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Subject[PATCH 16/24] tracing/kprobes: Show event name in trace output
Date
From: Masami Hiramatsu <mhiramat@redhat.com>

Show event name in tracing/trace output. This also fixes kprobes events
format to comply with other tracepoint events formats.

Before patching:
<...>-1447 [001] 1038282.286875: do_sys_open+0x0/0xd6: ...
<...>-1447 [001] 1038282.286878: sys_openat+0xc/0xe <- do_sys_open: ...

After patching:
<...>-1447 [001] 1038282.286875: myprobe: (do_sys_open+0x0/0xd6) ...
<...>-1447 [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) ...

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <20090910235345.22412.76527.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
Documentation/trace/kprobetrace.txt | 16 ++++++++--------
kernel/trace/trace_kprobe.c | 16 +++++++++++-----
2 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index aaa6c10..a849889 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -114,7 +114,7 @@ format:
field: unsigned long flags; offset:48;tsize:8;
field: unsigned long mode; offset:56;tsize:8;

-print fmt: "%lx: dfd=%lx filename=%lx flags=%lx mode=%lx", ip, REC->dfd, REC->filename, REC->flags, REC->mode
+print fmt: "(%lx) dfd=%lx filename=%lx flags=%lx mode=%lx", REC->ip, REC->dfd, REC->filename, REC->flags, REC->mode


You can see that the event has 4 arguments as in the expressions you specified.
@@ -129,15 +129,15 @@ print fmt: "%lx: dfd=%lx filename=%lx flags=%lx mode=%lx", ip, REC->dfd, REC->fi
#
# TASK-PID CPU# TIMESTAMP FUNCTION
# | | | | |
- <...>-1447 [001] 1038282.286875: do_sys_open+0x0/0xd6: dfd=3 filename=7fffd1ec4440 flags=8000 mode=0
- <...>-1447 [001] 1038282.286878: sys_openat+0xc/0xe <- do_sys_open: rv=fffffffffffffffe ra=ffffffff81367a3a
- <...>-1447 [001] 1038282.286885: do_sys_open+0x0/0xd6: dfd=ffffff9c filename=40413c flags=8000 mode=1b6
- <...>-1447 [001] 1038282.286915: sys_open+0x1b/0x1d <- do_sys_open: rv=3 ra=ffffffff81367a3a
- <...>-1447 [001] 1038282.286969: do_sys_open+0x0/0xd6: dfd=ffffff9c filename=4041c6 flags=98800 mode=10
- <...>-1447 [001] 1038282.286976: sys_open+0x1b/0x1d <- do_sys_open: rv=3 ra=ffffffff81367a3a
+ <...>-1447 [001] 1038282.286875: myprobe: (do_sys_open+0x0/0xd6) dfd=3 filename=7fffd1ec4440 flags=8000 mode=0
+ <...>-1447 [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) rv=fffffffffffffffe ra=ffffffff81367a3a
+ <...>-1447 [001] 1038282.286885: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=40413c flags=8000 mode=1b6
+ <...>-1447 [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) rv=3 ra=ffffffff81367a3a
+ <...>-1447 [001] 1038282.286969: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=4041c6 flags=98800 mode=10
+ <...>-1447 [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) rv=3 ra=ffffffff81367a3a


- Each line shows when the kernel hits a probe, and <- SYMBOL means kernel
+ Each line shows when the kernel hits an event, and <- SYMBOL means kernel
returns from SYMBOL(e.g. "sys_open+0x1b/0x1d <- do_sys_open" means kernel
returns from do_sys_open to sys_open+0x1b).

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 44dad1a..1746afe 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -902,10 +902,13 @@ print_kprobe_event(struct trace_iterator *iter, int flags)
event = ftrace_find_event(field->ent.type);
tp = container_of(event, struct trace_probe, event);

+ if (!trace_seq_printf(s, "%s: (", tp->call.name))
+ goto partial;
+
if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
goto partial;

- if (!trace_seq_puts(s, ":"))
+ if (!trace_seq_puts(s, ")"))
goto partial;

for (i = 0; i < field->nargs; i++)
@@ -934,6 +937,9 @@ print_kretprobe_event(struct trace_iterator *iter, int flags)
event = ftrace_find_event(field->ent.type);
tp = container_of(event, struct trace_probe, event);

+ if (!trace_seq_printf(s, "%s: (", tp->call.name))
+ goto partial;
+
if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
goto partial;

@@ -943,7 +949,7 @@ print_kretprobe_event(struct trace_iterator *iter, int flags)
if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
goto partial;

- if (!trace_seq_puts(s, ":"))
+ if (!trace_seq_puts(s, ")"))
goto partial;

for (i = 0; i < field->nargs; i++)
@@ -1087,7 +1093,7 @@ static int kprobe_event_show_format(struct ftrace_event_call *call,
SHOW_FIELD(unsigned long, args[i], tp->args[i].name);
trace_seq_puts(s, "\n");

- return __probe_event_show_format(s, tp, "%lx:", "ip");
+ return __probe_event_show_format(s, tp, "(%lx)", "REC->ip");
}

static int kretprobe_event_show_format(struct ftrace_event_call *call,
@@ -1106,8 +1112,8 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
SHOW_FIELD(unsigned long, args[i], tp->args[i].name);
trace_seq_puts(s, "\n");

- return __probe_event_show_format(s, tp, "%lx <- %lx:",
- "func, ret_ip");
+ return __probe_event_show_format(s, tp, "(%lx <- %lx)",
+ "REC->func, REC->ret_ip");
}

#ifdef CONFIG_EVENT_PROFILE
--
1.6.2.3


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