diff options
| -rw-r--r-- | include/linux/perf_event.h | 2 | ||||
| -rw-r--r-- | include/uapi/linux/perf_event.h | 6 | ||||
| -rw-r--r-- | kernel/bpf/stackmap.c | 2 | ||||
| -rw-r--r-- | kernel/events/callchain.c | 14 | ||||
| -rw-r--r-- | kernel/events/core.c | 5 |
5 files changed, 23 insertions, 6 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 6b87be908790..0e43355c7aad 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1076,7 +1076,7 @@ extern void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct extern struct perf_callchain_entry * get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user, u32 max_stack, bool crosstask, bool add_mark); -extern int get_callchain_buffers(void); +extern int get_callchain_buffers(int max_stack); extern void put_callchain_buffers(void); extern int sysctl_perf_event_max_stack; diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index 36ce552cf6a9..c66a485a24ac 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -276,6 +276,9 @@ enum perf_event_read_format { /* * Hardware event_id to monitor via a performance monitoring event: + * + * @sample_max_stack: Max number of frame pointers in a callchain, + * should be < /proc/sys/kernel/perf_event_max_stack */ struct perf_event_attr { @@ -385,7 +388,8 @@ struct perf_event_attr { * Wakeup watermark for AUX area */ __u32 aux_watermark; - __u32 __reserved_2; /* align to __u64 */ + __u16 sample_max_stack; + __u16 __reserved_2; /* align to __u64 */ }; #define perf_flags(attr) (*(&(attr)->read_format + 1)) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index a82d7605db3f..f1de5c1a2af6 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -99,7 +99,7 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr) if (err) goto free_smap; - err = get_callchain_buffers(); + err = get_callchain_buffers(sysctl_perf_event_max_stack); if (err) goto free_smap; diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c index 179ef4640964..e9fdb5203de5 100644 --- a/kernel/events/callchain.c +++ b/kernel/events/callchain.c @@ -104,7 +104,7 @@ fail: return -ENOMEM; } -int get_callchain_buffers(void) +int get_callchain_buffers(int event_max_stack) { int err = 0; int count; @@ -121,6 +121,15 @@ int get_callchain_buffers(void) /* If the allocation failed, give up */ if (!callchain_cpus_entries) err = -ENOMEM; + /* + * If requesting per event more than the global cap, + * return a different error to help userspace figure + * this out. + * + * And also do it here so that we have &callchain_mutex held. + */ + if (event_max_stack > sysctl_perf_event_max_stack) + err = -EOVERFLOW; goto exit; } @@ -174,11 +183,12 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs) bool user = !event->attr.exclude_callchain_user; /* Disallow cross-task user callchains. */ bool crosstask = event->ctx->task && event->ctx->task != current; + const u32 max_stack = event->attr.sample_max_stack; if (!kernel && !user) return NULL; - return get_perf_callchain(regs, 0, kernel, user, sysctl_perf_event_max_stack, crosstask, true); + return get_perf_callchain(regs, 0, kernel, user, max_stack, crosstask, true); } struct perf_callchain_entry * diff --git a/kernel/events/core.c b/kernel/events/core.c index 050a290c72c7..79363f298445 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8843,7 +8843,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, if (!event->parent) { if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) { - err = get_callchain_buffers(); + err = get_callchain_buffers(attr->sample_max_stack); if (err) goto err_addr_filters; } @@ -9165,6 +9165,9 @@ SYSCALL_DEFINE5(perf_event_open, return -EINVAL; } + if (!attr.sample_max_stack) + attr.sample_max_stack = sysctl_perf_event_max_stack; + /* * In cgroup mode, the pid argument is used to pass the fd * opened to the cgroup directory in cgroupfs. The cpu argument |