[for-next][PATCH 17/26] tracing/uprobes: Support perf-style return probe

Steven Rostedt
2020-09-22T01:25:41Z

Support perf-style return probe ("SYMBOL%return") for uprobe events
as same as kprobe events does.

Link: https://lkml.kernel.org/r/159972814601.428528.7641183316212425445.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace.c | 2 +-
kernel/trace/trace_uprobe.c | 15 ++++++++++++++-
2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ca6da462326d..c35fcd2f2529 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5125,7 +5125,7 @@ static const char readme_msg[] =
"place (kretprobe): [<module>:]<symbol>[+<offset>]%return|<memaddr>\n"
#endif
#ifdef CONFIG_UPROBE_EVENTS
- " place (uprobe): <path>:<offset>[(ref_ctr_offset)]\n"
+ " place (uprobe): <path>:<offset>[%return][(ref_ctr_offset)]\n"
#endif
"\t args: <name>=fetcharg[:type]\n"
"\t fetcharg: %<register>, @ , @<symbol>[+|-<offset>],\n"
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 56729c6b6614..3cf7128e1ad3 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -528,7 +528,7 @@ static int register_trace_uprobe(struct trace_uprobe *tu)

/*
* Argument syntax:
- * - Add uprobe: p|r[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS]
+ * - Add uprobe: p|r[:[GRP/]EVENT] PATH:OFFSET[%return][(REF)] [FETCHARGS]
*/
static int trace_uprobe_create(int argc, const char **argv)
{
@@ -617,6 +617,19 @@ static int trace_uprobe_create(int argc, const char **argv)
}
}

+ /* Check if there is %return suffix */
+ tmp = strchr(arg, '%');
+ if (tmp) {
+ if (!strcmp(tmp, "%return")) {
+ *tmp = '\0';
+ is_return = true;
+ } else {
+ trace_probe_log_err(tmp - filename, BAD_ADDR_SUFFIX);
+ ret = -EINVAL;
+ goto fail_address_parse;
+ }
+ }
+
/* Parse uprobe offset. */
ret = kstrtoul(arg, 0, &offset);
if (ret) {
--
2.28.0