perf: Add perf probe subcommand, a kprobe-event setup helper
Add perf probe subcommand that implements a kprobe-event setup helper
to the perf command.
This allows user to define kprobe events using C expressions (C line
numbers, C function names, and C local variables).
Usage
-----
perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]
-k, --vmlinux <file> vmlinux/module pathname
-P, --probe <p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]>
probe point definition, where
p: kprobe probe
r: kretprobe probe
GRP: Group name (optional)
NAME: Event name
FUNC: Function name
OFFS: Offset from function entry (in byte)
SRC: Source code path
LINE: Line number
ARG: Probe argument (local variable name or
kprobe-tracer argument format is supported.)
Changes in v4:
- Add _GNU_SOURCE macro for strndup().
Changes in v3:
- Remove -r option because perf always be used for online kernel.
- Check malloc/calloc results.
Changes in v2:
- Check synthesized string length.
- Rename perf kprobe to perf probe.
- Use spaces for separator and update usage comment.
- Check error paths in parse_probepoint().
- Check optimized-out variables.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
LKML-Reference: <20091008211737.29299.14784.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
new file mode 100644
index 0000000..24b64b5
--- /dev/null
+++ b/tools/perf/builtin-probe.c
@@ -0,0 +1,358 @@
+/*
+ * builtin-probe.c
+ *
+ * Builtin probe command: Set up probe events by C expression
+ *
+ * Written by Masami Hiramatsu <mhiramat@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ */
+#define _GNU_SOURCE
+#include <sys/utsname.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+
+#undef _GNU_SOURCE
+#include "perf.h"
+#include "builtin.h"
+#include "util/util.h"
+#include "util/parse-options.h"
+#include "util/parse-events.h" /* For debugfs_path */
+#include "util/probe-finder.h"
+
+/* Default vmlinux search paths */
+#define NR_SEARCH_PATH 3
+const char *default_search_path[NR_SEARCH_PATH] = {
+"/lib/modules/%s/build/vmlinux", /* Custom build kernel */
+"/usr/lib/debug/lib/modules/%s/vmlinux", /* Red Hat debuginfo */
+"/boot/vmlinux-debug-%s", /* Ubuntu */
+};
+
+#define MAX_PATH_LEN 256
+#define MAX_PROBES 128
+
+/* Session management structure */
+static struct {
+ char *vmlinux;
+ char *release;
+ int nr_probe;
+ struct probe_point probes[MAX_PROBES];
+ char *events[MAX_PROBES];
+} session;
+
+static void semantic_error(const char *msg)
+{
+ fprintf(stderr, "Semantic error: %s\n", msg);
+ exit(1);
+}
+
+static void perror_exit(const char *msg)
+{
+ perror(msg);
+ exit(1);
+}
+
+#define MAX_PROBE_ARGS 128
+
+static int parse_probepoint(const struct option *opt __used,
+ const char *str, int unset __used)
+{
+ char *argv[MAX_PROBE_ARGS + 2]; /* Event + probe + args */
+ int argc, i;
+ char *arg, *ptr;
+ struct probe_point *pp = &session.probes[session.nr_probe];
+ char **event = &session.events[session.nr_probe];
+ int retp = 0;
+
+ if (!str) /* The end of probe points */
+ return 0;
+
+ debug("Probe-define(%d): %s\n", session.nr_probe, str);
+ if (++session.nr_probe == MAX_PROBES)
+ semantic_error("Too many probes");
+
+ /* Separate arguments, similar to argv_split */
+ argc = 0;
+ do {
+ /* Skip separators */
+ while (isspace(*str))
+ str++;
+
+ /* Add an argument */
+ if (*str != '\0') {
+ const char *s = str;
+
+ /* Skip the argument */
+ while (!isspace(*str) && *str != '\0')
+ str++;
+
+ /* Duplicate the argument */
+ argv[argc] = strndup(s, str - s);
+ if (argv[argc] == NULL)
+ perror_exit("strndup");
+ if (++argc == MAX_PROBE_ARGS)
+ semantic_error("Too many arguments");
+ debug("argv[%d]=%s\n", argc, argv[argc - 1]);
+ }
+ } while (*str != '\0');
+ if (argc < 2)
+ semantic_error("Need event-name and probe-point at least.");
+
+ /* Parse the event name */
+ if (argv[0][0] == 'r')
+ retp = 1;
+ else if (argv[0][0] != 'p')
+ semantic_error("You must specify 'p'(kprobe) or"
+ " 'r'(kretprobe) first.");
+ /* TODO: check event name */
+ *event = argv[0];
+
+ /* Parse probe point */
+ arg = argv[1];
+ if (arg[0] == '@') {
+ /* Source Line */
+ arg++;
+ ptr = strchr(arg, ':');
+ if (!ptr || !isdigit(ptr[1]))
+ semantic_error("Line number is required.");
+ *ptr++ = '\0';
+ if (strlen(arg) == 0)
+ semantic_error("No file name.");
+ pp->file = strdup(arg);
+ pp->line = atoi(ptr);
+ if (!pp->file || !pp->line)
+ semantic_error("Failed to parse line.");
+ debug("file:%s line:%d\n", pp->file, pp->line);
+ } else {
+ /* Function name */
+ ptr = strchr(arg, '+');
+ if (ptr) {
+ if (!isdigit(ptr[1]))
+ semantic_error("Offset is required.");
+ *ptr++ = '\0';
+ pp->offset = atoi(ptr);
+ } else
+ ptr = arg;
+ ptr = strchr(ptr, '@');
+ if (ptr) {
+ *ptr++ = '\0';
+ pp->file = strdup(ptr);
+ }
+ pp->function = strdup(arg);
+ debug("symbol:%s file:%s offset:%d\n",
+ pp->function, pp->file, pp->offset);
+ }
+ free(argv[1]);
+
+ /* Copy arguments */
+ pp->nr_args = argc - 2;
+ if (pp->nr_args > 0) {
+ pp->args = (char **)malloc(sizeof(char *) * pp->nr_args);
+ if (!pp->args)
+ perror_exit("malloc");
+ memcpy(pp->args, &argv[2], sizeof(char *) * pp->nr_args);
+ }
+
+ /* Ensure return probe has no C argument */
+ if (retp)
+ for (i = 0; i < pp->nr_args; i++)
+ if (is_c_varname(pp->args[i]))
+ semantic_error("You can't specify local"
+ " variable for kretprobe");
+ debug("%d arguments\n", pp->nr_args);
+ return 0;
+}
+
+static int open_default_vmlinux(void)
+{
+ struct utsname uts;
+ char fname[MAX_PATH_LEN];
+ int fd, ret, i;
+
+ ret = uname(&uts);
+ if (ret) {
+ debug("uname() failed.\n");
+ return -errno;
+ }
+ session.release = uts.release;
+ for (i = 0; i < NR_SEARCH_PATH; i++) {
+ ret = snprintf(fname, MAX_PATH_LEN,
+ default_search_path[i], session.release);
+ if (ret >= MAX_PATH_LEN || ret < 0) {
+ debug("Filename(%d,%s) is too long.\n", i, uts.release);
+ errno = E2BIG;
+ return -E2BIG;
+ }
+ debug("try to open %s\n", fname);
+ fd = open(fname, O_RDONLY);
+ if (fd >= 0)
+ break;
+ }
+ return fd;
+}
+
+static const char * const probe_usage[] = {
+ "perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]",
+ NULL
+};
+
+static const struct option options[] = {
+ OPT_STRING('k', "vmlinux", &session.vmlinux, "file",
+ "vmlinux/module pathname"),
+ OPT_CALLBACK('P', "probe", NULL,
+ "p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]",
+ "probe point definition, where\n"
+ "\t\tp:\tkprobe probe\n"
+ "\t\tr:\tkretprobe probe\n"
+ "\t\tGRP:\tGroup name (optional)\n"
+ "\t\tNAME:\tEvent name\n"
+ "\t\tFUNC:\tFunction name\n"
+ "\t\tOFFS:\tOffset from function entry (in byte)\n"
+ "\t\tSRC:\tSource code path\n"
+ "\t\tLINE:\tLine number\n"
+ "\t\tARG:\tProbe argument (local variable name or\n"
+ "\t\t\tkprobe-tracer argument format is supported.)\n",
+ parse_probepoint),
+ OPT_END()
+};
+
+static int write_new_event(int fd, const char *buf)
+{
+ int ret;
+
+ printf("Adding new event: %s\n", buf);
+ ret = write(fd, buf, strlen(buf));
+ if (ret <= 0)
+ perror("Error: Failed to create event");
+
+ return ret;
+}
+
+#define MAX_CMDLEN 256
+
+static int synthesize_probepoint(struct probe_point *pp)
+{
+ char *buf;
+ int i, len, ret;
+ pp->probes[0] = buf = (char *)calloc(MAX_CMDLEN, sizeof(char));
+ if (!buf)
+ perror_exit("calloc");
+ ret = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);
+ if (ret <= 0 || ret >= MAX_CMDLEN)
+ 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)
+ goto error;
+ len += ret;
+ }
+ pp->found = 1;
+ return pp->found;
+error:
+ free(pp->probes[0]);
+ if (ret > 0)
+ ret = -E2BIG;
+ return ret;
+}
+
+int cmd_probe(int argc, const char **argv, const char *prefix __used)
+{
+ int i, j, fd, ret, need_dwarf = 0;
+ struct probe_point *pp;
+ char buf[MAX_CMDLEN];
+
+ argc = parse_options(argc, argv, options, probe_usage,
+ PARSE_OPT_STOP_AT_NON_OPTION);
+ if (argc || session.nr_probe == 0)
+ usage_with_options(probe_usage, options);
+
+ /* Synthesize return probes */
+ for (j = 0; j < session.nr_probe; j++) {
+ if (session.events[j][0] != 'r') {
+ need_dwarf = 1;
+ continue;
+ }
+ ret = synthesize_probepoint(&session.probes[j]);
+ if (ret == -E2BIG)
+ semantic_error("probe point is too long.");
+ else if (ret < 0) {
+ perror("snprintf");
+ return -1;
+ }
+ }
+
+ if (!need_dwarf)
+ goto setup_probes;
+
+ if (session.vmlinux)
+ fd = open(session.vmlinux, O_RDONLY);
+ else
+ fd = open_default_vmlinux();
+ if (fd < 0) {
+ perror("vmlinux/module file open");
+ return -1;
+ }
+
+ /* Searching probe points */
+ for (j = 0; j < session.nr_probe; j++) {
+ pp = &session.probes[j];
+ if (pp->found)
+ continue;
+
+ lseek(fd, SEEK_SET, 0);
+ ret = find_probepoint(fd, pp);
+ if (ret <= 0) {
+ fprintf(stderr, "Error: No probe point found.\n");
+ return -1;
+ }
+ debug("probe event %s found\n", session.events[j]);
+ }
+ close(fd);
+
+setup_probes:
+ /* Settng up probe points */
+ snprintf(buf, MAX_CMDLEN, "%s/../kprobe_events", debugfs_path);
+ fd = open(buf, O_WRONLY, O_APPEND);
+ if (fd < 0) {
+ perror("kprobe_events open");
+ return -1;
+ }
+ for (j = 0; j < session.nr_probe; j++) {
+ pp = &session.probes[j];
+ if (pp->found == 1) {
+ snprintf(buf, MAX_CMDLEN, "%s %s\n",
+ session.events[j], pp->probes[0]);
+ write_new_event(fd, buf);
+ } else
+ for (i = 0; i < pp->found; i++) {
+ snprintf(buf, MAX_CMDLEN, "%s%d %s\n",
+ session.events[j], i, pp->probes[i]);
+ write_new_event(fd, buf);
+ }
+ }
+ close(fd);
+ return 0;
+}
+