[tip:perf/core] perf probe: Show better error message when failed to find variable

tip-bot for He Kuang
2015-05-15T06:44:51Z

Commit-ID: 7d5eaba9b33682b734e3a79c21c4a9a5f91624b1
Gitweb: http://git.kernel.org/tip/7d5eaba9b33682b734e3a79c21c4a9a5f91624b1
Author: He Kuang <hekuang@huawei.com>
AuthorDate: Mon, 11 May 2015 09:25:04 +0000
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 12 May 2015 09:59:50 -0300

perf probe: Show better error message when failed to find variable

Indicate to check variable location range in error message when we got
failed to find the variable.

Before this patch:

$ perf probe --add 'generic_perform_write+118 bytes'
Failed to find the location of bytes at this address.
Perhaps, it has been optimized out.
Error: Failed to add events.

After this patch:

$ perf probe --add 'generic_perform_write+118 bytes'
Failed to find the location of the 'bytes' variable at this address.
Perhaps it has been optimized out.
Use -V with the --range option to show 'bytes' location range.
Error: Failed to add events.

Signed-off-by: He Kuang <hekuang@huawei.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1431336304-16863-3-git-send-email-hekuang@huawei.com
[ Improve the error message based on lkml thread ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/probe-finder.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 5804086..590a24a 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -527,10 +527,12 @@ static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)

ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
&pf->sp_die, pf->tvar);
- if (ret == -ENOENT || ret == -EINVAL)
- pr_err("Failed to find the location of %s at this address.\n"
- " Perhaps, it has been optimized out.\n", pf->pvar->var);
- else if (ret == -ENOTSUP)
+ if (ret == -ENOENT || ret == -EINVAL) {
+ pr_err("Failed to find the location of the '%s' variable at this address.\n"
+ " Perhaps it has been optimized out.\n"
+ " Use -V with the --range option to show '%s' location range.\n",
+ pf->pvar->var, pf->pvar->var);
+ } else if (ret == -ENOTSUP)
pr_err("Sorry, we don't support this variable location yet.\n");
else if (ret == 0 && pf->pvar->field) {
ret = convert_variable_fields(vr_die, pf->pvar->var,