Commit f21cb520 authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo

perf stat: Support old kernels for bperf cgroup counting

The recent change in the cgroup will break the backward compatiblity in
the BPF program.  It should support both old and new kernels using BPF
CO-RE technique.

Like the task_struct->__state handling in the offcpu analysis, we can
check the field name in the cgroup struct.
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: bpf@vger.kernel.org
Cc: cgroups@vger.kernel.org
Cc: zefan li <lizefan.x@bytedance.com>
Link: http://lore.kernel.org/lkml/20221011052808.282394-1-namhyung@kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 9c9155a3
......@@ -43,6 +43,18 @@ struct {
__uint(value_size, sizeof(struct bpf_perf_event_value));
} cgrp_readings SEC(".maps");
/* new kernel cgroup definition */
struct cgroup___new {
int level;
struct cgroup *ancestors[];
} __attribute__((preserve_access_index));
/* old kernel cgroup definition */
struct cgroup___old {
int level;
u64 ancestor_ids[];
} __attribute__((preserve_access_index));
const volatile __u32 num_events = 1;
const volatile __u32 num_cpus = 1;
......@@ -50,6 +62,21 @@ int enabled = 0;
int use_cgroup_v2 = 0;
int perf_subsys_id = -1;
static inline __u64 get_cgroup_v1_ancestor_id(struct cgroup *cgrp, int level)
{
/* recast pointer to capture new type for compiler */
struct cgroup___new *cgrp_new = (void *)cgrp;
if (bpf_core_field_exists(cgrp_new->ancestors)) {
return BPF_CORE_READ(cgrp_new, ancestors[level], kn, id);
} else {
/* recast pointer to capture old type for compiler */
struct cgroup___old *cgrp_old = (void *)cgrp;
return BPF_CORE_READ(cgrp_old, ancestor_ids[level]);
}
}
static inline int get_cgroup_v1_idx(__u32 *cgrps, int size)
{
struct task_struct *p = (void *)bpf_get_current_task();
......@@ -77,7 +104,7 @@ static inline int get_cgroup_v1_idx(__u32 *cgrps, int size)
break;
// convert cgroup-id to a map index
cgrp_id = BPF_CORE_READ(cgrp, ancestors[i], kn, id);
cgrp_id = get_cgroup_v1_ancestor_id(cgrp, i);
elem = bpf_map_lookup_elem(&cgrp_idx, &cgrp_id);
if (!elem)
continue;
......
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