tools/testing/selftests/x86/vdso_restorer.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * vdso_restorer.c - tests vDSO-based signal restore
   4  * Copyright (c) 2015 Andrew Lutomirski
   5  *
   6  * This makes sure that sa_restorer == NULL keeps working on 32-bit
   7  * configurations.  Modern glibc doesn't use it under any circumstances,
   8  * so it's easy to overlook breakage.
   9  *
  10  * 64-bit userspace has never supported sa_restorer == NULL, so this is
  11  * 32-bit only.
  12  */
  13
  14 #define _GNU_SOURCE
  15
  16 #include <err.h>
  17 #include <stdio.h>
  18 #include <string.h>
  19 #include <signal.h>
  20 #include <unistd.h>
  21 #include <syscall.h>
  22 #include <sys/syscall.h>
  23
  24 /* Open-code this -- the headers are too messy to easily use them. */
  25 struct real_sigaction {
  26         void *handler;
  27         unsigned long flags;
  28         void *restorer;
  29         unsigned int mask[2];
  30 };
  31
  32 static volatile sig_atomic_t handler_called;
  33
  34 static void handler_with_siginfo(int sig, siginfo_t *info, void *ctx_void)
  35 {
  36         handler_called = 1;
  37 }
  38
  39 static void handler_without_siginfo(int sig)
  40 {
  41         handler_called = 1;
  42 }
  43
  44 int main()
  45 {
  46         int nerrs = 0;
  47         struct real_sigaction sa;
  48
  49         memset(&sa, 0, sizeof(sa));
  50         sa.handler = handler_with_siginfo;
  51         sa.flags = SA_SIGINFO;
  52         sa.restorer = NULL;     /* request kernel-provided restorer */
  53
  54         if (syscall(SYS_rt_sigaction, SIGUSR1, &sa, NULL, 8) != 0)
  55                 err(1, "raw rt_sigaction syscall");
  56
  57         raise(SIGUSR1);
  58
  59         if (handler_called) {
  60                 printf("[OK]\tSA_SIGINFO handler returned successfully\n");
  61         } else {
  62                 printf("[FAIL]\tSA_SIGINFO handler was not called\n");
  63                 nerrs++;
  64         }
  65
  66         sa.flags = 0;
  67         sa.handler = handler_without_siginfo;
  68         if (syscall(SYS_sigaction, SIGUSR1, &sa, 0) != 0)
  69                 err(1, "raw sigaction syscall");
  70         handler_called = 0;
  71
  72         raise(SIGUSR1);
  73
  74         if (handler_called) {
  75                 printf("[OK]\t!SA_SIGINFO handler returned successfully\n");
  76         } else {
  77                 printf("[FAIL]\t!SA_SIGINFO handler was not called\n");
  78                 nerrs++;
  79         }
  80 }