Merge branch 'perf/core' into perf/probes

[safe/jmp/linux-2.6] / include / trace / ftrace.h

diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index a7f9460..4945d1c 100644 (file)
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -649,6 +649,7 @@ __attribute__((section("_ftrace_events"))) event_##call = {         \
  *     struct ftrace_event_call *event_call = &event_<call>;
  *     extern void perf_tp_event(int, u64, u64, void *, int);
  *     struct ftrace_raw_##call *entry;
+ *     struct perf_trace_buf *trace_buf;
  *     u64 __addr = 0, __count = 1;
  *     unsigned long irq_flags;
  *     struct trace_entry *ent;
@@ -673,14 +674,25 @@ __attribute__((section("_ftrace_events"))) event_##call = {               \
  *     __cpu = smp_processor_id();
  *
  *     if (in_nmi())
- *             raw_data = rcu_dereference(trace_profile_buf_nmi);
+ *             trace_buf = rcu_dereference(perf_trace_buf_nmi);
  *     else
- *             raw_data = rcu_dereference(trace_profile_buf);
+ *             trace_buf = rcu_dereference(perf_trace_buf);
  *
- *     if (!raw_data)
+ *     if (!trace_buf)
  *             goto end;
  *
- *     raw_data = per_cpu_ptr(raw_data, __cpu);
+ *     trace_buf = per_cpu_ptr(trace_buf, __cpu);
+ *
+ *     // Avoid recursion from perf that could mess up the buffer
+ *     if (trace_buf->recursion++)
+ *             goto end_recursion;
+ *
+ *     raw_data = trace_buf->buf;
+ *
+ *     // Make recursion update visible before entering perf_tp_event
+ *     // so that we protect from perf recursions.
+ *
+ *     barrier();
  *
  *     //zero dead bytes from alignment to avoid stack leak to userspace:
  *     *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL;
@@ -713,8 +725,9 @@ static void ftrace_profile_##call(proto)                            \
 {                                                                      \
        struct ftrace_data_offsets_##call __maybe_unused __data_offsets;\
        struct ftrace_event_call *event_call = &event_##call;           \
-       extern void perf_tp_event(int, u64, u64, void *, int);  \
+       extern void perf_tp_event(int, u64, u64, void *, int);          \
        struct ftrace_raw_##call *entry;                                \
+       struct perf_trace_buf *trace_buf;                               \
        u64 __addr = 0, __count = 1;                                    \
        unsigned long irq_flags;                                        \
        struct trace_entry *ent;                                        \
@@ -739,14 +752,20 @@ static void ftrace_profile_##call(proto)                          \
        __cpu = smp_processor_id();                                     \
                                                                        \
        if (in_nmi())                                                   \
-               raw_data = rcu_dereference(trace_profile_buf_nmi);              \
+               trace_buf = rcu_dereference(perf_trace_buf_nmi);        \
        else                                                            \
-               raw_data = rcu_dereference(trace_profile_buf);          \
+               trace_buf = rcu_dereference(perf_trace_buf);            \
                                                                        \
-       if (!raw_data)                                                  \
+       if (!trace_buf)                                                 \
                goto end;                                               \
                                                                        \
-       raw_data = per_cpu_ptr(raw_data, __cpu);                        \
+       trace_buf = per_cpu_ptr(trace_buf, __cpu);                      \
+       if (trace_buf->recursion++)                                     \
+               goto end_recursion;                                     \
+                                                                       \
+       barrier();                                                      \
+                                                                       \
+       raw_data = trace_buf->buf;                                      \
                                                                        \
        *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL;         \
        entry = (struct ftrace_raw_##call *)raw_data;                   \
@@ -761,6 +780,8 @@ static void ftrace_profile_##call(proto)                            \
        perf_tp_event(event_call->id, __addr, __count, entry,           \
                             __entry_size);                             \
                                                                        \
+end_recursion:                                                         \
+       trace_buf->recursion--;                                         \
 end:                                                                   \
        local_irq_restore(irq_flags);                                   \
                                                                        \