perf unwind: Unwind with libdw doesn't take symfs into account

BugLink: https://bugs.launchpad.net/bugs/1818803

[ Upstream commit 3d20c624 ]

Path passed to libdw for unwinding doesn't include symfs path
if specified, so unwinding fails because ELF file is not found.

Similar to unwinding with libunwind, pass symsrc_filename instead
of long_name. If there is no symsrc_filename, fallback to long_name.
Signed-off-by: Martin Vuille <jpmv27@aim.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20180211212420.18388-1-jpmv27@aim.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

tools/perf/util/unwind-libdw.c

@@ -47,7 +47,7 @@ static int __report_module(struct addr_location *al, u64 ip,
 
 	if (!mod)
 		mod = dwfl_report_elf(ui->dwfl, dso->short_name,
-				      dso->long_name, -1, al->map->start,
+				      (dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start,
 				      false);
 
 	return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;