1 /*-
2 * SPDX-License-Identifier: BSD-4-Clause
3 *
4 * Copyright (c) 1982, 1986 The Regents of the University of California.
5 * Copyright (c) 1989, 1990 William Jolitz
6 * Copyright (c) 1994 John Dyson
7 * All rights reserved.
8 *
9 * This code is derived from software contributed to Berkeley by
10 * the Systems Programming Group of the University of Utah Computer
11 * Science Department, and William Jolitz.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. All advertising materials mentioning features or use of this software
22 * must display the following acknowledgement:
23 * This product includes software developed by the University of
24 * California, Berkeley and its contributors.
25 * 4. Neither the name of the University nor the names of its contributors
26 * may be used to endorse or promote products derived from this software
27 * without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 * SUCH DAMAGE.
40 *
41 * from: @(#)vm_machdep.c 7.3 (Berkeley) 5/13/91
42 * Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
43 */
44
45 #include <sys/cdefs.h>
46 __FBSDID("$FreeBSD$");
47
48 #include "opt_isa.h"
49 #include "opt_cpu.h"
50
51 #include <sys/param.h>
52 #include <sys/systm.h>
53 #include <sys/bio.h>
54 #include <sys/buf.h>
55 #include <sys/kernel.h>
56 #include <sys/ktr.h>
57 #include <sys/lock.h>
58 #include <sys/malloc.h>
59 #include <sys/mbuf.h>
60 #include <sys/mutex.h>
61 #include <sys/priv.h>
62 #include <sys/proc.h>
63 #include <sys/procctl.h>
64 #include <sys/smp.h>
65 #include <sys/sysctl.h>
66 #include <sys/sysent.h>
67 #include <sys/unistd.h>
68 #include <sys/vnode.h>
69 #include <sys/vmmeter.h>
70 #include <sys/wait.h>
71
72 #include <machine/cpu.h>
73 #include <machine/md_var.h>
74 #include <machine/pcb.h>
75 #include <machine/smp.h>
76 #include <machine/specialreg.h>
77 #include <machine/tss.h>
78
79 #include <vm/vm.h>
80 #include <vm/vm_extern.h>
81 #include <vm/vm_kern.h>
82 #include <vm/vm_page.h>
83 #include <vm/vm_map.h>
84 #include <vm/vm_param.h>
85
86 _Static_assert(OFFSETOF_MONITORBUF == offsetof(struct pcpu, pc_monitorbuf),
87 "OFFSETOF_MONITORBUF does not correspond with offset of pc_monitorbuf.");
88
89 void
90 set_top_of_stack_td(struct thread *td)
91 {
92 td->td_md.md_stack_base = td->td_kstack +
93 td->td_kstack_pages * PAGE_SIZE;
94 }
95
96 struct savefpu *
97 get_pcb_user_save_td(struct thread *td)
98 {
99 KASSERT(((vm_offset_t)td->td_md.md_usr_fpu_save %
100 XSAVE_AREA_ALIGN) == 0,
101 ("Unaligned pcb_user_save area ptr %p td %p",
102 td->td_md.md_usr_fpu_save, td));
103 return (td->td_md.md_usr_fpu_save);
104 }
105
106 struct pcb *
107 get_pcb_td(struct thread *td)
108 {
109
110 return (&td->td_md.md_pcb);
111 }
112
113 struct savefpu *
114 get_pcb_user_save_pcb(struct pcb *pcb)
115 {
116 struct thread *td;
117
118 td = __containerof(pcb, struct thread, td_md.md_pcb);
119 return (get_pcb_user_save_td(td));
120 }
121
122 void *
123 alloc_fpusave(int flags)
124 {
125 void *res;
126 struct savefpu_ymm *sf;
127
128 res = malloc(cpu_max_ext_state_size, M_DEVBUF, flags);
129 if (use_xsave) {
130 sf = (struct savefpu_ymm *)res;
131 bzero(&sf->sv_xstate.sx_hd, sizeof(sf->sv_xstate.sx_hd));
132 sf->sv_xstate.sx_hd.xstate_bv = xsave_mask;
133 }
134 return (res);
135 }
136
137 /*
138 * Common code shared between cpu_fork() and cpu_copy_thread() for
139 * initializing a thread.
140 */
141 static void
142 copy_thread(struct thread *td1, struct thread *td2)
143 {
144 struct pcb *pcb2;
145
146 pcb2 = td2->td_pcb;
147
148 /* Ensure that td1's pcb is up to date for user threads. */
149 if ((td2->td_pflags & TDP_KTHREAD) == 0) {
150 MPASS(td1 == curthread);
151 fpuexit(td1);
152 update_pcb_bases(td1->td_pcb);
153 }
154
155 /* Copy td1's pcb */
156 bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
157
158 /* Properly initialize pcb_save */
159 pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
160
161 /* Kernel threads start with clean FPU and segment bases. */
162 if ((td2->td_pflags & TDP_KTHREAD) != 0) {
163 pcb2->pcb_fsbase = 0;
164 pcb2->pcb_gsbase = 0;
165 clear_pcb_flags(pcb2, PCB_FPUINITDONE | PCB_USERFPUINITDONE |
166 PCB_KERNFPU | PCB_KERNFPU_THR);
167 } else {
168 MPASS((pcb2->pcb_flags & (PCB_KERNFPU | PCB_KERNFPU_THR)) == 0);
169 bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2),
170 cpu_max_ext_state_size);
171 }
172
173 td2->td_frame = (struct trapframe *)td2->td_md.md_stack_base - 1;
174
175 /*
176 * Set registers for trampoline to user mode. Leave space for the
177 * return address on stack. These are the kernel mode register values.
178 */
179 pcb2->pcb_r12 = (register_t)fork_return; /* fork_trampoline argument */
180 pcb2->pcb_rbp = 0;
181 pcb2->pcb_rsp = (register_t)td2->td_frame - sizeof(void *);
182 pcb2->pcb_rbx = (register_t)td2; /* fork_trampoline argument */
183 pcb2->pcb_rip = (register_t)fork_trampoline;
184 /*-
185 * pcb2->pcb_dr*: cloned above.
186 * pcb2->pcb_savefpu: cloned above.
187 * pcb2->pcb_flags: cloned above.
188 * pcb2->pcb_onfault: cloned above (always NULL here?).
189 * pcb2->pcb_[fg]sbase: cloned above
190 */
191
192 pcb2->pcb_tssp = NULL;
193
194 /* Setup to release spin count in fork_exit(). */
195 td2->td_md.md_spinlock_count = 1;
196 td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
197 pmap_thread_init_invl_gen(td2);
198
199 /*
200 * Copy the trap frame for the return to user mode as if from a syscall.
201 * This copies most of the user mode register values. Some of these
202 * registers are rewritten by cpu_set_upcall() and linux_set_upcall().
203 */
204 if ((td1->td_proc->p_flag & P_KPROC) == 0) {
205 bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));
206
207 /*
208 * If the current thread has the trap bit set (i.e. a debugger
209 * had single stepped the process to the system call), we need
210 * to clear the trap flag from the new frame. Otherwise, the new
211 * thread will receive a (likely unexpected) SIGTRAP when it
212 * executes the first instruction after returning to userland.
213 */
214 td2->td_frame->tf_rflags &= ~PSL_T;
215 }
216 }
217
218 /*
219 * Finish a fork operation, with process p2 nearly set up.
220 * Copy and update the pcb, set up the stack so that the child
221 * ready to run and return to user mode.
222 */
223 void
224 cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
225 {
226 struct proc *p1;
227 struct pcb *pcb2;
228 struct mdproc *mdp1, *mdp2;
229 struct proc_ldt *pldt;
230
231 p1 = td1->td_proc;
232 if ((flags & RFPROC) == 0) {
233 if ((flags & RFMEM) == 0) {
234 /* unshare user LDT */
235 mdp1 = &p1->p_md;
236 mtx_lock(&dt_lock);
237 if ((pldt = mdp1->md_ldt) != NULL &&
238 pldt->ldt_refcnt > 1 &&
239 user_ldt_alloc(p1, 1) == NULL)
240 panic("could not copy LDT");
241 mtx_unlock(&dt_lock);
242 }
243 return;
244 }
245
246 /* Point the stack and pcb to the actual location */
247 set_top_of_stack_td(td2);
248 td2->td_pcb = pcb2 = get_pcb_td(td2);
249
250 copy_thread(td1, td2);
251
252 /* Reset debug registers in the new process */
253 x86_clear_dbregs(pcb2);
254
255 /* Point mdproc and then copy over p1's contents */
256 mdp2 = &p2->p_md;
257 bcopy(&p1->p_md, mdp2, sizeof(*mdp2));
258
259 /* Set child return values. */
260 p2->p_sysent->sv_set_fork_retval(td2);
261
262 /* As on i386, do not copy io permission bitmap. */
263 pcb2->pcb_tssp = NULL;
264
265 /* New segment registers. */
266 set_pcb_flags_raw(pcb2, PCB_FULL_IRET);
267
268 /* Copy the LDT, if necessary. */
269 mdp1 = &td1->td_proc->p_md;
270 mdp2 = &p2->p_md;
271 if (mdp1->md_ldt == NULL) {
272 mdp2->md_ldt = NULL;
273 return;
274 }
275 mtx_lock(&dt_lock);
276 if (mdp1->md_ldt != NULL) {
277 if (flags & RFMEM) {
278 mdp1->md_ldt->ldt_refcnt++;
279 mdp2->md_ldt = mdp1->md_ldt;
280 bcopy(&mdp1->md_ldt_sd, &mdp2->md_ldt_sd, sizeof(struct
281 system_segment_descriptor));
282 } else {
283 mdp2->md_ldt = NULL;
284 mdp2->md_ldt = user_ldt_alloc(p2, 0);
285 if (mdp2->md_ldt == NULL)
286 panic("could not copy LDT");
287 amd64_set_ldt_data(td2, 0, max_ldt_segment,
288 (struct user_segment_descriptor *)
289 mdp1->md_ldt->ldt_base);
290 }
291 } else
292 mdp2->md_ldt = NULL;
293 mtx_unlock(&dt_lock);
294
295 /*
296 * Now, cpu_switch() can schedule the new process.
297 * pcb_rsp is loaded pointing to the cpu_switch() stack frame
298 * containing the return address when exiting cpu_switch.
299 * This will normally be to fork_trampoline(), which will have
300 * %rbx loaded with the new proc's pointer. fork_trampoline()
301 * will set up a stack to call fork_return(p, frame); to complete
302 * the return to user-mode.
303 */
304 }
305
306 void
307 x86_set_fork_retval(struct thread *td)
308 {
309 struct trapframe *frame = td->td_frame;
310
311 frame->tf_rax = 0; /* Child returns zero */
312 frame->tf_rflags &= ~PSL_C; /* success */
313 frame->tf_rdx = 1; /* System V emulation */
314 }
315
316 /*
317 * Intercept the return address from a freshly forked process that has NOT
318 * been scheduled yet.
319 *
320 * This is needed to make kernel threads stay in kernel mode.
321 */
322 void
323 cpu_fork_kthread_handler(struct thread *td, void (*func)(void *), void *arg)
324 {
325 /*
326 * Note that the trap frame follows the args, so the function
327 * is really called like this: func(arg, frame);
328 */
329 td->td_pcb->pcb_r12 = (long) func; /* function */
330 td->td_pcb->pcb_rbx = (long) arg; /* first arg */
331 }
332
333 void
334 cpu_exit(struct thread *td)
335 {
336
337 /*
338 * If this process has a custom LDT, release it.
339 */
340 if (td->td_proc->p_md.md_ldt != NULL)
341 user_ldt_free(td);
342 }
343
344 void
345 cpu_thread_exit(struct thread *td)
346 {
347 struct pcb *pcb;
348
349 critical_enter();
350 if (td == PCPU_GET(fpcurthread))
351 fpudrop();
352 critical_exit();
353
354 pcb = td->td_pcb;
355
356 /* Disable any hardware breakpoints. */
357 if (pcb->pcb_flags & PCB_DBREGS) {
358 reset_dbregs();
359 clear_pcb_flags(pcb, PCB_DBREGS);
360 }
361 }
362
363 void
364 cpu_thread_clean(struct thread *td)
365 {
366 struct pcb *pcb;
367
368 pcb = td->td_pcb;
369
370 /*
371 * Clean TSS/iomap
372 */
373 if (pcb->pcb_tssp != NULL) {
374 pmap_pti_remove_kva((vm_offset_t)pcb->pcb_tssp,
375 (vm_offset_t)pcb->pcb_tssp + ctob(IOPAGES + 1));
376 kmem_free(pcb->pcb_tssp, ctob(IOPAGES + 1));
377 pcb->pcb_tssp = NULL;
378 }
379 }
380
381 void
382 cpu_thread_swapin(struct thread *td)
383 {
384 }
385
386 void
387 cpu_thread_swapout(struct thread *td)
388 {
389 }
390
391 void
392 cpu_thread_alloc(struct thread *td)
393 {
394 struct pcb *pcb;
395 struct xstate_hdr *xhdr;
396
397 set_top_of_stack_td(td);
398 td->td_pcb = pcb = get_pcb_td(td);
399 td->td_frame = (struct trapframe *)td->td_md.md_stack_base - 1;
400 td->td_md.md_usr_fpu_save = fpu_save_area_alloc();
401 pcb->pcb_save = get_pcb_user_save_pcb(pcb);
402 if (use_xsave) {
403 xhdr = (struct xstate_hdr *)(pcb->pcb_save + 1);
404 bzero(xhdr, sizeof(*xhdr));
405 xhdr->xstate_bv = xsave_mask;
406 }
407 }
408
409 void
410 cpu_thread_free(struct thread *td)
411 {
412 cpu_thread_clean(td);
413
414 fpu_save_area_free(td->td_md.md_usr_fpu_save);
415 td->td_md.md_usr_fpu_save = NULL;
416 }
417
418 bool
419 cpu_exec_vmspace_reuse(struct proc *p, vm_map_t map)
420 {
421
422 return (((curproc->p_md.md_flags & P_MD_KPTI) != 0) ==
423 (vm_map_pmap(map)->pm_ucr3 != PMAP_NO_CR3));
424 }
425
426 static void
427 cpu_procctl_kpti_ctl(struct proc *p, int val)
428 {
429
430 if (pti && val == PROC_KPTI_CTL_ENABLE_ON_EXEC)
431 p->p_md.md_flags |= P_MD_KPTI;
432 if (val == PROC_KPTI_CTL_DISABLE_ON_EXEC)
433 p->p_md.md_flags &= ~P_MD_KPTI;
434 }
435
436 static void
437 cpu_procctl_kpti_status(struct proc *p, int *val)
438 {
439 *val = (p->p_md.md_flags & P_MD_KPTI) != 0 ?
440 PROC_KPTI_CTL_ENABLE_ON_EXEC:
441 PROC_KPTI_CTL_DISABLE_ON_EXEC;
442 if (vmspace_pmap(p->p_vmspace)->pm_ucr3 != PMAP_NO_CR3)
443 *val |= PROC_KPTI_STATUS_ACTIVE;
444 }
445
446 static int
447 cpu_procctl_la_ctl(struct proc *p, int val)
448 {
449 int error;
450
451 error = 0;
452 switch (val) {
453 case PROC_LA_CTL_LA48_ON_EXEC:
454 p->p_md.md_flags |= P_MD_LA48;
455 p->p_md.md_flags &= ~P_MD_LA57;
456 break;
457 case PROC_LA_CTL_LA57_ON_EXEC:
458 if (la57) {
459 p->p_md.md_flags &= ~P_MD_LA48;
460 p->p_md.md_flags |= P_MD_LA57;
461 } else {
462 error = ENOTSUP;
463 }
464 break;
465 case PROC_LA_CTL_DEFAULT_ON_EXEC:
466 p->p_md.md_flags &= ~(P_MD_LA48 | P_MD_LA57);
467 break;
468 }
469 return (error);
470 }
471
472 static void
473 cpu_procctl_la_status(struct proc *p, int *val)
474 {
475 int res;
476
477 if ((p->p_md.md_flags & P_MD_LA48) != 0)
478 res = PROC_LA_CTL_LA48_ON_EXEC;
479 else if ((p->p_md.md_flags & P_MD_LA57) != 0)
480 res = PROC_LA_CTL_LA57_ON_EXEC;
481 else
482 res = PROC_LA_CTL_DEFAULT_ON_EXEC;
483 if (p->p_sysent->sv_maxuser == VM_MAXUSER_ADDRESS_LA48)
484 res |= PROC_LA_STATUS_LA48;
485 else
486 res |= PROC_LA_STATUS_LA57;
487 *val = res;
488 }
489
490 int
491 cpu_procctl(struct thread *td, int idtype, id_t id, int com, void *data)
492 {
493 struct proc *p;
494 int error, val;
495
496 switch (com) {
497 case PROC_KPTI_CTL:
498 case PROC_KPTI_STATUS:
499 case PROC_LA_CTL:
500 case PROC_LA_STATUS:
501 if (idtype != P_PID) {
502 error = EINVAL;
503 break;
504 }
505 if (com == PROC_KPTI_CTL) {
506 /* sad but true and not a joke */
507 error = priv_check(td, PRIV_IO);
508 if (error != 0)
509 break;
510 }
511 if (com == PROC_KPTI_CTL || com == PROC_LA_CTL) {
512 error = copyin(data, &val, sizeof(val));
513 if (error != 0)
514 break;
515 }
516 if (com == PROC_KPTI_CTL &&
517 val != PROC_KPTI_CTL_ENABLE_ON_EXEC &&
518 val != PROC_KPTI_CTL_DISABLE_ON_EXEC) {
519 error = EINVAL;
520 break;
521 }
522 if (com == PROC_LA_CTL &&
523 val != PROC_LA_CTL_LA48_ON_EXEC &&
524 val != PROC_LA_CTL_LA57_ON_EXEC &&
525 val != PROC_LA_CTL_DEFAULT_ON_EXEC) {
526 error = EINVAL;
527 break;
528 }
529 error = pget(id, PGET_CANSEE | PGET_NOTWEXIT | PGET_NOTID, &p);
530 if (error != 0)
531 break;
532 switch (com) {
533 case PROC_KPTI_CTL:
534 cpu_procctl_kpti_ctl(p, val);
535 break;
536 case PROC_KPTI_STATUS:
537 cpu_procctl_kpti_status(p, &val);
538 break;
539 case PROC_LA_CTL:
540 error = cpu_procctl_la_ctl(p, val);
541 break;
542 case PROC_LA_STATUS:
543 cpu_procctl_la_status(p, &val);
544 break;
545 }
546 PROC_UNLOCK(p);
547 if (com == PROC_KPTI_STATUS || com == PROC_LA_STATUS)
548 error = copyout(&val, data, sizeof(val));
549 break;
550 default:
551 error = EINVAL;
552 break;
553 }
554 return (error);
555 }
556
557 void
558 cpu_set_syscall_retval(struct thread *td, int error)
559 {
560 struct trapframe *frame;
561
562 frame = td->td_frame;
563 if (__predict_true(error == 0)) {
564 frame->tf_rax = td->td_retval[0];
565 frame->tf_rdx = td->td_retval[1];
566 frame->tf_rflags &= ~PSL_C;
567 return;
568 }
569
570 switch (error) {
571 case ERESTART:
572 /*
573 * Reconstruct pc, we know that 'syscall' is 2 bytes,
574 * lcall $X,y is 7 bytes, int 0x80 is 2 bytes.
575 * We saved this in tf_err.
576 * %r10 (which was holding the value of %rcx) is restored
577 * for the next iteration.
578 * %r10 restore is only required for freebsd/amd64 processes,
579 * but shall be innocent for any ia32 ABI.
580 *
581 * Require full context restore to get the arguments
582 * in the registers reloaded at return to usermode.
583 */
584 frame->tf_rip -= frame->tf_err;
585 frame->tf_r10 = frame->tf_rcx;
586 set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
587 break;
588
589 case EJUSTRETURN:
590 break;
591
592 default:
593 frame->tf_rax = error;
594 frame->tf_rflags |= PSL_C;
595 break;
596 }
597 }
598
599 /*
600 * Initialize machine state, mostly pcb and trap frame for a new
601 * thread, about to return to userspace. Put enough state in the new
602 * thread's PCB to get it to go back to the fork_return(), which
603 * finalizes the thread state and handles peculiarities of the first
604 * return to userspace for the new thread.
605 */
606 void
607 cpu_copy_thread(struct thread *td, struct thread *td0)
608 {
609 copy_thread(td0, td);
610
611 set_pcb_flags_raw(td->td_pcb, PCB_FULL_IRET);
612 }
613
614 /*
615 * Set that machine state for performing an upcall that starts
616 * the entry function with the given argument.
617 */
618 void
619 cpu_set_upcall(struct thread *td, void (*entry)(void *), void *arg,
620 stack_t *stack)
621 {
622
623 /*
624 * Do any extra cleaning that needs to be done.
625 * The thread may have optional components
626 * that are not present in a fresh thread.
627 * This may be a recycled thread so make it look
628 * as though it's newly allocated.
629 */
630 cpu_thread_clean(td);
631
632 #ifdef COMPAT_FREEBSD32
633 if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
634 /*
635 * Set the trap frame to point at the beginning of the entry
636 * function.
637 */
638 td->td_frame->tf_rbp = 0;
639 td->td_frame->tf_rsp =
640 (((uintptr_t)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4;
641 td->td_frame->tf_rip = (uintptr_t)entry;
642
643 /* Return address sentinel value to stop stack unwinding. */
644 suword32((void *)td->td_frame->tf_rsp, 0);
645
646 /* Pass the argument to the entry point. */
647 suword32((void *)(td->td_frame->tf_rsp + sizeof(int32_t)),
648 (uint32_t)(uintptr_t)arg);
649
650 return;
651 }
652 #endif
653
654 /*
655 * Set the trap frame to point at the beginning of the uts
656 * function.
657 */
658 td->td_frame->tf_rbp = 0;
659 td->td_frame->tf_rsp =
660 ((register_t)stack->ss_sp + stack->ss_size) & ~0x0f;
661 td->td_frame->tf_rsp -= 8;
662 td->td_frame->tf_rip = (register_t)entry;
663 td->td_frame->tf_ds = _udatasel;
664 td->td_frame->tf_es = _udatasel;
665 td->td_frame->tf_fs = _ufssel;
666 td->td_frame->tf_gs = _ugssel;
667 td->td_frame->tf_flags = TF_HASSEGS;
668
669 /* Return address sentinel value to stop stack unwinding. */
670 suword((void *)td->td_frame->tf_rsp, 0);
671
672 /* Pass the argument to the entry point. */
673 td->td_frame->tf_rdi = (register_t)arg;
674 }
675
676 int
677 cpu_set_user_tls(struct thread *td, void *tls_base)
678 {
679 struct pcb *pcb;
680
681 if ((u_int64_t)tls_base >= VM_MAXUSER_ADDRESS)
682 return (EINVAL);
683
684 pcb = td->td_pcb;
685 set_pcb_flags(pcb, PCB_FULL_IRET);
686 #ifdef COMPAT_FREEBSD32
687 if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
688 pcb->pcb_gsbase = (register_t)tls_base;
689 return (0);
690 }
691 #endif
692 pcb->pcb_fsbase = (register_t)tls_base;
693 return (0);
694 }
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