builtin-probe.c

/*
 * 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/strlist.h"
#include "util/event.h"
#include "util/debug.h"
#include "util/debugfs.h"
#include "util/symbol.h"
#include "util/thread.h"
#include "util/session.h"
#include "util/parse-options.h"
#include "util/parse-events.h"	/* For debugfs_path */
#include "util/probe-finder.h"
#include "util/probe-event.h"

#define MAX_PATH_LEN 256
#define MAX_PROBES 128

/* Session management structure */
static struct {
	bool need_dwarf;
	bool list_events;
	bool force_add;
	int nr_probe;
	struct probe_point probes[MAX_PROBES];
	struct strlist *dellist;
	struct perf_session *psession;
	struct map *kmap;
} session;


/* Parse an event definition. Note that any error must die. */
static void parse_probe_event(const char *str)
{
	struct probe_point *pp = &session.probes[session.nr_probe];

	pr_debug("probe-definition(%d): %s\n", session.nr_probe, str);
	if (++session.nr_probe == MAX_PROBES)
		die("Too many probes (> %d) are specified.", MAX_PROBES);

	/* Parse perf-probe event into probe_point */
	parse_perf_probe_event(str, pp, &session.need_dwarf);

	pr_debug("%d arguments\n", pp->nr_args);
}

static void parse_probe_event_argv(int argc, const char **argv)
{
	int i, len;
	char *buf;

	/* Bind up rest arguments */
	len = 0;
	for (i = 0; i < argc; i++)
		len += strlen(argv[i]) + 1;
	buf = zalloc(len + 1);
	if (!buf)
		die("Failed to allocate memory for binding arguments.");
	len = 0;
	for (i = 0; i < argc; i++)
		len += sprintf(&buf[len], "%s ", argv[i]);
	parse_probe_event(buf);
	free(buf);
}

static int opt_add_probe_event(const struct option *opt __used,
			      const char *str, int unset __used)
{
	if (str)
		parse_probe_event(str);
	return 0;
}

static int opt_del_probe_event(const struct option *opt __used,
			       const char *str, int unset __used)
{
	if (str) {
		if (!session.dellist)
			session.dellist = strlist__new(true, NULL);
		strlist__add(session.dellist, str);
	}
	return 0;
}

/* Currently just checking function name from symbol map */
static void evaluate_probe_point(struct probe_point *pp)
{
	struct symbol *sym;
	sym = map__find_symbol_by_name(session.kmap, pp->function,
				       session.psession, NULL);
	if (!sym)
		die("Kernel symbol \'%s\' not found - probe not added.",
		    pp->function);
}

#ifndef NO_LIBDWARF
static int open_vmlinux(void)
{
	if (map__load(session.kmap, session.psession, NULL) < 0) {
		pr_debug("Failed to load kernel map.\n");
		return -EINVAL;
	}
	pr_debug("Try to open %s\n", session.kmap->dso->long_name);
	return open(session.kmap->dso->long_name, O_RDONLY);
}
#endif

static const char * const probe_usage[] = {
	"perf probe [<options>] 'PROBEDEF' ['PROBEDEF' ...]",
	"perf probe [<options>] --add 'PROBEDEF' [--add 'PROBEDEF' ...]",
	"perf probe [<options>] --del '[GROUP:]EVENT' ...",
	"perf probe --list",
	NULL
};

static const struct option options[] = {
	OPT_BOOLEAN('v', "verbose", &verbose,
		    "be more verbose (show parsed arguments, etc)"),
#ifndef NO_LIBDWARF
	OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
		   "file", "vmlinux pathname"),
#endif
	OPT_BOOLEAN('l', "list", &session.list_events,
		    "list up current probe events"),
	OPT_CALLBACK('d', "del", NULL, "[GROUP:]EVENT", "delete a probe event.",
		opt_del_probe_event),
	OPT_CALLBACK('a', "add", NULL,
#ifdef NO_LIBDWARF
		"[EVENT=]FUNC[+OFFS|%return] [ARG ...]",
#else
		"[EVENT=]FUNC[+OFFS|%return|:RLN][@SRC]|SRC:ALN [ARG ...]",
#endif
		"probe point definition, where\n"
		"\t\tGROUP:\tGroup name (optional)\n"
		"\t\tEVENT:\tEvent name\n"
		"\t\tFUNC:\tFunction name\n"
		"\t\tOFFS:\tOffset from function entry (in byte)\n"
		"\t\t%return:\tPut the probe at function return\n"
#ifdef NO_LIBDWARF
		"\t\tARG:\tProbe argument (only \n"
#else
		"\t\tSRC:\tSource code path\n"
		"\t\tRLN:\tRelative line number from function entry.\n"
		"\t\tALN:\tAbsolute line number in file.\n"
		"\t\tARG:\tProbe argument (local variable name or\n"
#endif
		"\t\t\tkprobe-tracer argument format.)\n",
		opt_add_probe_event),
	OPT_BOOLEAN('f', "force", &session.force_add, "forcibly add events"
		    " with existing name"),
	OPT_END()
};

int cmd_probe(int argc, const char **argv, const char *prefix __used)
{
	int i, ret;
#ifndef NO_LIBDWARF
	int fd;
#endif
	struct probe_point *pp;

	argc = parse_options(argc, argv, options, probe_usage,
			     PARSE_OPT_STOP_AT_NON_OPTION);
	if (argc > 0) {
		if (strcmp(argv[0], "-") == 0) {
			pr_warning("  Error: '-' is not supported.\n");
			usage_with_options(probe_usage, options);
		}
		parse_probe_event_argv(argc, argv);
	}

	if ((!session.nr_probe && !session.dellist && !session.list_events))
		usage_with_options(probe_usage, options);

	if (debugfs_valid_mountpoint(debugfs_path) < 0)
		die("Failed to find debugfs path.");

	if (session.list_events) {
		if (session.nr_probe != 0 || session.dellist) {
			pr_warning("  Error: Don't use --list with"
				   " --add/--del.\n");
			usage_with_options(probe_usage, options);
		}
		show_perf_probe_events();
		return 0;
	}

	if (session.dellist) {
		del_trace_kprobe_events(session.dellist);
		strlist__delete(session.dellist);
		if (session.nr_probe == 0)
			return 0;
	}

	/* Initialize symbol maps for vmlinux */
	symbol_conf.sort_by_name = true;
	if (symbol_conf.vmlinux_name == NULL)
		symbol_conf.try_vmlinux_path = true;
	if (symbol__init() < 0)
		die("Failed to init symbol map.");
	session.psession = perf_session__new(NULL, O_WRONLY, false);
	if (session.psession == NULL)
		die("Failed to init perf_session.");
	session.kmap = map_groups__find_by_name(&session.psession->kmaps,
						MAP__FUNCTION,
						"[kernel.kallsyms]");
	if (!session.kmap)
		die("Could not find kernel map.\n");

	if (session.need_dwarf)
#ifdef NO_LIBDWARF
		die("Debuginfo-analysis is not supported");
#else	/* !NO_LIBDWARF */
		pr_debug("Some probes require debuginfo.\n");

	fd = open_vmlinux();
	if (fd < 0) {
		if (session.need_dwarf)
			die("Could not open debuginfo file.");

		pr_debug("Could not open vmlinux/module file."
			 " Try to use symbols.\n");
		goto end_dwarf;
	}

	/* Searching probe points */
	for (i = 0; i < session.nr_probe; i++) {
		pp = &session.probes[i];
		if (pp->found)
			continue;

		lseek(fd, SEEK_SET, 0);
		ret = find_probepoint(fd, pp);
		if (ret > 0)
			continue;
		if (ret == 0) {	/* No error but failed to find probe point. */
			synthesize_perf_probe_point(pp);
			die("Probe point '%s' not found. - probe not added.",
			    pp->probes[0]);
		}
		/* Error path */
		if (session.need_dwarf) {
			if (ret == -ENOENT)
				pr_warning("No dwarf info found in the vmlinux - please rebuild with CONFIG_DEBUG_INFO=y.\n");
			die("Could not analyze debuginfo.");
		}
		pr_debug("An error occurred in debuginfo analysis."
			 " Try to use symbols.\n");
		break;
	}
	close(fd);

end_dwarf:
#endif /* !NO_LIBDWARF */

	/* Synthesize probes without dwarf */
	for (i = 0; i < session.nr_probe; i++) {
		pp = &session.probes[i];
		if (pp->found)	/* This probe is already found. */
			continue;

		evaluate_probe_point(pp);
		ret = synthesize_trace_kprobe_event(pp);
		if (ret == -E2BIG)
			die("probe point definition becomes too long.");
		else if (ret < 0)
			die("Failed to synthesize a probe point.");
	}

	/* Settng up probe points */
	add_trace_kprobe_events(session.probes, session.nr_probe,
				session.force_add);
	return 0;
}