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authorMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>2011-06-08 16:09:34 +0900
committerSteven Rostedt <rostedt@goodmis.org>2011-06-14 22:48:53 -0400
commit1fd8df2c3970c9e7e4e262354154ee39e58bdd7c (patch)
tree640fbc584af8870917ea6d1fab4da49d299038ad /kernel
parentc624d33f61cd05241e85b906311f0b712fdb0f32 (diff)
tracing/kprobes: Fix kprobe-tracer to support stack trace
Fix to support kernel stack trace correctly on kprobe-tracer. Since the execution path of kprobe-based dynamic events is different from other tracepoint-based events, normal ftrace_trace_stack() doesn't work correctly. To fix that, this introduces ftrace_trace_stack_regs() which traces stack via pt_regs instead of current stack register. e.g. # echo p schedule+4 > /sys/kernel/debug/tracing/kprobe_events # echo 1 > /sys/kernel/debug/tracing/options/stacktrace # echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable # head -n 20 /sys/kernel/debug/tracing/trace bash-2968 [000] 10297.050245: p_schedule_4: (schedule+0x4/0x4ca) bash-2968 [000] 10297.050247: <stack trace> => schedule_timeout => n_tty_read => tty_read => vfs_read => sys_read => system_call_fastpath kworker/0:1-2940 [000] 10297.050265: p_schedule_4: (schedule+0x4/0x4ca) kworker/0:1-2940 [000] 10297.050266: <stack trace> => worker_thread => kthread => kernel_thread_helper sshd-1132 [000] 10297.050365: p_schedule_4: (schedule+0x4/0x4ca) sshd-1132 [000] 10297.050365: <stack trace> => sysret_careful Note: Even with this fix, the first entry will be skipped if the probe is put on the function entry area before the frame pointer is set up (usually, that is 4 bytes (push %bp; mov %sp %bp) on x86), because stack unwinder depends on the frame pointer. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: yrl.pp-manager.tt@hitachi.com Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Namhyung Kim <namhyung@gmail.com> Link: http://lkml.kernel.org/r/20110608070934.17777.17116.stgit@fedora15 Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace.c34
-rw-r--r--kernel/trace/trace.h9
-rw-r--r--kernel/trace/trace_kprobe.c6
3 files changed, 42 insertions, 7 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c977018e87c2..d9c16123f6e2 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1193,6 +1193,18 @@ void trace_nowake_buffer_unlock_commit(struct ring_buffer *buffer,
}
EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit);
+void trace_nowake_buffer_unlock_commit_regs(struct ring_buffer *buffer,
+ struct ring_buffer_event *event,
+ unsigned long flags, int pc,
+ struct pt_regs *regs)
+{
+ ring_buffer_unlock_commit(buffer, event);
+
+ ftrace_trace_stack_regs(buffer, flags, 0, pc, regs);
+ ftrace_trace_userstack(buffer, flags, pc);
+}
+EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit_regs);
+
void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event)
{
@@ -1238,7 +1250,7 @@ ftrace(struct trace_array *tr, struct trace_array_cpu *data,
#ifdef CONFIG_STACKTRACE
static void __ftrace_trace_stack(struct ring_buffer *buffer,
unsigned long flags,
- int skip, int pc)
+ int skip, int pc, struct pt_regs *regs)
{
struct ftrace_event_call *call = &event_kernel_stack;
struct ring_buffer_event *event;
@@ -1257,24 +1269,36 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
trace.skip = skip;
trace.entries = entry->caller;
- save_stack_trace(&trace);
+ if (regs)
+ save_stack_trace_regs(regs, &trace);
+ else
+ save_stack_trace(&trace);
if (!filter_check_discard(call, entry, buffer, event))
ring_buffer_unlock_commit(buffer, event);
}
+void ftrace_trace_stack_regs(struct ring_buffer *buffer, unsigned long flags,
+ int skip, int pc, struct pt_regs *regs)
+{
+ if (!(trace_flags & TRACE_ITER_STACKTRACE))
+ return;
+
+ __ftrace_trace_stack(buffer, flags, skip, pc, regs);
+}
+
void ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags,
int skip, int pc)
{
if (!(trace_flags & TRACE_ITER_STACKTRACE))
return;
- __ftrace_trace_stack(buffer, flags, skip, pc);
+ __ftrace_trace_stack(buffer, flags, skip, pc, NULL);
}
void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
int pc)
{
- __ftrace_trace_stack(tr->buffer, flags, skip, pc);
+ __ftrace_trace_stack(tr->buffer, flags, skip, pc, NULL);
}
/**
@@ -1290,7 +1314,7 @@ void trace_dump_stack(void)
local_save_flags(flags);
/* skipping 3 traces, seems to get us at the caller of this function */
- __ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count());
+ __ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count(), NULL);
}
static DEFINE_PER_CPU(int, user_stack_count);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 742f545ae185..a3e2db708072 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -389,6 +389,9 @@ void update_max_tr_single(struct trace_array *tr,
void ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags,
int skip, int pc);
+void ftrace_trace_stack_regs(struct ring_buffer *buffer, unsigned long flags,
+ int skip, int pc, struct pt_regs *regs);
+
void ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags,
int pc);
@@ -400,6 +403,12 @@ static inline void ftrace_trace_stack(struct ring_buffer *buffer,
{
}
+static inline void ftrace_trace_stack_regs(struct ring_buffer *buffer,
+ unsigned long flags, int skip,
+ int pc, struct pt_regs *regs)
+{
+}
+
static inline void ftrace_trace_userstack(struct ring_buffer *buffer,
unsigned long flags, int pc)
{
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index f925c45f0afa..7053ef3d73d2 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1397,7 +1397,8 @@ static __kprobes void kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
if (!filter_current_check_discard(buffer, call, entry, event))
- trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
+ trace_nowake_buffer_unlock_commit_regs(buffer, event,
+ irq_flags, pc, regs);
}
/* Kretprobe handler */
@@ -1429,7 +1430,8 @@ static __kprobes void kretprobe_trace_func(struct kretprobe_instance *ri,
store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
if (!filter_current_check_discard(buffer, call, entry, event))
- trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
+ trace_nowake_buffer_unlock_commit_regs(buffer, event,
+ irq_flags, pc, regs);
}
/* Event entry printers */