1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2004 Marcel Moolenaar, Peter Grehan 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include <sys/param.h> 33 #include <sys/ucontext.h> 34 #include <signal.h> 35 #include <stdlib.h> 36 #include <strings.h> 37 38 typedef void (*handler_t)(uint32_t, uint32_t, uint32_t); 39 40 /* Prototypes */ 41 static void ctx_wrapper(ucontext_t *ucp, handler_t func, uint32_t sig, 42 uint32_t sig_si, uint32_t sig_uc); 43 44 __weak_reference(__signalcontext, signalcontext); 45 46 int 47 __signalcontext(ucontext_t *ucp, int sig, __sighandler_t *func) 48 { 49 siginfo_t *sig_si; 50 ucontext_t *sig_uc; 51 uintptr_t sp; 52 53 /* Bail out if we don't have a valid ucontext pointer. */ 54 if (ucp == NULL) 55 abort(); 56 57 /* 58 * Build a 16-byte-aligned signal frame 59 */ 60 sp = (ucp->uc_mcontext.mc_gpr[1] - sizeof(ucontext_t)) & ~15UL; 61 sig_uc = (ucontext_t *)sp; 62 bcopy(ucp, sig_uc, sizeof(*sig_uc)); 63 sp = (sp - sizeof(siginfo_t)) & ~15UL; 64 sig_si = (siginfo_t *)sp; 65 bzero(sig_si, sizeof(*sig_si)); 66 sig_si->si_signo = sig; 67 68 /* 69 * Subtract 48 bytes from stack to allow for frameptr 70 */ 71 sp -= 6*sizeof(uint64_t); 72 sp &= ~15UL; 73 74 /* 75 * Setup the ucontext of the signal handler. 76 */ 77 bzero(&ucp->uc_mcontext, sizeof(ucp->uc_mcontext)); 78 ucp->uc_link = sig_uc; 79 sigdelset(&ucp->uc_sigmask, sig); 80 81 ucp->uc_mcontext.mc_vers = _MC_VERSION; 82 ucp->uc_mcontext.mc_len = sizeof(struct __mcontext); 83 ucp->uc_mcontext.mc_srr0 = (uint64_t) ctx_wrapper; 84 ucp->uc_mcontext.mc_gpr[1] = (uint64_t) sp; 85 ucp->uc_mcontext.mc_gpr[3] = (uint64_t) func; 86 ucp->uc_mcontext.mc_gpr[4] = (uint64_t) sig; 87 ucp->uc_mcontext.mc_gpr[5] = (uint64_t) sig_si; 88 ucp->uc_mcontext.mc_gpr[6] = (uint64_t) sig_uc; 89 90 return (0); 91 } 92 93 static void 94 ctx_wrapper(ucontext_t *ucp, handler_t func, uint32_t sig, uint32_t sig_si, 95 uint32_t sig_uc) 96 { 97 98 (*func)(sig, sig_si, sig_uc); 99 if (ucp->uc_link == NULL) 100 exit(0); 101 setcontext((const ucontext_t *)ucp->uc_link); 102 /* should never get here */ 103 abort(); 104 /* NOTREACHED */ 105 } 106