From 1fd8df2c3970c9e7e4e262354154ee39e58bdd7c Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Wed, 8 Jun 2011 16:09:34 +0900 Subject: 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: => 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: => worker_thread => kthread => kernel_thread_helper sshd-1132 [000] 10297.050365: p_schedule_4: (schedule+0x4/0x4ca) sshd-1132 [000] 10297.050365: => 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 Cc: Frederic Weisbecker Cc: yrl.pp-manager.tt@hitachi.com Cc: Peter Zijlstra Cc: Namhyung Kim Link: http://lkml.kernel.org/r/20110608070934.17777.17116.stgit@fedora15 Signed-off-by: Steven Rostedt --- kernel/trace/trace_kprobe.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'kernel/trace/trace_kprobe.c') 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 */ -- cgit v1.2.3