1 /* 2 * Copyright (c) 2007 Matthew T. Emmerton <matt@gsicomp.on.ca> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Neither the name of the author nor the names of its contributors 11 * may be used to endorse or promote products derived from this software 12 * without specific prior written permission. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include "namespace.h" 28 #include <sys/param.h> 29 #include <sys/signal.h> 30 #include <sys/ucontext.h> 31 32 #include <errno.h> 33 #include <stdarg.h> 34 #include <stdlib.h> 35 #include <unistd.h> 36 #include <signal.h> 37 #include "un-namespace.h" 38 39 /* 40 * We need to block most signals during a context switch so we do not 41 * dispatch a signal vector during a context switch. 42 */ 43 #if 0 44 static sigset_t sigset_block_all; 45 46 static void __sigset_block_all_setup(void) __attribute__ ((constructor)); 47 48 static void 49 __sigset_block_all_setup(void) 50 { 51 sigfillset(&sigset_block_all); 52 sigdelset(&sigset_block_all, SIGSEGV); 53 sigdelset(&sigset_block_all, SIGBUS); 54 sigdelset(&sigset_block_all, SIGILL); 55 } 56 #endif 57 58 /* 59 * Save the calling context in (oucp) then switch to (ucp). 60 */ 61 int 62 _swapcontext(ucontext_t *oucp, const ucontext_t *ucp) 63 { 64 int ret; 65 66 if (getcontext(oucp) == 0) { 67 ret = sigreturn(__DECONST(ucontext_t *, ucp)); 68 } else { 69 ret = 0; 70 } 71 return(ret); 72 } 73 74 /* 75 * Switch to the target context, use sigreturn() to properly restore 76 * everything, including rflags and to avoid scribbling over the 77 * target stack's red-zone. 78 * 79 * Note that setcontext() can be called with a ucontext from a signal, 80 * so the signal state must be restored and there is really no way to 81 * avoid making a system call :-( 82 */ 83 int 84 _setcontext(const ucontext_t *ucp) 85 { 86 int ret; 87 88 /* XXX: shouldn't sigreturn() take const? or does it modify ucp? */ 89 ret = sigreturn(__DECONST(ucontext_t *, ucp)); 90 91 return(ret); 92 } 93 94 __weak_reference(_swapcontext, swapcontext); 95 __weak_reference(_setcontext, setcontext); 96