perf probe: Fix to probe on gcc generated functions in modules

Fix to probe on gcc generated functions on modules. Since
probing on a module is based on its symbol name, it should
be adjusted on actual symbols.

E.g. without this fix, perf probe shows probe definition
on non-exist symbol as below.

  $ perf probe -m build-x86_64/net/netfilter/nf_nat.ko -F in_range*
  in_range.isra.12
  $ perf probe -m build-x86_64/net/netfilter/nf_nat.ko -D in_range
  p:probe/in_range nf_nat:in_range+0

With this fix, perf probe correctly shows a probe on
gcc-generated symbol.

  $ perf probe -m build-x86_64/net/netfilter/nf_nat.ko -D in_range
  p:probe/in_range nf_nat:in_range.isra.12+0

This also fixes same problem on online module as below.

  $ perf probe -m i915 -D assert_plane
  p:probe/assert_plane i915:assert_plane.constprop.134+0

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/148411450673.9978.14905987549651656075.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index aa8a9227080a9c6612ccef9992e8f6736d0fd5c9..6a6f44dd594bc4c6275694335ebaa02b22118982 100644 (file)
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -698,18 +698,31 @@ static int add_exec_to_probe_trace_events(struct probe_trace_event *tevs,
        return ret;
 }
 
-static int add_module_to_probe_trace_events(struct probe_trace_event *tevs,
-                                           int ntevs, const char *module)
+static int
+post_process_module_probe_trace_events(struct probe_trace_event *tevs,
+                                      int ntevs, const char *module,
+                                      struct debuginfo *dinfo)
 {
+       Dwarf_Addr text_offs = 0;
        int i, ret = 0;
        char *mod_name = NULL;
+       struct map *map;
 
        if (!module)
                return 0;
 
-       mod_name = find_module_name(module);
+       map = get_target_map(module, false);
+       if (!map || debuginfo__get_text_offset(dinfo, &text_offs, true) < 0) {
+               pr_warning("Failed to get ELF symbols for %s\n", module);
+               return -EINVAL;
+       }
 
+       mod_name = find_module_name(module);
        for (i = 0; i < ntevs; i++) {
+               ret = post_process_probe_trace_point(&tevs[i].point,
+                                               map, (unsigned long)text_offs);
+               if (ret < 0)
+                       break;
                tevs[i].point.module =
                        strdup(mod_name ? mod_name : module);
                if (!tevs[i].point.module) {
@@ -719,6 +732,8 @@ static int add_module_to_probe_trace_events(struct probe_trace_event *tevs,
        }
 
        free(mod_name);
+       map__put(map);
+
        return ret;
 }
 
@@ -776,7 +791,7 @@ arch__post_process_probe_trace_events(struct perf_probe_event *pev __maybe_unuse
 static int post_process_probe_trace_events(struct perf_probe_event *pev,
                                           struct probe_trace_event *tevs,
                                           int ntevs, const char *module,
-                                          bool uprobe)
+                                          bool uprobe, struct debuginfo *dinfo)
 {
        int ret;
 
@@ -784,7 +799,8 @@ static int post_process_probe_trace_events(struct perf_probe_event *pev,
                ret = add_exec_to_probe_trace_events(tevs, ntevs, module);
        else if (module)
                /* Currently ref_reloc_sym based probe is not for drivers */
-               ret = add_module_to_probe_trace_events(tevs, ntevs, module);
+               ret = post_process_module_probe_trace_events(tevs, ntevs,
+                                                            module, dinfo);
        else
                ret = post_process_kernel_probe_trace_events(tevs, ntevs);
 
@@ -828,30 +844,27 @@ static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
                }
        }
 
-       debuginfo__delete(dinfo);
-
        if (ntevs > 0) {        /* Succeeded to find trace events */
                pr_debug("Found %d probe_trace_events.\n", ntevs);
                ret = post_process_probe_trace_events(pev, *tevs, ntevs,
-                                               pev->target, pev->uprobes);
+                                       pev->target, pev->uprobes, dinfo);
                if (ret < 0 || ret == ntevs) {
+                       pr_debug("Post processing failed or all events are skipped. (%d)\n", ret);
                        clear_probe_trace_events(*tevs, ntevs);
                        zfree(tevs);
+                       ntevs = 0;
                }
-               if (ret != ntevs)
-                       return ret < 0 ? ret : ntevs;
-               ntevs = 0;
-               /* Fall through */
        }
 
+       debuginfo__delete(dinfo);
+
        if (ntevs == 0) {       /* No error but failed to find probe point. */
                pr_warning("Probe point '%s' not found.\n",
                           synthesize_perf_probe_point(&pev->point));
                return -ENOENT;
-       }
-       /* Error path : ntevs < 0 */
-       pr_debug("An error occurred in debuginfo analysis (%d).\n", ntevs);
-       if (ntevs < 0) {
+       } else if (ntevs < 0) {
+               /* Error path : ntevs < 0 */
+               pr_debug("An error occurred in debuginfo analysis (%d).\n", ntevs);
                if (ntevs == -EBADF)
                        pr_warning("Warning: No dwarf info found in the vmlinux - "
                                "please rebuild kernel with CONFIG_DEBUG_INFO=y.\n");

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 0278fe1a4cc6f1f165bc1fb9233ce524eac45ddd..0d9d6e0803b88b6fe3909c0b8b83f24fa47580f6 100644 (file)
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1501,7 +1501,8 @@ int debuginfo__find_available_vars_at(struct debuginfo *dbg,
 }
 
 /* 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 debuginfo__get_text_offset(struct debuginfo *dbg, Dwarf_Addr *offs,
+                               bool adjust_offset)
 {
        int n, i;
        Elf32_Word shndx;
@@ -1530,6 +1531,8 @@ static int debuginfo__get_text_offset(struct debuginfo *dbg, Dwarf_Addr *offs)
                        if (!shdr)
                                return -ENOENT;
                        *offs = shdr->sh_addr;
+                       if (adjust_offset)
+                               *offs -= shdr->sh_offset;
                }
        }
        return 0;
@@ -1545,7 +1548,7 @@ int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
        int baseline = 0, lineno = 0, ret = 0;
 
        /* We always need to relocate the address for aranges */
-       if (debuginfo__get_text_offset(dbg, &baseaddr) == 0)
+       if (debuginfo__get_text_offset(dbg, &baseaddr, false) == 0)
                addr += baseaddr;
        /* Find cu die */
        if (!dwarf_addrdie(dbg->dbg, (Dwarf_Addr)addr, &cudie)) {

diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index f1d8558f498e96771c13b3f42046a757e888bdf2..2956c51986529ee7481f922d488a449c0a7619a0 100644 (file)
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -46,6 +46,9 @@ int debuginfo__find_trace_events(struct debuginfo *dbg,
 int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
                                struct perf_probe_point *ppt);
 
+int debuginfo__get_text_offset(struct debuginfo *dbg, Dwarf_Addr *offs,
+                              bool adjust_offset);
+
 /* Find a line range */
 int debuginfo__find_line_range(struct debuginfo *dbg, struct line_range *lr);