/* $OpenBSD: uvm_km.c,v 1.64 2007/08/03 22:49:07 art Exp $ */ /* $NetBSD: uvm_km.c,v 1.42 2001/01/14 02:10:01 thorpej Exp $ */ /* * Copyright (c) 1997 Charles D. Cranor and Washington University. * Copyright (c) 1991, 1993, The Regents of the University of California. * * All rights reserved. * * This code is derived from software contributed to Berkeley by * The Mach Operating System project at Carnegie-Mellon University. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Charles D. Cranor, * Washington University, the University of California, Berkeley and * its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)vm_kern.c 8.3 (Berkeley) 1/12/94 * from: Id: uvm_km.c,v 1.1.2.14 1998/02/06 05:19:27 chs Exp * * * Copyright (c) 1987, 1990 Carnegie-Mellon University. * All rights reserved. * * Permission to use, copy, modify and distribute this software and * its documentation is hereby granted, provided that both the copyright * notice and this permission notice appear in all copies of the * software, derivative works or modified versions, and any portions * thereof, and that both notices appear in supporting documentation. * * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. * * Carnegie Mellon requests users of this software to return to * * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU * School of Computer Science * Carnegie Mellon University * Pittsburgh PA 15213-3890 * * any improvements or extensions that they make and grant Carnegie the * rights to redistribute these changes. */ /* * uvm_km.c: handle kernel memory allocation and management */ /* * overview of kernel memory management: * * the kernel virtual address space is mapped by "kernel_map." kernel_map * starts at VM_MIN_KERNEL_ADDRESS and goes to VM_MAX_KERNEL_ADDRESS. * note that VM_MIN_KERNEL_ADDRESS is equal to vm_map_min(kernel_map). * * the kernel_map has several "submaps." submaps can only appear in * the kernel_map (user processes can't use them). submaps "take over" * the management of a sub-range of the kernel's address space. submaps * are typically allocated at boot time and are never released. kernel * virtual address space that is mapped by a submap is locked by the * submap's lock -- not the kernel_map's lock. * * thus, the useful feature of submaps is that they allow us to break * up the locking and protection of the kernel address space into smaller * chunks. * * the vm system has several standard kernel submaps, including: * kmem_map => contains only wired kernel memory for the kernel * malloc. *** access to kmem_map must be protected * by splvm() because we are allowed to call malloc() * at interrupt time *** * pager_map => used to map "buf" structures into kernel space * exec_map => used during exec to handle exec args * etc... * * the kernel allocates its private memory out of special uvm_objects whose * reference count is set to UVM_OBJ_KERN (thus indicating that the objects * are "special" and never die). all kernel objects should be thought of * as large, fixed-sized, sparsely populated uvm_objects. each kernel * object is equal to the size of kernel virtual address space (i.e. the * value "VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS"). * * most kernel private memory lives in kernel_object. the only exception * to this is for memory that belongs to submaps that must be protected * by splvm(). each of these submaps manages their own pages. * * note that just because a kernel object spans the entire kernel virtual * address space doesn't mean that it has to be mapped into the entire space. * large chunks of a kernel object's space go unused either because * that area of kernel VM is unmapped, or there is some other type of * object mapped into that range (e.g. a vnode). for submap's kernel * objects, the only part of the object that can ever be populated is the * offsets that are managed by the submap. * * note that the "offset" in a kernel object is always the kernel virtual * address minus the VM_MIN_KERNEL_ADDRESS (aka vm_map_min(kernel_map)). * example: * suppose VM_MIN_KERNEL_ADDRESS is 0xf8000000 and the kernel does a * uvm_km_alloc(kernel_map, PAGE_SIZE) [allocate 1 wired down page in the * kernel map]. if uvm_km_alloc returns virtual address 0xf8235000, * then that means that the page at offset 0x235000 in kernel_object is * mapped at 0xf8235000. * * kernel objects have one other special property: when the kernel virtual * memory mapping them is unmapped, the backing memory in the object is * freed right away. this is done with the uvm_km_pgremove() function. * this has to be done because there is no backing store for kernel pages * and no need to save them after they are no longer referenced. */ #include #include #include #include #include /* * global data structures */ struct vm_map *kernel_map = NULL; /* * local data structues */ static struct vm_map kernel_map_store; /* * uvm_km_init: init kernel maps and objects to reflect reality (i.e. * KVM already allocated for text, data, bss, and static data structures). * * => KVM is defined by VM_MIN_KERNEL_ADDRESS/VM_MAX_KERNEL_ADDRESS. * we assume that [min -> start] has already been allocated and that * "end" is the end. */ void uvm_km_init(vaddr_t start, vaddr_t end) { vaddr_t base = VM_MIN_KERNEL_ADDRESS; /* * next, init kernel memory objects. */ /* kernel_object: for pageable anonymous kernel memory */ uao_init(); uvm.kernel_object = uao_create(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS, UAO_FLAG_KERNOBJ); /* * init the map and reserve already allocated kernel space * before installing. */ uvm_map_setup(&kernel_map_store, base, end, VM_MAP_PAGEABLE); kernel_map_store.pmap = pmap_kernel(); if (base != start && uvm_map(&kernel_map_store, &base, start - base, NULL, UVM_UNKNOWN_OFFSET, 0, UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE, UVM_ADV_RANDOM,UVM_FLAG_FIXED)) != 0) panic("uvm_km_init: could not reserve space for kernel"); /* * install! */ kernel_map = &kernel_map_store; } /* * uvm_km_suballoc: allocate a submap in the kernel map. once a submap * is allocated all references to that area of VM must go through it. this * allows the locking of VAs in kernel_map to be broken up into regions. * * => if `fixed' is true, *min specifies where the region described * by the submap must start * => if submap is non NULL we use that as the submap, otherwise we * alloc a new map */ struct vm_map * uvm_km_suballoc(struct vm_map *map, vaddr_t *min, vaddr_t *max, vsize_t size, int flags, boolean_t fixed, struct vm_map *submap) { int mapflags = UVM_FLAG_NOMERGE | (fixed ? UVM_FLAG_FIXED : 0); size = round_page(size); /* round up to pagesize */ /* * first allocate a blank spot in the parent map */ if (uvm_map(map, min, size, NULL, UVM_UNKNOWN_OFFSET, 0, UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE, UVM_ADV_RANDOM, mapflags)) != 0) { panic("uvm_km_suballoc: unable to allocate space in parent map"); } /* * set VM bounds (min is filled in by uvm_map) */ *max = *min + size; /* * add references to pmap and create or init the submap */ pmap_reference(vm_map_pmap(map)); if (submap == NULL) { submap = uvm_map_create(vm_map_pmap(map), *min, *max, flags); if (submap == NULL) panic("uvm_km_suballoc: unable to create submap"); } else { uvm_map_setup(submap, *min, *max, flags); submap->pmap = vm_map_pmap(map); } /* * now let uvm_map_submap plug in it... */ if (uvm_map_submap(map, *min, *max, submap) != 0) panic("uvm_km_suballoc: submap allocation failed"); return(submap); } /* * uvm_km_pgremove: remove pages from a kernel uvm_object. * * => when you unmap a part of anonymous kernel memory you want to toss * the pages right away. (this gets called from uvm_unmap_...). */ void uvm_km_pgremove(struct uvm_object *uobj, vaddr_t start, vaddr_t end) { struct vm_page *pp; voff_t curoff; UVMHIST_FUNC("uvm_km_pgremove"); UVMHIST_CALLED(maphist); KASSERT(uobj->pgops == &aobj_pager); for (curoff = start ; curoff < end ; curoff += PAGE_SIZE) { pp = uvm_pagelookup(uobj, curoff); if (pp == NULL) continue; UVMHIST_LOG(maphist," page %p, busy=%ld", pp, pp->pg_flags & PG_BUSY, 0, 0); if (pp->pg_flags & PG_BUSY) { /* owner must check for this when done */ atomic_setbits_int(&pp->pg_flags, PG_RELEASED); } else { /* free the swap slot... */ uao_dropswap(uobj, curoff >> PAGE_SHIFT); /* * ...and free the page; note it may be on the * active or inactive queues. */ uvm_lock_pageq(); uvm_pagefree(pp); uvm_unlock_pageq(); } } } /* * uvm_km_pgremove_intrsafe: like uvm_km_pgremove(), but for "intrsafe" * objects * * => when you unmap a part of anonymous kernel memory you want to toss * the pages right away. (this gets called from uvm_unmap_...). * => none of the pages will ever be busy, and none of them will ever * be on the active or inactive queues (because these objects are * never allowed to "page"). */ void uvm_km_pgremove_intrsafe(vaddr_t start, vaddr_t end) { struct vm_page *pg; vaddr_t va; paddr_t pa; for (va = start; va < end; va += PAGE_SIZE) { if (!pmap_extract(pmap_kernel(), va, &pa)) continue; pg = PHYS_TO_VM_PAGE(pa); if (pg == NULL) panic("uvm_km_pgremove_intrsafe: no page"); uvm_pagefree(pg); } } /* * uvm_km_kmemalloc: lower level kernel memory allocator for malloc() * * => we map wired memory into the specified map using the obj passed in * => NOTE: we can return NULL even if we can wait if there is not enough * free VM space in the map... caller should be prepared to handle * this case. * => we return KVA of memory allocated * => flags: NOWAIT, VALLOC - just allocate VA, TRYLOCK - fail if we can't * lock the map */ vaddr_t uvm_km_kmemalloc(struct vm_map *map, struct uvm_object *obj, vsize_t size, int flags) { vaddr_t kva, loopva; voff_t offset; struct vm_page *pg; UVMHIST_FUNC("uvm_km_kmemalloc"); UVMHIST_CALLED(maphist); UVMHIST_LOG(maphist," (map=%p, obj=%p, size=0x%lx, flags=%d)", map, obj, size, flags); KASSERT(vm_map_pmap(map) == pmap_kernel()); /* * setup for call */ size = round_page(size); kva = vm_map_min(map); /* hint */ /* * allocate some virtual space */ if (__predict_false(uvm_map(map, &kva, size, obj, UVM_UNKNOWN_OFFSET, 0, UVM_MAPFLAG(UVM_PROT_RW, UVM_PROT_RW, UVM_INH_NONE, UVM_ADV_RANDOM, (flags & UVM_KMF_TRYLOCK))) != 0)) { UVMHIST_LOG(maphist, "<- done (no VM)",0,0,0,0); return(0); } /* * if all we wanted was VA, return now */ if (flags & UVM_KMF_VALLOC) { UVMHIST_LOG(maphist,"<- done valloc (kva=0x%lx)", kva,0,0,0); return(kva); } /* * recover object offset from virtual address */ if (obj != NULL) offset = kva - vm_map_min(kernel_map); else offset = 0; UVMHIST_LOG(maphist, " kva=0x%lx, offset=0x%lx", kva, offset,0,0); /* * now allocate and map in the memory... note that we are the only ones * whom should ever get a handle on this area of VM. */ loopva = kva; while (loopva != kva + size) { pg = uvm_pagealloc(obj, offset, NULL, 0); if (pg) { atomic_clearbits_int(&pg->pg_flags, PG_BUSY); UVM_PAGE_OWN(pg, NULL); } if (__predict_false(pg == NULL)) { if ((flags & UVM_KMF_NOWAIT) || ((flags & UVM_KMF_CANFAIL) && uvmexp.swpgonly == uvmexp.swpages)) { /* free everything! */ uvm_unmap(map, kva, kva + size); return (0); } else { uvm_wait("km_getwait2"); /* sleep here */ continue; } } /* * map it in: note that we call pmap_enter with the map and * object unlocked in case we are kmem_map. */ if (obj == NULL) { pmap_kenter_pa(loopva, VM_PAGE_TO_PHYS(pg), UVM_PROT_RW); } else { pmap_enter(map->pmap, loopva, VM_PAGE_TO_PHYS(pg), UVM_PROT_RW, PMAP_WIRED | VM_PROT_READ | VM_PROT_WRITE); } loopva += PAGE_SIZE; offset += PAGE_SIZE; } pmap_update(pmap_kernel()); UVMHIST_LOG(maphist,"<- done (kva=0x%lx)", kva,0,0,0); return(kva); } /* * uvm_km_free: free an area of kernel memory */ void uvm_km_free(struct vm_map *map, vaddr_t addr, vsize_t size) { uvm_unmap(map, trunc_page(addr), round_page(addr+size)); } /* * uvm_km_free_wakeup: free an area of kernel memory and wake up * anyone waiting for vm space. * * => XXX: "wanted" bit + unlock&wait on other end? */ void uvm_km_free_wakeup(struct vm_map *map, vaddr_t addr, vsize_t size) { struct vm_map_entry *dead_entries; vm_map_lock(map); uvm_unmap_remove(map, trunc_page(addr), round_page(addr+size), &dead_entries, NULL); wakeup(map); vm_map_unlock(map); if (dead_entries != NULL) uvm_unmap_detach(dead_entries, 0); } /* * uvm_km_alloc1: allocate wired down memory in the kernel map. * * => we can sleep if needed */ vaddr_t uvm_km_alloc1(struct vm_map *map, vsize_t size, vsize_t align, boolean_t zeroit) { vaddr_t kva, loopva; voff_t offset; struct vm_page *pg; UVMHIST_FUNC("uvm_km_alloc1"); UVMHIST_CALLED(maphist); UVMHIST_LOG(maphist,"(map=%p, size=0x%lx)", map, size,0,0); KASSERT(vm_map_pmap(map) == pmap_kernel()); size = round_page(size); kva = vm_map_min(map); /* hint */ /* * allocate some virtual space */ if (__predict_false(uvm_map(map, &kva, size, uvm.kernel_object, UVM_UNKNOWN_OFFSET, align, UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE, UVM_ADV_RANDOM, 0)) != 0)) { UVMHIST_LOG(maphist,"<- done (no VM)",0,0,0,0); return(0); } /* * recover object offset from virtual address */ offset = kva - vm_map_min(kernel_map); UVMHIST_LOG(maphist," kva=0x%lx, offset=0x%lx", kva, offset,0,0); /* * now allocate the memory. we must be careful about released pages. */ loopva = kva; while (size) { simple_lock(&uvm.kernel_object->vmobjlock); pg = uvm_pagelookup(uvm.kernel_object, offset); /* * if we found a page in an unallocated region, it must be * released */ if (pg) { if ((pg->pg_flags & PG_RELEASED) == 0) panic("uvm_km_alloc1: non-released page"); atomic_setbits_int(&pg->pg_flags, PG_WANTED); UVM_UNLOCK_AND_WAIT(pg, &uvm.kernel_object->vmobjlock, FALSE, "km_alloc", 0); continue; /* retry */ } /* allocate ram */ pg = uvm_pagealloc(uvm.kernel_object, offset, NULL, 0); if (pg) { atomic_clearbits_int(&pg->pg_flags, PG_BUSY); UVM_PAGE_OWN(pg, NULL); } simple_unlock(&uvm.kernel_object->vmobjlock); if (__predict_false(pg == NULL)) { if (curproc == uvm.pagedaemon_proc) { /* * It is unfeasible for the page daemon to * sleep for memory, so free what we have * allocated and fail. */ uvm_unmap(map, kva, loopva - kva); return (NULL); } else { uvm_wait("km_alloc1w"); /* wait for memory */ continue; } } /* * map it in; note we're never called with an intrsafe * object, so we always use regular old pmap_enter(). */ pmap_enter(map->pmap, loopva, VM_PAGE_TO_PHYS(pg), UVM_PROT_ALL, PMAP_WIRED | VM_PROT_READ | VM_PROT_WRITE); loopva += PAGE_SIZE; offset += PAGE_SIZE; size -= PAGE_SIZE; } pmap_update(map->pmap); /* * zero on request (note that "size" is now zero due to the above loop * so we need to subtract kva from loopva to reconstruct the size). */ if (zeroit) memset((caddr_t)kva, 0, loopva - kva); UVMHIST_LOG(maphist,"<- done (kva=0x%lx)", kva,0,0,0); return(kva); } /* * uvm_km_valloc: allocate zero-fill memory in the kernel's address space * * => memory is not allocated until fault time */ vaddr_t uvm_km_valloc(struct vm_map *map, vsize_t size) { return(uvm_km_valloc_align(map, size, 0)); } vaddr_t uvm_km_valloc_align(struct vm_map *map, vsize_t size, vsize_t align) { vaddr_t kva; UVMHIST_FUNC("uvm_km_valloc"); UVMHIST_CALLED(maphist); UVMHIST_LOG(maphist, "(map=%p, size=0x%lx)", map, size, 0,0); KASSERT(vm_map_pmap(map) == pmap_kernel()); size = round_page(size); kva = vm_map_min(map); /* hint */ /* * allocate some virtual space. will be demand filled by kernel_object. */ if (__predict_false(uvm_map(map, &kva, size, uvm.kernel_object, UVM_UNKNOWN_OFFSET, align, UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE, UVM_ADV_RANDOM, 0)) != 0)) { UVMHIST_LOG(maphist, "<- done (no VM)", 0,0,0,0); return(0); } UVMHIST_LOG(maphist, "<- done (kva=0x%lx)", kva,0,0,0); return(kva); } /* * uvm_km_valloc_wait: allocate zero-fill memory in the kernel's address space * * => memory is not allocated until fault time * => if no room in map, wait for space to free, unless requested size * is larger than map (in which case we return 0) */ vaddr_t uvm_km_valloc_prefer_wait(struct vm_map *map, vsize_t size, voff_t prefer) { vaddr_t kva; UVMHIST_FUNC("uvm_km_valloc_prefer_wait"); UVMHIST_CALLED(maphist); UVMHIST_LOG(maphist, "(map=%p, size=0x%lx)", map, size, 0,0); KASSERT(vm_map_pmap(map) == pmap_kernel()); size = round_page(size); if (size > vm_map_max(map) - vm_map_min(map)) return(0); while (1) { kva = vm_map_min(map); /* hint */ /* * allocate some virtual space. will be demand filled * by kernel_object. */ if (__predict_true(uvm_map(map, &kva, size, uvm.kernel_object, prefer, 0, UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE, UVM_ADV_RANDOM, 0)) == 0)) { UVMHIST_LOG(maphist,"<- done (kva=0x%lx)", kva,0,0,0); return(kva); } /* * failed. sleep for a while (on map) */ UVMHIST_LOG(maphist,"<<>>",0,0,0,0); tsleep((caddr_t)map, PVM, "vallocwait", 0); } /*NOTREACHED*/ } vaddr_t uvm_km_valloc_wait(struct vm_map *map, vsize_t size) { return uvm_km_valloc_prefer_wait(map, size, UVM_UNKNOWN_OFFSET); } /* * uvm_km_alloc_poolpage: allocate a page for the pool allocator * * => if the pmap specifies an alternate mapping method, we use it. */ /* ARGSUSED */ vaddr_t uvm_km_alloc_poolpage1(struct vm_map *map, struct uvm_object *obj, boolean_t waitok) { #if defined(__HAVE_PMAP_DIRECT) struct vm_page *pg; vaddr_t va; again: pg = uvm_pagealloc(NULL, 0, NULL, UVM_PGA_USERESERVE); if (__predict_false(pg == NULL)) { if (waitok) { uvm_wait("plpg"); goto again; } else return (0); } va = pmap_map_direct(pg); if (__predict_false(va == 0)) uvm_pagefree(pg); return (va); #else vaddr_t va; int s; /* * NOTE: We may be called with a map that doesn't require splvm * protection (e.g. kernel_map). However, it does not hurt to * go to splvm in this case (since unprotected maps will never be * accessed in interrupt context). * * XXX We may want to consider changing the interface to this * XXX function. */ s = splvm(); va = uvm_km_kmemalloc(map, obj, PAGE_SIZE, waitok ? 0 : UVM_KMF_NOWAIT); splx(s); return (va); #endif /* __HAVE_PMAP_DIRECT */ } /* * uvm_km_free_poolpage: free a previously allocated pool page * * => if the pmap specifies an alternate unmapping method, we use it. */ /* ARGSUSED */ void uvm_km_free_poolpage1(struct vm_map *map, vaddr_t addr) { #if defined(__HAVE_PMAP_DIRECT) uvm_pagefree(pmap_unmap_direct(addr)); #else int s; /* * NOTE: We may be called with a map that doesn't require splvm * protection (e.g. kernel_map). However, it does not hurt to * go to splvm in this case (since unprocted maps will never be * accessed in interrupt context). * * XXX We may want to consider changing the interface to this * XXX function. */ s = splvm(); uvm_km_free(map, addr, PAGE_SIZE); splx(s); #endif /* __HAVE_PMAP_DIRECT */ } #if defined(__HAVE_PMAP_DIRECT) /* * uvm_km_page allocator, __HAVE_PMAP_DIRECT arch * On architectures with machine memory direct mapped into a portion * of KVM, we have very little work to do. Just get a physical page, * and find and return its VA. We use the poolpage functions for this. */ void uvm_km_page_init(void) { /* nothing */ } void * uvm_km_getpage(boolean_t waitok) { return ((void *)uvm_km_alloc_poolpage1(NULL, NULL, waitok)); } void uvm_km_putpage(void *v) { uvm_km_free_poolpage1(NULL, (vaddr_t)v); } #else /* * uvm_km_page allocator, non __HAVE_PMAP_DIRECT archs * This is a special allocator that uses a reserve of free pages * to fulfill requests. It is fast and interrupt safe, but can only * return page sized regions. Its primary use is as a backend for pool. * * The memory returned is allocated from the larger kernel_map, sparing * pressure on the small interrupt-safe kmem_map. It is wired, but * not zero filled. */ int uvm_km_pages_lowat; /* allocate more when reserve drops below this */ int uvm_km_pages_free; /* number of pages currently on free list */ struct km_page { struct km_page *next; } *uvm_km_pages_head; void uvm_km_createthread(void *); void uvm_km_thread(void *); /* * Allocate the initial reserve, and create the thread which will * keep the reserve full. For bootstrapping, we allocate more than * the lowat amount, because it may be a while before the thread is * running. */ void uvm_km_page_init(void) { struct km_page *page; int i; if (!uvm_km_pages_lowat) { /* based on physmem, calculate a good value here */ uvm_km_pages_lowat = physmem / 256; if (uvm_km_pages_lowat > 2048) uvm_km_pages_lowat = 2048; if (uvm_km_pages_lowat < 128) uvm_km_pages_lowat = 128; } for (i = 0; i < uvm_km_pages_lowat * 4; i++) { page = (void *)uvm_km_alloc(kernel_map, PAGE_SIZE); page->next = uvm_km_pages_head; uvm_km_pages_head = page; } uvm_km_pages_free = i; /* tone down if really high */ if (uvm_km_pages_lowat > 512) uvm_km_pages_lowat = 512; kthread_create_deferred(uvm_km_createthread, NULL); } void uvm_km_createthread(void *arg) { kthread_create(uvm_km_thread, NULL, NULL, "kmthread"); } /* * Endless loop. We grab pages in increments of 16 pages, then * quickly swap them into the list. At some point we can consider * returning memory to the system if we have too many free pages, * but that's not implemented yet. */ void uvm_km_thread(void *arg) { struct km_page *head, *tail, *page; int i, s, want; for (i = want = 16; ; ) { if (i < want || uvm_km_pages_free >= uvm_km_pages_lowat) tsleep(&uvm_km_pages_head, PVM, "kmalloc", 0); for (i = 0; i < want; i++) { page = (void *)uvm_km_alloc(kernel_map, PAGE_SIZE); if (i == 0) head = tail = page; if (page == NULL) break; page->next = head; head = page; } if (head != NULL) { s = splvm(); tail->next = uvm_km_pages_head; uvm_km_pages_head = head; uvm_km_pages_free += i; splx(s); } if (uvm_km_pages_free) wakeup(&uvm_km_pages_free); } } /* * Allocate one page. We can sleep for more if the caller * permits it. Wake up the thread if we've dropped below lowat. */ void * uvm_km_getpage(boolean_t waitok) { struct km_page *page = NULL; int s; s = splvm(); for (;;) { page = uvm_km_pages_head; if (page) { uvm_km_pages_head = page->next; uvm_km_pages_free--; break; } if (!waitok) break; tsleep(&uvm_km_pages_free, PVM, "getpage", 0); } splx(s); if (uvm_km_pages_free < uvm_km_pages_lowat) wakeup(&uvm_km_pages_head); return (page); } void uvm_km_putpage(void *v) { struct km_page *page = v; int s; s = splvm(); page->next = uvm_km_pages_head; uvm_km_pages_head = page; uvm_km_pages_free++; splx(s); } #endif