}; };
for (field = sc->tp_format->format.fields->next; field; for (field = sc->args; field;
field = field->next, ++arg.idx, bit <<= 1) { field = field->next, ++arg.idx, bit <<= 1) {
if (arg.mask & bit) if (arg.mask & bit)
continue; continue;