perf probe: Add basic module support

Add basic module probe support on perf probe. This introduces "--module
<MODNAME>" option to perf probe for putting probes and showing lines and
variables in the given module.

Currently, this supports only probing on running modules.  Supporting off-line
module probing is the next step.

e.g.)
[show lines]
 # ./perf probe --module drm -L drm_vblank_info
<drm_vblank_info:0>
      0  int drm_vblank_info(struct seq_file *m, void *data)
      1  {
                struct drm_info_node *node = (struct drm_info_node *) m->private
      3         struct drm_device *dev = node->minor->dev;
 ...
[show vars]
 # ./perf probe --module drm -V drm_vblank_info:3
Available variables at drm_vblank_info:3
        @<drm_vblank_info+20>
                (unknown_type)  data
                struct drm_info_node*   node
                struct seq_file*        m
[put a probe]
 # ./perf probe --module drm drm_vblank_info:3 node m
Add new event:
  probe:drm_vblank_info (on drm_vblank_info:3 with node m)

You can now use it on all perf tools, such as:

        perf record -e probe:drm_vblank_info -aR sleep 1
[list probes]
 # ./perf probe -l
probe:drm_vblank_info (on drm_vblank_info:3@drivers/gpu/drm/drm_info.c with ...

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20101021101341.3542.71638.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 79 insertions, 44 deletions

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 82b0976e2053..3b6a5297bf16 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -74,10 +74,9 @@ static int e_snprintf(char *str, size_t size, const char *format, ...)
 static char *synthesize_perf_probe_point(struct perf_probe_point *pp);
 static struct machine machine;
 
-/* Initialize symbol maps and path of vmlinux */
+/* Initialize symbol maps and path of vmlinux/modules */
 static int init_vmlinux(void)
 {
-        struct dso *kernel;
         int ret;
 
         symbol_conf.sort_by_name = true;
@@ -91,33 +90,61 @@ static int init_vmlinux(void)
                 goto out;
         }
 
-        ret = machine__init(&machine, "/", 0);
+        ret = machine__init(&machine, "", HOST_KERNEL_ID);
         if (ret < 0)
                 goto out;
 
-        kernel = dso__new_kernel(symbol_conf.vmlinux_name);
-        if (kernel == NULL)
-                die("Failed to create kernel dso.");
-
-        ret = __machine__create_kernel_maps(&machine, kernel);
-        if (ret < 0)
-                pr_debug("Failed to create kernel maps.\n");
-
+        if (machine__create_kernel_maps(&machine) < 0) {
+                pr_debug("machine__create_kernel_maps ");
+                goto out;
+        }
 out:
         if (ret < 0)
                 pr_warning("Failed to init vmlinux path.\n");
         return ret;
 }
 
+static struct symbol *__find_kernel_function_by_name(const char *name,
+                                                     struct map **mapp)
+{
+        return machine__find_kernel_function_by_name(&machine, name, mapp,
+                                                     NULL);
+}
+
+const char *kernel_get_module_path(const char *module)
+{
+        struct dso *dso;
+
+        if (module) {
+                list_for_each_entry(dso, &machine.kernel_dsos, node) {
+                        if (strncmp(dso->short_name + 1, module,
+                                    dso->short_name_len - 2) == 0)
+                                goto found;
+                }
+                pr_debug("Failed to find module %s.\n", module);
+                return NULL;
+        } else {
+                dso = machine.vmlinux_maps[MAP__FUNCTION]->dso;
+                if (dso__load_vmlinux_path(dso,
+                         machine.vmlinux_maps[MAP__FUNCTION], NULL) < 0) {
+                        pr_debug("Failed to load kernel map.\n");
+                        return NULL;
+                }
+        }
+found:
+        return dso->long_name;
+}
+
 #ifdef DWARF_SUPPORT
-static int open_vmlinux(void)
+static int open_vmlinux(const char *module)
 {
-        if (map__load(machine.vmlinux_maps[MAP__FUNCTION], NULL) < 0) {
-                pr_debug("Failed to load kernel map.\n");
-                return -EINVAL;
+        const char *path = kernel_get_module_path(module);
+        if (!path) {
+                pr_err("Failed to find path of %s module", module ?: "kernel");
+                return -ENOENT;
         }
-        pr_debug("Try to open %s\n", machine.vmlinux_maps[MAP__FUNCTION]->dso->long_name);
-        return open(machine.vmlinux_maps[MAP__FUNCTION]->dso->long_name, O_RDONLY);
+        pr_debug("Try to open %s\n", path);
+        return open(path, O_RDONLY);
 }
 
 /*
@@ -125,20 +152,19 @@ static int open_vmlinux(void)
  * Currently only handles kprobes.
  */
 static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
-                                       struct perf_probe_point *pp)
+                                        struct perf_probe_point *pp)
 {
         struct symbol *sym;
-        int fd, ret = -ENOENT;
+        struct map *map;
+        u64 addr;
+        int ret = -ENOENT;
 
-        sym = map__find_symbol_by_name(machine.vmlinux_maps[MAP__FUNCTION],
-                                       tp->symbol, NULL);
+        sym = __find_kernel_function_by_name(tp->symbol, &map);
         if (sym) {
-                fd = open_vmlinux();
-                if (fd >= 0) {
-                        ret = find_perf_probe_point(fd,
-                                                 sym->start + tp->offset, pp);
-                        close(fd);
-                }
+                addr = map->unmap_ip(map, sym->start + tp->offset);
+                pr_debug("try to find %s+%ld@%llx\n", tp->symbol,
+                         tp->offset, addr);
+                ret = find_perf_probe_point((unsigned long)addr, pp);
         }
         if (ret <= 0) {
                 pr_debug("Failed to find corresponding probes from "
@@ -156,12 +182,12 @@ static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
 /* Try to find perf_probe_event with debuginfo */
 static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
                                            struct probe_trace_event **tevs,
-                                           int max_tevs)
+                                           int max_tevs, const char *module)
 {
         bool need_dwarf = perf_probe_event_need_dwarf(pev);
         int fd, ntevs;
 
-        fd = open_vmlinux();
+        fd = open_vmlinux(module);
         if (fd < 0) {
                 if (need_dwarf) {
                         pr_warning("Failed to open debuginfo file.\n");
@@ -300,7 +326,7 @@ error:
  * Show line-range always requires debuginfo to find source file and
  * line number.
  */
-int show_line_range(struct line_range *lr)
+int show_line_range(struct line_range *lr, const char *module)
 {
         int l = 1;
         struct line_node *ln;
@@ -313,7 +339,7 @@ int show_line_range(struct line_range *lr)
         if (ret < 0)
                 return ret;
 
-        fd = open_vmlinux();
+        fd = open_vmlinux(module);
         if (fd < 0) {
                 pr_warning("Failed to open debuginfo file.\n");
                 return fd;
@@ -421,7 +447,7 @@ static int show_available_vars_at(int fd, struct perf_probe_event *pev,
 
 /* Show available variables on given probe point */
 int show_available_vars(struct perf_probe_event *pevs, int npevs,
-                        int max_vls, bool externs)
+                        int max_vls, const char *module, bool externs)
 {
         int i, fd, ret = 0;
 
@@ -429,7 +455,7 @@ int show_available_vars(struct perf_probe_event *pevs, int npevs,
         if (ret < 0)
                 return ret;
 
-        fd = open_vmlinux();
+        fd = open_vmlinux(module);
         if (fd < 0) {
                 pr_warning("Failed to open debuginfo file.\n");
                 return fd;
@@ -447,8 +473,15 @@ int show_available_vars(struct perf_probe_event *pevs, int npevs,
 #else   /* !DWARF_SUPPORT */
 
 static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
-                                       struct perf_probe_point *pp)
+                                        struct perf_probe_point *pp)
 {
+        struct symbol *sym;
+
+        sym = __find_kernel_function_by_name(tp->symbol, NULL);
+        if (!sym) {
+                pr_err("Failed to find symbol %s in kernel.\n", tp->symbol);
+                return -ENOENT;
+        }
         pp->function = strdup(tp->symbol);
         if (pp->function == NULL)
                 return -ENOMEM;
@@ -460,7 +493,7 @@ static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
 
 static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
                                 struct probe_trace_event **tevs __unused,
-                                int max_tevs __unused)
+                                int max_tevs __unused, const char *mod __unused)
 {
         if (perf_probe_event_need_dwarf(pev)) {
                 pr_warning("Debuginfo-analysis is not supported.\n");
@@ -469,14 +502,15 @@ static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
         return 0;
 }
 
-int show_line_range(struct line_range *lr __unused)
+int show_line_range(struct line_range *lr __unused, const char *module __unused)
 {
         pr_warning("Debuginfo-analysis is not supported.\n");
         return -ENOSYS;
 }
 
 int show_available_vars(struct perf_probe_event *pevs __unused,
-                        int npevs __unused, int max_probe_points __unused)
+                        int npevs __unused, int max_vls __unused,
+                        const char *module __unused, bool externs __unused)
 {
         pr_warning("Debuginfo-analysis is not supported.\n");
         return -ENOSYS;
@@ -1159,7 +1193,7 @@ error:
 }
 
 static int convert_to_perf_probe_event(struct probe_trace_event *tev,
-                                struct perf_probe_event *pev)
+                                       struct perf_probe_event *pev)
 {
         char buf[64] = "";
         int i, ret;
@@ -1588,14 +1622,14 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
 
 static int convert_to_probe_trace_events(struct perf_probe_event *pev,
                                           struct probe_trace_event **tevs,
-                                          int max_tevs)
+                                          int max_tevs, const char *module)
 {
         struct symbol *sym;
         int ret = 0, i;
         struct probe_trace_event *tev;
 
         /* Convert perf_probe_event with debuginfo */
-        ret = try_to_find_probe_trace_events(pev, tevs, max_tevs);
+        ret = try_to_find_probe_trace_events(pev, tevs, max_tevs, module);
         if (ret != 0)
                 return ret;
 
@@ -1644,8 +1678,7 @@ static int convert_to_probe_trace_events(struct perf_probe_event *pev,
         }
 
         /* Currently just checking function name from symbol map */
-        sym = map__find_symbol_by_name(machine.vmlinux_maps[MAP__FUNCTION],
-                                       tev->point.symbol, NULL);
+        sym = __find_kernel_function_by_name(tev->point.symbol, NULL);
         if (!sym) {
                 pr_warning("Kernel symbol \'%s\' not found.\n",
                            tev->point.symbol);
@@ -1668,7 +1701,7 @@ struct __event_package {
 };
 
 int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
-                          int max_tevs, bool force_add)
+                          int max_tevs, const char *module, bool force_add)
 {
         int i, j, ret;
         struct __event_package *pkgs;
@@ -1689,7 +1722,9 @@ int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
                 pkgs[i].pev = &pevs[i];
                 /* Convert with or without debuginfo */
                 ret  = convert_to_probe_trace_events(pkgs[i].pev,
-                                                      &pkgs[i].tevs, max_tevs);
+                                                     &pkgs[i].tevs,
+                                                     max_tevs,
+                                                     module);
                 if (ret < 0)
                         goto end;
                 pkgs[i].ntevs = ret;