[PATCH] perf probe: Ignore vmlinux build-id when offline vmlinux and dry-run used

From: Josh Hunt
Date: Tue Jan 24 2017 - 16:50:12 EST

Commit e50243bb ("perf probe: Ignore vmlinux Build-id when offline vmlinux given")
added the ability to ignore vmlinux when an offline vmlinux is passed and no
l, d, or a flag is also passed. This extends that to ignore build-id when
-n/--dry-run is used. This way we can gather probe information for offline kernels
using the method Brendan Gregg mentions in this post:
http://www.brendangregg.com/blog/2014-09-11/perf-kernel-line-tracing.html .

$ ./perf probe -k ./vmlinux-3.14.59 -nv 'do_sys_open=do_sys_open:7 filename:string dfd flags op'

will generate:
do_sys_open+91 filename_string=+0(%si):string dfd=%di:s32 flags=%bx:s32 op=-60(%bp):u64

and then copy/paste this to the machine running the 3.14.59 kernel.

Signed-off-by: Josh Hunt <johunt@xxxxxxxxxx>
tools/perf/builtin-probe.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index f87996b..e0eea723 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -616,7 +616,7 @@ static int perf_del_probe_events(struct strfilter *filter)
* nor change running kernel. So if user gives offline vmlinux,
* ignore its buildid.
- if (!strchr("lda", params.command) && symbol_conf.vmlinux_name)
+ if ((!strchr("lda", params.command) || probe_event_dry_run) && symbol_conf.vmlinux_name)
symbol_conf.ignore_vmlinux_buildid = true;

switch (params.command) {