1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2003 Marcel Moolenaar 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/types.h> 33 #include <sys/ucontext.h> 34 #include <signal.h> 35 #include <stdlib.h> 36 #include <strings.h> 37 38 typedef void (*handler_t)(uint64_t, uint64_t, uint64_t); 39 40 /* Prototypes */ 41 static void sigctx_wrapper(ucontext_t *ucp, handler_t func, uint64_t *args); 42 43 __weak_reference(__signalcontext, signalcontext); 44 45 int 46 __signalcontext(ucontext_t *ucp, int sig, __sighandler_t *func) 47 { 48 uint64_t *args; 49 siginfo_t *sig_si; 50 ucontext_t *sig_uc; 51 uint64_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 signal frame and copy the arguments of signal handler 59 * 'func' onto the stack and do the funky stack alignment. 60 * This means that we need an 8-byte-odd alignment since the ABI expects 61 * the return address to be pushed, thus breaking the 16 byte alignment. 62 */ 63 sp = (ucp->uc_mcontext.mc_rsp - 128 - sizeof(ucontext_t)) & ~15UL; 64 sig_uc = (ucontext_t *)sp; 65 bcopy(ucp, sig_uc, sizeof(*sig_uc)); 66 sp = (sp - sizeof(siginfo_t)) & ~15UL; 67 sig_si = (siginfo_t *)sp; 68 bzero(sig_si, sizeof(*sig_si)); 69 sig_si->si_signo = sig; 70 sp -= 3 * sizeof(uint64_t); 71 args = (uint64_t *)sp; 72 args[0] = sig; 73 args[1] = (intptr_t)sig_si; 74 args[2] = (intptr_t)sig_uc; 75 sp -= 16; 76 77 /* 78 * Setup the ucontext of the signal handler. 79 */ 80 bzero(&ucp->uc_mcontext, sizeof(ucp->uc_mcontext)); 81 ucp->uc_mcontext.mc_fpformat = _MC_FPFMT_NODEV; 82 ucp->uc_mcontext.mc_ownedfp = _MC_FPOWNED_NONE; 83 ucp->uc_link = sig_uc; 84 sigdelset(&ucp->uc_sigmask, sig); 85 86 ucp->uc_mcontext.mc_len = sizeof(mcontext_t); 87 ucp->uc_mcontext.mc_rdi = (register_t)ucp; 88 ucp->uc_mcontext.mc_rsi = (register_t)func; 89 ucp->uc_mcontext.mc_rdx = (register_t)args; 90 ucp->uc_mcontext.mc_rbp = (register_t)sp; 91 ucp->uc_mcontext.mc_rbx = (register_t)sp; 92 ucp->uc_mcontext.mc_rsp = (register_t)sp; 93 ucp->uc_mcontext.mc_rip = (register_t)sigctx_wrapper; 94 return (0); 95 } 96 97 static void 98 sigctx_wrapper(ucontext_t *ucp, handler_t func, uint64_t *args) 99 { 100 101 (*func)(args[0], args[1], args[2]); 102 if (ucp->uc_link == NULL) 103 exit(0); 104 setcontext((const ucontext_t *)ucp->uc_link); 105 /* should never get here */ 106 abort(); 107 /* NOTREACHED */ 108 } 109