/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ /* * gethostlatency Show latency for getaddrinfo/gethostbyname[2] calls. * * Copyright (c) 2021 Hengqi Chen * * Based on gethostlatency(8) from BCC by Brendan Gregg. * 24-Mar-2021 Hengqi Chen Created this. */ #include #include #include #include #include #include #include "gethostlatency.h" #include "gethostlatency.skel.h" #include "trace_helpers.h" #include "uprobe_helpers.h" #define PERF_BUFFER_PAGES 16 #define PERF_POLL_TIMEOUT_MS 100 #define warn(...) fprintf(stderr, __VA_ARGS__) static volatile sig_atomic_t exiting = 0; static pid_t target_pid = 0; static const char *libc_path = NULL; const char *argp_program_version = "gethostlatency 0.1"; const char *argp_program_bug_address = "https://github.com/iovisor/bcc/tree/master/libbpf-tools"; const char argp_program_doc[] = "Show latency for getaddrinfo/gethostbyname[2] calls.\n" "\n" "USAGE: gethostlatency [-h] [-p PID] [-l LIBC]\n" "\n" "EXAMPLES:\n" " gethostlatency # time getaddrinfo/gethostbyname[2] calls\n" " gethostlatency -p 1216 # only trace PID 1216\n"; static const struct argp_option opts[] = { { "pid", 'p', "PID", 0, "Process ID to trace" }, { "libc", 'l', "LIBC", 0, "Specify which libc.so to use" }, { NULL, 'h', NULL, OPTION_HIDDEN, "Show the full help" }, {}, }; static error_t parse_arg(int key, char *arg, struct argp_state *state) { long 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); } target_pid = pid; break; case 'l': libc_path = strdup(arg); if (access(libc_path, F_OK)) { warn("Invalid libc: %s\n", arg); argp_usage(state); } break; case 'h': argp_state_help(state, stderr, ARGP_HELP_STD_HELP); break; default: return ARGP_ERR_UNKNOWN; } return 0; } static void sig_int(int signo) { exiting = 1; } static void handle_event(void *ctx, int cpu, void *data, __u32 data_sz) { const struct event *e = data; struct tm *tm; char ts[16]; time_t t; time(&t); tm = localtime(&t); strftime(ts, sizeof(ts), "%H:%M:%S", tm); printf("%-8s %-7d %-16s %-10.3f %-s\n", ts, e->pid, e->comm, (double)e->time/1000000, e->host); } static void handle_lost_events(void *ctx, int cpu, __u64 lost_cnt) { warn("lost %llu events on CPU #%d\n", lost_cnt, cpu); } static int get_libc_path(char *path) { FILE *f; char buf[PATH_MAX] = {}; char *filename; float version; if (libc_path) { memcpy(path, libc_path, strlen(libc_path)); return 0; } f = fopen("/proc/self/maps", "r"); if (!f) return -errno; while (fscanf(f, "%*x-%*x %*s %*s %*s %*s %[^\n]\n", buf) != EOF) { if (strchr(buf, '/') != buf) continue; filename = strrchr(buf, '/') + 1; if (sscanf(filename, "libc-%f.so", &version) == 1) { memcpy(path, buf, strlen(buf)); fclose(f); return 0; } } fclose(f); return -1; } static int attach_uprobes(struct gethostlatency_bpf *obj, struct bpf_link *links[]) { int err; char libc_path[PATH_MAX] = {}; off_t func_off; err = get_libc_path(libc_path); if (err) { warn("could not find libc.so\n"); return -1; } func_off = get_elf_func_offset(libc_path, "getaddrinfo"); if (func_off < 0) { warn("could not find getaddrinfo in %s\n", libc_path); return -1; } links[0] = bpf_program__attach_uprobe(obj->progs.handle_entry, false, target_pid ?: -1, libc_path, func_off); err = libbpf_get_error(links[0]); if (err) { warn("failed to attach getaddrinfo: %d\n", err); return -1; } links[1] = bpf_program__attach_uprobe(obj->progs.handle_return, true, target_pid ?: -1, libc_path, func_off); err = libbpf_get_error(links[1]); if (err) { warn("failed to attach getaddrinfo: %d\n", err); return -1; } func_off = get_elf_func_offset(libc_path, "gethostbyname"); if (func_off < 0) { warn("could not find gethostbyname in %s\n", libc_path); return -1; } links[2] = bpf_program__attach_uprobe(obj->progs.handle_entry, false, target_pid ?: -1, libc_path, func_off); err = libbpf_get_error(links[2]); if (err) { warn("failed to attach gethostbyname: %d\n", err); return -1; } links[3] = bpf_program__attach_uprobe(obj->progs.handle_return, true, target_pid ?: -1, libc_path, func_off); err = libbpf_get_error(links[3]); if (err) { warn("failed to attach gethostbyname: %d\n", err); return -1; } func_off = get_elf_func_offset(libc_path, "gethostbyname2"); if (func_off < 0) { warn("could not find gethostbyname2 in %s\n", libc_path); return -1; } links[4] = bpf_program__attach_uprobe(obj->progs.handle_entry, false, target_pid ?: -1, libc_path, func_off); err = libbpf_get_error(links[4]); if (err) { warn("failed to attach gethostbyname2: %d\n", err); return -1; } links[5] = bpf_program__attach_uprobe(obj->progs.handle_return, true, target_pid ?: -1, libc_path, func_off); err = libbpf_get_error(links[5]); if (err) { warn("failed to attach gethostbyname2: %d\n", err); return -1; } return 0; } int main(int argc, char **argv) { static const struct argp argp = { .options = opts, .parser = parse_arg, .doc = argp_program_doc, }; struct perf_buffer_opts pb_opts; struct perf_buffer *pb = NULL; struct bpf_link *links[6] = {}; struct gethostlatency_bpf *obj; int i, err; err = argp_parse(&argp, argc, argv, 0, NULL, NULL); if (err) return err; err = bump_memlock_rlimit(); if (err) { warn("failed to increase rlimit: %d\n", err); return 1; } obj = gethostlatency_bpf__open(); if (!obj) { warn("failed to open BPF object\n"); return 1; } obj->rodata->target_pid = target_pid; err = gethostlatency_bpf__load(obj); if (err) { warn("failed to load BPF object: %d\n", err); goto cleanup; } err = attach_uprobes(obj, links); if (err) goto cleanup; pb_opts.sample_cb = handle_event; pb_opts.lost_cb = handle_lost_events; pb = perf_buffer__new(bpf_map__fd(obj->maps.events), PERF_BUFFER_PAGES, &pb_opts); err = libbpf_get_error(pb); if (err) { warn("failed to open perf buffer: %d\n", err); goto cleanup; } if (signal(SIGINT, sig_int) == SIG_ERR) { warn("can't set signal handler: %s\n", strerror(errno)); err = 1; goto cleanup; } printf("%-8s %-7s %-16s %-10s %-s\n", "TIME", "PID", "COMM", "LATms", "HOST"); while (!exiting) { err = perf_buffer__poll(pb, PERF_POLL_TIMEOUT_MS); if (err < 0 && errno != EINTR) { warn("error polling perf buffer: %s\n", strerror(errno)); goto cleanup; } /* reset err to return 0 if exiting */ err = 0; } cleanup: perf_buffer__free(pb); for (i = 0; i < 6; i++) bpf_link__destroy(links[i]); gethostlatency_bpf__destroy(obj); return err != 0; }