Commit 9e3282b9 authored Oct 30, 2019 by Masami Hiramatsu Committed by Greg Kroah-Hartman Dec 31, 2019

perf probe: Skip overlapped location on searching variables



[ Upstream commit dee36a2abb67c175265d49b9a8c7dfa564463d9a ]

Since debuginfo__find_probes() callback function can be called with  the
location which already passed, the callback function must filter out
such overlapped locations.

add_probe_trace_event() has already done it by commit 1a375ae7659a
("perf probe: Skip same probe address for a given line"), but
add_available_vars() doesn't. Thus perf probe -v shows same address
repeatedly as below:

  # perf probe -V vfs_read:18
  Available variables at vfs_read:18
          @<vfs_read+217>
                  char*   buf
                  loff_t* pos
                  ssize_t ret
                  struct file*    file
          @<vfs_read+217>
                  char*   buf
                  loff_t* pos
                  ssize_t ret
                  struct file*    file
          @<vfs_read+226>
                  char*   buf
                  loff_t* pos
                  ssize_t ret
                  struct file*    file

With this fix, perf probe -V shows it correctly:

  # perf probe -V vfs_read:18
  Available variables at vfs_read:18
          @<vfs_read+217>
                  char*   buf
                  loff_t* pos
                  ssize_t ret
                  struct file*    file
          @<vfs_read+226>
                  char*   buf
                  loff_t* pos
                  ssize_t ret
                  struct file*    file

Fixes: cf6eb489 ("perf probe: Show accessible local variables")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lore.kernel.org/lkml/157241938927.32002.4026859017790562751.stgit@devnote2


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent e00d45cd

tools/perf/util/probe-finder.c

+20 −0

Original line number	Diff line number	Diff line
		@@ -1414,6 +1414,18 @@ static int collect_variables_cb(Dwarf_Die die_mem, void data)
		return DIE_FIND_CB_END;
		}

		static bool available_var_finder_overlap(struct available_var_finder *af)
		{
		int i;

		for (i = 0; i < af->nvls; i++) {
		if (af->pf.addr == af->vls[i].point.address)
		return true;
		}
		return false;

		}

		/* Add a found vars into available variables list */
		static int add_available_vars(Dwarf_Die sc_die, struct probe_finder pf)
		{
		@@ -1424,6 +1436,14 @@ static int add_available_vars(Dwarf_Die sc_die, struct probe_finder pf)
		Dwarf_Die die_mem;
		int ret;

		/*
		* For some reason (e.g. different column assigned to same address),
		* this callback can be called with the address which already passed.
		* Ignore it first.
		*/
		if (available_var_finder_overlap(af))
		return 0;

		/* Check number of tevs */
		if (af->nvls == af->max_vls) {
		pr_warning("Too many( > %d) probe point found.\n", af->max_vls);