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perf tools: Get a perf cgroup more portably in BPF

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The perf_event_cgrp_id can be different on other configurations.

To be more portable as CO-RE, it needs to get the cgroup subsys id using
the bpf_core_enum_value() helper.

Suggested-by: Ian Rogers <irogers@google.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20220923063205.772936-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Namhyung Kim 2022-09-22 23:32:05 -07:00 committed by Arnaldo Carvalho de Melo
parent f76349cf41
commit e42c9c54f2
2 changed files with 24 additions and 5 deletions
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11
tools/perf/util/bpf_skel/bperf_cgroup.bpf.c
View File

@ -48,6 +48,7 @@ const volatile __u32 num_cpus = 1;
int enabled = 0;
int use_cgroup_v2 = 0;
int perf_subsys_id = -1;
static inline int get_cgroup_v1_idx(__u32 *cgrps, int size)
{
@ -58,7 +59,15 @@ static inline int get_cgroup_v1_idx(__u32 *cgrps, int size)
int level;
int cnt;
cgrp = BPF_CORE_READ(p, cgroups, subsys[perf_event_cgrp_id], cgroup);
if (perf_subsys_id == -1) {
#if __has_builtin(__builtin_preserve_enum_value)
perf_subsys_id = bpf_core_enum_value(enum cgroup_subsys_id,
perf_event_cgrp_id);
#else
perf_subsys_id = perf_event_cgrp_id;
#endif
}
cgrp = BPF_CORE_READ(p, cgroups, subsys[perf_subsys_id], cgroup);
level = BPF_CORE_READ(cgrp, level);
for (cnt = 0; i < MAX_LEVELS; i++) {

18
tools/perf/util/bpf_skel/off_cpu.bpf.c
View File

@ -94,6 +94,8 @@ const volatile bool has_prev_state = false;
const volatile bool needs_cgroup = false;
const volatile bool uses_cgroup_v1 = false;
int perf_subsys_id = -1;
/*
* Old kernel used to call it task_struct->state and now it's '__state'.
* Use BPF CO-RE "ignored suffix rule" to deal with it like below:
@ -119,11 +121,19 @@ static inline __u64 get_cgroup_id(struct task_struct *t)
{
struct cgroup *cgrp;
if (uses_cgroup_v1)
cgrp = BPF_CORE_READ(t, cgroups, subsys[perf_event_cgrp_id], cgroup);
else
cgrp = BPF_CORE_READ(t, cgroups, dfl_cgrp);
if (!uses_cgroup_v1)
return BPF_CORE_READ(t, cgroups, dfl_cgrp, kn, id);
if (perf_subsys_id == -1) {
#if __has_builtin(__builtin_preserve_enum_value)
perf_subsys_id = bpf_core_enum_value(enum cgroup_subsys_id,
perf_event_cgrp_id);
#else
perf_subsys_id = perf_event_cgrp_id;
#endif
}
cgrp = BPF_CORE_READ(t, cgroups, subsys[perf_subsys_id], cgroup);
return BPF_CORE_READ(cgrp, kn, id);
}