* [PATCH] perf lock contention: Fix builtin detection
@ 2023-03-07 3:21 Ian Rogers
2023-03-07 4:43 ` Namhyung Kim
0 siblings, 1 reply; 4+ messages in thread
From: Ian Rogers @ 2023-03-07 3:21 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Namhyung Kim,
Ian Rogers, Martin KaFai Lau, linux-perf-users, linux-kernel, bpf
__has_builtin was passed the macro rather than the actual builtin
feature.
Fixes: 1bece1351c65 ("perf lock contention: Support old rw_semaphore type")
Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/bpf_skel/lock_contention.bpf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index e6007eaeda1a..e422eee0f942 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -182,7 +182,7 @@ static inline struct task_struct *get_lock_owner(__u64 lock, __u32 flags)
struct mutex *mutex = (void *)lock;
owner = BPF_CORE_READ(mutex, owner.counter);
} else if (flags == LCB_F_READ || flags == LCB_F_WRITE) {
-#if __has_builtin(bpf_core_type_matches)
+#if __has_builtin(__builtin_preserve_type_info)
if (bpf_core_type_matches(struct rw_semaphore___old)) {
struct rw_semaphore___old *rwsem = (void *)lock;
owner = (unsigned long)BPF_CORE_READ(rwsem, owner);
--
2.40.0.rc0.216.gc4246ad0f0-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] perf lock contention: Fix builtin detection
2023-03-07 3:21 [PATCH] perf lock contention: Fix builtin detection Ian Rogers
@ 2023-03-07 4:43 ` Namhyung Kim
2023-03-07 5:56 ` Ian Rogers
0 siblings, 1 reply; 4+ messages in thread
From: Namhyung Kim @ 2023-03-07 4:43 UTC (permalink / raw)
To: Ian Rogers
Cc: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Martin KaFai Lau,
linux-perf-users, linux-kernel, bpf
Hi Ian,
On Mon, Mar 6, 2023 at 7:21 PM Ian Rogers <irogers@google.com> wrote:
>
> __has_builtin was passed the macro rather than the actual builtin
> feature.
Oh, I missed it's a macro define in tools/lib/bpf/bpf_core_read.h file.
Looking at some BPF test codes, it seems you also need to check the
clang compiler version. Please take a look at the file below:
tools/testing/selftests/bpf/progs/test_core_reloc_type_base.c
Thanks,
Namhyung
>
> Fixes: 1bece1351c65 ("perf lock contention: Support old rw_semaphore type")
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/util/bpf_skel/lock_contention.bpf.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> index e6007eaeda1a..e422eee0f942 100644
> --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> @@ -182,7 +182,7 @@ static inline struct task_struct *get_lock_owner(__u64 lock, __u32 flags)
> struct mutex *mutex = (void *)lock;
> owner = BPF_CORE_READ(mutex, owner.counter);
> } else if (flags == LCB_F_READ || flags == LCB_F_WRITE) {
> -#if __has_builtin(bpf_core_type_matches)
> +#if __has_builtin(__builtin_preserve_type_info)
> if (bpf_core_type_matches(struct rw_semaphore___old)) {
> struct rw_semaphore___old *rwsem = (void *)lock;
> owner = (unsigned long)BPF_CORE_READ(rwsem, owner);
> --
> 2.40.0.rc0.216.gc4246ad0f0-goog
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] perf lock contention: Fix builtin detection
2023-03-07 4:43 ` Namhyung Kim
@ 2023-03-07 5:56 ` Ian Rogers
2023-03-07 16:52 ` Namhyung Kim
0 siblings, 1 reply; 4+ messages in thread
From: Ian Rogers @ 2023-03-07 5:56 UTC (permalink / raw)
To: Namhyung Kim, bpf
Cc: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Martin KaFai Lau,
linux-perf-users, linux-kernel
On Mon, Mar 6, 2023 at 8:43 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> Hi Ian,
>
> On Mon, Mar 6, 2023 at 7:21 PM Ian Rogers <irogers@google.com> wrote:
> >
> > __has_builtin was passed the macro rather than the actual builtin
> > feature.
>
> Oh, I missed it's a macro define in tools/lib/bpf/bpf_core_read.h file.
>
> Looking at some BPF test codes, it seems you also need to check the
> clang compiler version. Please take a look at the file below:
>
> tools/testing/selftests/bpf/progs/test_core_reloc_type_base.c
>
> Thanks,
> Namhyung
Hmm..
tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c:
...
/* Support for the BPF_TYPE_MATCHES argument to the
* __builtin_preserve_type_info builtin was added at some point during
* development of clang 15 and it's what we require for this test.
*/
#if __has_builtin(__builtin_preserve_type_info) && __clang_major__ >= 15
...
I'm not sure we need to worry about development clang builds and just
the __has_builtin is cleaner. Perhaps the BPF folks can chime in.
Thanks,
Ian
> >
> > Fixes: 1bece1351c65 ("perf lock contention: Support old rw_semaphore type")
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> > tools/perf/util/bpf_skel/lock_contention.bpf.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > index e6007eaeda1a..e422eee0f942 100644
> > --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > @@ -182,7 +182,7 @@ static inline struct task_struct *get_lock_owner(__u64 lock, __u32 flags)
> > struct mutex *mutex = (void *)lock;
> > owner = BPF_CORE_READ(mutex, owner.counter);
> > } else if (flags == LCB_F_READ || flags == LCB_F_WRITE) {
> > -#if __has_builtin(bpf_core_type_matches)
> > +#if __has_builtin(__builtin_preserve_type_info)
> > if (bpf_core_type_matches(struct rw_semaphore___old)) {
> > struct rw_semaphore___old *rwsem = (void *)lock;
> > owner = (unsigned long)BPF_CORE_READ(rwsem, owner);
> > --
> > 2.40.0.rc0.216.gc4246ad0f0-goog
> >
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] perf lock contention: Fix builtin detection
2023-03-07 5:56 ` Ian Rogers
@ 2023-03-07 16:52 ` Namhyung Kim
0 siblings, 0 replies; 4+ messages in thread
From: Namhyung Kim @ 2023-03-07 16:52 UTC (permalink / raw)
To: Ian Rogers
Cc: bpf, Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Martin KaFai Lau,
linux-perf-users, linux-kernel
On Mon, Mar 6, 2023 at 9:56 PM Ian Rogers <irogers@google.com> wrote:
>
> On Mon, Mar 6, 2023 at 8:43 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > Hi Ian,
> >
> > On Mon, Mar 6, 2023 at 7:21 PM Ian Rogers <irogers@google.com> wrote:
> > >
> > > __has_builtin was passed the macro rather than the actual builtin
> > > feature.
> >
> > Oh, I missed it's a macro define in tools/lib/bpf/bpf_core_read.h file.
> >
> > Looking at some BPF test codes, it seems you also need to check the
> > clang compiler version. Please take a look at the file below:
> >
> > tools/testing/selftests/bpf/progs/test_core_reloc_type_base.c
> >
> > Thanks,
> > Namhyung
>
> Hmm..
>
> tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c:
> ...
> /* Support for the BPF_TYPE_MATCHES argument to the
> * __builtin_preserve_type_info builtin was added at some point during
> * development of clang 15 and it's what we require for this test.
> */
> #if __has_builtin(__builtin_preserve_type_info) && __clang_major__ >= 15
> ...
>
> I'm not sure we need to worry about development clang builds and just
> the __has_builtin is cleaner. Perhaps the BPF folks can chime in.
My understanding is that __builtin_preserve_type_info is supported
before. But clang 15 added BPF_TYPE_MATCHES which is used for
bpf_core_type_matches(). So just checking the builtin would not work.
Thanks,
Namhyung
^ permalink raw reply [flat|nested] 4+ messages in thread
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2023-03-07 3:21 [PATCH] perf lock contention: Fix builtin detection Ian Rogers
2023-03-07 4:43 ` Namhyung Kim
2023-03-07 5:56 ` Ian Rogers
2023-03-07 16:52 ` Namhyung Kim
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