linux-kernel - [PATCH] tracing/kprobes: allow to create probe with a module name starting with a digit

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Date:   Thu, 22 Jun 2017 11:24:42 +0200
From:   Sabrina Dubroca <sd@...asysnail.net>
To:     linux-kernel@...r.kernel.org
Cc:     Sabrina Dubroca <sd@...asysnail.net>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>
Subject: [PATCH] tracing/kprobes: allow to create probe with a module name starting with a digit

Always try to parse an address, since kstrtoul() will safely fail when
given a symbol as input. If that fails (which will be the case for a
symbol), try to parse a symbol instead.

This allows creating a probe such as:

    p:probe/vlan_gro_receive 8021q:vlan_gro_receive+0

Which is necessary for this command to work:

    perf probe -m 8021q -a vlan_gro_receive

Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
---
 kernel/trace/trace_kprobe.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index c129fca6ec99..b53c8d369163 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -707,20 +707,16 @@ static int create_trace_kprobe(int argc, char **argv)
 		pr_info("Probe point is not specified.\n");
 		return -EINVAL;
 	}
-	if (isdigit(argv[1][0])) {
-		/* an address specified */
-		ret = kstrtoul(&argv[1][0], 0, (unsigned long *)&addr);
-		if (ret) {
-			pr_info("Failed to parse address.\n");
-			return ret;
-		}
-	} else {
+
+	/* try to parse an address. if that fails, try to read the
+	 * input as a symbol. */
+	if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
 		/* a symbol specified */
 		symbol = argv[1];
 		/* TODO: support .init module functions */
 		ret = traceprobe_split_symbol_offset(symbol, &offset);
 		if (ret) {
-			pr_info("Failed to parse symbol.\n");
+			pr_info("Failed to parse either an address or a symbol.\n");
 			return ret;
 		}
 		if (offset && is_return &&
-- 
2.13.1