tools/testing/selftests/bpf/prog_tests/exhandler.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (c) 2021, Oracle and/or its affiliates. */
   3
   4 #include <test_progs.h>
   5
   6 /* Test that verifies exception handling is working. fork()
   7  * triggers task_newtask tracepoint; that new task will have a
   8  * NULL pointer task_works, and the associated task->task_works->func
   9  * should not be NULL if task_works itself is non-NULL.
  10  *
  11  * So to verify exception handling we want to see a NULL task_works
  12  * and task_works->func; if we see this we can conclude that the
  13  * exception handler ran when we attempted to dereference task->task_works
  14  * and zeroed the destination register.
  15  */
  16 #include "exhandler_kern.skel.h"
  17
  18 void test_exhandler(void)
  19 {
  20         int err = 0, duration = 0, status;
  21         struct exhandler_kern *skel;
  22         pid_t cpid;
  23
  24         skel = exhandler_kern__open_and_load();
  25         if (CHECK(!skel, "skel_load", "skeleton failed: %d\n", err))
  26                 goto cleanup;
  27
  28         skel->bss->test_pid = getpid();
  29
  30         err = exhandler_kern__attach(skel);
  31         if (!ASSERT_OK(err, "attach"))
  32                 goto cleanup;
  33         cpid = fork();
  34         if (!ASSERT_GT(cpid, -1, "fork failed"))
  35                 goto cleanup;
  36         if (cpid == 0)
  37                 _exit(0);
  38         waitpid(cpid, &status, 0);
  39
  40         ASSERT_NEQ(skel->bss->exception_triggered, 0, "verify exceptions occurred");
  41 cleanup:
  42         exhandler_kern__destroy(skel);
  43 }