Quelle  perf_branches.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <pthread.h>
#include <sched.h>
#include <sys/socket.h>
#include <test_progs.h>
#include "bpf/libbpf_internal.h"
#include "test_perf_branches.skel.h"

static void check_good_sample(struct test_perf_branches *skel)
{
 int written_global = skel->bss->written_global_out;
 int required_size = skel->bss->required_size_out;
 int written_stack = skel->bss->written_stack_out;
 int pbe_size = sizeof(struct perf_branch_entry);
 int duration = 0;

 if (CHECK(!skel->bss->valid, "output not valid",
   "no valid sample from prog"))
  return;

 /*
 * It's hard to validate the contents of the branch entries b/c it
 * would require some kind of disassembler and also encoding the
 * valid jump instructions for supported architectures. So just check
 * the easy stuff for now.
 */
 CHECK(required_size <= 0, "read_branches_size", "err %d\n", required_size);
 CHECK(written_stack < 0, "read_branches_stack", "err %d\n", written_stack);
 CHECK(written_stack % pbe_size != 0, "read_branches_stack",
       "stack bytes written=%d not multiple of struct size=%d\n",
       written_stack, pbe_size);
 CHECK(written_global < 0, "read_branches_global", "err %d\n", written_global);
 CHECK(written_global % pbe_size != 0, "read_branches_global",
       "global bytes written=%d not multiple of struct size=%d\n",
       written_global, pbe_size);
 CHECK(written_global < written_stack, "read_branches_size",
       "written_global=%d < written_stack=%d\n", written_global, written_stack);
}

static void check_bad_sample(struct test_perf_branches *skel)
{
 int written_global = skel->bss->written_global_out;
 int required_size = skel->bss->required_size_out;
 int written_stack = skel->bss->written_stack_out;
 int duration = 0;

 if (CHECK(!skel->bss->valid, "output not valid",
   "no valid sample from prog"))
  return;

 CHECK((required_size != -EINVAL && required_size != -ENOENT),
       "read_branches_size", "err %d\n", required_size);
 CHECK((written_stack != -EINVAL && written_stack != -ENOENT),
       "read_branches_stack", "written %d\n", written_stack);
 CHECK((written_global != -EINVAL && written_global != -ENOENT),
       "read_branches_global", "written %d\n", written_global);
}

static void test_perf_branches_common(int perf_fd,
          void (*cb)(struct test_perf_branches *))
{
 struct test_perf_branches *skel;
 int err, i, duration = 0;
 bool detached = false;
 struct bpf_link *link;
 volatile int j = 0;
 cpu_set_t cpu_set;

 skel = test_perf_branches__open_and_load();
 if (CHECK(!skel, "test_perf_branches_load",
    "perf_branches skeleton failed\n"))
  return;

 /* attach perf_event */
 link = bpf_program__attach_perf_event(skel->progs.perf_branches, perf_fd);
 if (!ASSERT_OK_PTR(link, "attach_perf_event"))
  goto out_destroy_skel;

 /* generate some branches on cpu 0 */
 CPU_ZERO(&cpu_set);
 CPU_SET(0, &cpu_set);
 err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set), &cpu_set);
 if (CHECK(err, "set_affinity", "cpu #0, err %d\n", err))
  goto out_destroy;
 /* spin the loop for a while (random high number) */
 for (i = 0; i < 1000000; ++i)
  ++j;

 test_perf_branches__detach(skel);
 detached = true;

 cb(skel);
out_destroy:
 bpf_link__destroy(link);
out_destroy_skel:
 if (!detached)
  test_perf_branches__detach(skel);
 test_perf_branches__destroy(skel);
}

static void test_perf_branches_hw(void)
{
 struct perf_event_attr attr = {0};
 int duration = 0;
 int pfd;

 /* create perf event */
 attr.size = sizeof(attr);
 attr.type = PERF_TYPE_HARDWARE;
 attr.config = PERF_COUNT_HW_CPU_CYCLES;
 attr.freq = 1;
 attr.sample_freq = 1000;
 attr.sample_type = PERF_SAMPLE_BRANCH_STACK;
 attr.branch_sample_type = PERF_SAMPLE_BRANCH_USER | PERF_SAMPLE_BRANCH_ANY;
 pfd = syscall(__NR_perf_event_open, &attr, -1, 0, -1, PERF_FLAG_FD_CLOEXEC);

 /*
 * Some setups don't support branch records (virtual machines, !x86),
 * so skip test in this case.
 */
 if (pfd < 0) {
  if (errno == ENOENT || errno == EOPNOTSUPP) {
   printf("%s:SKIP:no PERF_SAMPLE_BRANCH_STACK\n",
          __func__);
   test__skip();
   return;
  }
  if (CHECK(pfd < 0, "perf_event_open", "err %d errno %d\n",
     pfd, errno))
   return;
 }

 test_perf_branches_common(pfd, check_good_sample);

 close(pfd);
}

/*
 * Tests negative case -- run bpf_read_branch_records() on improperly configured
 * perf event.
 */
static void test_perf_branches_no_hw(void)
{
 struct perf_event_attr attr = {0};
 int duration = 0;
 int pfd;

 /* create perf event */
 attr.size = sizeof(attr);
 attr.type = PERF_TYPE_SOFTWARE;
 attr.config = PERF_COUNT_SW_CPU_CLOCK;
 attr.freq = 1;
 attr.sample_freq = 1000;
 pfd = syscall(__NR_perf_event_open, &attr, -1, 0, -1, PERF_FLAG_FD_CLOEXEC);
 if (CHECK(pfd < 0, "perf_event_open", "err %d\n", pfd))
  return;

 test_perf_branches_common(pfd, check_bad_sample);

 close(pfd);
}

void test_perf_branches(void)
{
 if (test__start_subtest("perf_branches_hw"))
  test_perf_branches_hw();
 if (test__start_subtest("perf_branches_no_hw"))
  test_perf_branches_no_hw();
}