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authorMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>2015-09-30 19:41:33 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2015-10-01 00:34:35 +0300
commit9b239a12bc872f212cefbaee4d028c838abe6ff3 (patch)
tree483e19ee3b88364bbb7ac4d08b2a7c53cc1f4c3e /tools/perf/util/probe-finder.c
parent9135949ddd9d0d8d73a2f441912508d25a4a82a2 (diff)
downloadlinux-9b239a12bc872f212cefbaee4d028c838abe6ff3.tar.xz
perf probe: Show correct source lines of probes on kmodules
Perf probe always failed to find appropriate line numbers because of failing to find .text start address offset from debuginfo. e.g. ---- # ./perf probe -m pcspkr pcspkr_event:5 Added new events: probe:pcspkr_event (on pcspkr_event:5 in pcspkr) probe:pcspkr_event_1 (on pcspkr_event:5 in pcspkr) You can now use it in all perf tools, such as: perf record -e probe:pcspkr_event_1 -aR sleep 1 # ./perf probe -l Failed to find debug information for address ffffffffa031f006 Failed to find debug information for address ffffffffa031f016 probe:pcspkr_event (on pcspkr_event+6 in pcspkr) probe:pcspkr_event_1 (on pcspkr_event+22 in pcspkr) ---- This fixes the above issue as below. 1. Get the relative address of the symbol in .text by using map->start. 2. Adjust the address by adding the offset of .text section in the kernel module binary. With this fix, perf probe -l shows lines correctly. ---- # ./perf probe -l probe:pcspkr_event (on pcspkr_event:5@drivers/input/misc/pcspkr.c in pcspkr) probe:pcspkr_event_1 (on pcspkr_event:5@drivers/input/misc/pcspkr.c in pcspkr) ---- Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.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/20150930164132.3733.24643.stgit@localhost.localdomain Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/probe-finder.c')
-rw-r--r--tools/perf/util/probe-finder.c42
1 files changed, 42 insertions, 0 deletions
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 35f905f4f34c..f0708ffd5e07 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1402,6 +1402,41 @@ int debuginfo__find_available_vars_at(struct debuginfo *dbg,
return (ret < 0) ? ret : af.nvls;
}
+/* For the kernel module, we need a special code to get a DIE */
+static int debuginfo__get_text_offset(struct debuginfo *dbg, Dwarf_Addr *offs)
+{
+ int n, i;
+ Elf32_Word shndx;
+ Elf_Scn *scn;
+ Elf *elf;
+ GElf_Shdr mem, *shdr;
+ const char *p;
+
+ elf = dwfl_module_getelf(dbg->mod, &dbg->bias);
+ if (!elf)
+ return -EINVAL;
+
+ /* Get the number of relocations */
+ n = dwfl_module_relocations(dbg->mod);
+ if (n < 0)
+ return -ENOENT;
+ /* Search the relocation related .text section */
+ for (i = 0; i < n; i++) {
+ p = dwfl_module_relocation_info(dbg->mod, i, &shndx);
+ if (strcmp(p, ".text") == 0) {
+ /* OK, get the section header */
+ scn = elf_getscn(elf, shndx);
+ if (!scn)
+ return -ENOENT;
+ shdr = gelf_getshdr(scn, &mem);
+ if (!shdr)
+ return -ENOENT;
+ *offs = shdr->sh_addr;
+ }
+ }
+ return 0;
+}
+
/* Reverse search */
int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
struct perf_probe_point *ppt)
@@ -1410,9 +1445,16 @@ int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
Dwarf_Addr _addr = 0, baseaddr = 0;
const char *fname = NULL, *func = NULL, *basefunc = NULL, *tmp;
int baseline = 0, lineno = 0, ret = 0;
+ bool reloc = false;
+retry:
/* Find cu die */
if (!dwarf_addrdie(dbg->dbg, (Dwarf_Addr)addr, &cudie)) {
+ if (!reloc && debuginfo__get_text_offset(dbg, &baseaddr) == 0) {
+ addr += baseaddr;
+ reloc = true;
+ goto retry;
+ }
pr_warning("Failed to find debug information for address %lx\n",
addr);
ret = -EINVAL;