xref: /freebsd/sys/vm/vm_glue.c (revision 3b9b64457676561b8de2bec7c94c561bbd807b0c)
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,int flags)444 vm_thread_stack_create(struct domainset *ds, int pages, int flags)
445 {
446 	vm_page_t ma[KSTACK_MAX_PAGES];
447 	struct vm_domainset_iter di;
448 	int req;
449 	vm_offset_t ks;
450 	int domain, i;
451 
452 	vm_domainset_iter_policy_init(&di, ds, &domain, &flags);
453 	req = malloc2vm_flags(flags);
454 	do {
455 		/*
456 		 * Get a kernel virtual address for this thread's kstack.
457 		 */
458 		ks = vm_thread_alloc_kstack_kva(ptoa(pages + KSTACK_GUARD_PAGES),
459 		    domain);
460 		if (ks == 0)
461 			continue;
462 		ks += ptoa(KSTACK_GUARD_PAGES);
463 
464 		/*
465 		 * Allocate physical pages to back the stack.
466 		 */
467 		if (vm_thread_stack_back(ks, ma, pages, req, domain) != 0) {
468 			vm_thread_free_kstack_kva(ks - ptoa(KSTACK_GUARD_PAGES),
469 			    ptoa(pages + KSTACK_GUARD_PAGES), domain);
470 			continue;
471 		}
472 		if (KSTACK_GUARD_PAGES != 0) {
473 			pmap_qremove(ks - ptoa(KSTACK_GUARD_PAGES),
474 			    KSTACK_GUARD_PAGES);
475 		}
476 		for (i = 0; i < pages; i++)
477 			vm_page_valid(ma[i]);
478 		pmap_qenter(ks, ma, pages);
479 		return (ks);
480 	} while (vm_domainset_iter_policy(&di, &domain) == 0);
481 
482 	return (0);
483 }
484 
485 static __noinline void
vm_thread_stack_dispose(vm_offset_t ks,int pages)486 vm_thread_stack_dispose(vm_offset_t ks, int pages)
487 {
488 	vm_page_t m;
489 	vm_pindex_t pindex;
490 	int i, domain;
491 	vm_object_t obj = vm_thread_kstack_size_to_obj(pages);
492 
493 	pindex = vm_kstack_pindex(ks, pages);
494 	domain = vm_phys_domain(vtophys(ks));
495 	pmap_qremove(ks, pages);
496 	VM_OBJECT_WLOCK(obj);
497 	for (i = 0; i < pages; i++) {
498 		m = vm_page_lookup(obj, pindex + i);
499 		if (m == NULL)
500 			panic("%s: kstack already missing?", __func__);
501 		KASSERT(vm_page_domain(m) == domain,
502 		    ("%s: page %p domain mismatch, expected %d got %d",
503 		    __func__, m, domain, vm_page_domain(m)));
504 		vm_page_xbusy_claim(m);
505 		vm_page_unwire_noq(m);
506 		vm_page_free(m);
507 	}
508 	VM_OBJECT_WUNLOCK(obj);
509 	kasan_mark((void *)ks, ptoa(pages), ptoa(pages), 0);
510 	vm_thread_free_kstack_kva(ks - (KSTACK_GUARD_PAGES * PAGE_SIZE),
511 	    ptoa(pages + KSTACK_GUARD_PAGES), domain);
512 }
513 
514 /*
515  * Allocate the kernel stack for a new thread.
516  */
517 int
vm_thread_new(struct thread * td,int pages)518 vm_thread_new(struct thread *td, int pages)
519 {
520 	vm_offset_t ks;
521 	u_short ks_domain;
522 
523 	/* Bounds check */
524 	if (pages <= 1)
525 		pages = kstack_pages;
526 	else if (pages > KSTACK_MAX_PAGES)
527 		pages = KSTACK_MAX_PAGES;
528 
529 	ks = 0;
530 	if (pages == kstack_pages && kstack_cache != NULL)
531 		ks = (vm_offset_t)uma_zalloc(kstack_cache, M_NOWAIT);
532 	if (ks == 0)
533 		ks = vm_thread_stack_create(DOMAINSET_PREF(PCPU_GET(domain)),
534 		    pages, M_NOWAIT);
535 	if (ks == 0)
536 		return (0);
537 
538 	ks_domain = vm_phys_domain(vtophys(ks));
539 	KASSERT(ks_domain >= 0 && ks_domain < vm_ndomains,
540 	    ("%s: invalid domain for kstack %p", __func__, (void *)ks));
541 	td->td_kstack = ks;
542 	td->td_kstack_pages = pages;
543 	td->td_kstack_domain = ks_domain;
544 	return (1);
545 }
546 
547 /*
548  * Dispose of a thread's kernel stack.
549  */
550 void
vm_thread_dispose(struct thread * td)551 vm_thread_dispose(struct thread *td)
552 {
553 	vm_offset_t ks;
554 	int pages;
555 
556 	pages = td->td_kstack_pages;
557 	ks = td->td_kstack;
558 	td->td_kstack = 0;
559 	td->td_kstack_pages = 0;
560 	td->td_kstack_domain = MAXMEMDOM;
561 	if (pages == kstack_pages) {
562 		kasan_mark((void *)ks, 0, ptoa(pages), KASAN_KSTACK_FREED);
563 		uma_zfree(kstack_cache, (void *)ks);
564 	} else {
565 		vm_thread_stack_dispose(ks, pages);
566 	}
567 }
568 
569 /*
570  * Calculate kstack pindex.
571  *
572  * Uses a non-identity mapping if guard pages are
573  * active to avoid pindex holes in the kstack object.
574  */
575 static vm_pindex_t
vm_kstack_pindex(vm_offset_t ks,int kpages)576 vm_kstack_pindex(vm_offset_t ks, int kpages)
577 {
578 	vm_pindex_t pindex = atop(ks - VM_MIN_KERNEL_ADDRESS);
579 
580 #ifdef __ILP32__
581 	return (pindex);
582 #else
583 	/*
584 	 * Return the linear pindex if guard pages aren't active or if we are
585 	 * allocating a non-standard kstack size.
586 	 */
587 	if (KSTACK_GUARD_PAGES == 0 || kpages != kstack_pages) {
588 		return (pindex);
589 	}
590 	KASSERT(pindex % (kpages + KSTACK_GUARD_PAGES) >= KSTACK_GUARD_PAGES,
591 	    ("%s: Attempting to calculate kstack guard page pindex", __func__));
592 
593 	return (pindex -
594 	    (pindex / (kpages + KSTACK_GUARD_PAGES) + 1) * KSTACK_GUARD_PAGES);
595 #endif
596 }
597 
598 /*
599  * Allocate physical pages, following the specified NUMA policy, to back a
600  * kernel stack.
601  */
602 static int
vm_thread_stack_back(vm_offset_t ks,vm_page_t ma[],int npages,int req_class,int domain)603 vm_thread_stack_back(vm_offset_t ks, vm_page_t ma[], int npages, int req_class,
604     int domain)
605 {
606 	struct pctrie_iter pages;
607 	vm_object_t obj = vm_thread_kstack_size_to_obj(npages);
608 	vm_pindex_t pindex;
609 	vm_page_t m;
610 	int n;
611 
612 	pindex = vm_kstack_pindex(ks, npages);
613 
614 	vm_page_iter_init(&pages, obj);
615 	VM_OBJECT_WLOCK(obj);
616 	for (n = 0; n < npages; ma[n++] = m) {
617 		m = vm_page_grab_iter(obj, pindex + n,
618 		    VM_ALLOC_NOCREAT | VM_ALLOC_WIRED, &pages);
619 		if (m != NULL)
620 			continue;
621 		m = vm_page_alloc_domain_iter(obj, pindex + n,
622 		    domain, req_class | VM_ALLOC_WIRED, &pages);
623 		if (m != NULL)
624 			continue;
625 		for (int i = 0; i < n; i++) {
626 			m = ma[i];
627 			(void)vm_page_unwire_noq(m);
628 			vm_page_free(m);
629 		}
630 		break;
631 	}
632 	VM_OBJECT_WUNLOCK(obj);
633 	return (n < npages ? ENOMEM : 0);
634 }
635 
636 static vm_object_t
vm_thread_kstack_size_to_obj(int npages)637 vm_thread_kstack_size_to_obj(int npages)
638 {
639 	return (npages == kstack_pages ? kstack_object : kstack_alt_object);
640 }
641 
642 static int
kstack_import(void * arg,void ** store,int cnt,int domain,int flags)643 kstack_import(void *arg, void **store, int cnt, int domain, int flags)
644 {
645 	struct domainset *ds;
646 	int i;
647 
648 	if (domain == UMA_ANYDOMAIN)
649 		ds = DOMAINSET_RR();
650 	else
651 		ds = DOMAINSET_PREF(domain);
652 
653 	for (i = 0; i < cnt; i++) {
654 		store[i] = (void *)vm_thread_stack_create(ds, kstack_pages,
655 		    flags);
656 		if (store[i] == NULL)
657 			break;
658 	}
659 	return (i);
660 }
661 
662 static void
kstack_release(void * arg,void ** store,int cnt)663 kstack_release(void *arg, void **store, int cnt)
664 {
665 	vm_offset_t ks;
666 	int i;
667 
668 	for (i = 0; i < cnt; i++) {
669 		ks = (vm_offset_t)store[i];
670 		vm_thread_stack_dispose(ks, kstack_pages);
671 	}
672 }
673 
674 static void
kstack_cache_init(void * null)675 kstack_cache_init(void *null)
676 {
677 	vm_size_t kstack_quantum;
678 	int domain;
679 
680 	kstack_object = vm_object_allocate(OBJT_PHYS,
681 	    atop(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS));
682 	kstack_cache = uma_zcache_create("kstack_cache",
683 	    kstack_pages * PAGE_SIZE, NULL, NULL, NULL, NULL,
684 	    kstack_import, kstack_release, NULL,
685 	    UMA_ZONE_FIRSTTOUCH);
686 	kstack_cache_size = imax(128, mp_ncpus * 4);
687 	uma_zone_set_maxcache(kstack_cache, kstack_cache_size);
688 
689 	kstack_alt_object = vm_object_allocate(OBJT_PHYS,
690 	    atop(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS));
691 
692 	kstack_quantum = vm_thread_kstack_import_quantum();
693 	/*
694 	 * Reduce size used by the kstack arena to allow for
695 	 * alignment adjustments in vm_thread_kstack_arena_import.
696 	 */
697 	kstack_quantum -= (kstack_pages + KSTACK_GUARD_PAGES) * PAGE_SIZE;
698 	/*
699 	 * Create the kstack_arena for each domain and set kernel_arena as
700 	 * parent.
701 	 */
702 	for (domain = 0; domain < vm_ndomains; domain++) {
703 		vmd_kstack_arena[domain] = vmem_create("kstack arena", 0, 0,
704 		    PAGE_SIZE, 0, M_WAITOK);
705 		KASSERT(vmd_kstack_arena[domain] != NULL,
706 		    ("%s: failed to create domain %d kstack_arena", __func__,
707 		    domain));
708 		vmem_set_import(vmd_kstack_arena[domain],
709 		    vm_thread_kstack_arena_import,
710 		    vm_thread_kstack_arena_release,
711 		    vm_dom[domain].vmd_kernel_arena, kstack_quantum);
712 	}
713 }
714 SYSINIT(vm_kstacks, SI_SUB_KMEM, SI_ORDER_ANY, kstack_cache_init, NULL);
715 
716 #ifdef KSTACK_USAGE_PROF
717 /*
718  * Track maximum stack used by a thread in kernel.
719  */
720 static int max_kstack_used;
721 
722 SYSCTL_INT(_debug, OID_AUTO, max_kstack_used, CTLFLAG_RD,
723     &max_kstack_used, 0,
724     "Maximum stack depth used by a thread in kernel");
725 
726 void
intr_prof_stack_use(struct thread * td,struct trapframe * frame)727 intr_prof_stack_use(struct thread *td, struct trapframe *frame)
728 {
729 	vm_offset_t stack_top;
730 	vm_offset_t current;
731 	int used, prev_used;
732 
733 	/*
734 	 * Testing for interrupted kernel mode isn't strictly
735 	 * needed. It optimizes the execution, since interrupts from
736 	 * usermode will have only the trap frame on the stack.
737 	 */
738 	if (TRAPF_USERMODE(frame))
739 		return;
740 
741 	stack_top = td->td_kstack + td->td_kstack_pages * PAGE_SIZE;
742 	current = (vm_offset_t)(uintptr_t)&stack_top;
743 
744 	/*
745 	 * Try to detect if interrupt is using kernel thread stack.
746 	 * Hardware could use a dedicated stack for interrupt handling.
747 	 */
748 	if (stack_top <= current || current < td->td_kstack)
749 		return;
750 
751 	used = stack_top - current;
752 	for (;;) {
753 		prev_used = max_kstack_used;
754 		if (prev_used >= used)
755 			break;
756 		if (atomic_cmpset_int(&max_kstack_used, prev_used, used))
757 			break;
758 	}
759 }
760 #endif /* KSTACK_USAGE_PROF */
761 
762 /*
763  * Implement fork's actions on an address space.
764  * Here we arrange for the address space to be copied or referenced,
765  * allocate a user struct (pcb and kernel stack), then call the
766  * machine-dependent layer to fill those in and make the new process
767  * ready to run.  The new process is set up so that it returns directly
768  * to user mode to avoid stack copying and relocation problems.
769  */
770 int
vm_forkproc(struct thread * td,struct proc * p2,struct thread * td2,struct vmspace * vm2,int flags)771 vm_forkproc(struct thread *td, struct proc *p2, struct thread *td2,
772     struct vmspace *vm2, int flags)
773 {
774 	struct proc *p1 = td->td_proc;
775 	struct domainset *dset;
776 	int error;
777 
778 	if ((flags & RFPROC) == 0) {
779 		/*
780 		 * Divorce the memory, if it is shared, essentially
781 		 * this changes shared memory amongst threads, into
782 		 * COW locally.
783 		 */
784 		if ((flags & RFMEM) == 0) {
785 			error = vmspace_unshare(p1);
786 			if (error)
787 				return (error);
788 		}
789 		cpu_fork(td, p2, td2, flags);
790 		return (0);
791 	}
792 
793 	if (flags & RFMEM) {
794 		p2->p_vmspace = p1->p_vmspace;
795 		refcount_acquire(&p1->p_vmspace->vm_refcnt);
796 	}
797 	dset = td2->td_domain.dr_policy;
798 	while (vm_page_count_severe_set(&dset->ds_mask)) {
799 		vm_wait_doms(&dset->ds_mask, 0);
800 	}
801 
802 	if ((flags & RFMEM) == 0) {
803 		p2->p_vmspace = vm2;
804 		if (p1->p_vmspace->vm_shm)
805 			shmfork(p1, p2);
806 	}
807 
808 	/*
809 	 * cpu_fork will copy and update the pcb, set up the kernel stack,
810 	 * and make the child ready to run.
811 	 */
812 	cpu_fork(td, p2, td2, flags);
813 	return (0);
814 }
815 
816 /*
817  * Called after process has been wait(2)'ed upon and is being reaped.
818  * The idea is to reclaim resources that we could not reclaim while
819  * the process was still executing.
820  */
821 void
vm_waitproc(struct proc * p)822 vm_waitproc(struct proc *p)
823 {
824 
825 	vmspace_exitfree(p);		/* and clean-out the vmspace */
826 }
827