Commit 981a2379 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Arnaldo Carvalho de Melo

perf probe: Do not add offset twice to uprobe address

Fix perf-probe not to add offset value twice to uprobe probe address
when post processing.

The tevs[i].point.address struct member 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 fb7345bbSigned-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: "David A. Long" <dave.long@linaro.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: yrl.pp-manager.tt@hitachi.com
Link: http://lkml.kernel.org/r/20140205051858.6519.27314.stgit@kbuild-fedora.yrl.intra.hitachi.co.jpSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 0e9f2204
...@@ -336,8 +336,8 @@ static int add_exec_to_probe_trace_events(struct probe_trace_event *tevs, ...@@ -336,8 +336,8 @@ static int add_exec_to_probe_trace_events(struct probe_trace_event *tevs,
return ret; return ret;
for (i = 0; i < ntevs && ret >= 0; i++) { 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.address - stext;
offset += tevs[i].point.offset;
tevs[i].point.offset = 0; tevs[i].point.offset = 0;
zfree(&tevs[i].point.symbol); zfree(&tevs[i].point.symbol);
ret = e_snprintf(buf, 32, "0x%lx", offset); ret = e_snprintf(buf, 32, "0x%lx", offset);
......
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