perf: Add perf probe subcommand, a kprobe-event setup helper

	msg := $(error No libelf.h/libelf found, please install libelf-dev/elfutils-libelf-devel);

endif

ifneq ($(shell sh -c "(echo '\#include <libdwarf/dwarf.h>'; echo '\#include <libdwarf/libdwarf.h>'; echo 'int main(void) { Dwarf_Debug dbg; Dwarf_Error err; dwarf_init(0, DW_DLC_READ, 0, 0, &dbg, &err); return (long)dbg; }') | $(CC) -x c - $(ALL_CFLAGS) -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -ldwarf -lelf -o /dev/null $(ALL_LDFLAGS) > /dev/null 2>&1 && echo y"), y)

	msg := $(warning No libdwarf.h found, disables probe subcommand. Please install libdwarf-dev/libdwarf-devel);

else

	EXTLIBS += -lelf -ldwarf

	LIB_H += util/probe-finder.h

	LIB_OBJS += util/probe-finder.o

	BUILTIN_OBJS += builtin-probe.o

	BASIC_CFLAGS += -DSUPPORT_DWARF

endif

ifdef NO_DEMANGLE

	BASIC_CFLAGS += -DNO_DEMANGLE

else

/*

 * 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;

}

extern int cmd_top(int argc, const char **argv, const char *prefix);

extern int cmd_trace(int argc, const char **argv, const char *prefix);

extern int cmd_version(int argc, const char **argv, const char *prefix);

extern int cmd_probe(int argc, const char **argv, const char *prefix);

#endif

		{ "version", cmd_version, 0 },

		{ "trace", cmd_trace, 0 },

		{ "sched", cmd_sched, 0 },

#ifdef SUPPORT_DWARF

		{ "probe", cmd_probe, 0 },

#endif

	};

	unsigned int i;

	static const char ext[] = STRIP_EXTENSION;