If it runs on an old kernel, perf_event_open would fail because of the
new fields sigtrap and sig_data. Just skipping the test could miss an
actual bug in the kernel.
Let's check BTF if it has the perf_event_attr.sigtrap field.
Cc: Marco Elver <[email protected]>
Cc: Song Liu <[email protected]>
Signed-off-by: Namhyung Kim <[email protected]>
---
tools/perf/tests/sigtrap.c | 46 +++++++++++++++++++++++++++++++++++++-
1 file changed, 45 insertions(+), 1 deletion(-)
diff --git a/tools/perf/tests/sigtrap.c b/tools/perf/tests/sigtrap.c
index e32ece90e164..32f08ce0f2b0 100644
--- a/tools/perf/tests/sigtrap.c
+++ b/tools/perf/tests/sigtrap.c
@@ -16,6 +16,8 @@
#include <sys/syscall.h>
#include <unistd.h>
+#include <bpf/btf.h>
+
#include "cloexec.h"
#include "debug.h"
#include "event.h"
@@ -54,6 +56,42 @@ static struct perf_event_attr make_event_attr(void)
return attr;
}
+static bool attr_has_sigtrap(void)
+{
+ bool ret = false;
+
+#ifdef HAVE_BPF_SKEL
+
+ struct btf *btf;
+ const struct btf_type *t;
+ const struct btf_member *m;
+ const char *name;
+ int i, id;
+
+ /* just assume it doesn't have the field */
+ btf = btf__load_vmlinux_btf();
+ if (btf == NULL)
+ return false;
+
+ id = btf__find_by_name_kind(btf, "perf_event_attr", BTF_KIND_STRUCT);
+ if (id < 0)
+ goto out;
+
+ t = btf__type_by_id(btf, id);
+ for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
+ name = btf__name_by_offset(btf, m->name_off);
+ if (!strcmp(name, "sigtrap")) {
+ ret = true;
+ break;
+ }
+ }
+out:
+ btf__free(btf);
+#endif
+
+ return ret;
+}
+
static void
sigtrap_handler(int signum __maybe_unused, siginfo_t *info, void *ucontext __maybe_unused)
{
@@ -139,7 +177,13 @@ static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __m
fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag());
if (fd < 0) {
- pr_debug("FAILED sys_perf_event_open(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
+ if (attr_has_sigtrap()) {
+ pr_debug("FAILED sys_perf_event_open(): %s\n",
+ str_error_r(errno, sbuf, sizeof(sbuf)));
+ } else {
+ pr_debug("perf_event_attr doesn't have sigtrap\n");
+ ret = TEST_SKIP;
+ }
goto out_restore_sigaction;
}
--
2.37.2.789.g6183377224-goog
On Tue, Sep 6, 2022 at 10:04 PM Namhyung Kim <[email protected]> wrote:
>
> If it runs on an old kernel, perf_event_open would fail because of the
> new fields sigtrap and sig_data. Just skipping the test could miss an
> actual bug in the kernel.
>
> Let's check BTF if it has the perf_event_attr.sigtrap field.
>
> Cc: Marco Elver <[email protected]>
> Cc: Song Liu <[email protected]>
> Signed-off-by: Namhyung Kim <[email protected]>
> ---
> tools/perf/tests/sigtrap.c | 46 +++++++++++++++++++++++++++++++++++++-
> 1 file changed, 45 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/tests/sigtrap.c b/tools/perf/tests/sigtrap.c
> index e32ece90e164..32f08ce0f2b0 100644
> --- a/tools/perf/tests/sigtrap.c
> +++ b/tools/perf/tests/sigtrap.c
> @@ -16,6 +16,8 @@
> #include <sys/syscall.h>
> #include <unistd.h>
>
> +#include <bpf/btf.h>
> +
Do we need "#ifdef HAVE_BPF_SKEL" for the include part?
Other than this, looks good to me.
Acked-by: Song Liu <[email protected]>
> #include "cloexec.h"
> #include "debug.h"
> #include "event.h"
> @@ -54,6 +56,42 @@ static struct perf_event_attr make_event_attr(void)
> return attr;
> }
>
> +static bool attr_has_sigtrap(void)
> +{
> + bool ret = false;
> +
> +#ifdef HAVE_BPF_SKEL
> +
> + struct btf *btf;
> + const struct btf_type *t;
> + const struct btf_member *m;
> + const char *name;
> + int i, id;
> +
> + /* just assume it doesn't have the field */
> + btf = btf__load_vmlinux_btf();
> + if (btf == NULL)
> + return false;
> +
> + id = btf__find_by_name_kind(btf, "perf_event_attr", BTF_KIND_STRUCT);
> + if (id < 0)
> + goto out;
> +
> + t = btf__type_by_id(btf, id);
> + for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
> + name = btf__name_by_offset(btf, m->name_off);
> + if (!strcmp(name, "sigtrap")) {
> + ret = true;
> + break;
> + }
> + }
> +out:
> + btf__free(btf);
> +#endif
> +
> + return ret;
> +}
> +
> static void
> sigtrap_handler(int signum __maybe_unused, siginfo_t *info, void *ucontext __maybe_unused)
> {
> @@ -139,7 +177,13 @@ static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __m
>
> fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag());
> if (fd < 0) {
> - pr_debug("FAILED sys_perf_event_open(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
> + if (attr_has_sigtrap()) {
> + pr_debug("FAILED sys_perf_event_open(): %s\n",
> + str_error_r(errno, sbuf, sizeof(sbuf)));
> + } else {
> + pr_debug("perf_event_attr doesn't have sigtrap\n");
> + ret = TEST_SKIP;
> + }
> goto out_restore_sigaction;
> }
>
> --
> 2.37.2.789.g6183377224-goog
>
Hi Song,
On Tue, Sep 6, 2022 at 10:58 PM Song Liu <[email protected]> wrote:
>
> On Tue, Sep 6, 2022 at 10:04 PM Namhyung Kim <[email protected]> wrote:
> >
> > If it runs on an old kernel, perf_event_open would fail because of the
> > new fields sigtrap and sig_data. Just skipping the test could miss an
> > actual bug in the kernel.
> >
> > Let's check BTF if it has the perf_event_attr.sigtrap field.
> >
> > Cc: Marco Elver <[email protected]>
> > Cc: Song Liu <[email protected]>
> > Signed-off-by: Namhyung Kim <[email protected]>
> > ---
> > tools/perf/tests/sigtrap.c | 46 +++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 45 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/tests/sigtrap.c b/tools/perf/tests/sigtrap.c
> > index e32ece90e164..32f08ce0f2b0 100644
> > --- a/tools/perf/tests/sigtrap.c
> > +++ b/tools/perf/tests/sigtrap.c
> > @@ -16,6 +16,8 @@
> > #include <sys/syscall.h>
> > #include <unistd.h>
> >
> > +#include <bpf/btf.h>
> > +
>
> Do we need "#ifdef HAVE_BPF_SKEL" for the include part?
Right, it'd be better to move it under the #ifdef. Will change.
>
> Other than this, looks good to me.
>
> Acked-by: Song Liu <[email protected]>
Thanks for the review!
Namhyung
On Tue, Sep 06, 2022 at 10:04:07PM -0700, Namhyung Kim wrote:
> If it runs on an old kernel, perf_event_open would fail because of the
> new fields sigtrap and sig_data. Just skipping the test could miss an
> actual bug in the kernel.
>
> Let's check BTF if it has the perf_event_attr.sigtrap field.
>
> Cc: Marco Elver <[email protected]>
> Cc: Song Liu <[email protected]>
> Signed-off-by: Namhyung Kim <[email protected]>
> ---
> tools/perf/tests/sigtrap.c | 46 +++++++++++++++++++++++++++++++++++++-
> 1 file changed, 45 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/tests/sigtrap.c b/tools/perf/tests/sigtrap.c
> index e32ece90e164..32f08ce0f2b0 100644
> --- a/tools/perf/tests/sigtrap.c
> +++ b/tools/perf/tests/sigtrap.c
> @@ -16,6 +16,8 @@
> #include <sys/syscall.h>
> #include <unistd.h>
>
> +#include <bpf/btf.h>
> +
> #include "cloexec.h"
> #include "debug.h"
> #include "event.h"
> @@ -54,6 +56,42 @@ static struct perf_event_attr make_event_attr(void)
> return attr;
> }
>
> +static bool attr_has_sigtrap(void)
> +{
> + bool ret = false;
> +
> +#ifdef HAVE_BPF_SKEL
> +
> + struct btf *btf;
> + const struct btf_type *t;
> + const struct btf_member *m;
> + const char *name;
> + int i, id;
> +
> + /* just assume it doesn't have the field */
> + btf = btf__load_vmlinux_btf();
> + if (btf == NULL)
> + return false;
> +
> + id = btf__find_by_name_kind(btf, "perf_event_attr", BTF_KIND_STRUCT);
> + if (id < 0)
> + goto out;
> +
> + t = btf__type_by_id(btf, id);
> + for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
> + name = btf__name_by_offset(btf, m->name_off);
> + if (!strcmp(name, "sigtrap")) {
> + ret = true;
> + break;
> + }
> + }
> +out:
> + btf__free(btf);
> +#endif
would it be easier to call perf_event_open for simple event with
sigtrap set (and perhaps remove_on_exec) ? perf_copy_attr checks
on reserved fields
jirka
> +
> + return ret;
> +}
> +
> static void
> sigtrap_handler(int signum __maybe_unused, siginfo_t *info, void *ucontext __maybe_unused)
> {
> @@ -139,7 +177,13 @@ static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __m
>
> fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag());
> if (fd < 0) {
> - pr_debug("FAILED sys_perf_event_open(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
> + if (attr_has_sigtrap()) {
> + pr_debug("FAILED sys_perf_event_open(): %s\n",
> + str_error_r(errno, sbuf, sizeof(sbuf)));
> + } else {
> + pr_debug("perf_event_attr doesn't have sigtrap\n");
> + ret = TEST_SKIP;
> + }
> goto out_restore_sigaction;
> }
>
> --
> 2.37.2.789.g6183377224-goog
>
On Wed, Sep 7, 2022 at 1:32 AM Jiri Olsa <[email protected]> wrote:
>
> On Tue, Sep 06, 2022 at 10:04:07PM -0700, Namhyung Kim wrote:
> > If it runs on an old kernel, perf_event_open would fail because of the
> > new fields sigtrap and sig_data. Just skipping the test could miss an
> > actual bug in the kernel.
> >
> > Let's check BTF if it has the perf_event_attr.sigtrap field.
> >
> > Cc: Marco Elver <[email protected]>
> > Cc: Song Liu <[email protected]>
> > Signed-off-by: Namhyung Kim <[email protected]>
> > ---
> > tools/perf/tests/sigtrap.c | 46 +++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 45 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/tests/sigtrap.c b/tools/perf/tests/sigtrap.c
> > index e32ece90e164..32f08ce0f2b0 100644
> > --- a/tools/perf/tests/sigtrap.c
> > +++ b/tools/perf/tests/sigtrap.c
> > @@ -16,6 +16,8 @@
> > #include <sys/syscall.h>
> > #include <unistd.h>
> >
> > +#include <bpf/btf.h>
> > +
> > #include "cloexec.h"
> > #include "debug.h"
> > #include "event.h"
> > @@ -54,6 +56,42 @@ static struct perf_event_attr make_event_attr(void)
> > return attr;
> > }
> >
> > +static bool attr_has_sigtrap(void)
> > +{
> > + bool ret = false;
> > +
> > +#ifdef HAVE_BPF_SKEL
> > +
> > + struct btf *btf;
> > + const struct btf_type *t;
> > + const struct btf_member *m;
> > + const char *name;
> > + int i, id;
> > +
> > + /* just assume it doesn't have the field */
> > + btf = btf__load_vmlinux_btf();
> > + if (btf == NULL)
> > + return false;
> > +
> > + id = btf__find_by_name_kind(btf, "perf_event_attr", BTF_KIND_STRUCT);
> > + if (id < 0)
> > + goto out;
> > +
> > + t = btf__type_by_id(btf, id);
> > + for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
> > + name = btf__name_by_offset(btf, m->name_off);
> > + if (!strcmp(name, "sigtrap")) {
> > + ret = true;
> > + break;
> > + }
> > + }
> > +out:
> > + btf__free(btf);
> > +#endif
>
> would it be easier to call perf_event_open for simple event with
> sigtrap set (and perhaps remove_on_exec) ? perf_copy_attr checks
> on reserved fields
Hmm.. right. we could do that too. But it might still fail if there's a
bug in the path handling in sigtrap even for the simple case. I'm not
sure if it's a realistic concern though. :)
Thanks,
Namhyung
>
>
> > +
> > + return ret;
> > +}
> > +
> > static void
> > sigtrap_handler(int signum __maybe_unused, siginfo_t *info, void *ucontext __maybe_unused)
> > {
> > @@ -139,7 +177,13 @@ static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __m
> >
> > fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag());
> > if (fd < 0) {
> > - pr_debug("FAILED sys_perf_event_open(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
> > + if (attr_has_sigtrap()) {
> > + pr_debug("FAILED sys_perf_event_open(): %s\n",
> > + str_error_r(errno, sbuf, sizeof(sbuf)));
> > + } else {
> > + pr_debug("perf_event_attr doesn't have sigtrap\n");
> > + ret = TEST_SKIP;
> > + }
> > goto out_restore_sigaction;
> > }
> >
> > --
> > 2.37.2.789.g6183377224-goog
> >
On Wed, Sep 7, 2022 at 10:50 AM Namhyung Kim <[email protected]> wrote:
>
> On Wed, Sep 7, 2022 at 1:32 AM Jiri Olsa <[email protected]> wrote:
> >
> > On Tue, Sep 06, 2022 at 10:04:07PM -0700, Namhyung Kim wrote:
> > > If it runs on an old kernel, perf_event_open would fail because of the
> > > new fields sigtrap and sig_data. Just skipping the test could miss an
> > > actual bug in the kernel.
> > >
> > > Let's check BTF if it has the perf_event_attr.sigtrap field.
> > >
> > > Cc: Marco Elver <[email protected]>
> > > Cc: Song Liu <[email protected]>
> > > Signed-off-by: Namhyung Kim <[email protected]>
> > > ---
> > > tools/perf/tests/sigtrap.c | 46 +++++++++++++++++++++++++++++++++++++-
> > > 1 file changed, 45 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/tools/perf/tests/sigtrap.c b/tools/perf/tests/sigtrap.c
> > > index e32ece90e164..32f08ce0f2b0 100644
> > > --- a/tools/perf/tests/sigtrap.c
> > > +++ b/tools/perf/tests/sigtrap.c
> > > @@ -16,6 +16,8 @@
> > > #include <sys/syscall.h>
> > > #include <unistd.h>
> > >
> > > +#include <bpf/btf.h>
> > > +
> > > #include "cloexec.h"
> > > #include "debug.h"
> > > #include "event.h"
> > > @@ -54,6 +56,42 @@ static struct perf_event_attr make_event_attr(void)
> > > return attr;
> > > }
> > >
> > > +static bool attr_has_sigtrap(void)
> > > +{
> > > + bool ret = false;
> > > +
> > > +#ifdef HAVE_BPF_SKEL
> > > +
> > > + struct btf *btf;
> > > + const struct btf_type *t;
> > > + const struct btf_member *m;
> > > + const char *name;
> > > + int i, id;
> > > +
> > > + /* just assume it doesn't have the field */
> > > + btf = btf__load_vmlinux_btf();
> > > + if (btf == NULL)
> > > + return false;
> > > +
> > > + id = btf__find_by_name_kind(btf, "perf_event_attr", BTF_KIND_STRUCT);
> > > + if (id < 0)
> > > + goto out;
> > > +
> > > + t = btf__type_by_id(btf, id);
> > > + for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
> > > + name = btf__name_by_offset(btf, m->name_off);
> > > + if (!strcmp(name, "sigtrap")) {
> > > + ret = true;
> > > + break;
> > > + }
> > > + }
> > > +out:
> > > + btf__free(btf);
> > > +#endif
> >
> > would it be easier to call perf_event_open for simple event with
> > sigtrap set (and perhaps remove_on_exec) ? perf_copy_attr checks
> > on reserved fields
>
> Hmm.. right. we could do that too. But it might still fail if there's a
> bug in the path handling in sigtrap even for the simple case. I'm not
> sure if it's a realistic concern though. :)
I think we can do that when libbpf is not available.
Thanks,
Namhyung
Em Tue, Sep 06, 2022 at 10:04:07PM -0700, Namhyung Kim escreveu:
> If it runs on an old kernel, perf_event_open would fail because of the
> new fields sigtrap and sig_data. Just skipping the test could miss an
> actual bug in the kernel.
>
> Let's check BTF if it has the perf_event_attr.sigtrap field.
>
> Cc: Marco Elver <[email protected]>
> Cc: Song Liu <[email protected]>
> Signed-off-by: Namhyung Kim <[email protected]>
> ---
> tools/perf/tests/sigtrap.c | 46 +++++++++++++++++++++++++++++++++++++-
> 1 file changed, 45 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/tests/sigtrap.c b/tools/perf/tests/sigtrap.c
> index e32ece90e164..32f08ce0f2b0 100644
> --- a/tools/perf/tests/sigtrap.c
> +++ b/tools/perf/tests/sigtrap.c
> @@ -16,6 +16,8 @@
> #include <sys/syscall.h>
> #include <unistd.h>
>
> +#include <bpf/btf.h>
> +
> #include "cloexec.h"
> #include "debug.h"
> #include "event.h"
> @@ -54,6 +56,42 @@ static struct perf_event_attr make_event_attr(void)
> return attr;
> }
>
> +static bool attr_has_sigtrap(void)
> +{
> + bool ret = false;
> +
> +#ifdef HAVE_BPF_SKEL
> +
> + struct btf *btf;
> + const struct btf_type *t;
> + const struct btf_member *m;
> + const char *name;
> + int i, id;
> +
> + /* just assume it doesn't have the field */
> + btf = btf__load_vmlinux_btf();
Cool, at some point we'll probably move this to some other global place,
doing the lazy loading and keeping it in place as probably we'll use it
more often :-)
Waiting for v2.
Thanks for working on this.
- Arnaldo
> + if (btf == NULL)
> + return false;
> +
> + id = btf__find_by_name_kind(btf, "perf_event_attr", BTF_KIND_STRUCT);
> + if (id < 0)
> + goto out;
> +
> + t = btf__type_by_id(btf, id);
> + for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
> + name = btf__name_by_offset(btf, m->name_off);
> + if (!strcmp(name, "sigtrap")) {
> + ret = true;
> + break;
> + }
> + }
> +out:
> + btf__free(btf);
> +#endif
> +
> + return ret;
> +}
> +
> static void
> sigtrap_handler(int signum __maybe_unused, siginfo_t *info, void *ucontext __maybe_unused)
> {
> @@ -139,7 +177,13 @@ static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __m
>
> fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag());
> if (fd < 0) {
> - pr_debug("FAILED sys_perf_event_open(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
> + if (attr_has_sigtrap()) {
> + pr_debug("FAILED sys_perf_event_open(): %s\n",
> + str_error_r(errno, sbuf, sizeof(sbuf)));
> + } else {
> + pr_debug("perf_event_attr doesn't have sigtrap\n");
> + ret = TEST_SKIP;
> + }
> goto out_restore_sigaction;
> }
>
> --
> 2.37.2.789.g6183377224-goog
--
- Arnaldo