From: Masami Hiramatsu mhiramat@kernel.org
commit 11fd3eb874e73ee8069bcfd54e3c16fa7ce56fe6 upstream.
Fix a wrong "variable not found" warning when the probe point is not found in the debuginfo.
Since the debuginfo__find_probes() can return 0 even if it does not find given probe point in the debuginfo, fill_empty_trace_arg() can be called with tf.ntevs == 0 and it can emit a wrong warning. To fix this, reject ntevs == 0 in fill_empty_trace_arg().
E.g. without this patch;
# perf probe -x /lib64/libc-2.30.so -a "memcpy arg1=%di" Failed to find the location of the '%di' variable at this address. Perhaps it has been optimized out. Use -V with the --range option to show '%di' location range. Added new events: probe_libc:memcpy (on memcpy in /usr/lib64/libc-2.30.so with arg1=%di) probe_libc:memcpy (on memcpy in /usr/lib64/libc-2.30.so with arg1=%di)
You can now use it in all perf tools, such as:
perf record -e probe_libc:memcpy -aR sleep 1
With this;
# perf probe -x /lib64/libc-2.30.so -a "memcpy arg1=%di" Added new events: probe_libc:memcpy (on memcpy in /usr/lib64/libc-2.30.so with arg1=%di) probe_libc:memcpy (on memcpy in /usr/lib64/libc-2.30.so with arg1=%di)
You can now use it in all perf tools, such as:
perf record -e probe_libc:memcpy -aR sleep 1
Fixes: cb4027308570 ("perf probe: Trace a magic number if variable is not found") Reported-by: Andi Kleen andi@firstfloor.org Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Reviewed-by: Srikar Dronamraju srikar@linux.vnet.ibm.com Tested-by: Andi Kleen ak@linux.intel.com Cc: Oleg Nesterov oleg@redhat.com Cc: stable@vger.kernel.org Link: http://lore.kernel.org/lkml/159438667364.62703.2200642186798763202.stgit@dev... Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- tools/perf/util/probe-finder.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -1408,6 +1408,9 @@ static int fill_empty_trace_arg(struct p char *type; int i, j, ret;
+ if (!ntevs) + return -ENOENT; + for (i = 0; i < pev->nargs; i++) { type = NULL; for (j = 0; j < ntevs; j++) {