See http://www.infradead.org/rpr.html
From: Wang Nan <[email protected]> There is a nasty confusion that, for kernel module, dso->kernel is not necessary to be DSO_TYPE_KERNEL or DSO_TYPE_GUEST_KERNEL. These two enums are for vmlinux. See thread [1]. We tried to fix this part but it is costy. Code machine__write_buildid_table() is another unfortunate function fall into this trap that, when issuing buildid event for a kernel module, cpumode it gives to the event is PERF_RECORD_MISC_USER, not PERF_RECORD_MISC_KERNEL. However, even with this bug, most of the time it doesn't causes real problem. I find this issue when trying to use a perf before commit 3d39ac538629 ("perf machine: No need to have two DSOs lists") to parse a perf.data generated by newest perf. [1] https://lkml.org/lkml/2015/9/21/908 Signed-off-by: Wang Nan <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Li Zefan <[email protected]> Cc: Masami Hiramatsu <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]> --- tools/perf/util/build-id.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c index 6a7e273a514a..b28100ee1732 100644 --- a/tools/perf/util/build-id.c +++ b/tools/perf/util/build-id.c @@ -211,6 +211,7 @@ static int machine__write_buildid_table(struct machine *machine, int fd) dsos__for_each_with_build_id(pos, &machine->dsos.head) { const char *name; size_t name_len; + bool in_kernel = false; if (!pos->hit) continue; @@ -227,8 +228,11 @@ static int machine__write_buildid_table(struct machine *machine, int fd) name_len = pos->long_name_len + 1; } + in_kernel = pos->kernel || + is_kernel_module(name, + PERF_RECORD_MISC_CPUMODE_UNKNOWN); err = write_buildid(name, name_len, pos->build_id, machine->pid, - pos->kernel ? kmisc : umisc, fd); + in_kernel ? kmisc : umisc, fd); if (err) break; } -- 2.5.0
