[tip:perf/urgent] perf/ftrace: Fix double traces of perf on ftrace:function

From: tip-bot for Zhou Chengming
Date: Tue Aug 29 2017 - 09:10:32 EST

Commit-ID: 75e8387685f6c65feb195a4556110b58f852b848
Gitweb: http://git.kernel.org/tip/75e8387685f6c65feb195a4556110b58f852b848
Author: Zhou Chengming <zhouchengming1@xxxxxxxxxx>
AuthorDate: Fri, 25 Aug 2017 21:49:37 +0800
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 29 Aug 2017 13:29:29 +0200

perf/ftrace: Fix double traces of perf on ftrace:function

When running perf on the ftrace:function tracepoint, there is a bug
which can be reproduced by:

perf record -e ftrace:function -a sleep 20 &
perf record -e ftrace:function ls
perf script

ls 10304 [005] 171.853235: ftrace:function:
perf_output_begin
ls 10304 [005] 171.853237: ftrace:function:
perf_output_begin
ls 10304 [005] 171.853239: ftrace:function:
task_tgid_nr_ns
ls 10304 [005] 171.853240: ftrace:function:
task_tgid_nr_ns
ls 10304 [005] 171.853242: ftrace:function:
__task_pid_nr_ns
ls 10304 [005] 171.853244: ftrace:function:
__task_pid_nr_ns

We can see that all the function traces are doubled.

The problem is caused by the inconsistency of the register
function perf_ftrace_event_register() with the probe function
perf_ftrace_function_call(). The former registers one probe
for every perf_event. And the latter handles all perf_events
on the current cpu. So when two perf_events on the current cpu,
the traces of them will be doubled.

So this patch adds an extra parameter "event" for perf_tp_event,
only send sample data to this event when it's not NULL.

Signed-off-by: Zhou Chengming <zhouchengming1@xxxxxxxxxx>
Reviewed-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Acked-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: acme@xxxxxxxxxx
Cc: alexander.shishkin@xxxxxxxxxxxxxxx
Cc: huawei.libin@xxxxxxxxxx
Link: http://lkml.kernel.org/r/1503668977-12526-1-git-send-email-zhouchengming1@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/perf_event.h | 2 +-
include/linux/trace_events.h | 4 ++--
kernel/events/core.c | 13 +++++++++----
kernel/trace/trace_event_perf.c | 4 +++-
kernel/trace/trace_kprobe.c | 4 ++--
kernel/trace/trace_syscalls.c | 4 ++--
kernel/trace/trace_uprobe.c | 2 +-
7 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index b14095b..c00cd4b 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1201,7 +1201,7 @@ extern void perf_event_init(void);
extern void perf_tp_event(u16 event_type, u64 count, void *record,
int entry_size, struct pt_regs *regs,
struct hlist_head *head, int rctx,
- struct task_struct *task);
+ struct task_struct *task, struct perf_event *event);
extern void perf_bp_event(struct perf_event *event, void *data);

#ifndef perf_misc_flags
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 536c80f..5012b52 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -508,9 +508,9 @@ void perf_trace_run_bpf_submit(void *raw_data, int size, int rctx,
static inline void
perf_trace_buf_submit(void *raw_data, int size, int rctx, u16 type,
u64 count, struct pt_regs *regs, void *head,
- struct task_struct *task)
+ struct task_struct *task, struct perf_event *event)
{
- perf_tp_event(type, count, raw_data, size, regs, head, rctx, task);
+ perf_tp_event(type, count, raw_data, size, regs, head, rctx, task, event);
}
#endif

diff --git a/kernel/events/core.c b/kernel/events/core.c
index ce131d2..03ac9c8 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7906,16 +7906,15 @@ void perf_trace_run_bpf_submit(void *raw_data, int size, int rctx,
}
}
perf_tp_event(call->event.type, count, raw_data, size, regs, head,
- rctx, task);
+ rctx, task, NULL);
}
EXPORT_SYMBOL_GPL(perf_trace_run_bpf_submit);

void perf_tp_event(u16 event_type, u64 count, void *record, int entry_size,
struct pt_regs *regs, struct hlist_head *head, int rctx,
- struct task_struct *task)
+ struct task_struct *task, struct perf_event *event)
{
struct perf_sample_data data;
- struct perf_event *event;

struct perf_raw_record raw = {
.frag = {
@@ -7929,9 +7928,15 @@ void perf_tp_event(u16 event_type, u64 count, void *record, int entry_size,

perf_trace_buf_update(record, event_type);

- hlist_for_each_entry_rcu(event, head, hlist_entry) {
+ /* Use the given event instead of the hlist */
+ if (event) {
if (perf_tp_event_match(event, &data, regs))
perf_swevent_event(event, count, &data, regs);
+ } else {
+ hlist_for_each_entry_rcu(event, head, hlist_entry) {
+ if (perf_tp_event_match(event, &data, regs))
+ perf_swevent_event(event, count, &data, regs);
+ }
}

/*
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 562fa69..13ba2d3 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -306,6 +306,7 @@ static void
perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *ops, struct pt_regs *pt_regs)
{
+ struct perf_event *event;
struct ftrace_entry *entry;
struct hlist_head *head;
struct pt_regs regs;
@@ -329,8 +330,9 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,

entry->ip = ip;
entry->parent_ip = parent_ip;
+ event = container_of(ops, struct perf_event, ftrace_ops);
perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, TRACE_FN,
- 1, &regs, head, NULL);
+ 1, &regs, head, NULL, event);

#undef ENTRY_SIZE
}
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index c9b5aa1..8a907e1 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1200,7 +1200,7 @@ kprobe_perf_func(struct trace_kprobe *tk, struct pt_regs *regs)
memset(&entry[1], 0, dsize);
store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
- head, NULL);
+ head, NULL, NULL);
}
NOKPROBE_SYMBOL(kprobe_perf_func);

@@ -1236,7 +1236,7 @@ kretprobe_perf_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
entry->ret_ip = (unsigned long)ri->ret_addr;
store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
- head, NULL);
+ head, NULL, NULL);
}
NOKPROBE_SYMBOL(kretprobe_perf_func);
#endif /* CONFIG_PERF_EVENTS */
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 5e10395..74d9a86 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -596,7 +596,7 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
(unsigned long *)&rec->args);
perf_trace_buf_submit(rec, size, rctx,
sys_data->enter_event->event.type, 1, regs,
- head, NULL);
+ head, NULL, NULL);
}

static int perf_sysenter_enable(struct trace_event_call *call)
@@ -667,7 +667,7 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
rec->nr = syscall_nr;
rec->ret = syscall_get_return_value(current, regs);
perf_trace_buf_submit(rec, size, rctx, sys_data->exit_event->event.type,
- 1, regs, head, NULL);
+ 1, regs, head, NULL, NULL);
}

static int perf_sysexit_enable(struct trace_event_call *call)
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index a7581fe..4525e02 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -1156,7 +1156,7 @@ static void __uprobe_perf_func(struct trace_uprobe *tu,
}

perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
- head, NULL);
+ head, NULL, NULL);
out:
preempt_enable();
}