1 /*-
2 * SPDX-License-Identifier: (BSD-3-Clause AND MIT-CMU)
3 *
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * The Mach Operating System project at Carnegie-Mellon University.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
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. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 *
35 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
36 * All rights reserved.
37 *
38 * Permission to use, copy, modify and distribute this software and
39 * its documentation is hereby granted, provided that both the copyright
40 * notice and this permission notice appear in all copies of the
41 * software, derivative works or modified versions, and any portions
42 * thereof, and that both notices appear in supporting documentation.
43 *
44 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
45 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
46 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
47 *
48 * Carnegie Mellon requests users of this software to return to
49 *
50 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
51 * School of Computer Science
52 * Carnegie Mellon University
53 * Pittsburgh PA 15213-3890
54 *
55 * any improvements or extensions that they make and grant Carnegie the
56 * rights to redistribute these changes.
57 */
58
59 #include "opt_vm.h"
60 #include "opt_kstack_pages.h"
61 #include "opt_kstack_max_pages.h"
62 #include "opt_kstack_usage_prof.h"
63
64 #include <sys/param.h>
65 #include <sys/systm.h>
66 #include <sys/asan.h>
67 #include <sys/domainset.h>
68 #include <sys/limits.h>
69 #include <sys/lock.h>
70 #include <sys/malloc.h>
71 #include <sys/msan.h>
72 #include <sys/mutex.h>
73 #include <sys/proc.h>
74 #include <sys/racct.h>
75 #include <sys/refcount.h>
76 #include <sys/resourcevar.h>
77 #include <sys/rwlock.h>
78 #include <sys/sched.h>
79 #include <sys/sf_buf.h>
80 #include <sys/shm.h>
81 #include <sys/smp.h>
82 #include <sys/vmmeter.h>
83 #include <sys/vmem.h>
84 #include <sys/sx.h>
85 #include <sys/sysctl.h>
86 #include <sys/kernel.h>
87 #include <sys/ktr.h>
88 #include <sys/unistd.h>
89
90 #include <vm/uma.h>
91 #include <vm/vm.h>
92 #include <vm/vm_param.h>
93 #include <vm/pmap.h>
94 #include <vm/vm_domainset.h>
95 #include <vm/vm_map.h>
96 #include <vm/vm_page.h>
97 #include <vm/vm_pageout.h>
98 #include <vm/vm_pagequeue.h>
99 #include <vm/vm_object.h>
100 #include <vm/vm_kern.h>
101 #include <vm/vm_radix.h>
102 #include <vm/vm_extern.h>
103 #include <vm/vm_pager.h>
104 #include <vm/vm_phys.h>
105
106 #include <machine/cpu.h>
107
108 #if VM_NRESERVLEVEL > 1
109 #define KVA_KSTACK_QUANTUM_SHIFT (VM_LEVEL_1_ORDER + VM_LEVEL_0_ORDER + \
110 PAGE_SHIFT)
111 #elif VM_NRESERVLEVEL > 0
112 #define KVA_KSTACK_QUANTUM_SHIFT (VM_LEVEL_0_ORDER + PAGE_SHIFT)
113 #else
114 #define KVA_KSTACK_QUANTUM_SHIFT (8 + PAGE_SHIFT)
115 #endif
116 #define KVA_KSTACK_QUANTUM (1ul << KVA_KSTACK_QUANTUM_SHIFT)
117
118 /*
119 * MPSAFE
120 *
121 * WARNING! This code calls vm_map_check_protection() which only checks
122 * the associated vm_map_entry range. It does not determine whether the
123 * contents of the memory is actually readable or writable. In most cases
124 * just checking the vm_map_entry is sufficient within the kernel's address
125 * space.
126 */
127 bool
kernacc(void * addr,int len,int rw)128 kernacc(void *addr, int len, int rw)
129 {
130 boolean_t rv;
131 vm_offset_t saddr, eaddr;
132 vm_prot_t prot;
133
134 KASSERT((rw & ~VM_PROT_ALL) == 0,
135 ("illegal ``rw'' argument to kernacc (%x)\n", rw));
136
137 if ((vm_offset_t)addr + len > vm_map_max(kernel_map) ||
138 (vm_offset_t)addr + len < (vm_offset_t)addr)
139 return (false);
140
141 prot = rw;
142 saddr = trunc_page((vm_offset_t)addr);
143 eaddr = round_page((vm_offset_t)addr + len);
144 vm_map_lock_read(kernel_map);
145 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot);
146 vm_map_unlock_read(kernel_map);
147 return (rv == TRUE);
148 }
149
150 /*
151 * MPSAFE
152 *
153 * WARNING! This code calls vm_map_check_protection() which only checks
154 * the associated vm_map_entry range. It does not determine whether the
155 * contents of the memory is actually readable or writable. vmapbuf(),
156 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be
157 * used in conjunction with this call.
158 */
159 bool
useracc(void * addr,int len,int rw)160 useracc(void *addr, int len, int rw)
161 {
162 boolean_t rv;
163 vm_prot_t prot;
164 vm_map_t map;
165
166 KASSERT((rw & ~VM_PROT_ALL) == 0,
167 ("illegal ``rw'' argument to useracc (%x)\n", rw));
168 prot = rw;
169 map = &curproc->p_vmspace->vm_map;
170 if ((vm_offset_t)addr + len > vm_map_max(map) ||
171 (vm_offset_t)addr + len < (vm_offset_t)addr) {
172 return (false);
173 }
174 vm_map_lock_read(map);
175 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr),
176 round_page((vm_offset_t)addr + len), prot);
177 vm_map_unlock_read(map);
178 return (rv == TRUE);
179 }
180
181 int
vslock(void * addr,size_t len)182 vslock(void *addr, size_t len)
183 {
184 vm_offset_t end, last, start;
185 vm_size_t npages;
186 int error;
187
188 last = (vm_offset_t)addr + len;
189 start = trunc_page((vm_offset_t)addr);
190 end = round_page(last);
191 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr)
192 return (EINVAL);
193 npages = atop(end - start);
194 if (npages > vm_page_max_user_wired)
195 return (ENOMEM);
196 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end,
197 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
198 if (error == KERN_SUCCESS) {
199 curthread->td_vslock_sz += len;
200 return (0);
201 }
202
203 /*
204 * Return EFAULT on error to match copy{in,out}() behaviour
205 * rather than returning ENOMEM like mlock() would.
206 */
207 return (EFAULT);
208 }
209
210 void
vsunlock(void * addr,size_t len)211 vsunlock(void *addr, size_t len)
212 {
213
214 /* Rely on the parameter sanity checks performed by vslock(). */
215 MPASS(curthread->td_vslock_sz >= len);
216 curthread->td_vslock_sz -= len;
217 (void)vm_map_unwire(&curproc->p_vmspace->vm_map,
218 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len),
219 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
220 }
221
222 /*
223 * Pin the page contained within the given object at the given offset. If the
224 * page is not resident, allocate and load it using the given object's pager.
225 * Return the pinned page if successful; otherwise, return NULL.
226 */
227 static vm_page_t
vm_imgact_hold_page(vm_object_t object,vm_ooffset_t offset)228 vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset)
229 {
230 vm_page_t m;
231 vm_pindex_t pindex;
232
233 pindex = OFF_TO_IDX(offset);
234 (void)vm_page_grab_valid_unlocked(&m, object, pindex,
235 VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED);
236 return (m);
237 }
238
239 /*
240 * Return a CPU private mapping to the page at the given offset within the
241 * given object. The page is pinned before it is mapped.
242 */
243 struct sf_buf *
vm_imgact_map_page(vm_object_t object,vm_ooffset_t offset)244 vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset)
245 {
246 vm_page_t m;
247
248 m = vm_imgact_hold_page(object, offset);
249 if (m == NULL)
250 return (NULL);
251 sched_pin();
252 return (sf_buf_alloc(m, SFB_CPUPRIVATE));
253 }
254
255 /*
256 * Destroy the given CPU private mapping and unpin the page that it mapped.
257 */
258 void
vm_imgact_unmap_page(struct sf_buf * sf)259 vm_imgact_unmap_page(struct sf_buf *sf)
260 {
261 vm_page_t m;
262
263 m = sf_buf_page(sf);
264 sf_buf_free(sf);
265 sched_unpin();
266 vm_page_unwire(m, PQ_ACTIVE);
267 }
268
269 void
vm_sync_icache(vm_map_t map,vm_offset_t va,vm_offset_t sz)270 vm_sync_icache(vm_map_t map, vm_offset_t va, vm_offset_t sz)
271 {
272
273 pmap_sync_icache(map->pmap, va, sz);
274 }
275
276 static vm_object_t kstack_object;
277 static vm_object_t kstack_alt_object;
278 static uma_zone_t kstack_cache;
279 static int kstack_cache_size;
280 static vmem_t *vmd_kstack_arena[MAXMEMDOM];
281
282 static vm_pindex_t vm_kstack_pindex(vm_offset_t ks, int npages);
283 static vm_object_t vm_thread_kstack_size_to_obj(int npages);
284 static int vm_thread_stack_back(vm_offset_t kaddr, vm_page_t ma[], int npages,
285 int req_class, int domain);
286
287 static int
sysctl_kstack_cache_size(SYSCTL_HANDLER_ARGS)288 sysctl_kstack_cache_size(SYSCTL_HANDLER_ARGS)
289 {
290 int error, oldsize;
291
292 oldsize = kstack_cache_size;
293 error = sysctl_handle_int(oidp, arg1, arg2, req);
294 if (error == 0 && req->newptr && oldsize != kstack_cache_size)
295 uma_zone_set_maxcache(kstack_cache, kstack_cache_size);
296 return (error);
297 }
298 SYSCTL_PROC(_vm, OID_AUTO, kstack_cache_size,
299 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &kstack_cache_size, 0,
300 sysctl_kstack_cache_size, "IU", "Maximum number of cached kernel stacks");
301
302 /*
303 * Allocate a virtual address range from a domain kstack arena, following
304 * the specified NUMA policy.
305 */
306 static vm_offset_t
vm_thread_alloc_kstack_kva(vm_size_t size,int domain)307 vm_thread_alloc_kstack_kva(vm_size_t size, int domain)
308 {
309 #ifndef __ILP32__
310 int rv;
311 vmem_t *arena;
312 vm_offset_t addr = 0;
313
314 size = round_page(size);
315 /* Allocate from the kernel arena for non-standard kstack sizes. */
316 if (size != ptoa(kstack_pages + KSTACK_GUARD_PAGES)) {
317 arena = vm_dom[domain].vmd_kernel_arena;
318 } else {
319 arena = vmd_kstack_arena[domain];
320 }
321 rv = vmem_alloc(arena, size, M_BESTFIT | M_NOWAIT, &addr);
322 if (rv == ENOMEM)
323 return (0);
324 KASSERT(atop(addr - VM_MIN_KERNEL_ADDRESS) %
325 (kstack_pages + KSTACK_GUARD_PAGES) == 0,
326 ("%s: allocated kstack KVA not aligned to multiple of kstack size",
327 __func__));
328
329 return (addr);
330 #else
331 return (kva_alloc(size));
332 #endif
333 }
334
335 /*
336 * Release a region of kernel virtual memory
337 * allocated from the kstack arena.
338 */
339 static __noinline void
vm_thread_free_kstack_kva(vm_offset_t addr,vm_size_t size,int domain)340 vm_thread_free_kstack_kva(vm_offset_t addr, vm_size_t size, int domain)
341 {
342 vmem_t *arena;
343
344 size = round_page(size);
345 #ifdef __ILP32__
346 arena = kernel_arena;
347 #else
348 arena = vmd_kstack_arena[domain];
349 if (size != ptoa(kstack_pages + KSTACK_GUARD_PAGES)) {
350 arena = vm_dom[domain].vmd_kernel_arena;
351 }
352 #endif
353 vmem_free(arena, addr, size);
354 }
355
356 static vmem_size_t
vm_thread_kstack_import_quantum(void)357 vm_thread_kstack_import_quantum(void)
358 {
359 #ifndef __ILP32__
360 /*
361 * The kstack_quantum is larger than KVA_QUANTUM to account
362 * for holes induced by guard pages.
363 */
364 return (KVA_KSTACK_QUANTUM * (kstack_pages + KSTACK_GUARD_PAGES));
365 #else
366 return (KVA_KSTACK_QUANTUM);
367 #endif
368 }
369
370 /*
371 * Import KVA from a parent arena into the kstack arena. Imports must be
372 * a multiple of kernel stack pages + guard pages in size.
373 *
374 * Kstack VA allocations need to be aligned so that the linear KVA pindex
375 * is divisible by the total number of kstack VA pages. This is necessary to
376 * make vm_kstack_pindex work properly.
377 *
378 * We import a multiple of KVA_KSTACK_QUANTUM-sized region from the parent
379 * arena. The actual size used by the kstack arena is one kstack smaller to
380 * allow for the necessary alignment adjustments to be made.
381 */
382 static int
vm_thread_kstack_arena_import(void * arena,vmem_size_t size,int flags,vmem_addr_t * addrp)383 vm_thread_kstack_arena_import(void *arena, vmem_size_t size, int flags,
384 vmem_addr_t *addrp)
385 {
386 int error, rem;
387 size_t kpages = kstack_pages + KSTACK_GUARD_PAGES;
388
389 KASSERT(atop(size) % kpages == 0,
390 ("%s: Size %jd is not a multiple of kstack pages (%d)", __func__,
391 (intmax_t)size, (int)kpages));
392
393 error = vmem_xalloc(arena, vm_thread_kstack_import_quantum(),
394 KVA_KSTACK_QUANTUM, 0, 0, VMEM_ADDR_MIN, VMEM_ADDR_MAX, flags,
395 addrp);
396 if (error) {
397 return (error);
398 }
399
400 rem = atop(*addrp - VM_MIN_KERNEL_ADDRESS) % kpages;
401 if (rem != 0) {
402 /* Bump addr to next aligned address */
403 *addrp = *addrp + (kpages - rem) * PAGE_SIZE;
404 }
405
406 return (0);
407 }
408
409 /*
410 * Release KVA from a parent arena into the kstack arena. Released imports must
411 * be a multiple of kernel stack pages + guard pages in size.
412 */
413 static void
vm_thread_kstack_arena_release(void * arena,vmem_addr_t addr,vmem_size_t size)414 vm_thread_kstack_arena_release(void *arena, vmem_addr_t addr, vmem_size_t size)
415 {
416 int rem;
417 size_t kpages __diagused = kstack_pages + KSTACK_GUARD_PAGES;
418
419 KASSERT(size % kpages == 0,
420 ("%s: Size %jd is not a multiple of kstack pages (%d)", __func__,
421 (intmax_t)size, (int)kpages));
422
423 KASSERT((addr - VM_MIN_KERNEL_ADDRESS) % kpages == 0,
424 ("%s: Address %p is not properly aligned (%p)", __func__,
425 (void *)addr, (void *)VM_MIN_KERNEL_ADDRESS));
426 /*
427 * If the address is not KVA_KSTACK_QUANTUM-aligned we have to decrement
428 * it to account for the shift in kva_import_kstack.
429 */
430 rem = addr % KVA_KSTACK_QUANTUM;
431 if (rem) {
432 KASSERT(rem <= ptoa(kpages),
433 ("%s: rem > kpages (%d), (%d)", __func__, rem,
434 (int)kpages));
435 addr -= rem;
436 }
437 vmem_xfree(arena, addr, vm_thread_kstack_import_quantum());
438 }
439
440 /*
441 * Create the kernel stack for a new thread.
442 */
443 static vm_offset_t
vm_thread_stack_create(struct domainset * ds,int pages)444 vm_thread_stack_create(struct domainset *ds, int pages)
445 {
446 vm_page_t ma[KSTACK_MAX_PAGES];
447 struct vm_domainset_iter di;
448 int req = VM_ALLOC_NORMAL;
449 vm_object_t obj;
450 vm_offset_t ks;
451 int domain, i;
452
453 obj = vm_thread_kstack_size_to_obj(pages);
454 if (vm_ndomains > 1)
455 obj->domain.dr_policy = ds;
456 vm_domainset_iter_page_init(&di, obj, 0, &domain, &req, NULL);
457 do {
458 /*
459 * Get a kernel virtual address for this thread's kstack.
460 */
461 ks = vm_thread_alloc_kstack_kva(ptoa(pages + KSTACK_GUARD_PAGES),
462 domain);
463 if (ks == 0)
464 continue;
465 ks += ptoa(KSTACK_GUARD_PAGES);
466
467 /*
468 * Allocate physical pages to back the stack.
469 */
470 if (vm_thread_stack_back(ks, ma, pages, req, domain) != 0) {
471 vm_thread_free_kstack_kva(ks - ptoa(KSTACK_GUARD_PAGES),
472 ptoa(pages + KSTACK_GUARD_PAGES), domain);
473 continue;
474 }
475 if (KSTACK_GUARD_PAGES != 0) {
476 pmap_qremove(ks - ptoa(KSTACK_GUARD_PAGES),
477 KSTACK_GUARD_PAGES);
478 }
479 for (i = 0; i < pages; i++)
480 vm_page_valid(ma[i]);
481 pmap_qenter(ks, ma, pages);
482 return (ks);
483 } while (vm_domainset_iter_page(&di, obj, &domain, NULL) == 0);
484
485 return (0);
486 }
487
488 static __noinline void
vm_thread_stack_dispose(vm_offset_t ks,int pages)489 vm_thread_stack_dispose(vm_offset_t ks, int pages)
490 {
491 vm_page_t m;
492 vm_pindex_t pindex;
493 int i, domain;
494 vm_object_t obj = vm_thread_kstack_size_to_obj(pages);
495
496 pindex = vm_kstack_pindex(ks, pages);
497 domain = vm_phys_domain(vtophys(ks));
498 pmap_qremove(ks, pages);
499 VM_OBJECT_WLOCK(obj);
500 for (i = 0; i < pages; i++) {
501 m = vm_page_lookup(obj, pindex + i);
502 if (m == NULL)
503 panic("%s: kstack already missing?", __func__);
504 KASSERT(vm_page_domain(m) == domain,
505 ("%s: page %p domain mismatch, expected %d got %d",
506 __func__, m, domain, vm_page_domain(m)));
507 vm_page_xbusy_claim(m);
508 vm_page_unwire_noq(m);
509 vm_page_free(m);
510 }
511 VM_OBJECT_WUNLOCK(obj);
512 kasan_mark((void *)ks, ptoa(pages), ptoa(pages), 0);
513 vm_thread_free_kstack_kva(ks - (KSTACK_GUARD_PAGES * PAGE_SIZE),
514 ptoa(pages + KSTACK_GUARD_PAGES), domain);
515 }
516
517 /*
518 * Allocate the kernel stack for a new thread.
519 */
520 int
vm_thread_new(struct thread * td,int pages)521 vm_thread_new(struct thread *td, int pages)
522 {
523 vm_offset_t ks;
524 u_short ks_domain;
525
526 /* Bounds check */
527 if (pages <= 1)
528 pages = kstack_pages;
529 else if (pages > KSTACK_MAX_PAGES)
530 pages = KSTACK_MAX_PAGES;
531
532 ks = 0;
533 if (pages == kstack_pages && kstack_cache != NULL)
534 ks = (vm_offset_t)uma_zalloc(kstack_cache, M_NOWAIT);
535
536 /*
537 * Ensure that kstack objects can draw pages from any memory
538 * domain. Otherwise a local memory shortage can block a process
539 * swap-in.
540 */
541 if (ks == 0)
542 ks = vm_thread_stack_create(DOMAINSET_PREF(PCPU_GET(domain)),
543 pages);
544 if (ks == 0)
545 return (0);
546
547 ks_domain = vm_phys_domain(vtophys(ks));
548 KASSERT(ks_domain >= 0 && ks_domain < vm_ndomains,
549 ("%s: invalid domain for kstack %p", __func__, (void *)ks));
550 td->td_kstack = ks;
551 td->td_kstack_pages = pages;
552 td->td_kstack_domain = ks_domain;
553 return (1);
554 }
555
556 /*
557 * Dispose of a thread's kernel stack.
558 */
559 void
vm_thread_dispose(struct thread * td)560 vm_thread_dispose(struct thread *td)
561 {
562 vm_offset_t ks;
563 int pages;
564
565 pages = td->td_kstack_pages;
566 ks = td->td_kstack;
567 td->td_kstack = 0;
568 td->td_kstack_pages = 0;
569 td->td_kstack_domain = MAXMEMDOM;
570 if (pages == kstack_pages) {
571 kasan_mark((void *)ks, 0, ptoa(pages), KASAN_KSTACK_FREED);
572 uma_zfree(kstack_cache, (void *)ks);
573 } else {
574 vm_thread_stack_dispose(ks, pages);
575 }
576 }
577
578 /*
579 * Calculate kstack pindex.
580 *
581 * Uses a non-identity mapping if guard pages are
582 * active to avoid pindex holes in the kstack object.
583 */
584 static vm_pindex_t
vm_kstack_pindex(vm_offset_t ks,int kpages)585 vm_kstack_pindex(vm_offset_t ks, int kpages)
586 {
587 vm_pindex_t pindex = atop(ks - VM_MIN_KERNEL_ADDRESS);
588
589 #ifdef __ILP32__
590 return (pindex);
591 #else
592 /*
593 * Return the linear pindex if guard pages aren't active or if we are
594 * allocating a non-standard kstack size.
595 */
596 if (KSTACK_GUARD_PAGES == 0 || kpages != kstack_pages) {
597 return (pindex);
598 }
599 KASSERT(pindex % (kpages + KSTACK_GUARD_PAGES) >= KSTACK_GUARD_PAGES,
600 ("%s: Attempting to calculate kstack guard page pindex", __func__));
601
602 return (pindex -
603 (pindex / (kpages + KSTACK_GUARD_PAGES) + 1) * KSTACK_GUARD_PAGES);
604 #endif
605 }
606
607 /*
608 * Allocate physical pages, following the specified NUMA policy, to back a
609 * kernel stack.
610 */
611 static int
vm_thread_stack_back(vm_offset_t ks,vm_page_t ma[],int npages,int req_class,int domain)612 vm_thread_stack_back(vm_offset_t ks, vm_page_t ma[], int npages, int req_class,
613 int domain)
614 {
615 struct pctrie_iter pages;
616 vm_object_t obj = vm_thread_kstack_size_to_obj(npages);
617 vm_pindex_t pindex;
618 vm_page_t m;
619 int n;
620
621 pindex = vm_kstack_pindex(ks, npages);
622
623 vm_page_iter_init(&pages, obj);
624 VM_OBJECT_WLOCK(obj);
625 for (n = 0; n < npages; ma[n++] = m) {
626 m = vm_page_grab_iter(obj, pindex + n,
627 VM_ALLOC_NOCREAT | VM_ALLOC_WIRED, &pages);
628 if (m != NULL)
629 continue;
630 m = vm_page_alloc_domain_iter(obj, pindex + n,
631 domain, req_class | VM_ALLOC_WIRED, &pages);
632 if (m != NULL)
633 continue;
634 for (int i = 0; i < n; i++) {
635 m = ma[i];
636 (void)vm_page_unwire_noq(m);
637 vm_page_free(m);
638 }
639 break;
640 }
641 VM_OBJECT_WUNLOCK(obj);
642 return (n < npages ? ENOMEM : 0);
643 }
644
645 static vm_object_t
vm_thread_kstack_size_to_obj(int npages)646 vm_thread_kstack_size_to_obj(int npages)
647 {
648 return (npages == kstack_pages ? kstack_object : kstack_alt_object);
649 }
650
651 static int
kstack_import(void * arg,void ** store,int cnt,int domain,int flags)652 kstack_import(void *arg, void **store, int cnt, int domain, int flags)
653 {
654 struct domainset *ds;
655 int i;
656
657 if (domain == UMA_ANYDOMAIN)
658 ds = DOMAINSET_RR();
659 else
660 ds = DOMAINSET_PREF(domain);
661
662 for (i = 0; i < cnt; i++) {
663 store[i] = (void *)vm_thread_stack_create(ds, kstack_pages);
664 if (store[i] == NULL)
665 break;
666 }
667 return (i);
668 }
669
670 static void
kstack_release(void * arg,void ** store,int cnt)671 kstack_release(void *arg, void **store, int cnt)
672 {
673 vm_offset_t ks;
674 int i;
675
676 for (i = 0; i < cnt; i++) {
677 ks = (vm_offset_t)store[i];
678 vm_thread_stack_dispose(ks, kstack_pages);
679 }
680 }
681
682 static void
kstack_cache_init(void * null)683 kstack_cache_init(void *null)
684 {
685 vm_size_t kstack_quantum;
686 int domain;
687
688 kstack_object = vm_object_allocate(OBJT_PHYS,
689 atop(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS));
690 kstack_cache = uma_zcache_create("kstack_cache",
691 kstack_pages * PAGE_SIZE, NULL, NULL, NULL, NULL,
692 kstack_import, kstack_release, NULL,
693 UMA_ZONE_FIRSTTOUCH);
694 kstack_cache_size = imax(128, mp_ncpus * 4);
695 uma_zone_set_maxcache(kstack_cache, kstack_cache_size);
696
697 kstack_alt_object = vm_object_allocate(OBJT_PHYS,
698 atop(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS));
699
700 kstack_quantum = vm_thread_kstack_import_quantum();
701 /*
702 * Reduce size used by the kstack arena to allow for
703 * alignment adjustments in vm_thread_kstack_arena_import.
704 */
705 kstack_quantum -= (kstack_pages + KSTACK_GUARD_PAGES) * PAGE_SIZE;
706 /*
707 * Create the kstack_arena for each domain and set kernel_arena as
708 * parent.
709 */
710 for (domain = 0; domain < vm_ndomains; domain++) {
711 vmd_kstack_arena[domain] = vmem_create("kstack arena", 0, 0,
712 PAGE_SIZE, 0, M_WAITOK);
713 KASSERT(vmd_kstack_arena[domain] != NULL,
714 ("%s: failed to create domain %d kstack_arena", __func__,
715 domain));
716 vmem_set_import(vmd_kstack_arena[domain],
717 vm_thread_kstack_arena_import,
718 vm_thread_kstack_arena_release,
719 vm_dom[domain].vmd_kernel_arena, kstack_quantum);
720 }
721 }
722 SYSINIT(vm_kstacks, SI_SUB_KMEM, SI_ORDER_ANY, kstack_cache_init, NULL);
723
724 #ifdef KSTACK_USAGE_PROF
725 /*
726 * Track maximum stack used by a thread in kernel.
727 */
728 static int max_kstack_used;
729
730 SYSCTL_INT(_debug, OID_AUTO, max_kstack_used, CTLFLAG_RD,
731 &max_kstack_used, 0,
732 "Maximum stack depth used by a thread in kernel");
733
734 void
intr_prof_stack_use(struct thread * td,struct trapframe * frame)735 intr_prof_stack_use(struct thread *td, struct trapframe *frame)
736 {
737 vm_offset_t stack_top;
738 vm_offset_t current;
739 int used, prev_used;
740
741 /*
742 * Testing for interrupted kernel mode isn't strictly
743 * needed. It optimizes the execution, since interrupts from
744 * usermode will have only the trap frame on the stack.
745 */
746 if (TRAPF_USERMODE(frame))
747 return;
748
749 stack_top = td->td_kstack + td->td_kstack_pages * PAGE_SIZE;
750 current = (vm_offset_t)(uintptr_t)&stack_top;
751
752 /*
753 * Try to detect if interrupt is using kernel thread stack.
754 * Hardware could use a dedicated stack for interrupt handling.
755 */
756 if (stack_top <= current || current < td->td_kstack)
757 return;
758
759 used = stack_top - current;
760 for (;;) {
761 prev_used = max_kstack_used;
762 if (prev_used >= used)
763 break;
764 if (atomic_cmpset_int(&max_kstack_used, prev_used, used))
765 break;
766 }
767 }
768 #endif /* KSTACK_USAGE_PROF */
769
770 /*
771 * Implement fork's actions on an address space.
772 * Here we arrange for the address space to be copied or referenced,
773 * allocate a user struct (pcb and kernel stack), then call the
774 * machine-dependent layer to fill those in and make the new process
775 * ready to run. The new process is set up so that it returns directly
776 * to user mode to avoid stack copying and relocation problems.
777 */
778 int
vm_forkproc(struct thread * td,struct proc * p2,struct thread * td2,struct vmspace * vm2,int flags)779 vm_forkproc(struct thread *td, struct proc *p2, struct thread *td2,
780 struct vmspace *vm2, int flags)
781 {
782 struct proc *p1 = td->td_proc;
783 struct domainset *dset;
784 int error;
785
786 if ((flags & RFPROC) == 0) {
787 /*
788 * Divorce the memory, if it is shared, essentially
789 * this changes shared memory amongst threads, into
790 * COW locally.
791 */
792 if ((flags & RFMEM) == 0) {
793 error = vmspace_unshare(p1);
794 if (error)
795 return (error);
796 }
797 cpu_fork(td, p2, td2, flags);
798 return (0);
799 }
800
801 if (flags & RFMEM) {
802 p2->p_vmspace = p1->p_vmspace;
803 refcount_acquire(&p1->p_vmspace->vm_refcnt);
804 }
805 dset = td2->td_domain.dr_policy;
806 while (vm_page_count_severe_set(&dset->ds_mask)) {
807 vm_wait_doms(&dset->ds_mask, 0);
808 }
809
810 if ((flags & RFMEM) == 0) {
811 p2->p_vmspace = vm2;
812 if (p1->p_vmspace->vm_shm)
813 shmfork(p1, p2);
814 }
815
816 /*
817 * cpu_fork will copy and update the pcb, set up the kernel stack,
818 * and make the child ready to run.
819 */
820 cpu_fork(td, p2, td2, flags);
821 return (0);
822 }
823
824 /*
825 * Called after process has been wait(2)'ed upon and is being reaped.
826 * The idea is to reclaim resources that we could not reclaim while
827 * the process was still executing.
828 */
829 void
vm_waitproc(struct proc * p)830 vm_waitproc(struct proc *p)
831 {
832
833 vmspace_exitfree(p); /* and clean-out the vmspace */
834 }
835