LXR linux/tools/testing/selftests/bpf/prog_tests/fexit

   1// SPDX-License-Identifier: GPL-2.0
   2/* Copyright (c) 2021 Facebook */
   3#define _GNU_SOURCE
   4#include <sched.h>
   5#include <test_progs.h>
   6#include <time.h>
   7#include <sys/mman.h>
   8#include <sys/syscall.h>
   9#include "fexit_sleep.lskel.h"
  10
  11static int do_sleep(void *skel)
  12{
  13        struct fexit_sleep *fexit_skel = skel;
  14        struct timespec ts1 = { .tv_nsec = 1 };
  15        struct timespec ts2 = { .tv_sec = 10 };
  16
  17        fexit_skel->bss->pid = getpid();
  18        (void)syscall(__NR_nanosleep, &ts1, NULL);
  19        (void)syscall(__NR_nanosleep, &ts2, NULL);
  20        return 0;
  21}
  22
  23#define STACK_SIZE (1024 * 1024)
  24static char child_stack[STACK_SIZE];
  25
  26void test_fexit_sleep(void)
  27{
  28        struct fexit_sleep *fexit_skel = NULL;
  29        int wstatus, duration = 0;
  30        pid_t cpid;
  31        int err, fexit_cnt;
  32
  33        fexit_skel = fexit_sleep__open_and_load();
  34        if (CHECK(!fexit_skel, "fexit_skel_load", "fexit skeleton failed\n"))
  35                goto cleanup;
  36
  37        err = fexit_sleep__attach(fexit_skel);
  38        if (CHECK(err, "fexit_attach", "fexit attach failed: %d\n", err))
  39                goto cleanup;
  40
  41        cpid = clone(do_sleep, child_stack + STACK_SIZE, CLONE_FILES | SIGCHLD, fexit_skel);
  42        if (CHECK(cpid == -1, "clone", "%s\n", strerror(errno)))
  43                goto cleanup;
  44
  45        /* wait until first sys_nanosleep ends and second sys_nanosleep starts */
  46        while (READ_ONCE(fexit_skel->bss->fentry_cnt) != 2);
  47        fexit_cnt = READ_ONCE(fexit_skel->bss->fexit_cnt);
  48        if (CHECK(fexit_cnt != 1, "fexit_cnt", "%d", fexit_cnt))
  49                goto cleanup;
  50
  51        /* close progs and detach them. That will trigger two nop5->jmp5 rewrites
  52         * in the trampolines to skip nanosleep_fexit prog.
  53         * The nanosleep_fentry prog will get detached first.
  54         * The nanosleep_fexit prog will get detached second.
  55         * Detaching will trigger freeing of both progs JITed images.
  56         * There will be two dying bpf_tramp_image-s, but only the initial
  57         * bpf_tramp_image (with both _fentry and _fexit progs will be stuck
  58         * waiting for percpu_ref_kill to confirm). The other one
  59         * will be freed quickly.
  60         */
  61        close(fexit_skel->progs.nanosleep_fentry.prog_fd);
  62        close(fexit_skel->progs.nanosleep_fexit.prog_fd);
  63        fexit_sleep__detach(fexit_skel);
  64
  65        /* kill the thread to unwind sys_nanosleep stack through the trampoline */
  66        kill(cpid, 9);
  67
  68        if (CHECK(waitpid(cpid, &wstatus, 0) == -1, "waitpid", "%s\n", strerror(errno)))
  69                goto cleanup;
  70        if (CHECK(WEXITSTATUS(wstatus) != 0, "exitstatus", "failed"))
  71                goto cleanup;
  72
  73        /* The bypassed nanosleep_fexit prog shouldn't have executed.
  74         * Unlike progs the maps were not freed and directly accessible.
  75         */
  76        fexit_cnt = READ_ONCE(fexit_skel->bss->fexit_cnt);
  77        if (CHECK(fexit_cnt != 1, "fexit_cnt", "%d", fexit_cnt))
  78                goto cleanup;
  79
  80cleanup:
  81        fexit_sleep__destroy(fexit_skel);
  82}
  83