xref: /freebsd/sys/amd64/linux32/linux32_machdep.c (revision 924226fba12cc9a228c73b956e1b7fa24c60b055)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 2004 Tim J. Robbins
5  * Copyright (c) 2002 Doug Rabson
6  * Copyright (c) 2000 Marcel Moolenaar
7  * All rights reserved.
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  *    in this position and unchanged.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. The name of the author may not be used to endorse or promote products
19  *    derived from this software without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31  */
32 
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35 
36 #include "opt_compat.h"
37 
38 #include <sys/param.h>
39 #include <sys/capsicum.h>
40 #include <sys/clock.h>
41 #include <sys/fcntl.h>
42 #include <sys/file.h>
43 #include <sys/imgact.h>
44 #include <sys/kernel.h>
45 #include <sys/limits.h>
46 #include <sys/lock.h>
47 #include <sys/malloc.h>
48 #include <sys/mman.h>
49 #include <sys/mutex.h>
50 #include <sys/priv.h>
51 #include <sys/proc.h>
52 #include <sys/reg.h>
53 #include <sys/resource.h>
54 #include <sys/resourcevar.h>
55 #include <sys/syscallsubr.h>
56 #include <sys/sysproto.h>
57 #include <sys/systm.h>
58 #include <sys/unistd.h>
59 #include <sys/wait.h>
60 
61 #include <machine/frame.h>
62 #include <machine/md_var.h>
63 #include <machine/pcb.h>
64 #include <machine/psl.h>
65 #include <machine/segments.h>
66 #include <machine/specialreg.h>
67 #include <x86/ifunc.h>
68 
69 #include <vm/pmap.h>
70 #include <vm/vm.h>
71 #include <vm/vm_map.h>
72 
73 #include <security/audit/audit.h>
74 
75 #include <compat/freebsd32/freebsd32_util.h>
76 #include <amd64/linux32/linux.h>
77 #include <amd64/linux32/linux32_proto.h>
78 #include <compat/linux/linux_emul.h>
79 #include <compat/linux/linux_fork.h>
80 #include <compat/linux/linux_ipc.h>
81 #include <compat/linux/linux_misc.h>
82 #include <compat/linux/linux_mmap.h>
83 #include <compat/linux/linux_signal.h>
84 #include <compat/linux/linux_util.h>
85 
86 static void	bsd_to_linux_rusage(struct rusage *ru, struct l_rusage *lru);
87 
88 struct l_old_select_argv {
89 	l_int		nfds;
90 	l_uintptr_t	readfds;
91 	l_uintptr_t	writefds;
92 	l_uintptr_t	exceptfds;
93 	l_uintptr_t	timeout;
94 } __packed;
95 
96 static void
97 bsd_to_linux_rusage(struct rusage *ru, struct l_rusage *lru)
98 {
99 
100 	lru->ru_utime.tv_sec = ru->ru_utime.tv_sec;
101 	lru->ru_utime.tv_usec = ru->ru_utime.tv_usec;
102 	lru->ru_stime.tv_sec = ru->ru_stime.tv_sec;
103 	lru->ru_stime.tv_usec = ru->ru_stime.tv_usec;
104 	lru->ru_maxrss = ru->ru_maxrss;
105 	lru->ru_ixrss = ru->ru_ixrss;
106 	lru->ru_idrss = ru->ru_idrss;
107 	lru->ru_isrss = ru->ru_isrss;
108 	lru->ru_minflt = ru->ru_minflt;
109 	lru->ru_majflt = ru->ru_majflt;
110 	lru->ru_nswap = ru->ru_nswap;
111 	lru->ru_inblock = ru->ru_inblock;
112 	lru->ru_oublock = ru->ru_oublock;
113 	lru->ru_msgsnd = ru->ru_msgsnd;
114 	lru->ru_msgrcv = ru->ru_msgrcv;
115 	lru->ru_nsignals = ru->ru_nsignals;
116 	lru->ru_nvcsw = ru->ru_nvcsw;
117 	lru->ru_nivcsw = ru->ru_nivcsw;
118 }
119 
120 int
121 linux_copyout_rusage(struct rusage *ru, void *uaddr)
122 {
123 	struct l_rusage lru;
124 
125 	bsd_to_linux_rusage(ru, &lru);
126 
127 	return (copyout(&lru, uaddr, sizeof(struct l_rusage)));
128 }
129 
130 int
131 linux_execve(struct thread *td, struct linux_execve_args *args)
132 {
133 	struct image_args eargs;
134 	char *path;
135 	int error;
136 
137 	if (!LUSECONVPATH(td)) {
138 		error = freebsd32_exec_copyin_args(&eargs, args->path, UIO_USERSPACE,
139 		    args->argp, args->envp);
140 	} else {
141 		LCONVPATHEXIST(args->path, &path);
142 		error = freebsd32_exec_copyin_args(&eargs, path, UIO_SYSSPACE,
143 		    args->argp, args->envp);
144 		LFREEPATH(path);
145 	}
146 	if (error == 0)
147 		error = linux_common_execve(td, &eargs);
148 	AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td);
149 	return (error);
150 }
151 
152 CTASSERT(sizeof(struct l_iovec32) == 8);
153 
154 int
155 linux32_copyinuio(struct l_iovec32 *iovp, l_ulong iovcnt, struct uio **uiop)
156 {
157 	struct l_iovec32 iov32;
158 	struct iovec *iov;
159 	struct uio *uio;
160 	uint32_t iovlen;
161 	int error, i;
162 
163 	*uiop = NULL;
164 	if (iovcnt > UIO_MAXIOV)
165 		return (EINVAL);
166 	iovlen = iovcnt * sizeof(struct iovec);
167 	uio = malloc(iovlen + sizeof(*uio), M_IOV, M_WAITOK);
168 	iov = (struct iovec *)(uio + 1);
169 	for (i = 0; i < iovcnt; i++) {
170 		error = copyin(&iovp[i], &iov32, sizeof(struct l_iovec32));
171 		if (error) {
172 			free(uio, M_IOV);
173 			return (error);
174 		}
175 		iov[i].iov_base = PTRIN(iov32.iov_base);
176 		iov[i].iov_len = iov32.iov_len;
177 	}
178 	uio->uio_iov = iov;
179 	uio->uio_iovcnt = iovcnt;
180 	uio->uio_segflg = UIO_USERSPACE;
181 	uio->uio_offset = -1;
182 	uio->uio_resid = 0;
183 	for (i = 0; i < iovcnt; i++) {
184 		if (iov->iov_len > INT_MAX - uio->uio_resid) {
185 			free(uio, M_IOV);
186 			return (EINVAL);
187 		}
188 		uio->uio_resid += iov->iov_len;
189 		iov++;
190 	}
191 	*uiop = uio;
192 	return (0);
193 }
194 
195 int
196 linux32_copyiniov(struct l_iovec32 *iovp32, l_ulong iovcnt, struct iovec **iovp,
197     int error)
198 {
199 	struct l_iovec32 iov32;
200 	struct iovec *iov;
201 	uint32_t iovlen;
202 	int i;
203 
204 	*iovp = NULL;
205 	if (iovcnt > UIO_MAXIOV)
206 		return (error);
207 	iovlen = iovcnt * sizeof(struct iovec);
208 	iov = malloc(iovlen, M_IOV, M_WAITOK);
209 	for (i = 0; i < iovcnt; i++) {
210 		error = copyin(&iovp32[i], &iov32, sizeof(struct l_iovec32));
211 		if (error) {
212 			free(iov, M_IOV);
213 			return (error);
214 		}
215 		iov[i].iov_base = PTRIN(iov32.iov_base);
216 		iov[i].iov_len = iov32.iov_len;
217 	}
218 	*iovp = iov;
219 	return(0);
220 
221 }
222 
223 int
224 linux_readv(struct thread *td, struct linux_readv_args *uap)
225 {
226 	struct uio *auio;
227 	int error;
228 
229 	error = linux32_copyinuio(uap->iovp, uap->iovcnt, &auio);
230 	if (error)
231 		return (error);
232 	error = kern_readv(td, uap->fd, auio);
233 	free(auio, M_IOV);
234 	return (error);
235 }
236 
237 int
238 linux_writev(struct thread *td, struct linux_writev_args *uap)
239 {
240 	struct uio *auio;
241 	int error;
242 
243 	error = linux32_copyinuio(uap->iovp, uap->iovcnt, &auio);
244 	if (error)
245 		return (error);
246 	error = kern_writev(td, uap->fd, auio);
247 	free(auio, M_IOV);
248 	return (error);
249 }
250 
251 struct l_ipc_kludge {
252 	l_uintptr_t msgp;
253 	l_long msgtyp;
254 } __packed;
255 
256 int
257 linux_ipc(struct thread *td, struct linux_ipc_args *args)
258 {
259 
260 	switch (args->what & 0xFFFF) {
261 	case LINUX_SEMOP: {
262 
263 		return (kern_semop(td, args->arg1, PTRIN(args->ptr),
264 		    args->arg2, NULL));
265 	}
266 	case LINUX_SEMGET: {
267 		struct linux_semget_args a;
268 
269 		a.key = args->arg1;
270 		a.nsems = args->arg2;
271 		a.semflg = args->arg3;
272 		return (linux_semget(td, &a));
273 	}
274 	case LINUX_SEMCTL: {
275 		struct linux_semctl_args a;
276 		int error;
277 
278 		a.semid = args->arg1;
279 		a.semnum = args->arg2;
280 		a.cmd = args->arg3;
281 		error = copyin(PTRIN(args->ptr), &a.arg, sizeof(a.arg));
282 		if (error)
283 			return (error);
284 		return (linux_semctl(td, &a));
285 	}
286 	case LINUX_SEMTIMEDOP: {
287 		struct linux_semtimedop_args a;
288 
289 		a.semid = args->arg1;
290 		a.tsops = PTRIN(args->ptr);
291 		a.nsops = args->arg2;
292 		a.timeout = PTRIN(args->arg5);
293 		return (linux_semtimedop(td, &a));
294 	}
295 	case LINUX_MSGSND: {
296 		struct linux_msgsnd_args a;
297 
298 		a.msqid = args->arg1;
299 		a.msgp = PTRIN(args->ptr);
300 		a.msgsz = args->arg2;
301 		a.msgflg = args->arg3;
302 		return (linux_msgsnd(td, &a));
303 	}
304 	case LINUX_MSGRCV: {
305 		struct linux_msgrcv_args a;
306 
307 		a.msqid = args->arg1;
308 		a.msgsz = args->arg2;
309 		a.msgflg = args->arg3;
310 		if ((args->what >> 16) == 0) {
311 			struct l_ipc_kludge tmp;
312 			int error;
313 
314 			if (args->ptr == 0)
315 				return (EINVAL);
316 			error = copyin(PTRIN(args->ptr), &tmp, sizeof(tmp));
317 			if (error)
318 				return (error);
319 			a.msgp = PTRIN(tmp.msgp);
320 			a.msgtyp = tmp.msgtyp;
321 		} else {
322 			a.msgp = PTRIN(args->ptr);
323 			a.msgtyp = args->arg5;
324 		}
325 		return (linux_msgrcv(td, &a));
326 	}
327 	case LINUX_MSGGET: {
328 		struct linux_msgget_args a;
329 
330 		a.key = args->arg1;
331 		a.msgflg = args->arg2;
332 		return (linux_msgget(td, &a));
333 	}
334 	case LINUX_MSGCTL: {
335 		struct linux_msgctl_args a;
336 
337 		a.msqid = args->arg1;
338 		a.cmd = args->arg2;
339 		a.buf = PTRIN(args->ptr);
340 		return (linux_msgctl(td, &a));
341 	}
342 	case LINUX_SHMAT: {
343 		struct linux_shmat_args a;
344 		l_uintptr_t addr;
345 		int error;
346 
347 		a.shmid = args->arg1;
348 		a.shmaddr = PTRIN(args->ptr);
349 		a.shmflg = args->arg2;
350 		error = linux_shmat(td, &a);
351 		if (error != 0)
352 			return (error);
353 		addr = td->td_retval[0];
354 		error = copyout(&addr, PTRIN(args->arg3), sizeof(addr));
355 		td->td_retval[0] = 0;
356 		return (error);
357 	}
358 	case LINUX_SHMDT: {
359 		struct linux_shmdt_args a;
360 
361 		a.shmaddr = PTRIN(args->ptr);
362 		return (linux_shmdt(td, &a));
363 	}
364 	case LINUX_SHMGET: {
365 		struct linux_shmget_args a;
366 
367 		a.key = args->arg1;
368 		a.size = args->arg2;
369 		a.shmflg = args->arg3;
370 		return (linux_shmget(td, &a));
371 	}
372 	case LINUX_SHMCTL: {
373 		struct linux_shmctl_args a;
374 
375 		a.shmid = args->arg1;
376 		a.cmd = args->arg2;
377 		a.buf = PTRIN(args->ptr);
378 		return (linux_shmctl(td, &a));
379 	}
380 	default:
381 		break;
382 	}
383 
384 	return (EINVAL);
385 }
386 
387 int
388 linux_old_select(struct thread *td, struct linux_old_select_args *args)
389 {
390 	struct l_old_select_argv linux_args;
391 	struct linux_select_args newsel;
392 	int error;
393 
394 	error = copyin(args->ptr, &linux_args, sizeof(linux_args));
395 	if (error)
396 		return (error);
397 
398 	newsel.nfds = linux_args.nfds;
399 	newsel.readfds = PTRIN(linux_args.readfds);
400 	newsel.writefds = PTRIN(linux_args.writefds);
401 	newsel.exceptfds = PTRIN(linux_args.exceptfds);
402 	newsel.timeout = PTRIN(linux_args.timeout);
403 	return (linux_select(td, &newsel));
404 }
405 
406 int
407 linux_set_cloned_tls(struct thread *td, void *desc)
408 {
409 	struct l_user_desc info;
410 	struct pcb *pcb;
411 	int error;
412 
413 	error = copyin(desc, &info, sizeof(struct l_user_desc));
414 	if (error) {
415 		linux_msg(td, "set_cloned_tls copyin info failed!");
416 	} else {
417 		/* We might copy out the entry_number as GUGS32_SEL. */
418 		info.entry_number = GUGS32_SEL;
419 		error = copyout(&info, desc, sizeof(struct l_user_desc));
420 		if (error)
421 			linux_msg(td, "set_cloned_tls copyout info failed!");
422 
423 		pcb = td->td_pcb;
424 		update_pcb_bases(pcb);
425 		pcb->pcb_gsbase = (register_t)info.base_addr;
426 		td->td_frame->tf_gs = GSEL(GUGS32_SEL, SEL_UPL);
427 	}
428 
429 	return (error);
430 }
431 
432 int
433 linux_set_upcall(struct thread *td, register_t stack)
434 {
435 
436 	if (stack)
437 		td->td_frame->tf_rsp = stack;
438 
439 	/*
440 	 * The newly created Linux thread returns
441 	 * to the user space by the same path that a parent do.
442 	 */
443 	td->td_frame->tf_rax = 0;
444 	return (0);
445 }
446 
447 int
448 linux_mmap2(struct thread *td, struct linux_mmap2_args *args)
449 {
450 
451 	return (linux_mmap_common(td, PTROUT(args->addr), args->len, args->prot,
452 		args->flags, args->fd, (uint64_t)(uint32_t)args->pgoff *
453 		PAGE_SIZE));
454 }
455 
456 int
457 linux_mmap(struct thread *td, struct linux_mmap_args *args)
458 {
459 	int error;
460 	struct l_mmap_argv linux_args;
461 
462 	error = copyin(args->ptr, &linux_args, sizeof(linux_args));
463 	if (error)
464 		return (error);
465 
466 	return (linux_mmap_common(td, linux_args.addr, linux_args.len,
467 	    linux_args.prot, linux_args.flags, linux_args.fd,
468 	    (uint32_t)linux_args.pgoff));
469 }
470 
471 int
472 linux_mprotect(struct thread *td, struct linux_mprotect_args *uap)
473 {
474 
475 	return (linux_mprotect_common(td, PTROUT(uap->addr), uap->len, uap->prot));
476 }
477 
478 int
479 linux_madvise(struct thread *td, struct linux_madvise_args *uap)
480 {
481 
482 	return (linux_madvise_common(td, PTROUT(uap->addr), uap->len, uap->behav));
483 }
484 
485 int
486 linux_iopl(struct thread *td, struct linux_iopl_args *args)
487 {
488 	int error;
489 
490 	if (args->level < 0 || args->level > 3)
491 		return (EINVAL);
492 	if ((error = priv_check(td, PRIV_IO)) != 0)
493 		return (error);
494 	if ((error = securelevel_gt(td->td_ucred, 0)) != 0)
495 		return (error);
496 	td->td_frame->tf_rflags = (td->td_frame->tf_rflags & ~PSL_IOPL) |
497 	    (args->level * (PSL_IOPL / 3));
498 
499 	return (0);
500 }
501 
502 int
503 linux_sigaction(struct thread *td, struct linux_sigaction_args *args)
504 {
505 	l_osigaction_t osa;
506 	l_sigaction_t act, oact;
507 	int error;
508 
509 	if (args->nsa != NULL) {
510 		error = copyin(args->nsa, &osa, sizeof(l_osigaction_t));
511 		if (error)
512 			return (error);
513 		act.lsa_handler = osa.lsa_handler;
514 		act.lsa_flags = osa.lsa_flags;
515 		act.lsa_restorer = osa.lsa_restorer;
516 		LINUX_SIGEMPTYSET(act.lsa_mask);
517 		act.lsa_mask.__mask = osa.lsa_mask;
518 	}
519 
520 	error = linux_do_sigaction(td, args->sig, args->nsa ? &act : NULL,
521 	    args->osa ? &oact : NULL);
522 
523 	if (args->osa != NULL && !error) {
524 		osa.lsa_handler = oact.lsa_handler;
525 		osa.lsa_flags = oact.lsa_flags;
526 		osa.lsa_restorer = oact.lsa_restorer;
527 		osa.lsa_mask = oact.lsa_mask.__mask;
528 		error = copyout(&osa, args->osa, sizeof(l_osigaction_t));
529 	}
530 
531 	return (error);
532 }
533 
534 /*
535  * Linux has two extra args, restart and oldmask.  We don't use these,
536  * but it seems that "restart" is actually a context pointer that
537  * enables the signal to happen with a different register set.
538  */
539 int
540 linux_sigsuspend(struct thread *td, struct linux_sigsuspend_args *args)
541 {
542 	sigset_t sigmask;
543 	l_sigset_t mask;
544 
545 	LINUX_SIGEMPTYSET(mask);
546 	mask.__mask = args->mask;
547 	linux_to_bsd_sigset(&mask, &sigmask);
548 	return (kern_sigsuspend(td, sigmask));
549 }
550 
551 int
552 linux_pause(struct thread *td, struct linux_pause_args *args)
553 {
554 	struct proc *p = td->td_proc;
555 	sigset_t sigmask;
556 
557 	PROC_LOCK(p);
558 	sigmask = td->td_sigmask;
559 	PROC_UNLOCK(p);
560 	return (kern_sigsuspend(td, sigmask));
561 }
562 
563 int
564 linux_gettimeofday(struct thread *td, struct linux_gettimeofday_args *uap)
565 {
566 	struct timeval atv;
567 	l_timeval atv32;
568 	struct timezone rtz;
569 	int error = 0;
570 
571 	if (uap->tp) {
572 		microtime(&atv);
573 		atv32.tv_sec = atv.tv_sec;
574 		atv32.tv_usec = atv.tv_usec;
575 		error = copyout(&atv32, uap->tp, sizeof(atv32));
576 	}
577 	if (error == 0 && uap->tzp != NULL) {
578 		rtz.tz_minuteswest = 0;
579 		rtz.tz_dsttime = 0;
580 		error = copyout(&rtz, uap->tzp, sizeof(rtz));
581 	}
582 	return (error);
583 }
584 
585 int
586 linux_settimeofday(struct thread *td, struct linux_settimeofday_args *uap)
587 {
588 	l_timeval atv32;
589 	struct timeval atv, *tvp;
590 	struct timezone atz, *tzp;
591 	int error;
592 
593 	if (uap->tp) {
594 		error = copyin(uap->tp, &atv32, sizeof(atv32));
595 		if (error)
596 			return (error);
597 		atv.tv_sec = atv32.tv_sec;
598 		atv.tv_usec = atv32.tv_usec;
599 		tvp = &atv;
600 	} else
601 		tvp = NULL;
602 	if (uap->tzp) {
603 		error = copyin(uap->tzp, &atz, sizeof(atz));
604 		if (error)
605 			return (error);
606 		tzp = &atz;
607 	} else
608 		tzp = NULL;
609 	return (kern_settimeofday(td, tvp, tzp));
610 }
611 
612 int
613 linux_getrusage(struct thread *td, struct linux_getrusage_args *uap)
614 {
615 	struct rusage s;
616 	int error;
617 
618 	error = kern_getrusage(td, uap->who, &s);
619 	if (error != 0)
620 		return (error);
621 	if (uap->rusage != NULL)
622 		error = linux_copyout_rusage(&s, uap->rusage);
623 	return (error);
624 }
625 
626 int
627 linux_set_thread_area(struct thread *td,
628     struct linux_set_thread_area_args *args)
629 {
630 	struct l_user_desc info;
631 	struct pcb *pcb;
632 	int error;
633 
634 	error = copyin(args->desc, &info, sizeof(struct l_user_desc));
635 	if (error)
636 		return (error);
637 
638 	/*
639 	 * Semantics of Linux version: every thread in the system has array
640 	 * of three TLS descriptors. 1st is GLIBC TLS, 2nd is WINE, 3rd unknown.
641 	 * This syscall loads one of the selected TLS decriptors with a value
642 	 * and also loads GDT descriptors 6, 7 and 8 with the content of
643 	 * the per-thread descriptors.
644 	 *
645 	 * Semantics of FreeBSD version: I think we can ignore that Linux has
646 	 * three per-thread descriptors and use just the first one.
647 	 * The tls_array[] is used only in [gs]et_thread_area() syscalls and
648 	 * for loading the GDT descriptors. We use just one GDT descriptor
649 	 * for TLS, so we will load just one.
650 	 *
651 	 * XXX: This doesn't work when a user space process tries to use more
652 	 * than one TLS segment. Comment in the Linux source says wine might
653 	 * do this.
654 	 */
655 
656 	/*
657 	 * GLIBC reads current %gs and call set_thread_area() with it.
658 	 * We should let GUDATA_SEL and GUGS32_SEL proceed as well because
659 	 * we use these segments.
660 	 */
661 	switch (info.entry_number) {
662 	case GUGS32_SEL:
663 	case GUDATA_SEL:
664 	case 6:
665 	case -1:
666 		info.entry_number = GUGS32_SEL;
667 		break;
668 	default:
669 		return (EINVAL);
670 	}
671 
672 	/*
673 	 * We have to copy out the GDT entry we use.
674 	 *
675 	 * XXX: What if a user space program does not check the return value
676 	 * and tries to use 6, 7 or 8?
677 	 */
678 	error = copyout(&info, args->desc, sizeof(struct l_user_desc));
679 	if (error)
680 		return (error);
681 
682 	pcb = td->td_pcb;
683 	update_pcb_bases(pcb);
684 	pcb->pcb_gsbase = (register_t)info.base_addr;
685 	update_gdt_gsbase(td, info.base_addr);
686 
687 	return (0);
688 }
689 
690 void
691 bsd_to_linux_regset32(const struct reg32 *b_reg,
692     struct linux_pt_regset32 *l_regset)
693 {
694 
695 	l_regset->ebx = b_reg->r_ebx;
696 	l_regset->ecx = b_reg->r_ecx;
697 	l_regset->edx = b_reg->r_edx;
698 	l_regset->esi = b_reg->r_esi;
699 	l_regset->edi = b_reg->r_edi;
700 	l_regset->ebp = b_reg->r_ebp;
701 	l_regset->eax = b_reg->r_eax;
702 	l_regset->ds = b_reg->r_ds;
703 	l_regset->es = b_reg->r_es;
704 	l_regset->fs = b_reg->r_fs;
705 	l_regset->gs = b_reg->r_gs;
706 	l_regset->orig_eax = b_reg->r_eax;
707 	l_regset->eip = b_reg->r_eip;
708 	l_regset->cs = b_reg->r_cs;
709 	l_regset->eflags = b_reg->r_eflags;
710 	l_regset->esp = b_reg->r_esp;
711 	l_regset->ss = b_reg->r_ss;
712 }
713 
714 int futex_xchgl_nosmap(int oparg, uint32_t *uaddr, int *oldval);
715 int futex_xchgl_smap(int oparg, uint32_t *uaddr, int *oldval);
716 DEFINE_IFUNC(, int, futex_xchgl, (int, uint32_t *, int *))
717 {
718 
719 	return ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 ?
720 	    futex_xchgl_smap : futex_xchgl_nosmap);
721 }
722 
723 int futex_addl_nosmap(int oparg, uint32_t *uaddr, int *oldval);
724 int futex_addl_smap(int oparg, uint32_t *uaddr, int *oldval);
725 DEFINE_IFUNC(, int, futex_addl, (int, uint32_t *, int *))
726 {
727 
728 	return ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 ?
729 	    futex_addl_smap : futex_addl_nosmap);
730 }
731 
732 int futex_orl_nosmap(int oparg, uint32_t *uaddr, int *oldval);
733 int futex_orl_smap(int oparg, uint32_t *uaddr, int *oldval);
734 DEFINE_IFUNC(, int, futex_orl, (int, uint32_t *, int *))
735 {
736 
737 	return ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 ?
738 	    futex_orl_smap : futex_orl_nosmap);
739 }
740 
741 int futex_andl_nosmap(int oparg, uint32_t *uaddr, int *oldval);
742 int futex_andl_smap(int oparg, uint32_t *uaddr, int *oldval);
743 DEFINE_IFUNC(, int, futex_andl, (int, uint32_t *, int *))
744 {
745 
746 	return ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 ?
747 	    futex_andl_smap : futex_andl_nosmap);
748 }
749 
750 int futex_xorl_nosmap(int oparg, uint32_t *uaddr, int *oldval);
751 int futex_xorl_smap(int oparg, uint32_t *uaddr, int *oldval);
752 DEFINE_IFUNC(, int, futex_xorl, (int, uint32_t *, int *))
753 {
754 
755 	return ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 ?
756 	    futex_xorl_smap : futex_xorl_nosmap);
757 }
758