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 } 81