Warn if given uprobe event accesses memory on older kernel.
Until 3.14, uprobe event only supports accessing registers
so this warns to upgrade kernel if uprobe-event returns
-EINVAL and an argument of the event accesses memory ($stack,
@+offset, and +|-offs() symtax).
With this patch (on 3.10.0-123.13.2.el7.x86_64);
-----
# ./perf probe -x ./perf warn_uprobe_event_compat stack=-0\(%sp\)
Added new event:
Failed to write event: Invalid argument
Please upgrade your kernel to at least 3.14 to have access to feature -0(%sp)
Error: Failed to add events.
-----
Signed-off-by: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
---
tools/perf/util/probe-event.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 7c0e765..1c570c2fa7 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -2199,6 +2199,27 @@ static int get_new_event_name(char *buf, size_t len,
const char *base,
return ret;
}
+/* Warn if the current kernel's uprobe implementation is old */
+static void warn_uprobe_event_compat(struct probe_trace_event *tev)
+{
+ int i;
+ char *buf = synthesize_probe_trace_command(tev);
+
+ /* Old uprobe event doesn't support memory dereference */
+ if (!tev->uprobes || tev->nargs == 0 || !buf)
+ goto out;
+
+ for (i = 0; i < tev->nargs; i++)
+ if (strglobmatch(tev->args[i].value, "[$@+-]*")) {
+ pr_warning("Please upgrade your kernel to at least "
+ "3.14 to have access to feature %s\n",
+ tev->args[i].value);
+ break;
+ }
+out:
+ free(buf);
+}
+
static int __add_probe_trace_events(struct perf_probe_event *pev,
struct probe_trace_event *tevs,
int ntevs, bool allow_suffix)
@@ -2295,6 +2316,8 @@ static int __add_probe_trace_events(struct
perf_probe_event *pev,
*/
allow_suffix = true;
}
+ if (ret == -EINVAL && pev->uprobes)
+ warn_uprobe_event_compat(tev);
/* Note that it is possible to skip all events because of blacklist */
if (ret >= 0 && tev->event) {
--
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