Commit d5a00296 authored Sep 24, 2016 by Masami Hiramatsu Committed by Arnaldo Carvalho de Melo Sep 29, 2016

perf probe: Match linkage name with mangled name



Match linkage name with mangled name if exists. The linkage_name is used
for storing mangled name of the object.

Thus, this allows 'perf probe' to find appropriate probe point from
mangled symbol as below.

E.g. without this fix:
  ----
  $ perf probe -x /usr/lib64/libstdc++.so.6 \
    -D _ZNKSt15basic_fstreamXXIwSt11char_traitsIwEE7is_openEv
  Probe point '_ZNKSt15basic_fstreamXXIwSt11char_traitsIwEE7is_openEv'
  not found.
    Error: Failed to add events.
  ----

With this fix, perf probe can find the correct one.
  ----
  $ perf probe -x /usr/lib64/libstdc++.so.6 \
    -D _ZNKSt15basic_fstreamXXIwSt11char_traitsIwEE7is_openEv
  p:probe_libstdc/_ZNKSt15basic_fstreamXXIwSt11char_traitsIwEE7is_openEv
  /usr/lib64/libstdc++.so.6.0.22:0x8ca60
  ----

Committer notes:

After the fix, setting it for real (no -D/--definition, that amounts to
a --dry-run):

  # perf probe -x /usr/lib64/libstdc++.so.6 _ZNKSt15basic_fstreamXXIwSt11char_traitsIwEE7is_openEv
  Added new event:
    probe_libstdc:_ZNKSt15basic_fstreamXXIwSt11char_traitsIwEE7is_openEv (on _ZNKSt15basic_fstreamXXIwSt11char_traitsIwEE7is_openEv in /usr/lib64/libstdc++.so.6.0.22)

  You can now use it in all perf tools, such as:

	perf record -e probe_libstdc:_ZNKSt15basic_fstreamXXIwSt11char_traitsIwEE7is_openEv -aR sleep 1

  # perf probe -l probe_libstdc:*
    probe_libstdc:_ZNKSt15basic_fstreamXXIwSt11char_traitsIwEE7is_openEv (on is_open@libstdc++-v3/include/fstream in /usr/lib64/libstdc++.so.6.0.22)
  #

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/147464493162.29804.16715053505069382443.stgit@devbox


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 35726d3a

tools/perf/util/dwarf-aux.c

+26 −2

Original line number	Diff line number	Diff line
		@@ -129,6 +129,22 @@ int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr,

		}

		/**
		* die_get_linkage_name - Get the linkage name of the object
		* @dw_die: A DIE of the object
		*
		* Get the linkage name attiribute of given @dw_die.
		* For C++ binary, the linkage name will be the mangled symbol.
		*/
		const char die_get_linkage_name(Dwarf_Die dw_die)
		{
		Dwarf_Attribute attr;

		if (dwarf_attr_integrate(dw_die, DW_AT_linkage_name, &attr) == NULL)
		return NULL;
		return dwarf_formstring(&attr);
		}

		/**
		* die_compare_name - Compare diename and tname
		* @dw_die: a DIE
		@@ -145,18 +161,26 @@ bool die_compare_name(Dwarf_Die dw_die, const char tname)
		}

		/**
		* die_match_name - Match diename and glob
		* die_match_name - Match diename/linkage name and glob
		* @dw_die: a DIE
		* @glob: a string of target glob pattern
		*
		* Glob matching the name of @dw_die and @glob. Return false if matching fail.
		* This also match linkage name.
		*/
		bool die_match_name(Dwarf_Die dw_die, const char glob)
		{
		const char *name;

		name = dwarf_diename(dw_die);
		return name ? strglobmatch(name, glob) : false;
		if (name && strglobmatch(name, glob))
		return true;
		/* fall back to check linkage name */
		name = die_get_linkage_name(dw_die);
		if (name && strglobmatch(name, glob))
		return true;

		return false;
		}

		/**

tools/perf/util/dwarf-aux.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -38,6 +38,9 @@ int cu_find_lineinfo(Dwarf_Die *cudie, unsigned long addr,
		int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr,
		int (callback)(Dwarf_Die , void ), void data);

		/* Get DW_AT_linkage_name (should be NULL for C binary) */
		const char die_get_linkage_name(Dwarf_Die dw_die);

		/* Ensure that this DIE is a subprogram and definition (not declaration) */
		bool die_is_func_def(Dwarf_Die *dw_die);