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Subject[RFC PATCH tracing/kprobes 2/5] tracing/kprobes: Avoid field name confliction
Date
Check whether the argument name is conflict with other field names.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
---
kernel/trace/trace_kprobe.c | 64 +++++++++++++++++++++++++++++++++++--------
1 files changed, 52 insertions(+), 12 deletions(-)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index f63ead0..c09411f 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -38,6 +38,24 @@
#define MAX_EVENT_NAME_LEN 64
#define KPROBE_EVENT_SYSTEM "kprobes"

+/* Reserved field names */
+#define FIELD_STRING_IP "ip"
+#define FIELD_STRING_NARGS "nargs"
+#define FIELD_STRING_RETIP "ret_ip"
+#define FIELD_STRING_FUNC "func"
+
+const char *reserved_field_names[] = {
+ "common_type",
+ "common_flags",
+ "common_preempt_count",
+ "common_pid",
+ "common_tgid",
+ FIELD_STRING_IP,
+ FIELD_STRING_NARGS,
+ FIELD_STRING_RETIP,
+ FIELD_STRING_FUNC,
+};
+
/* currently, trace_kprobe only supports X86. */

struct fetch_func {
@@ -551,6 +569,20 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
return ret;
}

+/* Return 1 if name is reserved or already used by another argument */
+static int conflict_field_name(const char *name,
+ struct probe_arg *args, int narg)
+{
+ int i;
+ for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
+ if (!strcmp(reserved_field_names[i], name))
+ return 1;
+ for (i = 0; i < narg; i++)
+ if (!strcmp(args[i].name, name))
+ return 1;
+ return 0;
+}
+
static int create_trace_probe(int argc, char **argv)
{
/*
@@ -652,6 +684,12 @@ static int create_trace_probe(int argc, char **argv)
*arg++ = '\0';
else
arg = argv[i];
+
+ if (conflict_field_name(argv[i], tp->args, i)) {
+ ret = -EINVAL;
+ goto error;
+ }
+
tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);

/* Parse fetch argument */
@@ -1054,8 +1092,8 @@ static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
if (!ret)
return ret;

- DEFINE_FIELD(unsigned long, ip, "ip", 0);
- DEFINE_FIELD(int, nargs, "nargs", 1);
+ DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
+ DEFINE_FIELD(int, nargs, FIELD_STRING_NARGS, 1);
/* Set argument names as fields */
for (i = 0; i < tp->nr_args; i++)
DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
@@ -1072,9 +1110,9 @@ static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
if (!ret)
return ret;

- DEFINE_FIELD(unsigned long, func, "func", 0);
- DEFINE_FIELD(unsigned long, ret_ip, "ret_ip", 0);
- DEFINE_FIELD(int, nargs, "nargs", 1);
+ DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
+ DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
+ DEFINE_FIELD(int, nargs, FIELD_STRING_NARGS, 1);
/* Set argument names as fields */
for (i = 0; i < tp->nr_args; i++)
DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
@@ -1123,15 +1161,16 @@ static int kprobe_event_show_format(struct ftrace_event_call *call,
int ret, i;
struct trace_probe *tp = (struct trace_probe *)call->data;

- SHOW_FIELD(unsigned long, ip, "ip");
- SHOW_FIELD(int, nargs, "nargs");
+ SHOW_FIELD(unsigned long, ip, FIELD_STRING_IP);
+ SHOW_FIELD(int, nargs, FIELD_STRING_NARGS);

/* Show fields */
for (i = 0; i < tp->nr_args; i++)
SHOW_FIELD(unsigned long, args[i], tp->args[i].name);
trace_seq_puts(s, "\n");

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

static int kretprobe_event_show_format(struct ftrace_event_call *call,
@@ -1141,9 +1180,9 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
int ret, i;
struct trace_probe *tp = (struct trace_probe *)call->data;

- SHOW_FIELD(unsigned long, func, "func");
- SHOW_FIELD(unsigned long, ret_ip, "ret_ip");
- SHOW_FIELD(int, nargs, "nargs");
+ SHOW_FIELD(unsigned long, func, FIELD_STRING_FUNC);
+ SHOW_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP);
+ SHOW_FIELD(int, nargs, FIELD_STRING_NARGS);

/* Show fields */
for (i = 0; i < tp->nr_args; i++)
@@ -1151,7 +1190,8 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
trace_seq_puts(s, "\n");

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

#ifdef CONFIG_EVENT_PROFILE

--
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com


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