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![Teng Qin](/assets/img/avatar_default.png)
$ trace_event tests attaching BPF program to HW_CPU_CYCLES, SW_CPU_CLOCK, HW_CACHE_L1D and other events. It runs 'dd' in the background while bpf program collects user and kernel stack trace on counter overflow. User space expects to see sys_read and sys_write in the kernel stack. $ tracex6 tests reading of various perf counters from BPF program. Both tests were refactored to increase coverage and be more accurate. Signed-off-by: Teng Qin <qinteng@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
177 lines
4.2 KiB
C
177 lines
4.2 KiB
C
#define _GNU_SOURCE
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#include <assert.h>
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#include <fcntl.h>
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#include <linux/perf_event.h>
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#include <linux/bpf.h>
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#include <sched.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/ioctl.h>
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#include <sys/resource.h>
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#include <sys/time.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include "bpf_load.h"
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#include "libbpf.h"
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#include "perf-sys.h"
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#define SAMPLE_PERIOD 0x7fffffffffffffffULL
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static void check_on_cpu(int cpu, struct perf_event_attr *attr)
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{
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int pmu_fd, error = 0;
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cpu_set_t set;
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__u64 value;
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/* Move to target CPU */
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CPU_ZERO(&set);
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CPU_SET(cpu, &set);
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assert(sched_setaffinity(0, sizeof(set), &set) == 0);
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/* Open perf event and attach to the perf_event_array */
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pmu_fd = sys_perf_event_open(attr, -1/*pid*/, cpu/*cpu*/, -1/*group_fd*/, 0);
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if (pmu_fd < 0) {
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fprintf(stderr, "sys_perf_event_open failed on CPU %d\n", cpu);
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error = 1;
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goto on_exit;
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}
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assert(bpf_map_update_elem(map_fd[0], &cpu, &pmu_fd, BPF_ANY) == 0);
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assert(ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0) == 0);
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/* Trigger the kprobe */
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bpf_map_get_next_key(map_fd[1], &cpu, NULL);
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/* Check the value */
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if (bpf_map_lookup_elem(map_fd[1], &cpu, &value)) {
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fprintf(stderr, "Value missing for CPU %d\n", cpu);
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error = 1;
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goto on_exit;
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}
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fprintf(stderr, "CPU %d: %llu\n", cpu, value);
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on_exit:
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assert(bpf_map_delete_elem(map_fd[0], &cpu) == 0 || error);
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assert(ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE, 0) == 0 || error);
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assert(close(pmu_fd) == 0 || error);
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assert(bpf_map_delete_elem(map_fd[1], &cpu) == 0 || error);
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exit(error);
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}
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static void test_perf_event_array(struct perf_event_attr *attr,
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const char *name)
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{
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int i, status, nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
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pid_t pid[nr_cpus];
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int err = 0;
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printf("Test reading %s counters\n", name);
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for (i = 0; i < nr_cpus; i++) {
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pid[i] = fork();
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assert(pid[i] >= 0);
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if (pid[i] == 0) {
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check_on_cpu(i, attr);
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exit(1);
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}
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}
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for (i = 0; i < nr_cpus; i++) {
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assert(waitpid(pid[i], &status, 0) == pid[i]);
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err |= status;
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}
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if (err)
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printf("Test: %s FAILED\n", name);
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}
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static void test_bpf_perf_event(void)
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{
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struct perf_event_attr attr_cycles = {
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.freq = 0,
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.sample_period = SAMPLE_PERIOD,
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.inherit = 0,
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.type = PERF_TYPE_HARDWARE,
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.read_format = 0,
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.sample_type = 0,
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.config = PERF_COUNT_HW_CPU_CYCLES,
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};
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struct perf_event_attr attr_clock = {
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.freq = 0,
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.sample_period = SAMPLE_PERIOD,
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.inherit = 0,
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.type = PERF_TYPE_SOFTWARE,
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.read_format = 0,
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.sample_type = 0,
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.config = PERF_COUNT_SW_CPU_CLOCK,
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};
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struct perf_event_attr attr_raw = {
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.freq = 0,
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.sample_period = SAMPLE_PERIOD,
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.inherit = 0,
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.type = PERF_TYPE_RAW,
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.read_format = 0,
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.sample_type = 0,
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/* Intel Instruction Retired */
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.config = 0xc0,
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};
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struct perf_event_attr attr_l1d_load = {
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.freq = 0,
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.sample_period = SAMPLE_PERIOD,
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.inherit = 0,
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.type = PERF_TYPE_HW_CACHE,
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.read_format = 0,
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.sample_type = 0,
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.config =
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PERF_COUNT_HW_CACHE_L1D |
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(PERF_COUNT_HW_CACHE_OP_READ << 8) |
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(PERF_COUNT_HW_CACHE_RESULT_ACCESS << 16),
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};
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struct perf_event_attr attr_llc_miss = {
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.freq = 0,
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.sample_period = SAMPLE_PERIOD,
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.inherit = 0,
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.type = PERF_TYPE_HW_CACHE,
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.read_format = 0,
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.sample_type = 0,
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.config =
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PERF_COUNT_HW_CACHE_LL |
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(PERF_COUNT_HW_CACHE_OP_READ << 8) |
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(PERF_COUNT_HW_CACHE_RESULT_MISS << 16),
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};
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struct perf_event_attr attr_msr_tsc = {
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.freq = 0,
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.sample_period = 0,
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.inherit = 0,
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/* From /sys/bus/event_source/devices/msr/ */
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.type = 7,
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.read_format = 0,
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.sample_type = 0,
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.config = 0,
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};
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test_perf_event_array(&attr_cycles, "HARDWARE-cycles");
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test_perf_event_array(&attr_clock, "SOFTWARE-clock");
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test_perf_event_array(&attr_raw, "RAW-instruction-retired");
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test_perf_event_array(&attr_l1d_load, "HW_CACHE-L1D-load");
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/* below tests may fail in qemu */
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test_perf_event_array(&attr_llc_miss, "HW_CACHE-LLC-miss");
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test_perf_event_array(&attr_msr_tsc, "Dynamic-msr-tsc");
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}
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int main(int argc, char **argv)
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{
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struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
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char filename[256];
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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setrlimit(RLIMIT_MEMLOCK, &r);
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if (load_bpf_file(filename)) {
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printf("%s", bpf_log_buf);
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return 1;
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}
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test_bpf_perf_event();
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return 0;
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}
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