The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_kern.c

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    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  *      from: @(#)vm_kern.c     8.3 (Berkeley) 1/12/94
   35  *
   36  *
   37  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
   38  * All rights reserved.
   39  *
   40  * Authors: Avadis Tevanian, Jr., Michael Wayne Young
   41  *
   42  * Permission to use, copy, modify and distribute this software and
   43  * its documentation is hereby granted, provided that both the copyright
   44  * notice and this permission notice appear in all copies of the
   45  * software, derivative works or modified versions, and any portions
   46  * thereof, and that both notices appear in supporting documentation.
   47  *
   48  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
   49  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
   50  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   51  *
   52  * Carnegie Mellon requests users of this software to return to
   53  *
   54  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   55  *  School of Computer Science
   56  *  Carnegie Mellon University
   57  *  Pittsburgh PA 15213-3890
   58  *
   59  * any improvements or extensions that they make and grant Carnegie the
   60  * rights to redistribute these changes.
   61  */
   62 
   63 /*
   64  *      Kernel memory management.
   65  */
   66 
   67 #include <sys/cdefs.h>
   68 __FBSDID("$FreeBSD$");
   69 
   70 #include "opt_vm.h"
   71 
   72 #include <sys/param.h>
   73 #include <sys/systm.h>
   74 #include <sys/asan.h>
   75 #include <sys/domainset.h>
   76 #include <sys/eventhandler.h>
   77 #include <sys/kernel.h>
   78 #include <sys/lock.h>
   79 #include <sys/malloc.h>
   80 #include <sys/msan.h>
   81 #include <sys/proc.h>
   82 #include <sys/rwlock.h>
   83 #include <sys/sysctl.h>
   84 #include <sys/vmem.h>
   85 #include <sys/vmmeter.h>
   86 
   87 #include <vm/vm.h>
   88 #include <vm/vm_param.h>
   89 #include <vm/vm_domainset.h>
   90 #include <vm/vm_kern.h>
   91 #include <vm/pmap.h>
   92 #include <vm/vm_map.h>
   93 #include <vm/vm_object.h>
   94 #include <vm/vm_page.h>
   95 #include <vm/vm_pageout.h>
   96 #include <vm/vm_pagequeue.h>
   97 #include <vm/vm_phys.h>
   98 #include <vm/vm_radix.h>
   99 #include <vm/vm_extern.h>
  100 #include <vm/uma.h>
  101 
  102 struct vm_map kernel_map_store;
  103 struct vm_map exec_map_store;
  104 struct vm_map pipe_map_store;
  105 
  106 const void *zero_region;
  107 CTASSERT((ZERO_REGION_SIZE & PAGE_MASK) == 0);
  108 
  109 /* NB: Used by kernel debuggers. */
  110 const u_long vm_maxuser_address = VM_MAXUSER_ADDRESS;
  111 
  112 u_int exec_map_entry_size;
  113 u_int exec_map_entries;
  114 
  115 SYSCTL_ULONG(_vm, OID_AUTO, min_kernel_address, CTLFLAG_RD,
  116     SYSCTL_NULL_ULONG_PTR, VM_MIN_KERNEL_ADDRESS, "Min kernel address");
  117 
  118 SYSCTL_ULONG(_vm, OID_AUTO, max_kernel_address, CTLFLAG_RD,
  119 #if defined(__arm__)
  120     &vm_max_kernel_address, 0,
  121 #else
  122     SYSCTL_NULL_ULONG_PTR, VM_MAX_KERNEL_ADDRESS,
  123 #endif
  124     "Max kernel address");
  125 
  126 #if VM_NRESERVLEVEL > 0
  127 #define KVA_QUANTUM_SHIFT       (VM_LEVEL_0_ORDER + PAGE_SHIFT)
  128 #else
  129 /* On non-superpage architectures we want large import sizes. */
  130 #define KVA_QUANTUM_SHIFT       (8 + PAGE_SHIFT)
  131 #endif
  132 #define KVA_QUANTUM             (1ul << KVA_QUANTUM_SHIFT)
  133 #define KVA_NUMA_IMPORT_QUANTUM (KVA_QUANTUM * 128)
  134 
  135 extern void     uma_startup2(void);
  136 
  137 /*
  138  *      kva_alloc:
  139  *
  140  *      Allocate a virtual address range with no underlying object and
  141  *      no initial mapping to physical memory.  Any mapping from this
  142  *      range to physical memory must be explicitly created prior to
  143  *      its use, typically with pmap_qenter().  Any attempt to create
  144  *      a mapping on demand through vm_fault() will result in a panic. 
  145  */
  146 vm_offset_t
  147 kva_alloc(vm_size_t size)
  148 {
  149         vm_offset_t addr;
  150 
  151         TSENTER();
  152         size = round_page(size);
  153         if (vmem_alloc(kernel_arena, size, M_BESTFIT | M_NOWAIT, &addr))
  154                 return (0);
  155         TSEXIT();
  156 
  157         return (addr);
  158 }
  159 
  160 /*
  161  *      kva_free:
  162  *
  163  *      Release a region of kernel virtual memory allocated
  164  *      with kva_alloc, and return the physical pages
  165  *      associated with that region.
  166  *
  167  *      This routine may not block on kernel maps.
  168  */
  169 void
  170 kva_free(vm_offset_t addr, vm_size_t size)
  171 {
  172 
  173         size = round_page(size);
  174         vmem_free(kernel_arena, addr, size);
  175 }
  176 
  177 /*
  178  * Update sanitizer shadow state to reflect a new allocation.  Force inlining to
  179  * help make KMSAN origin tracking more precise.
  180  */
  181 static __always_inline void
  182 kmem_alloc_san(vm_offset_t addr, vm_size_t size, vm_size_t asize, int flags)
  183 {
  184         if ((flags & M_ZERO) == 0) {
  185                 kmsan_mark((void *)addr, asize, KMSAN_STATE_UNINIT);
  186                 kmsan_orig((void *)addr, asize, KMSAN_TYPE_KMEM,
  187                     KMSAN_RET_ADDR);
  188         } else {
  189                 kmsan_mark((void *)addr, asize, KMSAN_STATE_INITED);
  190         }
  191         kasan_mark((void *)addr, size, asize, KASAN_KMEM_REDZONE);
  192 }
  193 
  194 static vm_page_t
  195 kmem_alloc_contig_pages(vm_object_t object, vm_pindex_t pindex, int domain,
  196     int pflags, u_long npages, vm_paddr_t low, vm_paddr_t high,
  197     u_long alignment, vm_paddr_t boundary, vm_memattr_t memattr)
  198 {
  199         vm_page_t m;
  200         int tries;
  201         bool wait, reclaim;
  202 
  203         VM_OBJECT_ASSERT_WLOCKED(object);
  204 
  205         wait = (pflags & VM_ALLOC_WAITOK) != 0;
  206         reclaim = (pflags & VM_ALLOC_NORECLAIM) == 0;
  207         pflags &= ~(VM_ALLOC_NOWAIT | VM_ALLOC_WAITOK | VM_ALLOC_WAITFAIL);
  208         pflags |= VM_ALLOC_NOWAIT;
  209         for (tries = wait ? 3 : 1;; tries--) {
  210                 m = vm_page_alloc_contig_domain(object, pindex, domain, pflags,
  211                     npages, low, high, alignment, boundary, memattr);
  212                 if (m != NULL || tries == 0 || !reclaim)
  213                         break;
  214 
  215                 VM_OBJECT_WUNLOCK(object);
  216                 if (!vm_page_reclaim_contig_domain(domain, pflags, npages,
  217                     low, high, alignment, boundary) && wait)
  218                         vm_wait_domain(domain);
  219                 VM_OBJECT_WLOCK(object);
  220         }
  221         return (m);
  222 }
  223 
  224 /*
  225  *      Allocates a region from the kernel address map and physical pages
  226  *      within the specified address range to the kernel object.  Creates a
  227  *      wired mapping from this region to these pages, and returns the
  228  *      region's starting virtual address.  The allocated pages are not
  229  *      necessarily physically contiguous.  If M_ZERO is specified through the
  230  *      given flags, then the pages are zeroed before they are mapped.
  231  */
  232 static void *
  233 kmem_alloc_attr_domain(int domain, vm_size_t size, int flags, vm_paddr_t low,
  234     vm_paddr_t high, vm_memattr_t memattr)
  235 {
  236         vmem_t *vmem;
  237         vm_object_t object;
  238         vm_offset_t addr, i, offset;
  239         vm_page_t m;
  240         vm_size_t asize;
  241         int pflags;
  242         vm_prot_t prot;
  243 
  244         object = kernel_object;
  245         asize = round_page(size);
  246         vmem = vm_dom[domain].vmd_kernel_arena;
  247         if (vmem_alloc(vmem, asize, M_BESTFIT | flags, &addr))
  248                 return (0);
  249         offset = addr - VM_MIN_KERNEL_ADDRESS;
  250         pflags = malloc2vm_flags(flags) | VM_ALLOC_WIRED;
  251         prot = (flags & M_EXEC) != 0 ? VM_PROT_ALL : VM_PROT_RW;
  252         VM_OBJECT_WLOCK(object);
  253         for (i = 0; i < asize; i += PAGE_SIZE) {
  254                 m = kmem_alloc_contig_pages(object, atop(offset + i),
  255                     domain, pflags, 1, low, high, PAGE_SIZE, 0, memattr);
  256                 if (m == NULL) {
  257                         VM_OBJECT_WUNLOCK(object);
  258                         kmem_unback(object, addr, i);
  259                         vmem_free(vmem, addr, asize);
  260                         return (0);
  261                 }
  262                 KASSERT(vm_page_domain(m) == domain,
  263                     ("kmem_alloc_attr_domain: Domain mismatch %d != %d",
  264                     vm_page_domain(m), domain));
  265                 if ((flags & M_ZERO) && (m->flags & PG_ZERO) == 0)
  266                         pmap_zero_page(m);
  267                 vm_page_valid(m);
  268                 pmap_enter(kernel_pmap, addr + i, m, prot,
  269                     prot | PMAP_ENTER_WIRED, 0);
  270         }
  271         VM_OBJECT_WUNLOCK(object);
  272         kmem_alloc_san(addr, size, asize, flags);
  273         return ((void *)addr);
  274 }
  275 
  276 void *
  277 kmem_alloc_attr(vm_size_t size, int flags, vm_paddr_t low, vm_paddr_t high,
  278     vm_memattr_t memattr)
  279 {
  280 
  281         return (kmem_alloc_attr_domainset(DOMAINSET_RR(), size, flags, low,
  282             high, memattr));
  283 }
  284 
  285 void *
  286 kmem_alloc_attr_domainset(struct domainset *ds, vm_size_t size, int flags,
  287     vm_paddr_t low, vm_paddr_t high, vm_memattr_t memattr)
  288 {
  289         struct vm_domainset_iter di;
  290         void *addr;
  291         int domain;
  292 
  293         vm_domainset_iter_policy_init(&di, ds, &domain, &flags);
  294         do {
  295                 addr = kmem_alloc_attr_domain(domain, size, flags, low, high,
  296                     memattr);
  297                 if (addr != NULL)
  298                         break;
  299         } while (vm_domainset_iter_policy(&di, &domain) == 0);
  300 
  301         return (addr);
  302 }
  303 
  304 /*
  305  *      Allocates a region from the kernel address map and physically
  306  *      contiguous pages within the specified address range to the kernel
  307  *      object.  Creates a wired mapping from this region to these pages, and
  308  *      returns the region's starting virtual address.  If M_ZERO is specified
  309  *      through the given flags, then the pages are zeroed before they are
  310  *      mapped.
  311  */
  312 static void *
  313 kmem_alloc_contig_domain(int domain, vm_size_t size, int flags, vm_paddr_t low,
  314     vm_paddr_t high, u_long alignment, vm_paddr_t boundary,
  315     vm_memattr_t memattr)
  316 {
  317         vmem_t *vmem;
  318         vm_object_t object;
  319         vm_offset_t addr, offset, tmp;
  320         vm_page_t end_m, m;
  321         vm_size_t asize;
  322         u_long npages;
  323         int pflags;
  324 
  325         object = kernel_object;
  326         asize = round_page(size);
  327         vmem = vm_dom[domain].vmd_kernel_arena;
  328         if (vmem_alloc(vmem, asize, flags | M_BESTFIT, &addr))
  329                 return (NULL);
  330         offset = addr - VM_MIN_KERNEL_ADDRESS;
  331         pflags = malloc2vm_flags(flags) | VM_ALLOC_WIRED;
  332         npages = atop(asize);
  333         VM_OBJECT_WLOCK(object);
  334         m = kmem_alloc_contig_pages(object, atop(offset), domain,
  335             pflags, npages, low, high, alignment, boundary, memattr);
  336         if (m == NULL) {
  337                 VM_OBJECT_WUNLOCK(object);
  338                 vmem_free(vmem, addr, asize);
  339                 return (NULL);
  340         }
  341         KASSERT(vm_page_domain(m) == domain,
  342             ("kmem_alloc_contig_domain: Domain mismatch %d != %d",
  343             vm_page_domain(m), domain));
  344         end_m = m + npages;
  345         tmp = addr;
  346         for (; m < end_m; m++) {
  347                 if ((flags & M_ZERO) && (m->flags & PG_ZERO) == 0)
  348                         pmap_zero_page(m);
  349                 vm_page_valid(m);
  350                 pmap_enter(kernel_pmap, tmp, m, VM_PROT_RW,
  351                     VM_PROT_RW | PMAP_ENTER_WIRED, 0);
  352                 tmp += PAGE_SIZE;
  353         }
  354         VM_OBJECT_WUNLOCK(object);
  355         kmem_alloc_san(addr, size, asize, flags);
  356         return ((void *)addr);
  357 }
  358 
  359 void *
  360 kmem_alloc_contig(vm_size_t size, int flags, vm_paddr_t low, vm_paddr_t high,
  361     u_long alignment, vm_paddr_t boundary, vm_memattr_t memattr)
  362 {
  363 
  364         return (kmem_alloc_contig_domainset(DOMAINSET_RR(), size, flags, low,
  365             high, alignment, boundary, memattr));
  366 }
  367 
  368 void *
  369 kmem_alloc_contig_domainset(struct domainset *ds, vm_size_t size, int flags,
  370     vm_paddr_t low, vm_paddr_t high, u_long alignment, vm_paddr_t boundary,
  371     vm_memattr_t memattr)
  372 {
  373         struct vm_domainset_iter di;
  374         void *addr;
  375         int domain;
  376 
  377         vm_domainset_iter_policy_init(&di, ds, &domain, &flags);
  378         do {
  379                 addr = kmem_alloc_contig_domain(domain, size, flags, low, high,
  380                     alignment, boundary, memattr);
  381                 if (addr != NULL)
  382                         break;
  383         } while (vm_domainset_iter_policy(&di, &domain) == 0);
  384 
  385         return (addr);
  386 }
  387 
  388 /*
  389  *      kmem_subinit:
  390  *
  391  *      Initializes a map to manage a subrange
  392  *      of the kernel virtual address space.
  393  *
  394  *      Arguments are as follows:
  395  *
  396  *      parent          Map to take range from
  397  *      min, max        Returned endpoints of map
  398  *      size            Size of range to find
  399  *      superpage_align Request that min is superpage aligned
  400  */
  401 void
  402 kmem_subinit(vm_map_t map, vm_map_t parent, vm_offset_t *min, vm_offset_t *max,
  403     vm_size_t size, bool superpage_align)
  404 {
  405         int ret;
  406 
  407         size = round_page(size);
  408 
  409         *min = vm_map_min(parent);
  410         ret = vm_map_find(parent, NULL, 0, min, size, 0, superpage_align ?
  411             VMFS_SUPER_SPACE : VMFS_ANY_SPACE, VM_PROT_ALL, VM_PROT_ALL,
  412             MAP_ACC_NO_CHARGE);
  413         if (ret != KERN_SUCCESS)
  414                 panic("kmem_subinit: bad status return of %d", ret);
  415         *max = *min + size;
  416         vm_map_init(map, vm_map_pmap(parent), *min, *max);
  417         if (vm_map_submap(parent, *min, *max, map) != KERN_SUCCESS)
  418                 panic("kmem_subinit: unable to change range to submap");
  419 }
  420 
  421 /*
  422  *      kmem_malloc_domain:
  423  *
  424  *      Allocate wired-down pages in the kernel's address space.
  425  */
  426 static void *
  427 kmem_malloc_domain(int domain, vm_size_t size, int flags)
  428 {
  429         vmem_t *arena;
  430         vm_offset_t addr;
  431         vm_size_t asize;
  432         int rv;
  433 
  434         if (__predict_true((flags & M_EXEC) == 0))
  435                 arena = vm_dom[domain].vmd_kernel_arena;
  436         else
  437                 arena = vm_dom[domain].vmd_kernel_rwx_arena;
  438         asize = round_page(size);
  439         if (vmem_alloc(arena, asize, flags | M_BESTFIT, &addr))
  440                 return (0);
  441 
  442         rv = kmem_back_domain(domain, kernel_object, addr, asize, flags);
  443         if (rv != KERN_SUCCESS) {
  444                 vmem_free(arena, addr, asize);
  445                 return (0);
  446         }
  447         kasan_mark((void *)addr, size, asize, KASAN_KMEM_REDZONE);
  448         return ((void *)addr);
  449 }
  450 
  451 void *
  452 kmem_malloc(vm_size_t size, int flags)
  453 {
  454 
  455         return (kmem_malloc_domainset(DOMAINSET_RR(), size, flags));
  456 }
  457 
  458 void *
  459 kmem_malloc_domainset(struct domainset *ds, vm_size_t size, int flags)
  460 {
  461         struct vm_domainset_iter di;
  462         void *addr;
  463         int domain;
  464 
  465         vm_domainset_iter_policy_init(&di, ds, &domain, &flags);
  466         do {
  467                 addr = kmem_malloc_domain(domain, size, flags);
  468                 if (addr != NULL)
  469                         break;
  470         } while (vm_domainset_iter_policy(&di, &domain) == 0);
  471 
  472         return (addr);
  473 }
  474 
  475 /*
  476  *      kmem_back_domain:
  477  *
  478  *      Allocate physical pages from the specified domain for the specified
  479  *      virtual address range.
  480  */
  481 int
  482 kmem_back_domain(int domain, vm_object_t object, vm_offset_t addr,
  483     vm_size_t size, int flags)
  484 {
  485         vm_offset_t offset, i;
  486         vm_page_t m, mpred;
  487         vm_prot_t prot;
  488         int pflags;
  489 
  490         KASSERT(object == kernel_object,
  491             ("kmem_back_domain: only supports kernel object."));
  492 
  493         offset = addr - VM_MIN_KERNEL_ADDRESS;
  494         pflags = malloc2vm_flags(flags) | VM_ALLOC_WIRED;
  495         pflags &= ~(VM_ALLOC_NOWAIT | VM_ALLOC_WAITOK | VM_ALLOC_WAITFAIL);
  496         if (flags & M_WAITOK)
  497                 pflags |= VM_ALLOC_WAITFAIL;
  498         prot = (flags & M_EXEC) != 0 ? VM_PROT_ALL : VM_PROT_RW;
  499 
  500         i = 0;
  501         VM_OBJECT_WLOCK(object);
  502 retry:
  503         mpred = vm_radix_lookup_le(&object->rtree, atop(offset + i));
  504         for (; i < size; i += PAGE_SIZE, mpred = m) {
  505                 m = vm_page_alloc_domain_after(object, atop(offset + i),
  506                     domain, pflags, mpred);
  507 
  508                 /*
  509                  * Ran out of space, free everything up and return. Don't need
  510                  * to lock page queues here as we know that the pages we got
  511                  * aren't on any queues.
  512                  */
  513                 if (m == NULL) {
  514                         if ((flags & M_NOWAIT) == 0)
  515                                 goto retry;
  516                         VM_OBJECT_WUNLOCK(object);
  517                         kmem_unback(object, addr, i);
  518                         return (KERN_NO_SPACE);
  519                 }
  520                 KASSERT(vm_page_domain(m) == domain,
  521                     ("kmem_back_domain: Domain mismatch %d != %d",
  522                     vm_page_domain(m), domain));
  523                 if (flags & M_ZERO && (m->flags & PG_ZERO) == 0)
  524                         pmap_zero_page(m);
  525                 KASSERT((m->oflags & VPO_UNMANAGED) != 0,
  526                     ("kmem_malloc: page %p is managed", m));
  527                 vm_page_valid(m);
  528                 pmap_enter(kernel_pmap, addr + i, m, prot,
  529                     prot | PMAP_ENTER_WIRED, 0);
  530                 if (__predict_false((prot & VM_PROT_EXECUTE) != 0))
  531                         m->oflags |= VPO_KMEM_EXEC;
  532         }
  533         VM_OBJECT_WUNLOCK(object);
  534         kmem_alloc_san(addr, size, size, flags);
  535         return (KERN_SUCCESS);
  536 }
  537 
  538 /*
  539  *      kmem_back:
  540  *
  541  *      Allocate physical pages for the specified virtual address range.
  542  */
  543 int
  544 kmem_back(vm_object_t object, vm_offset_t addr, vm_size_t size, int flags)
  545 {
  546         vm_offset_t end, next, start;
  547         int domain, rv;
  548 
  549         KASSERT(object == kernel_object,
  550             ("kmem_back: only supports kernel object."));
  551 
  552         for (start = addr, end = addr + size; addr < end; addr = next) {
  553                 /*
  554                  * We must ensure that pages backing a given large virtual page
  555                  * all come from the same physical domain.
  556                  */
  557                 if (vm_ndomains > 1) {
  558                         domain = (addr >> KVA_QUANTUM_SHIFT) % vm_ndomains;
  559                         while (VM_DOMAIN_EMPTY(domain))
  560                                 domain++;
  561                         next = roundup2(addr + 1, KVA_QUANTUM);
  562                         if (next > end || next < start)
  563                                 next = end;
  564                 } else {
  565                         domain = 0;
  566                         next = end;
  567                 }
  568                 rv = kmem_back_domain(domain, object, addr, next - addr, flags);
  569                 if (rv != KERN_SUCCESS) {
  570                         kmem_unback(object, start, addr - start);
  571                         break;
  572                 }
  573         }
  574         return (rv);
  575 }
  576 
  577 /*
  578  *      kmem_unback:
  579  *
  580  *      Unmap and free the physical pages underlying the specified virtual
  581  *      address range.
  582  *
  583  *      A physical page must exist within the specified object at each index
  584  *      that is being unmapped.
  585  */
  586 static struct vmem *
  587 _kmem_unback(vm_object_t object, vm_offset_t addr, vm_size_t size)
  588 {
  589         struct vmem *arena;
  590         vm_page_t m, next;
  591         vm_offset_t end, offset;
  592         int domain;
  593 
  594         KASSERT(object == kernel_object,
  595             ("kmem_unback: only supports kernel object."));
  596 
  597         if (size == 0)
  598                 return (NULL);
  599         pmap_remove(kernel_pmap, addr, addr + size);
  600         offset = addr - VM_MIN_KERNEL_ADDRESS;
  601         end = offset + size;
  602         VM_OBJECT_WLOCK(object);
  603         m = vm_page_lookup(object, atop(offset)); 
  604         domain = vm_page_domain(m);
  605         if (__predict_true((m->oflags & VPO_KMEM_EXEC) == 0))
  606                 arena = vm_dom[domain].vmd_kernel_arena;
  607         else
  608                 arena = vm_dom[domain].vmd_kernel_rwx_arena;
  609         for (; offset < end; offset += PAGE_SIZE, m = next) {
  610                 next = vm_page_next(m);
  611                 vm_page_xbusy_claim(m);
  612                 vm_page_unwire_noq(m);
  613                 vm_page_free(m);
  614         }
  615         VM_OBJECT_WUNLOCK(object);
  616 
  617         return (arena);
  618 }
  619 
  620 void
  621 kmem_unback(vm_object_t object, vm_offset_t addr, vm_size_t size)
  622 {
  623 
  624         (void)_kmem_unback(object, addr, size);
  625 }
  626 
  627 /*
  628  *      kmem_free:
  629  *
  630  *      Free memory allocated with kmem_malloc.  The size must match the
  631  *      original allocation.
  632  */
  633 void
  634 kmem_free(void *addr, vm_size_t size)
  635 {
  636         struct vmem *arena;
  637 
  638         size = round_page(size);
  639         kasan_mark(addr, size, size, 0);
  640         arena = _kmem_unback(kernel_object, (uintptr_t)addr, size);
  641         if (arena != NULL)
  642                 vmem_free(arena, (uintptr_t)addr, size);
  643 }
  644 
  645 /*
  646  *      kmap_alloc_wait:
  647  *
  648  *      Allocates pageable memory from a sub-map of the kernel.  If the submap
  649  *      has no room, the caller sleeps waiting for more memory in the submap.
  650  *
  651  *      This routine may block.
  652  */
  653 vm_offset_t
  654 kmap_alloc_wait(vm_map_t map, vm_size_t size)
  655 {
  656         vm_offset_t addr;
  657 
  658         size = round_page(size);
  659         if (!swap_reserve(size))
  660                 return (0);
  661 
  662         for (;;) {
  663                 /*
  664                  * To make this work for more than one map, use the map's lock
  665                  * to lock out sleepers/wakers.
  666                  */
  667                 vm_map_lock(map);
  668                 addr = vm_map_findspace(map, vm_map_min(map), size);
  669                 if (addr + size <= vm_map_max(map))
  670                         break;
  671                 /* no space now; see if we can ever get space */
  672                 if (vm_map_max(map) - vm_map_min(map) < size) {
  673                         vm_map_unlock(map);
  674                         swap_release(size);
  675                         return (0);
  676                 }
  677                 map->needs_wakeup = TRUE;
  678                 vm_map_unlock_and_wait(map, 0);
  679         }
  680         vm_map_insert(map, NULL, 0, addr, addr + size, VM_PROT_RW, VM_PROT_RW,
  681             MAP_ACC_CHARGED);
  682         vm_map_unlock(map);
  683         return (addr);
  684 }
  685 
  686 /*
  687  *      kmap_free_wakeup:
  688  *
  689  *      Returns memory to a submap of the kernel, and wakes up any processes
  690  *      waiting for memory in that map.
  691  */
  692 void
  693 kmap_free_wakeup(vm_map_t map, vm_offset_t addr, vm_size_t size)
  694 {
  695 
  696         vm_map_lock(map);
  697         (void) vm_map_delete(map, trunc_page(addr), round_page(addr + size));
  698         if (map->needs_wakeup) {
  699                 map->needs_wakeup = FALSE;
  700                 vm_map_wakeup(map);
  701         }
  702         vm_map_unlock(map);
  703 }
  704 
  705 void
  706 kmem_init_zero_region(void)
  707 {
  708         vm_offset_t addr, i;
  709         vm_page_t m;
  710 
  711         /*
  712          * Map a single physical page of zeros to a larger virtual range.
  713          * This requires less looping in places that want large amounts of
  714          * zeros, while not using much more physical resources.
  715          */
  716         addr = kva_alloc(ZERO_REGION_SIZE);
  717         m = vm_page_alloc_noobj(VM_ALLOC_WIRED | VM_ALLOC_ZERO);
  718         for (i = 0; i < ZERO_REGION_SIZE; i += PAGE_SIZE)
  719                 pmap_qenter(addr + i, &m, 1);
  720         pmap_protect(kernel_pmap, addr, addr + ZERO_REGION_SIZE, VM_PROT_READ);
  721 
  722         zero_region = (const void *)addr;
  723 }
  724 
  725 /*
  726  * Import KVA from the kernel map into the kernel arena.
  727  */
  728 static int
  729 kva_import(void *unused, vmem_size_t size, int flags, vmem_addr_t *addrp)
  730 {
  731         vm_offset_t addr;
  732         int result;
  733 
  734         KASSERT((size % KVA_QUANTUM) == 0,
  735             ("kva_import: Size %jd is not a multiple of %d",
  736             (intmax_t)size, (int)KVA_QUANTUM));
  737         addr = vm_map_min(kernel_map);
  738         result = vm_map_find(kernel_map, NULL, 0, &addr, size, 0,
  739             VMFS_SUPER_SPACE, VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
  740         if (result != KERN_SUCCESS)
  741                 return (ENOMEM);
  742 
  743         *addrp = addr;
  744 
  745         return (0);
  746 }
  747 
  748 /*
  749  * Import KVA from a parent arena into a per-domain arena.  Imports must be
  750  * KVA_QUANTUM-aligned and a multiple of KVA_QUANTUM in size.
  751  */
  752 static int
  753 kva_import_domain(void *arena, vmem_size_t size, int flags, vmem_addr_t *addrp)
  754 {
  755 
  756         KASSERT((size % KVA_QUANTUM) == 0,
  757             ("kva_import_domain: Size %jd is not a multiple of %d",
  758             (intmax_t)size, (int)KVA_QUANTUM));
  759         return (vmem_xalloc(arena, size, KVA_QUANTUM, 0, 0, VMEM_ADDR_MIN,
  760             VMEM_ADDR_MAX, flags, addrp));
  761 }
  762 
  763 /*
  764  *      kmem_init:
  765  *
  766  *      Create the kernel map; insert a mapping covering kernel text, 
  767  *      data, bss, and all space allocated thus far (`boostrap' data).  The 
  768  *      new map will thus map the range between VM_MIN_KERNEL_ADDRESS and 
  769  *      `start' as allocated, and the range between `start' and `end' as free.
  770  *      Create the kernel vmem arena and its per-domain children.
  771  */
  772 void
  773 kmem_init(vm_offset_t start, vm_offset_t end)
  774 {
  775         vm_size_t quantum;
  776         int domain;
  777 
  778         vm_map_init(kernel_map, kernel_pmap, VM_MIN_KERNEL_ADDRESS, end);
  779         kernel_map->system_map = 1;
  780         vm_map_lock(kernel_map);
  781         /* N.B.: cannot use kgdb to debug, starting with this assignment ... */
  782         (void)vm_map_insert(kernel_map, NULL, 0,
  783 #ifdef __amd64__
  784             KERNBASE,
  785 #else                
  786             VM_MIN_KERNEL_ADDRESS,
  787 #endif
  788             start, VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
  789         /* ... and ending with the completion of the above `insert' */
  790 
  791 #ifdef __amd64__
  792         /*
  793          * Mark KVA used for the page array as allocated.  Other platforms
  794          * that handle vm_page_array allocation can simply adjust virtual_avail
  795          * instead.
  796          */
  797         (void)vm_map_insert(kernel_map, NULL, 0, (vm_offset_t)vm_page_array,
  798             (vm_offset_t)vm_page_array + round_2mpage(vm_page_array_size *
  799             sizeof(struct vm_page)),
  800             VM_PROT_RW, VM_PROT_RW, MAP_NOFAULT);
  801 #endif
  802         vm_map_unlock(kernel_map);
  803 
  804         /*
  805          * Use a large import quantum on NUMA systems.  This helps minimize
  806          * interleaving of superpages, reducing internal fragmentation within
  807          * the per-domain arenas.
  808          */
  809         if (vm_ndomains > 1 && PMAP_HAS_DMAP)
  810                 quantum = KVA_NUMA_IMPORT_QUANTUM;
  811         else
  812                 quantum = KVA_QUANTUM;
  813 
  814         /*
  815          * Initialize the kernel_arena.  This can grow on demand.
  816          */
  817         vmem_init(kernel_arena, "kernel arena", 0, 0, PAGE_SIZE, 0, 0);
  818         vmem_set_import(kernel_arena, kva_import, NULL, NULL, quantum);
  819 
  820         for (domain = 0; domain < vm_ndomains; domain++) {
  821                 /*
  822                  * Initialize the per-domain arenas.  These are used to color
  823                  * the KVA space in a way that ensures that virtual large pages
  824                  * are backed by memory from the same physical domain,
  825                  * maximizing the potential for superpage promotion.
  826                  */
  827                 vm_dom[domain].vmd_kernel_arena = vmem_create(
  828                     "kernel arena domain", 0, 0, PAGE_SIZE, 0, M_WAITOK);
  829                 vmem_set_import(vm_dom[domain].vmd_kernel_arena,
  830                     kva_import_domain, NULL, kernel_arena, quantum);
  831 
  832                 /*
  833                  * In architectures with superpages, maintain separate arenas
  834                  * for allocations with permissions that differ from the
  835                  * "standard" read/write permissions used for kernel memory,
  836                  * so as not to inhibit superpage promotion.
  837                  *
  838                  * Use the base import quantum since this arena is rarely used.
  839                  */
  840 #if VM_NRESERVLEVEL > 0
  841                 vm_dom[domain].vmd_kernel_rwx_arena = vmem_create(
  842                     "kernel rwx arena domain", 0, 0, PAGE_SIZE, 0, M_WAITOK);
  843                 vmem_set_import(vm_dom[domain].vmd_kernel_rwx_arena,
  844                     kva_import_domain, (vmem_release_t *)vmem_xfree,
  845                     kernel_arena, KVA_QUANTUM);
  846 #else
  847                 vm_dom[domain].vmd_kernel_rwx_arena =
  848                     vm_dom[domain].vmd_kernel_arena;
  849 #endif
  850         }
  851 
  852         /*
  853          * This must be the very first call so that the virtual address
  854          * space used for early allocations is properly marked used in
  855          * the map.
  856          */
  857         uma_startup2();
  858 }
  859 
  860 /*
  861  *      kmem_bootstrap_free:
  862  *
  863  *      Free pages backing preloaded data (e.g., kernel modules) to the
  864  *      system.  Currently only supported on platforms that create a
  865  *      vm_phys segment for preloaded data.
  866  */
  867 void
  868 kmem_bootstrap_free(vm_offset_t start, vm_size_t size)
  869 {
  870 #if defined(__i386__) || defined(__amd64__)
  871         struct vm_domain *vmd;
  872         vm_offset_t end, va;
  873         vm_paddr_t pa;
  874         vm_page_t m;
  875 
  876         end = trunc_page(start + size);
  877         start = round_page(start);
  878 
  879 #ifdef __amd64__
  880         /*
  881          * Preloaded files do not have execute permissions by default on amd64.
  882          * Restore the default permissions to ensure that the direct map alias
  883          * is updated.
  884          */
  885         pmap_change_prot(start, end - start, VM_PROT_RW);
  886 #endif
  887         for (va = start; va < end; va += PAGE_SIZE) {
  888                 pa = pmap_kextract(va);
  889                 m = PHYS_TO_VM_PAGE(pa);
  890 
  891                 vmd = vm_pagequeue_domain(m);
  892                 vm_domain_free_lock(vmd);
  893                 vm_phys_free_pages(m, 0);
  894                 vm_domain_free_unlock(vmd);
  895 
  896                 vm_domain_freecnt_inc(vmd, 1);
  897                 vm_cnt.v_page_count++;
  898         }
  899         pmap_remove(kernel_pmap, start, end);
  900         (void)vmem_add(kernel_arena, start, end - start, M_WAITOK);
  901 #endif
  902 }
  903 
  904 /*
  905  * Allow userspace to directly trigger the VM drain routine for testing
  906  * purposes.
  907  */
  908 static int
  909 debug_vm_lowmem(SYSCTL_HANDLER_ARGS)
  910 {
  911         int error, i;
  912 
  913         i = 0;
  914         error = sysctl_handle_int(oidp, &i, 0, req);
  915         if (error != 0)
  916                 return (error);
  917         if ((i & ~(VM_LOW_KMEM | VM_LOW_PAGES)) != 0)
  918                 return (EINVAL);
  919         if (i != 0)
  920                 EVENTHANDLER_INVOKE(vm_lowmem, i);
  921         return (0);
  922 }
  923 SYSCTL_PROC(_debug, OID_AUTO, vm_lowmem,
  924     CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, 0, 0, debug_vm_lowmem, "I",
  925     "set to trigger vm_lowmem event with given flags");
  926 
  927 static int
  928 debug_uma_reclaim(SYSCTL_HANDLER_ARGS)
  929 {
  930         int error, i;
  931 
  932         i = 0;
  933         error = sysctl_handle_int(oidp, &i, 0, req);
  934         if (error != 0 || req->newptr == NULL)
  935                 return (error);
  936         if (i != UMA_RECLAIM_TRIM && i != UMA_RECLAIM_DRAIN &&
  937             i != UMA_RECLAIM_DRAIN_CPU)
  938                 return (EINVAL);
  939         uma_reclaim(i);
  940         return (0);
  941 }
  942 SYSCTL_PROC(_debug, OID_AUTO, uma_reclaim,
  943     CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, 0, 0, debug_uma_reclaim, "I",
  944     "set to generate request to reclaim uma caches");
  945 
  946 static int
  947 debug_uma_reclaim_domain(SYSCTL_HANDLER_ARGS)
  948 {
  949         int domain, error, request;
  950 
  951         request = 0;
  952         error = sysctl_handle_int(oidp, &request, 0, req);
  953         if (error != 0 || req->newptr == NULL)
  954                 return (error);
  955 
  956         domain = request >> 4;
  957         request &= 0xf;
  958         if (request != UMA_RECLAIM_TRIM && request != UMA_RECLAIM_DRAIN &&
  959             request != UMA_RECLAIM_DRAIN_CPU)
  960                 return (EINVAL);
  961         if (domain < 0 || domain >= vm_ndomains)
  962                 return (EINVAL);
  963         uma_reclaim_domain(request, domain);
  964         return (0);
  965 }
  966 SYSCTL_PROC(_debug, OID_AUTO, uma_reclaim_domain,
  967     CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, 0, 0,
  968     debug_uma_reclaim_domain, "I",
  969     "");

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