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Before this patch, if a sample is triggered inside a module not in
/lib/modules/`uname -r`/, even if the module is in buildid-cache, 'perf
report' will still be unable to find the correct symbol. For example:
# rm -rf ~/.debug/
# perf buildid-cache -a ./mymodule.ko
# perf probe -m ./mymodule.ko -a get_mymodule_val
Added new event:
probe:get_mymodule_val (on get_mymodule_val in mymodule)
You can now use it in all perf tools, such as:
perf record -e probe:get_mymodule_val -aR sleep 1
# perf record -e probe:get_mymodule_val cat /proc/mymodule
mymodule:3
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.011 MB perf.data (1 samples) ]
# perf report --stdio
[SNIP]
#
# Overhead Command Shared Object Symbol
# ........ ....... ................ ......................
#
100.00% cat [mymodule] [k] 0x0000000000000001
# perf report -vvvv --stdio
dso__load_sym: adjusting symbol: st_value: 0 sh_addr: 0 sh_offset: 0x70
symbol__new: get_mymodule_val 0x70-0x8a
[SNIP]
This is caused by dso__load() -> dso__load_sym(). In dso__load(), kmod
is true only when its file is found in some well know directories. All
files loaded from buildid-cache are treated as user programs. Following
dso__load_sym() set map->pgoff incorrectly.
This patch gives kernel modules in buildid-cache a chance to adjust
value of kmod. After dso__load() get the type of symbols, if it is
buildid, check the last 3 chars of original filename against '.ko', and
adjust the value of kmod if the file is a kernel module.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Cody P Schafer <dev@codyps.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jeremie Galarneau <jeremie.galarneau@efficios.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kirill Smelkov <kirr@nexedi.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1454680939-24963-3-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
40 lines
1.4 KiB
C
40 lines
1.4 KiB
C
#ifndef PERF_BUILD_ID_H_
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#define PERF_BUILD_ID_H_ 1
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#define BUILD_ID_SIZE 20
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#define SBUILD_ID_SIZE (BUILD_ID_SIZE * 2 + 1)
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#include "tool.h"
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#include "strlist.h"
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#include <linux/types.h>
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extern struct perf_tool build_id__mark_dso_hit_ops;
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struct dso;
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int build_id__sprintf(const u8 *build_id, int len, char *bf);
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int sysfs__sprintf_build_id(const char *root_dir, char *sbuild_id);
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int filename__sprintf_build_id(const char *pathname, char *sbuild_id);
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char *dso__build_id_filename(const struct dso *dso, char *bf, size_t size);
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bool dso__build_id_is_kmod(const struct dso *dso, char *bf, size_t size);
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int build_id__mark_dso_hit(struct perf_tool *tool, union perf_event *event,
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struct perf_sample *sample, struct perf_evsel *evsel,
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struct machine *machine);
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int dsos__hit_all(struct perf_session *session);
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bool perf_session__read_build_ids(struct perf_session *session, bool with_hits);
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int perf_session__write_buildid_table(struct perf_session *session, int fd);
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int perf_session__cache_build_ids(struct perf_session *session);
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int build_id_cache__list_build_ids(const char *pathname,
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struct strlist **result);
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bool build_id_cache__cached(const char *sbuild_id);
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int build_id_cache__add_s(const char *sbuild_id,
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const char *name, bool is_kallsyms, bool is_vdso);
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int build_id_cache__remove_s(const char *sbuild_id);
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void disable_buildid_cache(void);
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#endif
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