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authorYonghong Song <yhs@fb.com>2017-10-23 23:53:08 -0700
committerDavid S. Miller <davem@davemloft.net>2017-10-25 10:47:47 +0900
commite87c6bc3852b981e71c757be20771546ce9f76f3 (patch)
treebad3be630137d8e873f4ad5a1ea77b4aa1853184 /kernel/events
parent0b4c6841fee03e096b735074a0c4aab3a8e92986 (diff)
downloadop-kernel-dev-e87c6bc3852b981e71c757be20771546ce9f76f3.zip
op-kernel-dev-e87c6bc3852b981e71c757be20771546ce9f76f3.tar.gz
bpf: permit multiple bpf attachments for a single perf event
This patch enables multiple bpf attachments for a kprobe/uprobe/tracepoint single trace event. Each trace_event keeps a list of attached perf events. When an event happens, all attached bpf programs will be executed based on the order of attachment. A global bpf_event_mutex lock is introduced to protect prog_array attaching and detaching. An alternative will be introduce a mutex lock in every trace_event_call structure, but it takes a lot of extra memory. So a global bpf_event_mutex lock is a good compromise. The bpf prog detachment involves allocation of memory. If the allocation fails, a dummy do-nothing program will replace to-be-detached program in-place. Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/core.c26
1 files changed, 8 insertions, 18 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9f78a682..9660ee6 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7954,11 +7954,9 @@ void perf_trace_run_bpf_submit(void *raw_data, int size, int rctx,
struct pt_regs *regs, struct hlist_head *head,
struct task_struct *task)
{
- struct bpf_prog *prog = call->prog;
-
- if (prog) {
+ if (bpf_prog_array_valid(call)) {
*(struct pt_regs **)raw_data = regs;
- if (!trace_call_bpf(prog, raw_data) || hlist_empty(head)) {
+ if (!trace_call_bpf(call, raw_data) || hlist_empty(head)) {
perf_swevent_put_recursion_context(rctx);
return;
}
@@ -8147,13 +8145,11 @@ static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd)
{
bool is_kprobe, is_tracepoint, is_syscall_tp;
struct bpf_prog *prog;
+ int ret;
if (event->attr.type != PERF_TYPE_TRACEPOINT)
return perf_event_set_bpf_handler(event, prog_fd);
- if (event->tp_event->prog)
- return -EEXIST;
-
is_kprobe = event->tp_event->flags & TRACE_EVENT_FL_UKPROBE;
is_tracepoint = event->tp_event->flags & TRACE_EVENT_FL_TRACEPOINT;
is_syscall_tp = is_syscall_trace_event(event->tp_event);
@@ -8181,26 +8177,20 @@ static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd)
return -EACCES;
}
}
- event->tp_event->prog = prog;
- event->tp_event->bpf_prog_owner = event;
- return 0;
+ ret = perf_event_attach_bpf_prog(event, prog);
+ if (ret)
+ bpf_prog_put(prog);
+ return ret;
}
static void perf_event_free_bpf_prog(struct perf_event *event)
{
- struct bpf_prog *prog;
-
if (event->attr.type != PERF_TYPE_TRACEPOINT) {
perf_event_free_bpf_handler(event);
return;
}
-
- prog = event->tp_event->prog;
- if (prog && event->tp_event->bpf_prog_owner == event) {
- event->tp_event->prog = NULL;
- bpf_prog_put(prog);
- }
+ perf_event_detach_bpf_prog(event);
}
#else
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