diff options
Diffstat (limited to 'samples/bpf/trace_event_user.c')
| -rw-r--r-- | samples/bpf/trace_event_user.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/samples/bpf/trace_event_user.c b/samples/bpf/trace_event_user.c new file mode 100644 index 000000000000..9a130d31ecf2 --- /dev/null +++ b/samples/bpf/trace_event_user.c @@ -0,0 +1,213 @@ +/* Copyright (c) 2016 Facebook + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + */ +#include <stdio.h> +#include <unistd.h> +#include <stdlib.h> +#include <stdbool.h> +#include <string.h> +#include <fcntl.h> +#include <poll.h> +#include <sys/ioctl.h> +#include <linux/perf_event.h> +#include <linux/bpf.h> +#include <signal.h> +#include <assert.h> +#include <errno.h> +#include <sys/resource.h> +#include "libbpf.h" +#include "bpf_load.h" + +#define SAMPLE_FREQ 50 + +static bool sys_read_seen, sys_write_seen; + +static void print_ksym(__u64 addr) +{ + struct ksym *sym; + + if (!addr) + return; + sym = ksym_search(addr); + printf("%s;", sym->name); + if (!strcmp(sym->name, "sys_read")) + sys_read_seen = true; + else if (!strcmp(sym->name, "sys_write")) + sys_write_seen = true; +} + +static void print_addr(__u64 addr) +{ + if (!addr) + return; + printf("%llx;", addr); +} + +#define TASK_COMM_LEN 16 + +struct key_t { + char comm[TASK_COMM_LEN]; + __u32 kernstack; + __u32 userstack; +}; + +static void print_stack(struct key_t *key, __u64 count) +{ + __u64 ip[PERF_MAX_STACK_DEPTH] = {}; + static bool warned; + int i; + + printf("%3lld %s;", count, key->comm); + if (bpf_lookup_elem(map_fd[1], &key->kernstack, ip) != 0) { + printf("---;"); + } else { + for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--) + print_ksym(ip[i]); + } + printf("-;"); + if (bpf_lookup_elem(map_fd[1], &key->userstack, ip) != 0) { + printf("---;"); + } else { + for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--) + print_addr(ip[i]); + } + printf("\n"); + + if (key->kernstack == -EEXIST && !warned) { + printf("stackmap collisions seen. Consider increasing size\n"); + warned = true; + } else if ((int)key->kernstack < 0 && (int)key->userstack < 0) { + printf("err stackid %d %d\n", key->kernstack, key->userstack); + } +} + +static void int_exit(int sig) +{ + kill(0, SIGKILL); + exit(0); +} + +static void print_stacks(void) +{ + struct key_t key = {}, next_key; + __u64 value; + __u32 stackid = 0, next_id; + int fd = map_fd[0], stack_map = map_fd[1]; + + sys_read_seen = sys_write_seen = false; + while (bpf_get_next_key(fd, &key, &next_key) == 0) { + bpf_lookup_elem(fd, &next_key, &value); + print_stack(&next_key, value); + bpf_delete_elem(fd, &next_key); + key = next_key; + } + + if (!sys_read_seen || !sys_write_seen) { + printf("BUG kernel stack doesn't contain sys_read() and sys_write()\n"); + int_exit(0); + } + + /* clear stack map */ + while (bpf_get_next_key(stack_map, &stackid, &next_id) == 0) { + bpf_delete_elem(stack_map, &next_id); + stackid = next_id; + } +} + +static void test_perf_event_all_cpu(struct perf_event_attr *attr) +{ + int nr_cpus = sysconf(_SC_NPROCESSORS_CONF); + int *pmu_fd = malloc(nr_cpus * sizeof(int)); + int i; + + /* open perf_event on all cpus */ + for (i = 0; i < nr_cpus; i++) { + pmu_fd[i] = perf_event_open(attr, -1, i, -1, 0); + if (pmu_fd[i] < 0) { + printf("perf_event_open failed\n"); + goto all_cpu_err; + } + assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0); + assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0) == 0); + } + system("dd if=/dev/zero of=/dev/null count=5000k"); + print_stacks(); +all_cpu_err: + for (i--; i >= 0; i--) + close(pmu_fd[i]); + free(pmu_fd); +} + +static void test_perf_event_task(struct perf_event_attr *attr) +{ + int pmu_fd; + + /* open task bound event */ + pmu_fd = perf_event_open(attr, 0, -1, -1, 0); + if (pmu_fd < 0) { + printf("perf_event_open failed\n"); + return; + } + assert(ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0); + assert(ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0) == 0); + system("dd if=/dev/zero of=/dev/null count=5000k"); + print_stacks(); + close(pmu_fd); +} + +static void test_bpf_perf_event(void) +{ + struct perf_event_attr attr_type_hw = { + .sample_freq = SAMPLE_FREQ, + .freq = 1, + .type = PERF_TYPE_HARDWARE, + .config = PERF_COUNT_HW_CPU_CYCLES, + .inherit = 1, + }; + struct perf_event_attr attr_type_sw = { + .sample_freq = SAMPLE_FREQ, + .freq = 1, + .type = PERF_TYPE_SOFTWARE, + .config = PERF_COUNT_SW_CPU_CLOCK, + .inherit = 1, + }; + + test_perf_event_all_cpu(&attr_type_hw); + test_perf_event_task(&attr_type_hw); + test_perf_event_all_cpu(&attr_type_sw); + test_perf_event_task(&attr_type_sw); +} + + +int main(int argc, char **argv) +{ + struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY}; + char filename[256]; + + snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); + setrlimit(RLIMIT_MEMLOCK, &r); + + signal(SIGINT, int_exit); + + if (load_kallsyms()) { + printf("failed to process /proc/kallsyms\n"); + return 1; + } + + if (load_bpf_file(filename)) { + printf("%s", bpf_log_buf); + return 2; + } + + if (fork() == 0) { + read_trace_pipe(); + return 0; + } + test_bpf_perf_event(); + + int_exit(0); + return 0; +} |