tools/testing/selftests/x86/vdso_restorer.c

   1 /*
   2  * vdso_restorer.c - tests vDSO-based signal restore
   3  * Copyright (c) 2015 Andrew Lutomirski
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms and conditions of the GNU General Public License,
   7  * version 2, as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * This makes sure that sa_restorer == NULL keeps working on 32-bit
  15  * configurations.  Modern glibc doesn't use it under any circumstances,
  16  * so it's easy to overlook breakage.
  17  *
  18  * 64-bit userspace has never supported sa_restorer == NULL, so this is
  19  * 32-bit only.
  20  */
  21
  22 #define _GNU_SOURCE
  23
  24 #include <err.h>
  25 #include <stdio.h>
  26 #include <string.h>
  27 #include <signal.h>
  28 #include <unistd.h>
  29 #include <syscall.h>
  30 #include <sys/syscall.h>
  31
  32 /* Open-code this -- the headers are too messy to easily use them. */
  33 struct real_sigaction {
  34         void *handler;
  35         unsigned long flags;
  36         void *restorer;
  37         unsigned int mask[2];
  38 };
  39
  40 static volatile sig_atomic_t handler_called;
  41
  42 static void handler_with_siginfo(int sig, siginfo_t *info, void *ctx_void)
  43 {
  44         handler_called = 1;
  45 }
  46
  47 static void handler_without_siginfo(int sig)
  48 {
  49         handler_called = 1;
  50 }
  51
  52 int main()
  53 {
  54         int nerrs = 0;
  55         struct real_sigaction sa;
  56
  57         memset(&sa, 0, sizeof(sa));
  58         sa.handler = handler_with_siginfo;
  59         sa.flags = SA_SIGINFO;
  60         sa.restorer = NULL;     /* request kernel-provided restorer */
  61
  62         if (syscall(SYS_rt_sigaction, SIGUSR1, &sa, NULL, 8) != 0)
  63                 err(1, "raw rt_sigaction syscall");
  64
  65         raise(SIGUSR1);
  66
  67         if (handler_called) {
  68                 printf("[OK]\tSA_SIGINFO handler returned successfully\n");
  69         } else {
  70                 printf("[FAIL]\tSA_SIGINFO handler was not called\n");
  71                 nerrs++;
  72         }
  73
  74         sa.flags = 0;
  75         sa.handler = handler_without_siginfo;
  76         if (syscall(SYS_sigaction, SIGUSR1, &sa, 0) != 0)
  77                 err(1, "raw sigaction syscall");
  78         handler_called = 0;
  79
  80         raise(SIGUSR1);
  81
  82         if (handler_called) {
  83                 printf("[OK]\t!SA_SIGINFO handler returned successfully\n");
  84         } else {
  85                 printf("[FAIL]\t!SA_SIGINFO handler was not called\n");
  86                 nerrs++;
  87         }
  88 }