From f74b4a199b842cc207dcb5ebbbfb917786928cb0 Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Fri, 5 Feb 2016 14:01:27 +0000 Subject: [PATCH] perf symbols: Fix symbols searching for module in buildid-cache 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 Cc: Adrian Hunter Cc: Alexei Starovoitov Cc: Brendan Gregg Cc: Cody P Schafer Cc: He Kuang Cc: Jeremie Galarneau Cc: Jiri Olsa Cc: Kirill Smelkov Cc: Li Zefan Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Peter Zijlstra 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 --- tools/perf/util/build-id.c | 44 ++++++++++++++++++++++++++++++++++++++ tools/perf/util/build-id.h | 1 + tools/perf/util/symbol.c | 4 ++++ 3 files changed, 49 insertions(+) diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c index b28100ee1732a..f1479eeef7daf 100644 --- a/tools/perf/util/build-id.c +++ b/tools/perf/util/build-id.c @@ -166,6 +166,50 @@ char *dso__build_id_filename(const struct dso *dso, char *bf, size_t size) return build_id__filename(build_id_hex, bf, size); } +bool dso__build_id_is_kmod(const struct dso *dso, char *bf, size_t size) +{ + char *id_name, *ch; + struct stat sb; + + id_name = dso__build_id_filename(dso, bf, size); + if (!id_name) + goto err; + if (access(id_name, F_OK)) + goto err; + if (lstat(id_name, &sb) == -1) + goto err; + if ((size_t)sb.st_size > size - 1) + goto err; + if (readlink(id_name, bf, size - 1) < 0) + goto err; + + bf[sb.st_size] = '\0'; + + /* + * link should be: + * ../../lib/modules/4.4.0-rc4/kernel/net/ipv4/netfilter/nf_nat_ipv4.ko/a09fe3eb3147dafa4e3b31dbd6257e4d696bdc92 + */ + ch = strrchr(bf, '/'); + if (!ch) + goto err; + if (ch - 3 < bf) + goto err; + + return strncmp(".ko", ch - 3, 3) == 0; +err: + /* + * If dso__build_id_filename work, get id_name again, + * because id_name points to bf and is broken. + */ + if (id_name) + id_name = dso__build_id_filename(dso, bf, size); + pr_err("Invalid build id: %s\n", id_name ? : + dso->long_name ? : + dso->short_name ? : + "[unknown]"); + return false; +} + #define dsos__for_each_with_build_id(pos, head) \ list_for_each_entry(pos, head, node) \ if (!pos->has_build_id) \ diff --git a/tools/perf/util/build-id.h b/tools/perf/util/build-id.h index 27a14a8a945be..64af3e20610d7 100644 --- a/tools/perf/util/build-id.h +++ b/tools/perf/util/build-id.h @@ -16,6 +16,7 @@ int sysfs__sprintf_build_id(const char *root_dir, char *sbuild_id); int filename__sprintf_build_id(const char *pathname, char *sbuild_id); char *dso__build_id_filename(const struct dso *dso, char *bf, size_t size); +bool dso__build_id_is_kmod(const struct dso *dso, char *bf, size_t size); int build_id__mark_dso_hit(struct perf_tool *tool, union perf_event *event, struct perf_sample *sample, struct perf_evsel *evsel, diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index 90cedfa30e43a..e7588dc915181 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -1529,6 +1529,10 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter) if (!runtime_ss && syms_ss) runtime_ss = syms_ss; + if (syms_ss && syms_ss->type == DSO_BINARY_TYPE__BUILD_ID_CACHE) + if (dso__build_id_is_kmod(dso, name, PATH_MAX)) + kmod = true; + if (syms_ss) ret = dso__load_sym(dso, map, syms_ss, runtime_ss, filter, kmod); else -- 2.39.5