[PATCH -tip ] [BUGFIX/URGENT] perf-probe: Do not add offset touprobe address

[Masami Hiramatsu]

Fix perf-probe not to add offset value to uprobe probe
address when post processing.
tevs[i].point.address is the address of symbol+offset,
but current perf-probe adjusts the point.address by
adding the offset. As a result, the probe address becomes
symbol+offset+offset. This may cause unexpected
code corruption. Urgent fix is needed.

Without this fix
  ---
  # ./perf probe -x ./perf dso__load_vmlinux+4
  # ./perf probe -l
    probe_perf:dso__load_vmlinux (on 0x000000000006d2b8)
  # nm ./perf.orig | grep dso__load_vmlinux\$
  000000000046d0a0 T dso__load_vmlinux
  ---
You can see the given offset is 3 but the actual probed
address is dso__load_vmlinux+8.

With this fix
  ---
  # ./perf probe -x ./perf dso__load_vmlinux+4
  # ./perf probe -l
    probe_perf:dso__load_vmlinux (on 0x000000000006d2b4)
  ---
Now the problem is fixed.

Note: This bug is introduced by
	commit fb7345bbf7fad9bf72ef63a19c707970b9685812

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
---
 tools/perf/util/probe-event.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index a8a9b6c..d8b048c 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -336,8 +336,8 @@ static int add_exec_to_probe_trace_events(struct probe_trace_event *tevs,
 		return ret;
 
 	for (i = 0; i < ntevs && ret >= 0; i++) {
+		/* point.address is the addres of point.symbol + point.offset */
 		offset = tevs[i].point.address - stext;
-		offset += tevs[i].point.offset;
 		tevs[i].point.offset = 0;
 		zfree(&tevs[i].point.symbol);
 		ret = e_snprintf(buf, 32, "0x%lx", offset);


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