To support cgroup tracking, add CGROUP event to save a link between cgroup path and inode number. The attr.cgroup bit was also added to enable cgroup tracking from userspace.
This event will be generated when a new cgroup becomes active. Userspace might need to synthesize those events for existing cgroups. As aux_output change is also going on, I just added the bit here as well to remove possible conflicts later. Cc: Tejun Heo <[email protected]> Cc: Li Zefan <[email protected]> Cc: Johannes Weiner <[email protected]> Cc: Adrian Hunter <[email protected]> Signed-off-by: Namhyung Kim <[email protected]> --- include/uapi/linux/perf_event.h | 15 ++++- kernel/events/core.c | 112 ++++++++++++++++++++++++++++++++ 2 files changed, 126 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index 7198ddd0c6b1..cb07c24b715f 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -374,7 +374,9 @@ struct perf_event_attr { namespaces : 1, /* include namespaces data */ ksymbol : 1, /* include ksymbol events */ bpf_event : 1, /* include bpf events */ - __reserved_1 : 33; + aux_output : 1, /* generate AUX records instead of events */ + cgroup : 1, /* include cgroup events */ + __reserved_1 : 31; union { __u32 wakeup_events; /* wakeup every n events */ @@ -999,6 +1001,17 @@ enum perf_event_type { */ PERF_RECORD_BPF_EVENT = 18, + /* + * struct { + * struct perf_event_header header; + * u64 ino; + * u64 path_len; + * char path[]; + * struct sample_id sample_id; + * }; + */ + PERF_RECORD_CGROUP = 19, + PERF_RECORD_MAX, /* non-ABI */ }; diff --git a/kernel/events/core.c b/kernel/events/core.c index 0463c1151bae..d898263db4fc 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -386,6 +386,7 @@ static atomic_t nr_freq_events __read_mostly; static atomic_t nr_switch_events __read_mostly; static atomic_t nr_ksymbol_events __read_mostly; static atomic_t nr_bpf_events __read_mostly; +static atomic_t nr_cgroup_events __read_mostly; static LIST_HEAD(pmus); static DEFINE_MUTEX(pmus_lock); @@ -4314,6 +4315,8 @@ static void unaccount_event(struct perf_event *event) atomic_dec(&nr_comm_events); if (event->attr.namespaces) atomic_dec(&nr_namespaces_events); + if (event->attr.cgroup) + atomic_dec(&nr_cgroup_events); if (event->attr.task) atomic_dec(&nr_task_events); if (event->attr.freq) @@ -7217,6 +7220,106 @@ void perf_event_namespaces(struct task_struct *task) NULL); } +/* + * cgroup tracking + */ +#ifdef CONFIG_CGROUPS + +struct perf_cgroup_event { + char *path; + struct { + struct perf_event_header header; + u64 ino; + u64 path_len; + char path[]; + } event_id; +}; + +static int perf_event_cgroup_match(struct perf_event *event) +{ + return event->attr.cgroup; +} + +static void perf_event_cgroup_output(struct perf_event *event, void *data) +{ + struct perf_cgroup_event *cgroup_event = data; + struct perf_output_handle handle; + struct perf_sample_data sample; + u16 header_size = cgroup_event->event_id.header.size; + int ret; + + if (!perf_event_cgroup_match(event)) + return; + + perf_event_header__init_id(&cgroup_event->event_id.header, + &sample, event); + ret = perf_output_begin(&handle, event, + cgroup_event->event_id.header.size); + if (ret) + goto out; + + perf_output_put(&handle, cgroup_event->event_id); + __output_copy(&handle, cgroup_event->path, + cgroup_event->event_id.path_len); + + perf_event__output_id_sample(event, &handle, &sample); + + perf_output_end(&handle); +out: + cgroup_event->event_id.header.size = header_size; +} + +void perf_event_cgroup(struct cgroup *cgrp) +{ + struct perf_cgroup_event cgroup_event; + char path_enomem[16] = "//enomem"; + char *pathname; + size_t size; + + if (!atomic_read(&nr_cgroup_events)) + return; + + cgroup_event = (struct perf_cgroup_event){ + .event_id = { + .header = { + .type = PERF_RECORD_CGROUP, + .misc = 0, + .size = sizeof(cgroup_event.event_id), + }, + .ino = cgrp->kn->id.ino, + }, + }; + + pathname = kmalloc(PATH_MAX, GFP_KERNEL); + if (pathname == NULL) { + cgroup_event.path = path_enomem; + } else { + /* just to be sure to have enough space for alignment */ + cgroup_path(cgrp, pathname, PATH_MAX - sizeof(u64)); + cgroup_event.path = pathname; + } + + /* + * Since our buffer works in 8 byte units we need to align our string + * size to a multiple of 8. However, we must guarantee the tail end is + * zero'd out to avoid leaking random bits to userspace. + */ + size = strlen(cgroup_event.path) + 1; + while (!IS_ALIGNED(size, sizeof(u64))) + cgroup_event.path[size++] = '\0'; + + cgroup_event.event_id.header.size += size; + cgroup_event.event_id.path_len = size; + + perf_iterate_sb(perf_event_cgroup_output, + &cgroup_event, + NULL); + + kfree(pathname); +} + +#endif + /* * mmap tracking */ @@ -10232,6 +10335,8 @@ static void account_event(struct perf_event *event) atomic_inc(&nr_comm_events); if (event->attr.namespaces) atomic_inc(&nr_namespaces_events); + if (event->attr.cgroup) + atomic_inc(&nr_cgroup_events); if (event->attr.task) atomic_inc(&nr_task_events); if (event->attr.freq) @@ -12186,6 +12291,12 @@ static void perf_cgroup_css_free(struct cgroup_subsys_state *css) kfree(jc); } +static int perf_cgroup_css_online(struct cgroup_subsys_state *css) +{ + perf_event_cgroup(css->cgroup); + return 0; +} + static int __perf_cgroup_move(void *info) { struct task_struct *task = info; @@ -12207,6 +12318,7 @@ static void perf_cgroup_attach(struct cgroup_taskset *tset) struct cgroup_subsys perf_event_cgrp_subsys = { .css_alloc = perf_cgroup_css_alloc, .css_free = perf_cgroup_css_free, + .css_online = perf_cgroup_css_online, .attach = perf_cgroup_attach, /* * Implicitly enable on dfl hierarchy so that perf events can -- 2.23.0.187.g17f5b7556c-goog
