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Subject[tip:perf/core] tracing/kprobes: Fix handling of argument names
Commit-ID:  aba91595cfcebd193425e20aabc407531526a1c5
Gitweb: http://git.kernel.org/tip/aba91595cfcebd193425e20aabc407531526a1c5
Author: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
AuthorDate: Fri, 27 Aug 2010 20:39:06 +0900
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Wed, 8 Sep 2010 11:47:19 -0300

tracing/kprobes: Fix handling of argument names

Set "argN" name for each argument automatically if it has no specified name.
Since dynamic trace event(kprobe_events) accepts special characters for its
argument, its format can show those special characters (e.g. '$', '%', '+').
However, perf can't parse those format because of the character (especially
'%') mess up the format. This sets "argX" name for those arguments if user
omitted the argument names.

E.g.
# echo 'p do_fork %ax IP=%ip $stack' > tracing/kprobe_events
# cat tracing/kprobe_events
p:kprobes/p_do_fork_0 do_fork arg1=%ax IP=%ip arg3=$stack

Reported-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
LKML-Reference: <20100827113906.22882.59312.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
kernel/trace/trace_kprobe.c | 17 ++++++++++-------
1 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 0116c03..a39251e 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -997,15 +997,18 @@ static int create_trace_probe(int argc, char **argv)

/* Parse argument name */
arg = strchr(argv[i], '=');
- if (arg)
+ if (arg) {
*arg++ = '\0';
- else
+ tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
+ } else {
arg = argv[i];
+ /* If argument name is omitted, set "argN" */
+ snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
+ tp->args[i].name = kstrdup(buf, GFP_KERNEL);
+ }

- tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
if (!tp->args[i].name) {
- pr_info("Failed to allocate argument%d name '%s'.\n",
- i, argv[i]);
+ pr_info("Failed to allocate argument[%d] name.\n", i);
ret = -ENOMEM;
goto error;
}
@@ -1014,7 +1017,7 @@ static int create_trace_probe(int argc, char **argv)
*tmp = '_'; /* convert : to _ */

if (conflict_field_name(tp->args[i].name, tp->args, i)) {
- pr_info("Argument%d name '%s' conflicts with "
+ pr_info("Argument[%d] name '%s' conflicts with "
"another field.\n", i, argv[i]);
ret = -EINVAL;
goto error;
@@ -1023,7 +1026,7 @@ static int create_trace_probe(int argc, char **argv)
/* Parse fetch argument */
ret = parse_probe_arg(arg, tp, &tp->args[i], is_return);
if (ret) {
- pr_info("Parse error at argument%d. (%d)\n", i, ret);
+ pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
goto error;
}
}

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