libbpf-tools/funclatency.c - platform/external/bcc - Git at Google

 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
 /* Copyright (c) 2021 Google LLC.
  *
  * Based on funclatency from BCC by Brendan Gregg and others
  * 2021-02-26   Barret Rhoden   Created this.
  *
  * TODO:
  * - support uprobes on libraries without -p PID. (parse ld.so.cache)
  * - support regexp pattern matching and per-function histograms
  */
 #include <argp.h>
 #include <errno.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
 #include <unistd.h>
 #include <fcntl.h>

 #include <bpf/libbpf.h>
 #include <bpf/bpf.h>
 #include "funclatency.h"
 #include "funclatency.skel.h"
 #include "trace_helpers.h"
 #include "map_helpers.h"
 #include "btf_helpers.h"
 #include "uprobe_helpers.h"

 #define warn(...) fprintf(stderr, __VA_ARGS__)

 static struct prog_env {
 	int units;
 	pid_t pid;
 	unsigned int duration;
 	unsigned int interval;
 	unsigned int iterations;
 	bool timestamp;
 	char *funcname;
 	bool verbose;
 	bool kprobes;
 	char *cgroupspath;
 	bool cg;
 	bool is_kernel_func;
 } env = {
 	.interval = 99999999,
 	.iterations = 99999999,
 };

 const char *argp_program_version = "funclatency 0.1";
 const char *argp_program_bug_address =
 	"https://github.com/iovisor/bcc/tree/master/libbpf-tools";
 static const char args_doc[] = "FUNCTION";
 static const char program_doc[] =
 "Time functions and print latency as a histogram\n"
 "\n"
 "Usage: funclatency [-h] [-m|-u] [-p PID] [-d DURATION] [ -i INTERVAL ] [-c CG]\n"
 "                   [-T] FUNCTION\n"
 "       Choices for FUNCTION: FUNCTION         (kprobe)\n"
 "                             LIBRARY:FUNCTION (uprobe a library in -p PID)\n"
 "                             :FUNCTION        (uprobe the binary of -p PID)\n"
 "                             PROGRAM:FUNCTION (uprobe the binary PROGRAM)\n"
 "\v"
 "Examples:\n"
 "  ./funclatency do_sys_open         # time the do_sys_open() kernel function\n"
 "  ./funclatency -m do_nanosleep     # time do_nanosleep(), in milliseconds\n"
 "  ./funclatency -c CG               # Trace process under cgroupsPath CG\n"
 "  ./funclatency -u vfs_read         # time vfs_read(), in microseconds\n"
 "  ./funclatency -p 181 vfs_read     # time process 181 only\n"
 "  ./funclatency -p 181 c:read       # time the read() C library function\n"
 "  ./funclatency -p 181 :foo         # time foo() from pid 181's userspace\n"
 "  ./funclatency -i 2 -d 10 vfs_read # output every 2 seconds, for 10s\n"
 "  ./funclatency -mTi 5 vfs_read     # output every 5 seconds, with timestamps\n"
 ;

 static const struct argp_option opts[] = {
 	{ "milliseconds", 'm', NULL, 0, "Output in milliseconds"},
 	{ "microseconds", 'u', NULL, 0, "Output in microseconds"},
 	{0, 0, 0, 0, ""},
 	{ "pid", 'p', "PID", 0, "Process ID to trace"},
 	{0, 0, 0, 0, ""},
 	{ "interval", 'i', "INTERVAL", 0, "Summary interval in seconds"},
 	{ "cgroup", 'c', "/sys/fs/cgroup/unified", 0, "Trace process in cgroup path" },
 	{ "duration", 'd', "DURATION", 0, "Duration to trace"},
 	{ "timestamp", 'T', NULL, 0, "Print timestamp"},
 	{ "verbose", 'v', NULL, 0, "Verbose debug output" },
 	{ "kprobes", 'k', NULL, 0, "Use kprobes instead of fentry" },
 	{ NULL, 'h', NULL, OPTION_HIDDEN, "Show the full help"},
 	{},
 };

 static error_t parse_arg(int key, char *arg, struct argp_state *state)
 {
 	struct prog_env *env = state->input;
 	long duration, interval, pid;

 	switch (key) {
 	case 'p':
 		errno = 0;
 		pid = strtol(arg, NULL, 10);
 		if (errno || pid <= 0) {
 			warn("Invalid PID: %s\n", arg);
 			argp_usage(state);
 		}
 		env->pid = pid;
 		break;
 	case 'm':
 		if (env->units != NSEC) {
 			warn("only set one of -m or -u\n");
 			argp_usage(state);
 		}
 		env->units = MSEC;
 		break;
 	case 'c':
 		env->cgroupspath = arg;
 		env->cg = true;
 		break;
 	case 'u':
 		if (env->units != NSEC) {
 			warn("only set one of -m or -u\n");
 			argp_usage(state);
 		}
 		env->units = USEC;
 		break;
 	case 'd':
 		errno = 0;
 		duration = strtol(arg, NULL, 10);
 		if (errno || duration <= 0) {
 			warn("Invalid duration: %s\n", arg);
 			argp_usage(state);
 		}
 		env->duration = duration;
 		break;
 	case 'i':
 		errno = 0;
 		interval = strtol(arg, NULL, 10);
 		if (errno || interval <= 0) {
 			warn("Invalid interval: %s\n", arg);
 			argp_usage(state);
 		}
 		env->interval = interval;
 		break;
 	case 'T':
 		env->timestamp = true;
 		break;
 	case 'k':
 		env->kprobes = true;
 		break;
 	case 'v':
 		env->verbose = true;
 		break;
 	case 'h':
 		argp_state_help(state, stderr, ARGP_HELP_STD_HELP);
 		break;
 	case ARGP_KEY_ARG:
 		if (env->funcname) {
 			warn("Too many function names: %s\n", arg);
 			argp_usage(state);
 		}
 		env->funcname = arg;
 		break;
 	case ARGP_KEY_END:
 		if (!env->funcname) {
 			warn("Need a function to trace\n");
 			argp_usage(state);
 		}
 		if (env->duration) {
 			if (env->interval > env->duration)
 				env->interval = env->duration;
 			env->iterations = env->duration / env->interval;
 		}
 		break;
 	default:
 		return ARGP_ERR_UNKNOWN;
 	}
 	return 0;
 }

 static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
 {
 	if (level == LIBBPF_DEBUG && !env.verbose)
 		return 0;
 	return vfprintf(stderr, format, args);
 }

 static const char *unit_str(void)
 {
 	switch (env.units) {
 	case NSEC:
 		return "nsec";
 	case USEC:
 		return "usec";
 	case MSEC:
 		return "msec";
 	};

 	return "bad units";
 }

 static bool try_fentry(struct funclatency_bpf *obj)
 {
 	long err;

 	if (env.kprobes || !env.is_kernel_func ||
 	    !fentry_can_attach(env.funcname, NULL)) {
 		goto out_no_fentry;
 	}

 	err = bpf_program__set_attach_target(obj->progs.dummy_fentry, 0,
 					     env.funcname);
 	if (err) {
 		warn("failed to set attach fentry: %s\n", strerror(-err));
 		goto out_no_fentry;
 	}

 	err = bpf_program__set_attach_target(obj->progs.dummy_fexit, 0,
 					     env.funcname);
 	if (err) {
 		warn("failed to set attach fexit: %s\n", strerror(-err));
 		goto out_no_fentry;
 	}

 	bpf_program__set_autoload(obj->progs.dummy_kprobe, false);
 	bpf_program__set_autoload(obj->progs.dummy_kretprobe, false);

 	return true;

 out_no_fentry:
 	bpf_program__set_autoload(obj->progs.dummy_fentry, false);
 	bpf_program__set_autoload(obj->progs.dummy_fexit, false);

 	return false;
 }

 static int attach_kprobes(struct funclatency_bpf *obj)
 {
 	obj->links.dummy_kprobe =
 		bpf_program__attach_kprobe(obj->progs.dummy_kprobe, false,
 					   env.funcname);
 	if (!obj->links.dummy_kprobe) {
 		warn("failed to attach kprobe: %d\n", -errno);
 		return -1;
 	}

 	obj->links.dummy_kretprobe =
 		bpf_program__attach_kprobe(obj->progs.dummy_kretprobe, true,
 					   env.funcname);
 	if (!obj->links.dummy_kretprobe) {
 		warn("failed to attach kretprobe: %d\n", -errno);
 		return -1;
 	}

 	return 0;
 }

 static int attach_uprobes(struct funclatency_bpf *obj)
 {
 	char *binary, *function;
 	char bin_path[PATH_MAX];
 	off_t func_off;
 	int ret = -1;
 	long err;

 	binary = strdup(env.funcname);
 	if (!binary) {
 		warn("strdup failed");
 		return -1;
 	}
 	function = strchr(binary, ':');
 	if (!function) {
 		warn("Binary should have contained ':' (internal bug!)\n");
 		return -1;
 	}
 	*function = '\0';
 	function++;

 	if (resolve_binary_path(binary, env.pid, bin_path, sizeof(bin_path)))
 		goto out_binary;

 	func_off = get_elf_func_offset(bin_path, function);
 	if (func_off < 0) {
 		warn("Could not find %s in %s\n", function, bin_path);
 		goto out_binary;
 	}

 	obj->links.dummy_kprobe =
 		bpf_program__attach_uprobe(obj->progs.dummy_kprobe, false,
 					   env.pid ?: -1, bin_path, func_off);
 	if (!obj->links.dummy_kprobe) {
 		err = -errno;
 		warn("Failed to attach uprobe: %ld\n", err);
 		goto out_binary;
 	}

 	obj->links.dummy_kretprobe =
 		bpf_program__attach_uprobe(obj->progs.dummy_kretprobe, true,
 					   env.pid ?: -1, bin_path, func_off);
 	if (!obj->links.dummy_kretprobe) {
 		err = -errno;
 		warn("Failed to attach uretprobe: %ld\n", err);
 		goto out_binary;
 	}

 	ret = 0;

 out_binary:
 	free(binary);

 	return ret;
 }

 static volatile bool exiting;

 static void sig_hand(int signr)
 {
 	exiting = true;
 }

 static struct sigaction sigact = {.sa_handler = sig_hand};

 int main(int argc, char **argv)
 {
 	LIBBPF_OPTS(bpf_object_open_opts, open_opts);
 	static const struct argp argp = {
 		.options = opts,
 		.parser = parse_arg,
 		.args_doc = args_doc,
 		.doc = program_doc,
 	};
 	struct funclatency_bpf *obj;
 	int i, err;
 	struct tm *tm;
 	char ts[32];
 	time_t t;
 	int idx, cg_map_fd;
 	int cgfd = -1;
 	bool used_fentry = false;

 	err = argp_parse(&argp, argc, argv, 0, NULL, &env);
 	if (err)
 		return err;

 	env.is_kernel_func = !strchr(env.funcname, ':');

 	sigaction(SIGINT, &sigact, 0);

 	libbpf_set_print(libbpf_print_fn);

 	err = ensure_core_btf(&open_opts);
 	if (err) {
 		fprintf(stderr, "failed to fetch necessary BTF for CO-RE: %s\n", strerror(-err));
 		return 1;
 	}

 	obj = funclatency_bpf__open_opts(&open_opts);
 	if (!obj) {
 		warn("failed to open BPF object\n");
 		return 1;
 	}

 	obj->rodata->units = env.units;
 	obj->rodata->targ_tgid = env.pid;
 	obj->rodata->filter_cg = env.cg;

 	used_fentry = try_fentry(obj);

 	err = funclatency_bpf__load(obj);
 	if (err) {
 		warn("failed to load BPF object\n");
 		return 1;
 	}

 /* update cgroup path fd to map */
 	if (env.cg) {
 		idx = 0;
 		cg_map_fd = bpf_map__fd(obj->maps.cgroup_map);
 		cgfd = open(env.cgroupspath, O_RDONLY);
 		if (cgfd < 0) {
 			fprintf(stderr, "Failed opening Cgroup path: %s", env.cgroupspath);
 			goto cleanup;
 		}
 		if (bpf_map_update_elem(cg_map_fd, &idx, &cgfd, BPF_ANY)) {
 			fprintf(stderr, "Failed adding target cgroup to map");
 			goto cleanup;
 		}
 	}

 	if (!obj->bss) {
 		warn("Memory-mapping BPF maps is supported starting from Linux 5.7, please upgrade.\n");
 		goto cleanup;
 	}

 	if (!used_fentry) {
 		if (env.is_kernel_func)
 			err = attach_kprobes(obj);
 		else
 			err = attach_uprobes(obj);
 		if (err)
 			goto cleanup;
 	}

 	err = funclatency_bpf__attach(obj);
 	if (err) {
 		fprintf(stderr, "failed to attach BPF programs: %s\n",
 			strerror(-err));
 		goto cleanup;
 	}

 	printf("Tracing %s.  Hit Ctrl-C to exit\n", env.funcname);

 	for (i = 0; i < env.iterations && !exiting; i++) {
 		sleep(env.interval);

 		printf("\n");
 		if (env.timestamp) {
 			time(&t);
 			tm = localtime(&t);
 			strftime(ts, sizeof(ts), "%H:%M:%S", tm);
 			printf("%-8s\n", ts);
 		}

 		print_log2_hist(obj->bss->hist, MAX_SLOTS, unit_str());

 		/* Cleanup histograms for interval output */
 		memset(obj->bss->hist, 0, sizeof(obj->bss->hist));
 	}

 	printf("Exiting trace of %s\n", env.funcname);

 cleanup:
 	funclatency_bpf__destroy(obj);
 	cleanup_core_btf(&open_opts);
 	if (cgfd > 0)
 		close(cgfd);

 	return err != 0;
 }
	// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
	/* Copyright (c) 2021 Google LLC.
	*
	* Based on funclatency from BCC by Brendan Gregg and others
	* 2021-02-26 Barret Rhoden Created this.
	*
	* TODO:
	* - support uprobes on libraries without -p PID. (parse ld.so.cache)
	* - support regexp pattern matching and per-function histograms
	*/
	#include <argp.h>
	#include <errno.h>
	#include <signal.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <time.h>
	#include <unistd.h>
	#include <fcntl.h>

	#include <bpf/libbpf.h>
	#include <bpf/bpf.h>
	#include "funclatency.h"
	#include "funclatency.skel.h"
	#include "trace_helpers.h"
	#include "map_helpers.h"
	#include "btf_helpers.h"
	#include "uprobe_helpers.h"

	#define warn(...) fprintf(stderr, __VA_ARGS__)

	static struct prog_env {
	int units;
	pid_t pid;
	unsigned int duration;
	unsigned int interval;
	unsigned int iterations;
	bool timestamp;
	char *funcname;
	bool verbose;
	bool kprobes;
	char *cgroupspath;
	bool cg;
	bool is_kernel_func;
	} env = {
	.interval = 99999999,
	.iterations = 99999999,
	};

	const char *argp_program_version = "funclatency 0.1";
	const char *argp_program_bug_address =
	"https://github.com/iovisor/bcc/tree/master/libbpf-tools";
	static const char args_doc[] = "FUNCTION";
	static const char program_doc[] =
	"Time functions and print latency as a histogram\n"
	"\n"
	"Usage: funclatency [-h] [-m\|-u] [-p PID] [-d DURATION] [ -i INTERVAL ] [-c CG]\n"
	" [-T] FUNCTION\n"
	" Choices for FUNCTION: FUNCTION (kprobe)\n"
	" LIBRARY:FUNCTION (uprobe a library in -p PID)\n"
	" :FUNCTION (uprobe the binary of -p PID)\n"
	" PROGRAM:FUNCTION (uprobe the binary PROGRAM)\n"
	"\v"
	"Examples:\n"
	" ./funclatency do_sys_open # time the do_sys_open() kernel function\n"
	" ./funclatency -m do_nanosleep # time do_nanosleep(), in milliseconds\n"
	" ./funclatency -c CG # Trace process under cgroupsPath CG\n"
	" ./funclatency -u vfs_read # time vfs_read(), in microseconds\n"
	" ./funclatency -p 181 vfs_read # time process 181 only\n"
	" ./funclatency -p 181 c:read # time the read() C library function\n"
	" ./funclatency -p 181 :foo # time foo() from pid 181's userspace\n"
	" ./funclatency -i 2 -d 10 vfs_read # output every 2 seconds, for 10s\n"
	" ./funclatency -mTi 5 vfs_read # output every 5 seconds, with timestamps\n"
	;

	static const struct argp_option opts[] = {
	{ "milliseconds", 'm', NULL, 0, "Output in milliseconds"},
	{ "microseconds", 'u', NULL, 0, "Output in microseconds"},
	{0, 0, 0, 0, ""},
	{ "pid", 'p', "PID", 0, "Process ID to trace"},
	{0, 0, 0, 0, ""},
	{ "interval", 'i', "INTERVAL", 0, "Summary interval in seconds"},
	{ "cgroup", 'c', "/sys/fs/cgroup/unified", 0, "Trace process in cgroup path" },
	{ "duration", 'd', "DURATION", 0, "Duration to trace"},
	{ "timestamp", 'T', NULL, 0, "Print timestamp"},
	{ "verbose", 'v', NULL, 0, "Verbose debug output" },
	{ "kprobes", 'k', NULL, 0, "Use kprobes instead of fentry" },
	{ NULL, 'h', NULL, OPTION_HIDDEN, "Show the full help"},
	{},
	};

	static error_t parse_arg(int key, char arg, struct argp_state state)
	{
	struct prog_env *env = state->input;
	long duration, interval, pid;

	switch (key) {
	case 'p':
	errno = 0;
	pid = strtol(arg, NULL, 10);
	if (errno \|\| pid <= 0) {
	warn("Invalid PID: %s\n", arg);
	argp_usage(state);
	}
	env->pid = pid;
	break;
	case 'm':
	if (env->units != NSEC) {
	warn("only set one of -m or -u\n");
	argp_usage(state);
	}
	env->units = MSEC;
	break;
	case 'c':
	env->cgroupspath = arg;
	env->cg = true;
	break;
	case 'u':
	if (env->units != NSEC) {
	warn("only set one of -m or -u\n");
	argp_usage(state);
	}
	env->units = USEC;
	break;
	case 'd':
	errno = 0;
	duration = strtol(arg, NULL, 10);
	if (errno \|\| duration <= 0) {
	warn("Invalid duration: %s\n", arg);
	argp_usage(state);
	}
	env->duration = duration;
	break;
	case 'i':
	errno = 0;
	interval = strtol(arg, NULL, 10);
	if (errno \|\| interval <= 0) {
	warn("Invalid interval: %s\n", arg);
	argp_usage(state);
	}
	env->interval = interval;
	break;
	case 'T':
	env->timestamp = true;
	break;
	case 'k':
	env->kprobes = true;
	break;
	case 'v':
	env->verbose = true;
	break;
	case 'h':
	argp_state_help(state, stderr, ARGP_HELP_STD_HELP);
	break;
	case ARGP_KEY_ARG:
	if (env->funcname) {
	warn("Too many function names: %s\n", arg);
	argp_usage(state);
	}
	env->funcname = arg;
	break;
	case ARGP_KEY_END:
	if (!env->funcname) {
	warn("Need a function to trace\n");
	argp_usage(state);
	}
	if (env->duration) {
	if (env->interval > env->duration)
	env->interval = env->duration;
	env->iterations = env->duration / env->interval;
	}
	break;
	default:
	return ARGP_ERR_UNKNOWN;
	}
	return 0;
	}

	static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
	{
	if (level == LIBBPF_DEBUG && !env.verbose)
	return 0;
	return vfprintf(stderr, format, args);
	}

	static const char *unit_str(void)
	{
	switch (env.units) {
	case NSEC:
	return "nsec";
	case USEC:
	return "usec";
	case MSEC:
	return "msec";
	};

	return "bad units";
	}

	static bool try_fentry(struct funclatency_bpf *obj)
	{
	long err;

	if (env.kprobes \|\| !env.is_kernel_func \|\|
	!fentry_can_attach(env.funcname, NULL)) {
	goto out_no_fentry;
	}

	err = bpf_program__set_attach_target(obj->progs.dummy_fentry, 0,
	env.funcname);
	if (err) {
	warn("failed to set attach fentry: %s\n", strerror(-err));
	goto out_no_fentry;
	}

	err = bpf_program__set_attach_target(obj->progs.dummy_fexit, 0,
	env.funcname);
	if (err) {
	warn("failed to set attach fexit: %s\n", strerror(-err));
	goto out_no_fentry;
	}

	bpf_program__set_autoload(obj->progs.dummy_kprobe, false);
	bpf_program__set_autoload(obj->progs.dummy_kretprobe, false);

	return true;

	out_no_fentry:
	bpf_program__set_autoload(obj->progs.dummy_fentry, false);
	bpf_program__set_autoload(obj->progs.dummy_fexit, false);

	return false;
	}

	static int attach_kprobes(struct funclatency_bpf *obj)
	{
	obj->links.dummy_kprobe =
	bpf_program__attach_kprobe(obj->progs.dummy_kprobe, false,
	env.funcname);
	if (!obj->links.dummy_kprobe) {
	warn("failed to attach kprobe: %d\n", -errno);
	return -1;
	}

	obj->links.dummy_kretprobe =
	bpf_program__attach_kprobe(obj->progs.dummy_kretprobe, true,
	env.funcname);
	if (!obj->links.dummy_kretprobe) {
	warn("failed to attach kretprobe: %d\n", -errno);
	return -1;
	}

	return 0;
	}

	static int attach_uprobes(struct funclatency_bpf *obj)
	{
	char binary, function;
	char bin_path[PATH_MAX];
	off_t func_off;
	int ret = -1;
	long err;

	binary = strdup(env.funcname);
	if (!binary) {
	warn("strdup failed");
	return -1;
	}
	function = strchr(binary, ':');
	if (!function) {
	warn("Binary should have contained ':' (internal bug!)\n");
	return -1;
	}
	*function = '\0';
	function++;

	if (resolve_binary_path(binary, env.pid, bin_path, sizeof(bin_path)))
	goto out_binary;

	func_off = get_elf_func_offset(bin_path, function);
	if (func_off < 0) {
	warn("Could not find %s in %s\n", function, bin_path);
	goto out_binary;
	}

	obj->links.dummy_kprobe =
	bpf_program__attach_uprobe(obj->progs.dummy_kprobe, false,
	env.pid ?: -1, bin_path, func_off);
	if (!obj->links.dummy_kprobe) {
	err = -errno;
	warn("Failed to attach uprobe: %ld\n", err);
	goto out_binary;
	}

	obj->links.dummy_kretprobe =
	bpf_program__attach_uprobe(obj->progs.dummy_kretprobe, true,
	env.pid ?: -1, bin_path, func_off);
	if (!obj->links.dummy_kretprobe) {
	err = -errno;
	warn("Failed to attach uretprobe: %ld\n", err);
	goto out_binary;
	}

	ret = 0;

	out_binary:
	free(binary);

	return ret;
	}

	static volatile bool exiting;

	static void sig_hand(int signr)
	{
	exiting = true;
	}

	static struct sigaction sigact = {.sa_handler = sig_hand};

	int main(int argc, char **argv)
	{
	LIBBPF_OPTS(bpf_object_open_opts, open_opts);
	static const struct argp argp = {
	.options = opts,
	.parser = parse_arg,
	.args_doc = args_doc,
	.doc = program_doc,
	};
	struct funclatency_bpf *obj;
	int i, err;
	struct tm *tm;
	char ts[32];
	time_t t;
	int idx, cg_map_fd;
	int cgfd = -1;
	bool used_fentry = false;

	err = argp_parse(&argp, argc, argv, 0, NULL, &env);
	if (err)
	return err;

	env.is_kernel_func = !strchr(env.funcname, ':');

	sigaction(SIGINT, &sigact, 0);

	libbpf_set_print(libbpf_print_fn);

	err = ensure_core_btf(&open_opts);
	if (err) {
	fprintf(stderr, "failed to fetch necessary BTF for CO-RE: %s\n", strerror(-err));
	return 1;
	}

	obj = funclatency_bpf__open_opts(&open_opts);
	if (!obj) {
	warn("failed to open BPF object\n");
	return 1;
	}

	obj->rodata->units = env.units;
	obj->rodata->targ_tgid = env.pid;
	obj->rodata->filter_cg = env.cg;

	used_fentry = try_fentry(obj);

	err = funclatency_bpf__load(obj);
	if (err) {
	warn("failed to load BPF object\n");
	return 1;
	}

	/* update cgroup path fd to map */
	if (env.cg) {
	idx = 0;
	cg_map_fd = bpf_map__fd(obj->maps.cgroup_map);
	cgfd = open(env.cgroupspath, O_RDONLY);
	if (cgfd < 0) {
	fprintf(stderr, "Failed opening Cgroup path: %s", env.cgroupspath);
	goto cleanup;
	}
	if (bpf_map_update_elem(cg_map_fd, &idx, &cgfd, BPF_ANY)) {
	fprintf(stderr, "Failed adding target cgroup to map");
	goto cleanup;
	}
	}

	if (!obj->bss) {
	warn("Memory-mapping BPF maps is supported starting from Linux 5.7, please upgrade.\n");
	goto cleanup;
	}

	if (!used_fentry) {
	if (env.is_kernel_func)
	err = attach_kprobes(obj);
	else
	err = attach_uprobes(obj);
	if (err)
	goto cleanup;
	}

	err = funclatency_bpf__attach(obj);
	if (err) {
	fprintf(stderr, "failed to attach BPF programs: %s\n",
	strerror(-err));
	goto cleanup;
	}

	printf("Tracing %s. Hit Ctrl-C to exit\n", env.funcname);

	for (i = 0; i < env.iterations && !exiting; i++) {
	sleep(env.interval);

	printf("\n");
	if (env.timestamp) {
	time(&t);
	tm = localtime(&t);
	strftime(ts, sizeof(ts), "%H:%M:%S", tm);
	printf("%-8s\n", ts);
	}

	print_log2_hist(obj->bss->hist, MAX_SLOTS, unit_str());

	/* Cleanup histograms for interval output */
	memset(obj->bss->hist, 0, sizeof(obj->bss->hist));
	}

	printf("Exiting trace of %s\n", env.funcname);

	cleanup:
	funclatency_bpf__destroy(obj);
	cleanup_core_btf(&open_opts);
	if (cgfd > 0)
	close(cgfd);

	return err != 0;
	}