perf probe: Add --list option for listing current probe events

Add --list option for listing currently defined probe events
in the kernel. This shows events in below format;

 [group:event]	<perf-probe probe-definition>

for example:

 [probe:schedule_0]	schedule+30 cpu

Note that source file/line information is not supported yet.
So even if you added a probe by line, it will be shown in
<symbol+offset>.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091201002017.10235.76575.stgit@harusame>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 214 insertions, 17 deletions

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index e3a683ab976f..7f4f288c642e 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -29,10 +29,13 @@
 #include <unistd.h>
 #include <stdlib.h>
 #include <string.h>
+#include <stdarg.h>
+#include <limits.h>
 
 #undef _GNU_SOURCE
 #include "event.h"
 #include "string.h"
+#include "strlist.h"
 #include "debug.h"
 #include "parse-events.h"  /* For debugfs_path */
 #include "probe-event.h"
@@ -43,6 +46,19 @@
 
 #define semantic_error(msg ...) die("Semantic error :" msg)
 
+/* If there is no space to write, returns -E2BIG. */
+static int e_snprintf(char *str, size_t size, const char *format, ...)
+{
+        int ret;
+        va_list ap;
+        va_start(ap, format);
+        ret = vsnprintf(str, size, format, ap);
+        va_end(ap);
+        if (ret >= (int)size)
+                ret = -E2BIG;
+        return ret;
+}
+
 /* Parse probepoint definition. */
 static void parse_perf_probe_probepoint(char *arg, struct probe_point *pp)
 {
@@ -166,6 +182,103 @@ int parse_perf_probe_event(const char *str, struct probe_point *pp)
         return need_dwarf;
 }
 
+/* Parse kprobe_events event into struct probe_point */
+void parse_trace_kprobe_event(const char *str, char **group, char **event,
+                              struct probe_point *pp)
+{
+        char pr;
+        char *p;
+        int ret, i, argc;
+        char **argv;
+
+        pr_debug("Parsing kprobe_events: %s\n", str);
+        argv = argv_split(str, &argc);
+        if (!argv)
+                die("argv_split failed.");
+        if (argc < 2)
+                semantic_error("Too less arguments.");
+
+        /* Scan event and group name. */
+        ret = sscanf(argv[0], "%c:%m[^/ \t]/%m[^ \t]",
+                     &pr, group, event);
+        if (ret != 3)
+                semantic_error("Failed to parse event name: %s", argv[0]);
+        pr_debug("Group:%s Event:%s probe:%c\n", *group, *event, pr);
+
+        if (!pp)
+                goto end;
+
+        pp->retprobe = (pr == 'r');
+
+        /* Scan function name and offset */
+        ret = sscanf(argv[1], "%m[^+]+%d", &pp->function, &pp->offset);
+        if (ret == 1)
+                pp->offset = 0;
+
+        /* kprobe_events doesn't have this information */
+        pp->line = 0;
+        pp->file = NULL;
+
+        pp->nr_args = argc - 2;
+        pp->args = zalloc(sizeof(char *) * pp->nr_args);
+        for (i = 0; i < pp->nr_args; i++) {
+                p = strchr(argv[i + 2], '=');
+                if (p)  /* We don't need which register is assigned. */
+                        *p = '\0';
+                pp->args[i] = strdup(argv[i + 2]);
+                if (!pp->args[i])
+                        die("Failed to copy argument.");
+        }
+
+end:
+        argv_free(argv);
+}
+
+int synthesize_perf_probe_event(struct probe_point *pp)
+{
+        char *buf;
+        char offs[64] = "", line[64] = "";
+        int i, len, ret;
+
+        pp->probes[0] = buf = zalloc(MAX_CMDLEN);
+        if (!buf)
+                die("Failed to allocate memory by zalloc.");
+        if (pp->offset) {
+                ret = e_snprintf(offs, 64, "+%d", pp->offset);
+                if (ret <= 0)
+                        goto error;
+        }
+        if (pp->line) {
+                ret = e_snprintf(line, 64, ":%d", pp->line);
+                if (ret <= 0)
+                        goto error;
+        }
+
+        if (pp->function)
+                ret = e_snprintf(buf, MAX_CMDLEN, "%s%s%s%s", pp->function,
+                                 offs, pp->retprobe ? "%return" : "", line);
+        else
+                ret = e_snprintf(buf, MAX_CMDLEN, "%s%s%s%s", pp->file, line);
+        if (ret <= 0)
+                goto error;
+        len = ret;
+
+        for (i = 0; i < pp->nr_args; i++) {
+                ret = e_snprintf(&buf[len], MAX_CMDLEN - len, " %s",
+                                 pp->args[i]);
+                if (ret <= 0)
+                        goto error;
+                len += ret;
+        }
+        pp->found = 1;
+
+        return pp->found;
+error:
+        free(pp->probes[0]);
+
+        return ret;
+}
+
 int synthesize_trace_kprobe_event(struct probe_point *pp)
 {
         char *buf;
@@ -174,15 +287,15 @@ int synthesize_trace_kprobe_event(struct probe_point *pp)
         pp->probes[0] = buf = zalloc(MAX_CMDLEN);
         if (!buf)
                 die("Failed to allocate memory by zalloc.");
-        ret = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
-        if (ret <= 0 || ret >= MAX_CMDLEN)
+        ret = e_snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
+        if (ret <= 0)
                 goto error;
         len = ret;
 
         for (i = 0; i < pp->nr_args; i++) {
-                ret = snprintf(&buf[len], MAX_CMDLEN - len, " %s",
-                               pp->args[i]);
-                if (ret <= 0 || ret >= MAX_CMDLEN - len)
+                ret = e_snprintf(&buf[len], MAX_CMDLEN - len, " %s",
+                                 pp->args[i]);
+                if (ret <= 0)
                         goto error;
                 len += ret;
         }
@@ -191,12 +304,105 @@ int synthesize_trace_kprobe_event(struct probe_point *pp)
         return pp->found;
 error:
         free(pp->probes[0]);
-        if (ret > 0)
-                ret = -E2BIG;
 
         return ret;
 }
 
+static int open_kprobe_events(int flags, int mode)
+{
+        char buf[PATH_MAX];
+        int ret;
+
+        ret = e_snprintf(buf, PATH_MAX, "%s/../kprobe_events", debugfs_path);
+        if (ret < 0)
+                die("Failed to make kprobe_events path.");
+
+        ret = open(buf, flags, mode);
+        if (ret < 0) {
+                if (errno == ENOENT)
+                        die("kprobe_events file does not exist -"
+                            " please rebuild with CONFIG_KPROBE_TRACER.");
+                else
+                        die("Could not open kprobe_events file: %s",
+                            strerror(errno));
+        }
+        return ret;
+}
+
+/* Get raw string list of current kprobe_events */
+static struct strlist *get_trace_kprobe_event_rawlist(int fd)
+{
+        int ret, idx;
+        FILE *fp;
+        char buf[MAX_CMDLEN];
+        char *p;
+        struct strlist *sl;
+
+        sl = strlist__new(true, NULL);
+
+        fp = fdopen(dup(fd), "r");
+        while (!feof(fp)) {
+                p = fgets(buf, MAX_CMDLEN, fp);
+                if (!p)
+                        break;
+
+                idx = strlen(p) - 1;
+                if (p[idx] == '\n')
+                        p[idx] = '\0';
+                ret = strlist__add(sl, buf);
+                if (ret < 0)
+                        die("strlist__add failed: %s", strerror(-ret));
+        }
+        fclose(fp);
+
+        return sl;
+}
+
+/* Free and zero clear probe_point */
+static void clear_probe_point(struct probe_point *pp)
+{
+        int i;
+
+        if (pp->function)
+                free(pp->function);
+        if (pp->file)
+                free(pp->file);
+        for (i = 0; i < pp->nr_args; i++)
+                free(pp->args[i]);
+        if (pp->args)
+                free(pp->args);
+        for (i = 0; i < pp->found; i++)
+                free(pp->probes[i]);
+        memset(pp, 0, sizeof(pp));
+}
+
+/* List up current perf-probe events */
+void show_perf_probe_events(void)
+{
+        unsigned int i;
+        int fd;
+        char *group, *event;
+        struct probe_point pp;
+        struct strlist *rawlist;
+        struct str_node *ent;
+
+        fd = open_kprobe_events(O_RDONLY, 0);
+        rawlist = get_trace_kprobe_event_rawlist(fd);
+        close(fd);
+
+        for (i = 0; i < strlist__nr_entries(rawlist); i++) {
+                ent = strlist__entry(rawlist, i);
+                parse_trace_kprobe_event(ent->s, &group, &event, &pp);
+                synthesize_perf_probe_event(&pp);
+                printf("[%s:%s]\t%s\n", group, event, pp.probes[0]);
+                free(group);
+                free(event);
+                clear_probe_point(&pp);
+        }
+
+        strlist__delete(rawlist);
+}
+
 static int write_trace_kprobe_event(int fd, const char *buf)
 {
         int ret;
@@ -216,16 +422,7 @@ void add_trace_kprobe_events(struct probe_point *probes, int nr_probes)
         struct probe_point *pp;
         char buf[MAX_CMDLEN];
 
-        snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
-        fd = open(buf, O_WRONLY, O_APPEND);
-        if (fd < 0) {
-                if (errno == ENOENT)
-                        die("kprobe_events file does not exist -"
-                            " please rebuild with CONFIG_KPROBE_TRACER.");
-                else
-                        die("Could not open kprobe_events file: %s",
-                            strerror(errno));
-        }
+        fd = open_kprobe_events(O_WRONLY, O_APPEND);
 
         for (j = 0; j < nr_probes; j++) {
                 pp = probes + j;