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>

1 files changed, 358 insertions, 0 deletions

diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
new file mode 100644
index 000000000000..24b64b5cefce
--- /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;
+}
+