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linux_signal.c revision 1.31.2.8
      1 /*	$NetBSD: linux_signal.c,v 1.31.2.8 2002/08/01 02:44:18 nathanw Exp $	*/
      2 /*-
      3  * Copyright (c) 1995, 1998 The NetBSD Foundation, Inc.
      4  * All rights reserved.
      5  *
      6  * This code is derived from software contributed to The NetBSD Foundation
      7  * by Frank van der Linden and Eric Haszlakiewicz.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  * 3. All advertising materials mentioning features or use of this software
     18  *    must display the following acknowledgement:
     19  *	This product includes software developed by the NetBSD
     20  *	Foundation, Inc. and its contributors.
     21  * 4. Neither the name of The NetBSD Foundation nor the names of its
     22  *    contributors may be used to endorse or promote products derived
     23  *    from this software without specific prior written permission.
     24  *
     25  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     26  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     27  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     28  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     29  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     30  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     31  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     32  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     33  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     34  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     35  * POSSIBILITY OF SUCH DAMAGE.
     36  */
     37 /*
     38  * heavily from: svr4_signal.c,v 1.7 1995/01/09 01:04:21 christos Exp
     39  */
     40 
     41 /*
     42  *   Functions in multiarch:
     43  *	linux_sys_signal	: linux_sig_notalpha.c
     44  *	linux_sys_siggetmask	: linux_sig_notalpha.c
     45  *	linux_sys_sigsetmask	: linux_sig_notalpha.c
     46  *	linux_sys_pause		: linux_sig_notalpha.c
     47  *	linux_sys_sigaction	: linux_sigaction.c
     48  *
     49  */
     50 
     51 /*
     52  *   Unimplemented:
     53  *	linux_sys_rt_sigtimedwait	: sigsuspend w/timeout.
     54  */
     55 
     56 #include <sys/cdefs.h>
     57 __KERNEL_RCSID(0, "$NetBSD: linux_signal.c,v 1.31.2.8 2002/08/01 02:44:18 nathanw Exp $");
     58 
     59 #define COMPAT_LINUX 1
     60 
     61 #include <sys/param.h>
     62 #include <sys/systm.h>
     63 #include <sys/namei.h>
     64 #include <sys/proc.h>
     65 #include <sys/filedesc.h>
     66 #include <sys/ioctl.h>
     67 #include <sys/mount.h>
     68 #include <sys/kernel.h>
     69 #include <sys/signal.h>
     70 #include <sys/signalvar.h>
     71 #include <sys/malloc.h>
     72 
     73 #include <sys/sa.h>
     74 #include <sys/syscallargs.h>
     75 
     76 #include <compat/linux/common/linux_types.h>
     77 #include <compat/linux/common/linux_signal.h>
     78 #include <compat/linux/common/linux_siginfo.h>
     79 #include <compat/linux/common/linux_util.h>
     80 
     81 #include <compat/linux/linux_syscallargs.h>
     82 
     83 /* Locally used defines (in bsd<->linux conversion functions): */
     84 #define	linux_sigemptyset(s)	memset((s), 0, sizeof(*(s)))
     85 #define	linux_sigismember(s, n)	((s)->sig[((n) - 1) / LINUX__NSIG_BPW]	\
     86 					& (1 << ((n) - 1) % LINUX__NSIG_BPW))
     87 #define	linux_sigaddset(s, n)	((s)->sig[((n) - 1) / LINUX__NSIG_BPW]	\
     88 					|= (1 << ((n) - 1) % LINUX__NSIG_BPW))
     89 
     90 #ifdef DEBUG_LINUX
     91 #define DPRINTF(a)	uprintf a
     92 #else
     93 #define DPRINTF(a)
     94 #endif
     95 
     96 extern const int native_to_linux_signo[];
     97 extern const int linux_to_native_signo[];
     98 
     99 /*
    100  * Convert between Linux and BSD signal sets.
    101  */
    102 #if LINUX__NSIG_WORDS > 1
    103 void
    104 linux_old_extra_to_native_sigset(bss, lss, extra)
    105 	sigset_t *bss;
    106 	const linux_old_sigset_t *lss;
    107 	const unsigned long *extra;
    108 {
    109 	linux_sigset_t lsnew;
    110 
    111 	/* convert old sigset to new sigset */
    112 	linux_sigemptyset(&lsnew);
    113 	lsnew.sig[0] = *lss;
    114 	if (extra)
    115 		memcpy(&lsnew.sig[1], extra,
    116 		    sizeof(linux_sigset_t) - sizeof(linux_old_sigset_t));
    117 
    118 	linux_to_native_sigset(bss, &lsnew);
    119 }
    120 
    121 void
    122 native_to_linux_old_extra_sigset(lss, extra, bss)
    123 	linux_old_sigset_t *lss;
    124 	unsigned long *extra;
    125 	const sigset_t *bss;
    126 {
    127 	linux_sigset_t lsnew;
    128 
    129 	native_to_linux_sigset(&lsnew, bss);
    130 
    131 	/* convert new sigset to old sigset */
    132 	*lss = lsnew.sig[0];
    133 	if (extra)
    134 		memcpy(extra, &lsnew.sig[1],
    135 		    sizeof(linux_sigset_t) - sizeof(linux_old_sigset_t));
    136 }
    137 #endif
    138 
    139 void
    140 linux_to_native_sigset(bss, lss)
    141 	sigset_t *bss;
    142 	const linux_sigset_t *lss;
    143 {
    144 	int i, newsig;
    145 
    146 	sigemptyset(bss);
    147 	for (i = 1; i < LINUX__NSIG; i++) {
    148 		if (linux_sigismember(lss, i)) {
    149 			newsig = linux_to_native_signo[i];
    150 			if (newsig)
    151 				sigaddset(bss, newsig);
    152 		}
    153 	}
    154 }
    155 
    156 void
    157 native_to_linux_sigset(lss, bss)
    158 	linux_sigset_t *lss;
    159 	const sigset_t *bss;
    160 {
    161 	int i, newsig;
    162 
    163 	linux_sigemptyset(lss);
    164 	for (i = 1; i < NSIG; i++) {
    165 		if (sigismember(bss, i)) {
    166 			newsig = native_to_linux_signo[i];
    167 			if (newsig)
    168 				linux_sigaddset(lss, newsig);
    169 		}
    170 	}
    171 }
    172 
    173 unsigned int
    174 native_to_linux_sigflags(bsf)
    175 	const int bsf;
    176 {
    177 	unsigned int lsf = 0;
    178 	if ((bsf & SA_NOCLDSTOP) != 0)
    179 		lsf |= LINUX_SA_NOCLDSTOP;
    180 	if ((bsf & SA_NOCLDWAIT) != 0)
    181 		lsf |= LINUX_SA_NOCLDWAIT;
    182 	if ((bsf & SA_ONSTACK) != 0)
    183 		lsf |= LINUX_SA_ONSTACK;
    184 	if ((bsf & SA_RESTART) != 0)
    185 		lsf |= LINUX_SA_RESTART;
    186 	if ((bsf & SA_NODEFER) != 0)
    187 		lsf |= LINUX_SA_NOMASK;
    188 	if ((bsf & SA_RESETHAND) != 0)
    189 		lsf |= LINUX_SA_ONESHOT;
    190 	if ((bsf & SA_SIGINFO) != 0)
    191 		lsf |= LINUX_SA_SIGINFO;
    192 	return lsf;
    193 }
    194 
    195 int
    196 linux_to_native_sigflags(lsf)
    197 	const unsigned long lsf;
    198 {
    199 	int bsf = 0;
    200 	if ((lsf & LINUX_SA_NOCLDSTOP) != 0)
    201 		bsf |= SA_NOCLDSTOP;
    202 	if ((lsf & LINUX_SA_NOCLDWAIT) != 0)
    203 		bsf |= SA_NOCLDWAIT;
    204 	if ((lsf & LINUX_SA_ONSTACK) != 0)
    205 		bsf |= SA_ONSTACK;
    206 	if ((lsf & LINUX_SA_RESTART) != 0)
    207 		bsf |= SA_RESTART;
    208 	if ((lsf & LINUX_SA_ONESHOT) != 0)
    209 		bsf |= SA_RESETHAND;
    210 	if ((lsf & LINUX_SA_NOMASK) != 0)
    211 		bsf |= SA_NODEFER;
    212 	if ((lsf & LINUX_SA_SIGINFO) != 0)
    213 		bsf |= SA_SIGINFO;
    214 	if ((lsf & ~LINUX_SA_ALLBITS) != 0)
    215 		DPRINTF(("linux_old_to_native_sigflags: "
    216 		    "%lx extra bits ignored\n", lsf));
    217 	return bsf;
    218 }
    219 
    220 /*
    221  * Convert between Linux and BSD sigaction structures. Linux sometimes
    222  * has one extra field (sa_restorer) which we don't support.
    223  */
    224 void
    225 linux_old_to_native_sigaction(bsa, lsa)
    226 	struct sigaction *bsa;
    227 	const struct linux_old_sigaction *lsa;
    228 {
    229 	bsa->sa_handler = lsa->sa_handler;
    230 	linux_old_to_native_sigset(&bsa->sa_mask, &lsa->sa_mask);
    231 	bsa->sa_flags = linux_to_native_sigflags(lsa->sa_flags);
    232 #ifndef __alpha__
    233 /*
    234  * XXX: On the alpha sa_restorer is elsewhere.
    235  */
    236 	if (lsa->sa_restorer != NULL)
    237 		DPRINTF(("linux_old_to_native_sigaction: "
    238 		    "sa_restorer ignored\n"));
    239 #endif
    240 }
    241 
    242 void
    243 native_to_linux_old_sigaction(lsa, bsa)
    244 	struct linux_old_sigaction *lsa;
    245 	const struct sigaction *bsa;
    246 {
    247 	lsa->sa_handler = bsa->sa_handler;
    248 	native_to_linux_old_sigset(&lsa->sa_mask, &bsa->sa_mask);
    249 	lsa->sa_flags = native_to_linux_sigflags(bsa->sa_flags);
    250 #ifndef __alpha__
    251 	lsa->sa_restorer = NULL;
    252 #endif
    253 }
    254 
    255 /* ...and the new sigaction conversion funcs. */
    256 void
    257 linux_to_native_sigaction(bsa, lsa)
    258 	struct sigaction *bsa;
    259 	const struct linux_sigaction *lsa;
    260 {
    261 	bsa->sa_handler = lsa->sa_handler;
    262 	linux_to_native_sigset(&bsa->sa_mask, &lsa->sa_mask);
    263 	bsa->sa_flags = linux_to_native_sigflags(lsa->sa_flags);
    264 #ifndef __alpha__
    265 	if (lsa->sa_restorer != 0)
    266 		DPRINTF(("linux_to_native_sigaction: sa_restorer ignored\n"));
    267 #endif
    268 }
    269 
    270 void
    271 native_to_linux_sigaction(lsa, bsa)
    272 	struct linux_sigaction *lsa;
    273 	const struct sigaction *bsa;
    274 {
    275 	lsa->sa_handler = bsa->sa_handler;
    276 	native_to_linux_sigset(&lsa->sa_mask, &bsa->sa_mask);
    277 	lsa->sa_flags = native_to_linux_sigflags(bsa->sa_flags);
    278 #ifndef __alpha__
    279 	lsa->sa_restorer = NULL;
    280 #endif
    281 }
    282 
    283 /* ----------------------------------------------------------------------- */
    284 
    285 /*
    286  * The Linux sigaction() system call. Do the usual conversions,
    287  * and just call sigaction(). Some flags and values are silently
    288  * ignored (see above).
    289  */
    290 int
    291 linux_sys_rt_sigaction(l, v, retval)
    292 	struct lwp *l;
    293 	void *v;
    294 	register_t *retval;
    295 {
    296 	struct linux_sys_rt_sigaction_args /* {
    297 		syscallarg(int) signum;
    298 		syscallarg(const struct linux_sigaction *) nsa;
    299 		syscallarg(struct linux_sigaction *) osa;
    300 		syscallarg(size_t) sigsetsize;
    301 	} */ *uap = v;
    302 	struct proc *p = l->l_proc;
    303 	struct linux_sigaction nlsa, olsa;
    304 	struct sigaction nbsa, obsa;
    305 	int error, sig;
    306 
    307 	if (SCARG(uap, sigsetsize) != sizeof(linux_sigset_t))
    308 		return (EINVAL);
    309 
    310 	if (SCARG(uap, nsa)) {
    311 		error = copyin(SCARG(uap, nsa), &nlsa, sizeof(nlsa));
    312 		if (error)
    313 			return (error);
    314 		linux_to_native_sigaction(&nbsa, &nlsa);
    315 	}
    316 	sig = SCARG(uap, signum);
    317 	if (sig < 0 || sig >= LINUX__NSIG)
    318 		return (EINVAL);
    319 	if (sig > 0 && !linux_to_native_signo[sig]) {
    320 		/* Pretend that we did something useful for unknown signals. */
    321 		obsa.sa_handler = SIG_IGN;
    322 		sigemptyset(&obsa.sa_mask);
    323 		obsa.sa_flags = 0;
    324 	} else {
    325 		error = sigaction1(p, linux_to_native_signo[sig],
    326 		    SCARG(uap, nsa) ? &nbsa : NULL,
    327 		    SCARG(uap, osa) ? &obsa : NULL,
    328 		    NULL, 0);
    329 		if (error)
    330 			return (error);
    331 	}
    332 	if (SCARG(uap, osa)) {
    333 		native_to_linux_sigaction(&olsa, &obsa);
    334 		error = copyout(&olsa, SCARG(uap, osa), sizeof(olsa));
    335 		if (error)
    336 			return (error);
    337 	}
    338 	return (0);
    339 }
    340 
    341 int
    342 linux_sigprocmask1(p, how, set, oset)
    343 	struct proc *p;
    344 	int how;
    345 	const linux_old_sigset_t *set;
    346 	linux_old_sigset_t *oset;
    347 {
    348 	linux_old_sigset_t nlss, olss;
    349 	sigset_t nbss, obss;
    350 	int error;
    351 
    352 	switch (how) {
    353 	case LINUX_SIG_BLOCK:
    354 		how = SIG_BLOCK;
    355 		break;
    356 	case LINUX_SIG_UNBLOCK:
    357 		how = SIG_UNBLOCK;
    358 		break;
    359 	case LINUX_SIG_SETMASK:
    360 		how = SIG_SETMASK;
    361 		break;
    362 	default:
    363 		return (EINVAL);
    364 	}
    365 
    366 	if (set) {
    367 		error = copyin(set, &nlss, sizeof(nlss));
    368 		if (error)
    369 			return (error);
    370 		linux_old_to_native_sigset(&nbss, &nlss);
    371 	}
    372 	error = sigprocmask1(p, how,
    373 	    set ? &nbss : NULL, oset ? &obss : NULL);
    374 	if (error)
    375 		return (error);
    376 	if (oset) {
    377 		native_to_linux_old_sigset(&olss, &obss);
    378 		error = copyout(&olss, oset, sizeof(olss));
    379 		if (error)
    380 			return (error);
    381 	}
    382 	return (error);
    383 }
    384 
    385 int
    386 linux_sys_rt_sigprocmask(l, v, retval)
    387 	struct lwp *l;
    388 	void *v;
    389 	register_t *retval;
    390 {
    391 	struct linux_sys_rt_sigprocmask_args /* {
    392 		syscallarg(int) how;
    393 		syscallarg(const linux_sigset_t *) set;
    394 		syscallarg(linux_sigset_t *) oset;
    395 		syscallarg(size_t) sigsetsize;
    396 	} */ *uap = v;
    397 	struct proc *p = l->l_proc;
    398 	linux_sigset_t nlss, olss, *oset;
    399 	const linux_sigset_t *set;
    400 	sigset_t nbss, obss;
    401 	int error, how;
    402 
    403 	if (SCARG(uap, sigsetsize) != sizeof(linux_sigset_t))
    404 		return (EINVAL);
    405 
    406 	switch (SCARG(uap, how)) {
    407 	case LINUX_SIG_BLOCK:
    408 		how = SIG_BLOCK;
    409 		break;
    410 	case LINUX_SIG_UNBLOCK:
    411 		how = SIG_UNBLOCK;
    412 		break;
    413 	case LINUX_SIG_SETMASK:
    414 		how = SIG_SETMASK;
    415 		break;
    416 	default:
    417 		return (EINVAL);
    418 	}
    419 
    420 	set = SCARG(uap, set);
    421 	oset = SCARG(uap, oset);
    422 
    423 	if (set) {
    424 		error = copyin(set, &nlss, sizeof(nlss));
    425 		if (error)
    426 			return (error);
    427 		linux_to_native_sigset(&nbss, &nlss);
    428 	}
    429 	error = sigprocmask1(p, how,
    430 	    set ? &nbss : NULL, oset ? &obss : NULL);
    431 	if (!error && oset) {
    432 		native_to_linux_sigset(&olss, &obss);
    433 		error = copyout(&olss, oset, sizeof(olss));
    434 	}
    435 	return (error);
    436 }
    437 
    438 int
    439 linux_sys_rt_sigpending(l, v, retval)
    440 	struct lwp *l;
    441 	void *v;
    442 	register_t *retval;
    443 {
    444 	struct linux_sys_rt_sigpending_args /* {
    445 		syscallarg(linux_sigset_t *) set;
    446 		syscallarg(size_t) sigsetsize;
    447 	} */ *uap = v;
    448 	struct proc *p = l->l_proc;
    449 	sigset_t bss;
    450 	linux_sigset_t lss;
    451 
    452 	if (SCARG(uap, sigsetsize) != sizeof(linux_sigset_t))
    453 		return (EINVAL);
    454 
    455 	sigpending1(p, &bss);
    456 	native_to_linux_sigset(&lss, &bss);
    457 	return copyout(&lss, SCARG(uap, set), sizeof(lss));
    458 }
    459 
    460 int
    461 linux_sys_sigpending(l, v, retval)
    462 	struct lwp *l;
    463 	void *v;
    464 	register_t *retval;
    465 {
    466 	struct linux_sys_sigpending_args /* {
    467 		syscallarg(linux_old_sigset_t *) mask;
    468 	} */ *uap = v;
    469 	struct proc *p = l->l_proc;
    470 	sigset_t bss;
    471 	linux_old_sigset_t lss;
    472 
    473 	sigpending1(p, &bss);
    474 	native_to_linux_old_sigset(&lss, &bss);
    475 	return copyout(&lss, SCARG(uap, set), sizeof(lss));
    476 }
    477 
    478 int
    479 linux_sys_sigsuspend(l, v, retval)
    480 	struct lwp *l;
    481 	void *v;
    482 	register_t *retval;
    483 {
    484 	struct linux_sys_sigsuspend_args /* {
    485 		syscallarg(caddr_t) restart;
    486 		syscallarg(int) oldmask;
    487 		syscallarg(int) mask;
    488 	} */ *uap = v;
    489 	struct proc *p = l->l_proc;
    490 	linux_old_sigset_t lss;
    491 	sigset_t bss;
    492 
    493 	lss = SCARG(uap, mask);
    494 	linux_old_to_native_sigset(&bss, &lss);
    495 	return (sigsuspend1(p, &bss));
    496 }
    497 int
    498 linux_sys_rt_sigsuspend(l, v, retval)
    499 	struct lwp *l;
    500 	void *v;
    501 	register_t *retval;
    502 {
    503 	struct linux_sys_rt_sigsuspend_args /* {
    504 		syscallarg(linux_sigset_t *) unewset;
    505 		syscallarg(size_t) sigsetsize;
    506 	} */ *uap = v;
    507 	struct proc *p = l->l_proc;
    508 	linux_sigset_t lss;
    509 	sigset_t bss;
    510 	int error;
    511 
    512 	if (SCARG(uap, sigsetsize) != sizeof(linux_sigset_t))
    513 		return (EINVAL);
    514 
    515 	error = copyin(SCARG(uap, unewset), &lss, sizeof(linux_sigset_t));
    516 	if (error)
    517 		return (error);
    518 
    519 	linux_to_native_sigset(&bss, &lss);
    520 
    521 	return (sigsuspend1(p, &bss));
    522 }
    523 
    524 /*
    525  * Once more: only a signal conversion is needed.
    526  * Note: also used as sys_rt_queueinfo.  The info field is ignored.
    527  */
    528 int
    529 linux_sys_rt_queueinfo(l, v, retval)
    530 	struct lwp *l;
    531 	void *v;
    532 	register_t *retval;
    533 {
    534 	/* XXX XAX This isn't this really int, int, siginfo_t *, is it? */
    535 #if 0
    536 	struct linux_sys_rt_queueinfo_args /* {
    537 		syscallarg(int) pid;
    538 		syscallarg(int) signum;
    539 		syscallarg(siginfo_t *) uinfo;
    540 	} */ *uap = v;
    541 #endif
    542 
    543 	/* XXX To really implement this we need to	*/
    544 	/* XXX keep a list of queued signals somewhere.	*/
    545 	return (linux_sys_kill(l, v, retval));
    546 }
    547 
    548 int
    549 linux_sys_kill(l, v, retval)
    550 	struct lwp *l;
    551 	void *v;
    552 	register_t *retval;
    553 {
    554 	struct linux_sys_kill_args /* {
    555 		syscallarg(int) pid;
    556 		syscallarg(int) signum;
    557 	} */ *uap = v;
    558 
    559 	struct sys_kill_args ka;
    560 	int sig;
    561 
    562 	SCARG(&ka, pid) = SCARG(uap, pid);
    563 	sig = SCARG(uap, signum);
    564 	if (sig < 0 || sig >= LINUX__NSIG)
    565 		return (EINVAL);
    566 	SCARG(&ka, signum) = linux_to_native_signo[sig];
    567 	return sys_kill(l, &ka, retval);
    568 }
    569 
    570 #ifdef LINUX_SS_ONSTACK
    571 static void linux_to_native_sigaltstack __P((struct sigaltstack *,
    572     const struct linux_sigaltstack *));
    573 static void native_to_linux_sigaltstack __P((struct linux_sigaltstack *,
    574     const struct sigaltstack *));
    575 
    576 static void
    577 linux_to_native_sigaltstack(bss, lss)
    578 	struct sigaltstack *bss;
    579 	const struct linux_sigaltstack *lss;
    580 {
    581 	bss->ss_sp = lss->ss_sp;
    582 	bss->ss_size = lss->ss_size;
    583 	if (lss->ss_flags & LINUX_SS_ONSTACK)
    584 	    bss->ss_flags = SS_ONSTACK;
    585 	else if (lss->ss_flags & LINUX_SS_DISABLE)
    586 	    bss->ss_flags = SS_DISABLE;
    587 	else
    588 	    bss->ss_flags = 0;
    589 }
    590 
    591 static void
    592 native_to_linux_sigaltstack(lss, bss)
    593 	struct linux_sigaltstack *lss;
    594 	const struct sigaltstack *bss;
    595 {
    596 	lss->ss_sp = bss->ss_sp;
    597 	lss->ss_size = bss->ss_size;
    598 	if (bss->ss_flags & SS_ONSTACK)
    599 	    lss->ss_flags = LINUX_SS_ONSTACK;
    600 	else if (bss->ss_flags & SS_DISABLE)
    601 	    lss->ss_flags = LINUX_SS_DISABLE;
    602 	else
    603 	    lss->ss_flags = 0;
    604 }
    605 
    606 int
    607 linux_sys_sigaltstack(l, v, retval)
    608 	struct lwp *l;
    609 	void *v;
    610 	register_t *retval;
    611 {
    612 	struct linux_sys_sigaltstack_args /* {
    613 		syscallarg(const struct linux_sigaltstack *) ss;
    614 		syscallarg(struct linux_sigaltstack *) oss;
    615 	} */ *uap = v;
    616 	struct proc *p = l->l_proc;
    617 	struct linux_sigaltstack ss;
    618 	struct sigaltstack nss, oss;
    619 	int error;
    620 
    621 	if (SCARG(uap, ss) != NULL) {
    622 		if ((error = copyin(SCARG(uap, ss), &ss, sizeof(ss))) != 0)
    623 			return error;
    624 		linux_to_native_sigaltstack(&nss, &ss);
    625 	}
    626 
    627 	error = sigaltstack1(p,
    628 	    SCARG(uap, ss) ? &nss : NULL, SCARG(uap, oss) ? &oss : NULL);
    629 	if (error)
    630 		return error;
    631 
    632 	if (SCARG(uap, oss) != NULL) {
    633 		native_to_linux_sigaltstack(&ss, &oss);
    634 		if ((error = copyout(&ss, SCARG(uap, oss), sizeof(ss))) != 0)
    635 			return error;
    636 	}
    637 	return 0;
    638 }
    639 #endif
    640