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authorAlexei Starovoitov <ast@fb.com>2016-09-01 18:37:24 -0700
committerDavid S. Miller <davem@davemloft.net>2016-09-02 10:46:44 -0700
commitaa6a5f3cb2b2edc5b9aab0b4fdfdfa9c3b5096a8 (patch)
tree8cf03de3cadf8e080094e1d1c671ada0d85d1ec2 /include
parentfdc15d388d600d5a1599e14c700af105a5b60761 (diff)
perf, bpf: add perf events core support for BPF_PROG_TYPE_PERF_EVENT programs
Allow attaching BPF_PROG_TYPE_PERF_EVENT programs to sw and hw perf events via overflow_handler mechanism. When program is attached the overflow_handlers become stacked. The program acts as a filter. Returning zero from the program means that the normal perf_event_output handler will not be called and sampling event won't be stored in the ring buffer. The overflow_handler_context==NULL is an additional safety check to make sure programs are not attached to hw breakpoints and watchdog in case other checks (that prevent that now anyway) get accidentally relaxed in the future. The program refcnt is incremented in case perf_events are inhereted when target task is forked. Similar to kprobe and tracepoint programs there is no ioctl to detach the program or swap already attached program. The user space expected to close(perf_event_fd) like it does right now for kprobe+bpf. That restriction simplifies the code quite a bit. The invocation of overflow_handler in __perf_event_overflow() is now done via READ_ONCE, since that pointer can be replaced when the program is attached while perf_event itself could have been active already. There is no need to do similar treatment for event->prog, since it's assigned only once before it's accessed. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/linux/bpf.h4
-rw-r--r--include/linux/perf_event.h4
2 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 11134238417d..9a904f63f8c1 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -297,6 +297,10 @@ static inline struct bpf_prog *bpf_prog_add(struct bpf_prog *prog, int i)
static inline void bpf_prog_put(struct bpf_prog *prog)
{
}
+static inline struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog)
+{
+ return ERR_PTR(-EOPNOTSUPP);
+}
#endif /* CONFIG_BPF_SYSCALL */
/* verifier prototypes for helper functions called from eBPF programs */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 97bfe62f30d7..ccb73a58113d 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -679,6 +679,10 @@ struct perf_event {
u64 (*clock)(void);
perf_overflow_handler_t overflow_handler;
void *overflow_handler_context;
+#ifdef CONFIG_BPF_SYSCALL
+ perf_overflow_handler_t orig_overflow_handler;
+ struct bpf_prog *prog;
+#endif
#ifdef CONFIG_EVENT_TRACING
struct trace_event_call *tp_event;