2 * Copyright (c) 2007 Matthew T. Emmerton <matt@gsicomp.on.ca>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
27 #include "namespace.h"
28 #include <sys/param.h>
29 #include <sys/signal.h>
30 #include <sys/ucontext.h>
37 #include "un-namespace.h"
40 __weak_reference(_swapcontext, swapcontext);
41 __weak_reference(_setcontext, setcontext);
44 * We need to block most signals during a context switch so we do not
45 * dispatch a signal vector during a context switch.
48 static sigset_t sigset_block_all;
50 static void __sigset_block_all_setup(void) __attribute__ ((constructor));
53 __sigset_block_all_setup(void)
55 sigfillset(&sigset_block_all);
56 sigdelset(&sigset_block_all, SIGSEGV);
57 sigdelset(&sigset_block_all, SIGBUS);
58 sigdelset(&sigset_block_all, SIGILL);
63 * Save the calling context in (oucp) then switch to (ucp).
66 _swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
70 if (getcontext(oucp) == 0) {
71 ret = sigreturn(__DECONST(ucontext_t *, ucp));
79 * Switch to the target context, use sigreturn() to properly restore
80 * everything, including rflags and to avoid scribbling over the
81 * target stack's red-zone.
83 * Note that setcontext() can be called with a ucontext from a signal,
84 * so the signal state must be restored and there is really no way to
85 * avoid making a system call :-(
88 _setcontext(ucontext_t *ucp)