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Subject[tip:tracing/core] tracing/kprobes: Init print_fmt for kprobe events
Commit-ID:  a342a0280b981c130e32dbb94dbd3a57959c4d04
Gitweb: http://git.kernel.org/tip/a342a0280b981c130e32dbb94dbd3a57959c4d04
Author: Lai Jiangshan <laijs@cn.fujitsu.com>
AuthorDate: Tue, 15 Dec 2009 15:39:49 +0800
Committer: Steven Rostedt <rostedt@goodmis.org>
CommitDate: Wed, 6 Jan 2010 12:01:35 -0500

tracing/kprobes: Init print_fmt for kprobe events

This is part of a patch set that removes the show_format method
in the ftrace event macros.

Add the print_fmt initialization to the kprobe events.
The print_fmt is still not used, but will be in the follow up
patches.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <4B273D45.3080100@cn.fujitsu.com>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace_kprobe.c | 64 ++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 63 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 6ea90c0..147491d 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1250,6 +1250,62 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
", REC->" FIELD_STRING_RETIP);
}

+static int __set_print_fmt(struct trace_probe *tp, char *buf, int len)
+{
+ int i;
+ int pos = 0;
+
+ const char *fmt, *arg;
+
+ if (!probe_is_return(tp)) {
+ fmt = "(%lx)";
+ arg = "REC->" FIELD_STRING_IP;
+ } else {
+ fmt = "(%lx <- %lx)";
+ arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
+ }
+
+ /* When len=0, we just calculate the needed length */
+#define LEN_OR_ZERO (len ? len - pos : 0)
+
+ pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
+
+ for (i = 0; i < tp->nr_args; i++) {
+ pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%%lx",
+ tp->args[i].name);
+ }
+
+ pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
+
+ for (i = 0; i < tp->nr_args; i++) {
+ pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
+ tp->args[i].name);
+ }
+
+#undef LEN_OR_ZERO
+
+ /* return the length of print_fmt */
+ return pos;
+}
+
+static int set_print_fmt(struct trace_probe *tp)
+{
+ int len;
+ char *print_fmt;
+
+ /* First: called with 0 length to calculate the needed length */
+ len = __set_print_fmt(tp, NULL, 0);
+ print_fmt = kmalloc(len + 1, GFP_KERNEL);
+ if (!print_fmt)
+ return -ENOMEM;
+
+ /* Second: actually write the @print_fmt */
+ __set_print_fmt(tp, print_fmt, len + 1);
+ tp->call.print_fmt = print_fmt;
+
+ return 0;
+}
+
#ifdef CONFIG_EVENT_PROFILE

/* Kprobe profile handler */
@@ -1456,10 +1512,14 @@ static int register_probe_event(struct trace_probe *tp)
call->show_format = kprobe_event_show_format;
call->define_fields = kprobe_event_define_fields;
}
+ if (set_print_fmt(tp) < 0)
+ return -ENOMEM;
call->event = &tp->event;
call->id = register_ftrace_event(&tp->event);
- if (!call->id)
+ if (!call->id) {
+ kfree(call->print_fmt);
return -ENODEV;
+ }
call->enabled = 0;
call->regfunc = probe_event_enable;
call->unregfunc = probe_event_disable;
@@ -1472,6 +1532,7 @@ static int register_probe_event(struct trace_probe *tp)
ret = trace_add_event_call(call);
if (ret) {
pr_info("Failed to register kprobe event: %s\n", call->name);
+ kfree(call->print_fmt);
unregister_ftrace_event(&tp->event);
}
return ret;
@@ -1481,6 +1542,7 @@ static void unregister_probe_event(struct trace_probe *tp)
{
/* tp->event is unregistered in trace_remove_event_call() */
trace_remove_event_call(&tp->call);
+ kfree(tp->call.print_fmt);
}

/* Make a debugfs interface for controling probe points */

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