tracing/kprobes: Allow to create probe with a module name starting with a digit

commit 9e52b32567126fe146f198971364f68d3bc5233f upstream.

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

Link: http://lkml.kernel.org/r/fd72d666f45b114e2c5b9cf7e27b91de1ec966f1.1498122881.git.sd@queasysnail.net
Fixes: 413d37d1e ("tracing: Add kprobe-based event tracer")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
[bwh: Backported to 3.16: preserve the check that an addresses isn't used for
 a kretprobe]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index b53aa5b9c0385531473319652bd26fbc14cda489..94b253911a2a317dc8f38d309231f19ad8b09005 100644 (file)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -671,24 +671,21 @@ static int create_trace_kprobe(int argc, char **argv)
                pr_info("Probe point is not specified.\n");
                return -EINVAL;
        }
-       if (isdigit(argv[1][0])) {
+
+       /* try to parse an address. if that fails, try to read the
+        * input as a symbol. */
+       if (!kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
                if (is_return) {
                        pr_info("Return probe point must be a symbol.\n");
                        return -EINVAL;
                }
-               /* an address specified */
-               ret = kstrtoul(&argv[1][0], 0, (unsigned long *)&addr);
-               if (ret) {
-                       pr_info("Failed to parse address.\n");
-                       return ret;
-               }
        } else {
                /* 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) {