* [PATCH 1/2] perf lock contention: Fix struct rq lock access
@ 2023-04-27 23:48 Namhyung Kim
2023-04-27 23:48 ` [PATCH 2/2] perf lock contention: Rework offset calculation with BPF CO-RE Namhyung Kim
2023-04-28 0:32 ` [PATCH 1/2] perf lock contention: Fix struct rq lock access Ian Rogers
0 siblings, 2 replies; 5+ messages in thread
From: Namhyung Kim @ 2023-04-27 23:48 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo, Jiri Olsa
Cc: Ian Rogers, Adrian Hunter, Peter Zijlstra, Ingo Molnar, LKML,
linux-perf-users, bpf, Andrii Nakryiko, Hao Luo, Song Liu
The BPF CO-RE's ignore suffix rule requires three underscores.
Otherwise it'd fail like below:
$ sudo perf lock contention -ab
libbpf: prog 'collect_lock_syms': BPF program load failed: Invalid argument
libbpf: prog 'collect_lock_syms': -- BEGIN PROG LOAD LOG --
reg type unsupported for arg#0 function collect_lock_syms#380
; int BPF_PROG(collect_lock_syms)
0: (b7) r6 = 0 ; R6_w=0
1: (b7) r7 = 0 ; R7_w=0
2: (b7) r9 = 1 ; R9_w=1
3: <invalid CO-RE relocation>
failed to resolve CO-RE relocation <byte_off> [381] struct rq__new.__lock (0:0 @ offset 0)
Fixes: 0c1228486bef ("perf lock contention: Support pre-5.14 kernels")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/perf/util/bpf_skel/lock_contention.bpf.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index 8911e2a077d8..30c193078bdb 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -418,11 +418,11 @@ int contention_end(u64 *ctx)
extern struct rq runqueues __ksym;
-struct rq__old {
+struct rq___old {
raw_spinlock_t lock;
} __attribute__((preserve_access_index));
-struct rq__new {
+struct rq___new {
raw_spinlock_t __lock;
} __attribute__((preserve_access_index));
@@ -434,8 +434,8 @@ int BPF_PROG(collect_lock_syms)
for (int i = 0; i < MAX_CPUS; i++) {
struct rq *rq = bpf_per_cpu_ptr(&runqueues, i);
- struct rq__new *rq_new = (void *)rq;
- struct rq__old *rq_old = (void *)rq;
+ struct rq___new *rq_new = (void *)rq;
+ struct rq___old *rq_old = (void *)rq;
if (rq == NULL)
break;
--
2.40.1.495.gc816e09b53d-goog
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH 2/2] perf lock contention: Rework offset calculation with BPF CO-RE
2023-04-27 23:48 [PATCH 1/2] perf lock contention: Fix struct rq lock access Namhyung Kim
@ 2023-04-27 23:48 ` Namhyung Kim
2023-04-28 0:32 ` Ian Rogers
2023-04-28 0:32 ` [PATCH 1/2] perf lock contention: Fix struct rq lock access Ian Rogers
1 sibling, 1 reply; 5+ messages in thread
From: Namhyung Kim @ 2023-04-27 23:48 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo, Jiri Olsa
Cc: Ian Rogers, Adrian Hunter, Peter Zijlstra, Ingo Molnar, LKML,
linux-perf-users, bpf, Andrii Nakryiko, Hao Luo, Song Liu,
Andrii Nakryiko
It seems BPF CO-RE reloc doesn't work well with the pattern that gets
the field-offset only. Use offsetof() to make it explicit so that
the compiler would generate the correct code.
Fixes: 0c1228486bef ("perf lock contention: Support pre-5.14 kernels")
Co-developed-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/perf/util/bpf_skel/lock_contention.bpf.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index 30c193078bdb..8d3cfbb3cc65 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -429,21 +429,21 @@ struct rq___new {
SEC("raw_tp/bpf_test_finish")
int BPF_PROG(collect_lock_syms)
{
- __u64 lock_addr;
+ __u64 lock_addr, lock_off;
__u32 lock_flag;
+ if (bpf_core_field_exists(struct rq___new, __lock))
+ lock_off = offsetof(struct rq___new, __lock);
+ else
+ lock_off = offsetof(struct rq___old, lock);
+
for (int i = 0; i < MAX_CPUS; i++) {
struct rq *rq = bpf_per_cpu_ptr(&runqueues, i);
- struct rq___new *rq_new = (void *)rq;
- struct rq___old *rq_old = (void *)rq;
if (rq == NULL)
break;
- if (bpf_core_field_exists(rq_new->__lock))
- lock_addr = (__u64)&rq_new->__lock;
- else
- lock_addr = (__u64)&rq_old->lock;
+ lock_addr = (__u64)(void *)rq + lock_off;
lock_flag = LOCK_CLASS_RQLOCK;
bpf_map_update_elem(&lock_syms, &lock_addr, &lock_flag, BPF_ANY);
}
--
2.40.1.495.gc816e09b53d-goog
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 1/2] perf lock contention: Fix struct rq lock access
2023-04-27 23:48 [PATCH 1/2] perf lock contention: Fix struct rq lock access Namhyung Kim
2023-04-27 23:48 ` [PATCH 2/2] perf lock contention: Rework offset calculation with BPF CO-RE Namhyung Kim
@ 2023-04-28 0:32 ` Ian Rogers
2023-04-29 1:27 ` Arnaldo Carvalho de Melo
1 sibling, 1 reply; 5+ messages in thread
From: Ian Rogers @ 2023-04-28 0:32 UTC (permalink / raw)
To: Namhyung Kim
Cc: Arnaldo Carvalho de Melo, Jiri Olsa, Adrian Hunter,
Peter Zijlstra, Ingo Molnar, LKML, linux-perf-users, bpf,
Andrii Nakryiko, Hao Luo, Song Liu
On Thu, Apr 27, 2023 at 4:48 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> The BPF CO-RE's ignore suffix rule requires three underscores.
> Otherwise it'd fail like below:
>
> $ sudo perf lock contention -ab
> libbpf: prog 'collect_lock_syms': BPF program load failed: Invalid argument
> libbpf: prog 'collect_lock_syms': -- BEGIN PROG LOAD LOG --
> reg type unsupported for arg#0 function collect_lock_syms#380
> ; int BPF_PROG(collect_lock_syms)
> 0: (b7) r6 = 0 ; R6_w=0
> 1: (b7) r7 = 0 ; R7_w=0
> 2: (b7) r9 = 1 ; R9_w=1
> 3: <invalid CO-RE relocation>
> failed to resolve CO-RE relocation <byte_off> [381] struct rq__new.__lock (0:0 @ offset 0)
>
> Fixes: 0c1228486bef ("perf lock contention: Support pre-5.14 kernels")
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Thanks,
Ian
> ---
> tools/perf/util/bpf_skel/lock_contention.bpf.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> index 8911e2a077d8..30c193078bdb 100644
> --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> @@ -418,11 +418,11 @@ int contention_end(u64 *ctx)
>
> extern struct rq runqueues __ksym;
>
> -struct rq__old {
> +struct rq___old {
> raw_spinlock_t lock;
> } __attribute__((preserve_access_index));
>
> -struct rq__new {
> +struct rq___new {
> raw_spinlock_t __lock;
> } __attribute__((preserve_access_index));
>
> @@ -434,8 +434,8 @@ int BPF_PROG(collect_lock_syms)
>
> for (int i = 0; i < MAX_CPUS; i++) {
> struct rq *rq = bpf_per_cpu_ptr(&runqueues, i);
> - struct rq__new *rq_new = (void *)rq;
> - struct rq__old *rq_old = (void *)rq;
> + struct rq___new *rq_new = (void *)rq;
> + struct rq___old *rq_old = (void *)rq;
>
> if (rq == NULL)
> break;
> --
> 2.40.1.495.gc816e09b53d-goog
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] perf lock contention: Rework offset calculation with BPF CO-RE
2023-04-27 23:48 ` [PATCH 2/2] perf lock contention: Rework offset calculation with BPF CO-RE Namhyung Kim
@ 2023-04-28 0:32 ` Ian Rogers
0 siblings, 0 replies; 5+ messages in thread
From: Ian Rogers @ 2023-04-28 0:32 UTC (permalink / raw)
To: Namhyung Kim
Cc: Arnaldo Carvalho de Melo, Jiri Olsa, Adrian Hunter,
Peter Zijlstra, Ingo Molnar, LKML, linux-perf-users, bpf,
Andrii Nakryiko, Hao Luo, Song Liu, Andrii Nakryiko
On Thu, Apr 27, 2023 at 4:48 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> It seems BPF CO-RE reloc doesn't work well with the pattern that gets
> the field-offset only. Use offsetof() to make it explicit so that
> the compiler would generate the correct code.
>
> Fixes: 0c1228486bef ("perf lock contention: Support pre-5.14 kernels")
> Co-developed-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Thanks,
Ian
> ---
> tools/perf/util/bpf_skel/lock_contention.bpf.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> index 30c193078bdb..8d3cfbb3cc65 100644
> --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> @@ -429,21 +429,21 @@ struct rq___new {
> SEC("raw_tp/bpf_test_finish")
> int BPF_PROG(collect_lock_syms)
> {
> - __u64 lock_addr;
> + __u64 lock_addr, lock_off;
> __u32 lock_flag;
>
> + if (bpf_core_field_exists(struct rq___new, __lock))
> + lock_off = offsetof(struct rq___new, __lock);
> + else
> + lock_off = offsetof(struct rq___old, lock);
> +
> for (int i = 0; i < MAX_CPUS; i++) {
> struct rq *rq = bpf_per_cpu_ptr(&runqueues, i);
> - struct rq___new *rq_new = (void *)rq;
> - struct rq___old *rq_old = (void *)rq;
>
> if (rq == NULL)
> break;
>
> - if (bpf_core_field_exists(rq_new->__lock))
> - lock_addr = (__u64)&rq_new->__lock;
> - else
> - lock_addr = (__u64)&rq_old->lock;
> + lock_addr = (__u64)(void *)rq + lock_off;
> lock_flag = LOCK_CLASS_RQLOCK;
> bpf_map_update_elem(&lock_syms, &lock_addr, &lock_flag, BPF_ANY);
> }
> --
> 2.40.1.495.gc816e09b53d-goog
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 1/2] perf lock contention: Fix struct rq lock access
2023-04-28 0:32 ` [PATCH 1/2] perf lock contention: Fix struct rq lock access Ian Rogers
@ 2023-04-29 1:27 ` Arnaldo Carvalho de Melo
0 siblings, 0 replies; 5+ messages in thread
From: Arnaldo Carvalho de Melo @ 2023-04-29 1:27 UTC (permalink / raw)
To: Ian Rogers
Cc: Namhyung Kim, Jiri Olsa, Adrian Hunter, Peter Zijlstra,
Ingo Molnar, LKML, linux-perf-users, bpf, Andrii Nakryiko,
Hao Luo, Song Liu
Em Thu, Apr 27, 2023 at 05:32:08PM -0700, Ian Rogers escreveu:
> On Thu, Apr 27, 2023 at 4:48 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > The BPF CO-RE's ignore suffix rule requires three underscores.
> > Otherwise it'd fail like below:
> >
> > $ sudo perf lock contention -ab
> > libbpf: prog 'collect_lock_syms': BPF program load failed: Invalid argument
> > libbpf: prog 'collect_lock_syms': -- BEGIN PROG LOAD LOG --
> > reg type unsupported for arg#0 function collect_lock_syms#380
> > ; int BPF_PROG(collect_lock_syms)
> > 0: (b7) r6 = 0 ; R6_w=0
> > 1: (b7) r7 = 0 ; R7_w=0
> > 2: (b7) r9 = 1 ; R9_w=1
> > 3: <invalid CO-RE relocation>
> > failed to resolve CO-RE relocation <byte_off> [381] struct rq__new.__lock (0:0 @ offset 0)
> >
> > Fixes: 0c1228486bef ("perf lock contention: Support pre-5.14 kernels")
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
>
> Acked-by: Ian Rogers <irogers@google.com>
Thanks, applied the series.
- Arnaldo
> Thanks,
> Ian
>
> > ---
> > tools/perf/util/bpf_skel/lock_contention.bpf.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > index 8911e2a077d8..30c193078bdb 100644
> > --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > @@ -418,11 +418,11 @@ int contention_end(u64 *ctx)
> >
> > extern struct rq runqueues __ksym;
> >
> > -struct rq__old {
> > +struct rq___old {
> > raw_spinlock_t lock;
> > } __attribute__((preserve_access_index));
> >
> > -struct rq__new {
> > +struct rq___new {
> > raw_spinlock_t __lock;
> > } __attribute__((preserve_access_index));
> >
> > @@ -434,8 +434,8 @@ int BPF_PROG(collect_lock_syms)
> >
> > for (int i = 0; i < MAX_CPUS; i++) {
> > struct rq *rq = bpf_per_cpu_ptr(&runqueues, i);
> > - struct rq__new *rq_new = (void *)rq;
> > - struct rq__old *rq_old = (void *)rq;
> > + struct rq___new *rq_new = (void *)rq;
> > + struct rq___old *rq_old = (void *)rq;
> >
> > if (rq == NULL)
> > break;
> > --
> > 2.40.1.495.gc816e09b53d-goog
> >
--
- Arnaldo
^ permalink raw reply [flat|nested] 5+ messages in thread
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Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2023-04-27 23:48 [PATCH 1/2] perf lock contention: Fix struct rq lock access Namhyung Kim
2023-04-27 23:48 ` [PATCH 2/2] perf lock contention: Rework offset calculation with BPF CO-RE Namhyung Kim
2023-04-28 0:32 ` Ian Rogers
2023-04-28 0:32 ` [PATCH 1/2] perf lock contention: Fix struct rq lock access Ian Rogers
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