vmlinux_dir $ grep -f good_enums -l /sys/kernel/tracing/events/*/*/format |=
sed "s/.*events\/\(.*\)\/\(.*\)\/.*/\1:\2/g"
cfg80211:cfg80211_chandef_dfs_required
cfg80211:cfg80211_ch_switch_notify
cfg80211:cfg80211_ch_switch_started_notify
cfg80211:cfg80211_get_bss
cfg80211:cfg80211_ibss_joined
cfg80211:cfg80211_inform_bss_frame
cfg80211:cfg80211_radar_event
cfg80211:cfg80211_ready_on_channel_expired
cfg80211:cfg80211_ready_on_channel
cfg80211:cfg80211_reg_can_beacon
cfg80211:cfg80211_return_bss
cfg80211:cfg80211_tx_mgmt_expired
cfg80211:rdev_add_virtual_intf
cfg80211:rdev_auth
cfg80211:rdev_change_virtual_intf
cfg80211:rdev_channel_switch
cfg80211:rdev_connect
cfg80211:rdev_inform_bss
cfg80211:rdev_libertas_set_mesh_channel
cfg80211:rdev_mgmt_tx
cfg80211:rdev_remain_on_channel
cfg80211:rdev_return_chandef
cfg80211:rdev_return_int_survey_info
cfg80211:rdev_set_ap_chanwidth
cfg80211:rdev_set_monitor_channel
cfg80211:rdev_set_radar_background
cfg80211:rdev_start_ap
cfg80211:rdev_start_radar_detection
cfg80211:rdev_tdls_channel_switch
compaction:mm_compaction_defer_compaction
compaction:mm_compaction_deferred
compaction:mm_compaction_defer_reset
compaction:mm_compaction_finished
compaction:mm_compaction_kcompactd_wake
compaction:mm_compaction_suitable
compaction:mm_compaction_wakeup_kcompactd
error_report:error_report_end
i2c_slave:i2c_slave
migrate:mm_migrate_pages
migrate:mm_migrate_pages_start
pagemap:mm_lru_insertion
power:dev_pm_qos_add_request
power:dev_pm_qos_remove_request
power:dev_pm_qos_update_request
power:pm_qos_update_flags
power:pm_qos_update_target
pwm:pwm_apply
pwm:pwm_get
sched:sched_skip_vma_numa
skb:kfree_skb
thermal:thermal_zone_trip
timer:hrtimer_init
timer:hrtimer_start
xen:xen_mc_batch
xen:xen_mc_extend_args
xen:xen_mc_flush_reason
xen:xen_mc_issue
=3D=3D=3D
v2 notes
In 'struct syscall_arg_fmt':
```
struct {
void *entry;
u16 nr_entries;
} btf_entry;
```
This is the new member btf_entry. 'struct btf_member' object, so that
we don't have to do btf__find_by_name(), btf__type_by_id(), btf_enum(),
and btf_vlen() everytime a landlock_add_rule() syscall entered.
Note that entry is of type 'void *', because this btf_entry can also be
applied to 'struct btf_member *' for 'BTF_KIND_STRUCT', hopefully in the
future.
=3D=3D=3D
v1 notes
This is a feature implemented on the basis of the previous bug fix
https://lore.kernel.org/linux-perf-users/d18a9606-ac9f-4ca7-afaf-fcf4c951cb=
90@xxxxxx/T/#t
In this patch, BTF is used to turn enum value to the corresponding
name. There is only one system call that uses enum value as its
argument, that is `landlock_add_rule()`.
The vmlinux btf is loaded lazily, when user decided to trace the
`landlock_add_rule` syscall. But if one decide to run `perf trace`
without any arguments, the behaviour is to trace `landlock_add_rule`,
so vmlinux btf will be loaded by default.
The laziest behaviour is to load vmlinux btf when a
`landlock_add_rule` syscall hits. But I think you could lose some
samples when loading vmlinux btf at run time, for it can delay the
handling of other samples. I might need your precious opinions on
this...
before:
```
perf $ ./perf trace -e landlock_add_rule
0.000 ( 0.008 ms): ldlck-test/438194 landlock_add_rule(rule_type: 2) =
=3D -1 EBADFD (File descriptor in bad =
state)
0.010 ( 0.001 ms): ldlck-test/438194 landlock_add_rule(rule_type: 1) =
=3D -1 EBADFD (File descriptor in bad =
state)
```
after:
```
perf $ ./perf trace -e landlock_add_rule
0.000 ( 0.029 ms): ldlck-test/438194 landlock_add_rule(rule_type: LAND=
LOCK_RULE_NET_PORT) =3D -1 EBADFD (File descriptor in bad =
state)
0.036 ( 0.004 ms): ldlck-test/438194 landlock_add_rule(rule_type: LAND=
LOCK_RULE_PATH_BENEATH) =3D -1 EBADFD (File descriptor in bad =
state)
```
Signed-off-by: Howard Chu <howardchu95@xxxxxxxxx>
---
tools/perf/builtin-trace.c | 121 ++++++++++++++++++++++++++++++++++---
1 file changed, 111 insertions(+), 10 deletions(-)
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 5cbe1748911d..0a168cb9b0c2 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -19,6 +19,7 @@
#ifdef HAVE_LIBBPF_SUPPORT
#include <bpf/bpf.h>
#include <bpf/libbpf.h>
+#include <bpf/btf.h>
#ifdef HAVE_BPF_SKEL
#include "bpf_skel/augmented_raw_syscalls.skel.h"
#endif
@@ -110,6 +111,11 @@ struct syscall_arg_fmt {
const char *name;
u16 nr_entries; // for arrays
bool show_zero;
+ bool is_enum;
+ struct {
+ void *entry;
+ u16 nr_entries;
+ } btf_entry;
};
=20
struct syscall_fmt {
@@ -140,6 +146,7 @@ struct trace {
#ifdef HAVE_BPF_SKEL
struct augmented_raw_syscalls_bpf *skel;
#endif
+ struct btf *btf;
struct record_opts opts;
struct evlist *evlist;
struct machine *host;
@@ -887,6 +894,56 @@ static size_t syscall_arg__scnprintf_getrandom_flags(c=
har *bf, size_t size,
=20
#define SCA_GETRANDOM_FLAGS syscall_arg__scnprintf_getrandom_flags
=20
+static int btf_enum_find_entry(struct btf *btf, char *type, struct syscall=
_arg_fmt *arg_fmt)
+{
+ const struct btf_type *bt;
+ char enum_prefix[][16] =3D { "enum", "const enum" }, *ep;
+ int id;
+ size_t i;
+
+ for (i =3D 0; i < ARRAY_SIZE(enum_prefix); i++) {
+ ep =3D enum_prefix[i];
+ if (strlen(type) > strlen(ep) + 1 && strstarts(type, ep))
+ type +=3D strlen(ep) + 1;
+ }
+
+ id =3D btf__find_by_name(btf, type);
+ if (id < 0)
+ return -1;
+
+ bt =3D btf__type_by_id(btf, id);
+ if (bt =3D=3D NULL)
+ return -1;
+
+ arg_fmt->btf_entry.entry =3D btf_enum(bt);
+ arg_fmt->btf_entry.nr_entries =3D btf_vlen(bt);
+
+ return 0;
+}
+
+static size_t btf_enum_scnprintf(char *bf, size_t size, int val, struct bt=
f *btf, char *type,
+ struct syscall_arg_fmt *arg_fmt)
+{
+ struct btf_enum *be;
+ int i;
+
+ /* if btf_entry is NULL, find and save it to arg_fmt */
+ if (arg_fmt->btf_entry.entry =3D=3D NULL)
+ if (btf_enum_find_entry(btf, type, arg_fmt))
+ return 0;
+
+ be =3D (struct btf_enum *)arg_fmt->btf_entry.entry;
+
+ for (i =3D 0; i < arg_fmt->btf_entry.nr_entries; ++i, ++be) {
+ if (be->val =3D=3D val) {
+ return scnprintf(bf, size, "%s",
+ btf__name_by_offset(btf, be->name_off));
+ }
+ }
+
+ return 0;
+}
+
#define STRARRAY(name, array) \
{ .scnprintf =3D SCA_STRARRAY, \
.strtoul =3D STUL_STRARRAY, \
@@ -1238,6 +1295,7 @@ struct syscall {
bool is_exit;
bool is_open;
bool nonexistent;
+ bool use_btf;
struct tep_format_field *args;
const char *name;
const struct syscall_fmt *fmt;
@@ -1699,6 +1757,15 @@ static void trace__symbols__exit(struct trace *trace)
symbol__exit();
}
=20
+static void trace__load_vmlinux_btf(struct trace *trace)
+{
+ trace->btf =3D btf__load_vmlinux_btf();
+ if (verbose > 0) {
+ fprintf(trace->output, trace->btf ? "vmlinux BTF loaded\n" :
+ "Failed to load vmlinux BTF\n");
+ }
+}
+
static int syscall__alloc_arg_fmts(struct syscall *sc, int nr_args)
{
int idx;
@@ -1744,7 +1811,8 @@ static const struct syscall_arg_fmt *syscall_arg_fmt_=
_find_by_name(const char *n
}
=20
static struct tep_format_field *
-syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format=
_field *field)
+syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format=
_field *field,
+ bool *use_btf)
{
struct tep_format_field *last_field =3D NULL;
int len;
@@ -1756,6 +1824,7 @@ syscall_arg_fmt__init_array(struct syscall_arg_fmt *a=
rg, struct tep_format_field
continue;
=20
len =3D strlen(field->name);
+ arg->is_enum =3D false;
=20
if (strcmp(field->type, "const char *") =3D=3D 0 &&
((len >=3D 4 && strcmp(field->name + len - 4, "name") =3D=3D 0) ||
@@ -1782,6 +1851,8 @@ syscall_arg_fmt__init_array(struct syscall_arg_fmt *a=
rg, struct tep_format_field
* 7 unsigned long
*/
arg->scnprintf =3D SCA_FD;
+ } else if (strstr(field->type, "enum") && use_btf !=3D NULL) {
+ *use_btf =3D arg->is_enum =3D true;
} else {
const struct syscall_arg_fmt *fmt =3D
syscall_arg_fmt__find_by_name(field->name);
@@ -1796,9 +1867,14 @@ syscall_arg_fmt__init_array(struct syscall_arg_fmt *=
arg, struct tep_format_field
return last_field;
}
=20
-static int syscall__set_arg_fmts(struct syscall *sc)
+static int syscall__set_arg_fmts(struct trace *trace, struct syscall *sc)
{
- struct tep_format_field *last_field =3D syscall_arg_fmt__init_array(sc->a=
rg_fmt, sc->args);
+ bool use_btf;
+ struct tep_format_field *last_field =3D syscall_arg_fmt__init_array(sc->a=
rg_fmt, sc->args,
+ &use_btf);
+
+ if (use_btf && trace->btf =3D=3D NULL)
+ trace__load_vmlinux_btf(trace);
=20
if (last_field)
sc->args_size =3D last_field->offset + last_field->size;
@@ -1883,15 +1959,20 @@ static int trace__read_syscall_info(struct trace *t=
race, int id)
sc->is_exit =3D !strcmp(name, "exit_group") || !strcmp(name, "exit");
sc->is_open =3D !strcmp(name, "open") || !strcmp(name, "openat");
=20
- return syscall__set_arg_fmts(sc);
+ return syscall__set_arg_fmts(trace, sc);
}
=20
-static int evsel__init_tp_arg_scnprintf(struct evsel *evsel)
+static int evsel__init_tp_arg_scnprintf(struct trace *trace, struct evsel =
*evsel)
{
struct syscall_arg_fmt *fmt =3D evsel__syscall_arg_fmt(evsel);
+ bool use_btf;
=20
if (fmt !=3D NULL) {
- syscall_arg_fmt__init_array(fmt, evsel->tp_format->format.fields);
+ syscall_arg_fmt__init_array(fmt, evsel->tp_format->format.fields, &use_b=
tf);
+
+ if (use_btf && trace->btf =3D=3D NULL)
+ trace__load_vmlinux_btf(trace);
+
return 0;
}
=20
@@ -2103,6 +2184,16 @@ static size_t syscall__scnprintf_args(struct syscall=
*sc, char *bf, size_t size,
if (trace->show_arg_names)
printed +=3D scnprintf(bf + printed, size - printed, "%s: ", field->na=
me);
=20
+ if (sc->arg_fmt[arg.idx].is_enum && trace->btf) {
+ size_t p =3D btf_enum_scnprintf(bf + printed, size - printed, val,
+ trace->btf, field->type,
+ &sc->arg_fmt[arg.idx]);
+ if (p) {
+ printed +=3D p;
+ continue;
+ }
+ }
+
printed +=3D syscall_arg_fmt__scnprintf_val(&sc->arg_fmt[arg.idx],
bf + printed, size - printed, &arg, val);
}
@@ -2791,7 +2882,7 @@ static size_t trace__fprintf_tp_fields(struct trace *=
trace, struct evsel *evsel,
val =3D syscall_arg_fmt__mask_val(arg, &syscall_arg, val);
=20
/* Suppress this argument if its value is zero and show_zero property is=
n't set. */
- if (val =3D=3D 0 && !trace->show_zeros && !arg->show_zero)
+ if (val =3D=3D 0 && !trace->show_zeros && !arg->show_zero && !arg->is_en=
um)
continue;
=20
printed +=3D scnprintf(bf + printed, size - printed, "%s", printed ? ", =
" : "");
@@ -2799,6 +2890,15 @@ static size_t trace__fprintf_tp_fields(struct trace =
*trace, struct evsel *evsel,
if (trace->show_arg_names)
printed +=3D scnprintf(bf + printed, size - printed, "%s: ", field->nam=
e);
=20
+ if (arg->is_enum && trace->btf) {
+ size_t p =3D btf_enum_scnprintf(bf + printed, size - printed, val, trac=
e->btf,
+ field->type, arg);
+ if (p) {
+ printed +=3D p;
+ continue;
+ }
+ }
+
printed +=3D syscall_arg_fmt__scnprintf_val(arg, bf + printed, size - pr=
inted, &syscall_arg, val);
}
=20
@@ -4461,8 +4561,9 @@ static void evsel__set_syscall_arg_fmt(struct evsel *=
evsel, const char *name)
}
}
=20
-static int evlist__set_syscall_tp_fields(struct evlist *evlist)
+static int evlist__set_syscall_tp_fields(struct trace *trace)
{
+ struct evlist *evlist =3D trace->evlist;
struct evsel *evsel;
=20
evlist__for_each_entry(evlist, evsel) {
@@ -4470,7 +4571,7 @@ static int evlist__set_syscall_tp_fields(struct evlis=
t *evlist)
continue;
=20
if (strcmp(evsel->tp_format->system, "syscalls")) {
- evsel__init_tp_arg_scnprintf(evsel);
+ evsel__init_tp_arg_scnprintf(trace, evsel);
continue;
}
=20
@@ -4949,7 +5050,7 @@ int cmd_trace(int argc, const char **argv)
=20
if (trace.evlist->core.nr_entries > 0) {
evlist__set_default_evsel_handler(trace.evlist, trace__event_handler);
- if (evlist__set_syscall_tp_fields(trace.evlist)) {
+ if (evlist__set_syscall_tp_fields(&trace)) {
perror("failed to set syscalls:* tracepoint fields");
goto out;
}
--=20
2.45.2
