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"
39 int _swapcontext(ucontext_t *, const ucontext_t *);
40 int _setcontext(const ucontext_t *);
43 * We need to block most signals during a context switch so we do not
44 * dispatch a signal vector during a context switch.
47 static sigset_t sigset_block_all;
49 static void __sigset_block_all_setup(void) __attribute__ ((constructor));
52 __sigset_block_all_setup(void)
54 sigfillset(&sigset_block_all);
55 sigdelset(&sigset_block_all, SIGSEGV);
56 sigdelset(&sigset_block_all, SIGBUS);
57 sigdelset(&sigset_block_all, SIGILL);
62 * Save the calling context in (oucp) then switch to (ucp).
65 _swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
69 if (getcontext(oucp) == 0) {
70 ret = sigreturn(__DECONST(ucontext_t *, ucp));
78 * Switch to the target context, use sigreturn() to properly restore
79 * everything, including rflags and to avoid scribbling over the
80 * target stack's red-zone.
82 * Note that setcontext() can be called with a ucontext from a signal,
83 * so the signal state must be restored and there is really no way to
84 * avoid making a system call :-(
87 _setcontext(const ucontext_t *ucp)
91 /* XXX: shouldn't sigreturn() take const? or does it modify ucp? */
92 ret = sigreturn(__DECONST(ucontext_t *, ucp));
97 __weak_reference(_swapcontext, swapcontext);
98 __weak_reference(_setcontext, setcontext);