2023-03-08 00:30:34

by Ian Rogers

Subject: [PATCH v2] perf lock contention: Fix builtin detection

__has_builtin was passed the macro rather than the actual builtin
feature. The builtin test isn't sufficient and a clang version test
also needs to be performed.

Fixes: 1bece1351c65 ("perf lock contention: Support old rw_semaphore type")
Signed-off-by: Ian Rogers <[email protected]>
---
tools/perf/util/bpf_skel/lock_contention.bpf.c | 8 +++++++-
1 file changed, 7 insertions(+), 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..141b36d13b19 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -182,7 +182,13 @@ 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)
+ /*
+ * 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 is needed for
+ * bpf_core_type_matches.
+ */
+#if __has_builtin(__builtin_preserve_type_info) && __clang_major__ >= 15
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

2023-03-08 01:41:37

by Namhyung Kim

Subject: Re: [PATCH v2] perf lock contention: Fix builtin detection

On Tue, Mar 7, 2023 at 4:30 PM Ian Rogers <[email protected]> wrote:
>
> __has_builtin was passed the macro rather than the actual builtin
> feature. The builtin test isn't sufficient and a clang version test
> also needs to be performed.
>
> Fixes: 1bece1351c65 ("perf lock contention: Support old rw_semaphore type")
> Signed-off-by: Ian Rogers <[email protected]>

Reviewed-by: Namhyung Kim <[email protected]>

Thanks,
Namhyung


> ---
> tools/perf/util/bpf_skel/lock_contention.bpf.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 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..141b36d13b19 100644
> --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> @@ -182,7 +182,13 @@ 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)
> + /*
> + * 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 is needed for
> + * bpf_core_type_matches.
> + */
> +#if __has_builtin(__builtin_preserve_type_info) && __clang_major__ >= 15
> 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
>

2023-03-13 19:15:44

by Arnaldo Carvalho de Melo

Subject: Re: [PATCH v2] perf lock contention: Fix builtin detection

Em Tue, Mar 07, 2023 at 05:41:19PM -0800, Namhyung Kim escreveu:
> On Tue, Mar 7, 2023 at 4:30 PM Ian Rogers <[email protected]> wrote:
> >
> > __has_builtin was passed the macro rather than the actual builtin
> > feature. The builtin test isn't sufficient and a clang version test
> > also needs to be performed.
> >
> > Fixes: 1bece1351c65 ("perf lock contention: Support old rw_semaphore type")
> > Signed-off-by: Ian Rogers <[email protected]>
>
> Reviewed-by: Namhyung Kim <[email protected]>

Thanks, applied.

- Arnaldo


> Thanks,
> Namhyung
>
>
> > ---
> > tools/perf/util/bpf_skel/lock_contention.bpf.c | 8 +++++++-
> > 1 file changed, 7 insertions(+), 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..141b36d13b19 100644
> > --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > @@ -182,7 +182,13 @@ 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)
> > + /*
> > + * 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 is needed for
> > + * bpf_core_type_matches.
> > + */
> > +#if __has_builtin(__builtin_preserve_type_info) && __clang_major__ >= 15
> > 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
> >

--

- Arnaldo