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 <dlfcn.h>
  19 #include <string.h>
  20 #include <signal.h>
  21 #include <unistd.h>
  22 #include <syscall.h>
  23 #include <sys/syscall.h>
  24
  25 /* Open-code this -- the headers are too messy to easily use them. */
  26 struct real_sigaction {
  27         void *handler;
  28         unsigned long flags;
  29         void *restorer;
  30         unsigned int mask[2];
  31 };
  32
  33 static volatile sig_atomic_t handler_called;
  34
  35 static void handler_with_siginfo(int sig, siginfo_t *info, void *ctx_void)
  36 {
  37         handler_called = 1;
  38 }
  39
  40 static void handler_without_siginfo(int sig)
  41 {
  42         handler_called = 1;
  43 }
  44
  45 int main()
  46 {
  47         int nerrs = 0;
  48         struct real_sigaction sa;
  49
  50         void *vdso = dlopen("linux-vdso.so.1",
  51                             RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
  52         if (!vdso)
  53                 vdso = dlopen("linux-gate.so.1",
  54                               RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
  55         if (!vdso) {
  56                 printf("[SKIP]\tFailed to find vDSO.  Tests are not expected to work.\n");
  57                 return 0;
  58         }
  59
  60         memset(&sa, 0, sizeof(sa));
  61         sa.handler = handler_with_siginfo;
  62         sa.flags = SA_SIGINFO;
  63         sa.restorer = NULL;     /* request kernel-provided restorer */
  64
  65         printf("[RUN]\tRaise a signal, SA_SIGINFO, sa.restorer == NULL\n");
  66
  67         if (syscall(SYS_rt_sigaction, SIGUSR1, &sa, NULL, 8) != 0)
  68                 err(1, "raw rt_sigaction syscall");
  69
  70         raise(SIGUSR1);
  71
  72         if (handler_called) {
  73                 printf("[OK]\tSA_SIGINFO handler returned successfully\n");
  74         } else {
  75                 printf("[FAIL]\tSA_SIGINFO handler was not called\n");
  76                 nerrs++;
  77         }
  78
  79         printf("[RUN]\tRaise a signal, !SA_SIGINFO, sa.restorer == NULL\n");
  80
  81         sa.flags = 0;
  82         sa.handler = handler_without_siginfo;
  83         if (syscall(SYS_sigaction, SIGUSR1, &sa, 0) != 0)
  84                 err(1, "raw sigaction syscall");
  85         handler_called = 0;
  86
  87         raise(SIGUSR1);
  88
  89         if (handler_called) {
  90                 printf("[OK]\t!SA_SIGINFO handler returned successfully\n");
  91         } else {
  92                 printf("[FAIL]\t!SA_SIGINFO handler was not called\n");
  93                 nerrs++;
  94         }
  95 }