1 /* 2 * Copyright 2008-2011, Ingo Weinhold, ingo_weinhold@gmx.de. 3 * Copyright 2002-2008, Axel Dörfler, axeld@pinc-software.de. 4 * Distributed under the terms of the MIT License. 5 * 6 * Copyright 2001-2002, Travis Geiselbrecht. All rights reserved. 7 * Distributed under the terms of the NewOS License. 8 */ 9 10 #include "VMAnonymousNoSwapCache.h" 11 12 #include <stdlib.h> 13 14 #include <arch_config.h> 15 #include <heap.h> 16 #include <KernelExport.h> 17 #include <slab/Slab.h> 18 #include <vm/vm_priv.h> 19 #include <vm/VMAddressSpace.h> 20 21 22 //#define TRACE_STORE 23 #ifdef TRACE_STORE 24 # define TRACE(x) dprintf x 25 #else 26 # define TRACE(x) ; 27 #endif 28 29 // The stack functionality looks like a good candidate to put into its own 30 // store. I have not done this because once we have a swap file backing up 31 // the memory, it would probably not be a good idea to separate this 32 // anymore. 33 34 35 VMAnonymousNoSwapCache::~VMAnonymousNoSwapCache() 36 { 37 vm_unreserve_memory(committed_size); 38 } 39 40 41 status_t 42 VMAnonymousNoSwapCache::Init(bool canOvercommit, int32 numPrecommittedPages, 43 int32 numGuardPages, uint32 allocationFlags) 44 { 45 TRACE(("VMAnonymousNoSwapCache::Init(canOvercommit = %s, numGuardPages = %ld) " 46 "at %p\n", canOvercommit ? "yes" : "no", numGuardPages, store)); 47 48 status_t error = VMCache::Init(CACHE_TYPE_RAM, allocationFlags); 49 if (error != B_OK) 50 return error; 51 52 fCanOvercommit = canOvercommit; 53 fHasPrecommitted = false; 54 fPrecommittedPages = min_c(numPrecommittedPages, 255); 55 fGuardedSize = numGuardPages * B_PAGE_SIZE; 56 57 return B_OK; 58 } 59 60 61 status_t 62 VMAnonymousNoSwapCache::Commit(off_t size, int priority) 63 { 64 // If we can overcommit, we don't commit here, but in Fault(). We always 65 // unreserve memory, if we're asked to shrink our commitment, though. 66 if (fCanOvercommit && size > committed_size) { 67 if (fHasPrecommitted) 68 return B_OK; 69 70 // pre-commit some pages to make a later failure less probable 71 fHasPrecommitted = true; 72 uint32 precommitted = fPrecommittedPages * B_PAGE_SIZE; 73 if (size > precommitted) 74 size = precommitted; 75 } 76 77 // Check to see how much we could commit - we need real memory 78 79 if (size > committed_size) { 80 // try to commit 81 if (vm_try_reserve_memory(size - committed_size, priority, 1000000) 82 != B_OK) { 83 return B_NO_MEMORY; 84 } 85 } else { 86 // we can release some 87 vm_unreserve_memory(committed_size - size); 88 } 89 90 committed_size = size; 91 return B_OK; 92 } 93 94 95 bool 96 VMAnonymousNoSwapCache::HasPage(off_t offset) 97 { 98 return false; 99 } 100 101 102 status_t 103 VMAnonymousNoSwapCache::Read(off_t offset, const iovec* vecs, size_t count, 104 uint32 flags, size_t* _numBytes) 105 { 106 panic("anonymous_store: read called. Invalid!\n"); 107 return B_ERROR; 108 } 109 110 111 status_t 112 VMAnonymousNoSwapCache::Write(off_t offset, const iovec* vecs, size_t count, 113 uint32 flags, size_t* _numBytes) 114 { 115 // no place to write, this will cause the page daemon to skip this store 116 return B_ERROR; 117 } 118 119 120 status_t 121 VMAnonymousNoSwapCache::Fault(struct VMAddressSpace* aspace, off_t offset) 122 { 123 if (fCanOvercommit) { 124 if (fGuardedSize > 0) { 125 uint32 guardOffset; 126 127 #ifdef STACK_GROWS_DOWNWARDS 128 guardOffset = 0; 129 #elif defined(STACK_GROWS_UPWARDS) 130 guardOffset = virtual_size - fGuardedSize; 131 #else 132 # error Stack direction has not been defined in arch_config.h 133 #endif 134 135 // report stack fault, guard page hit! 136 if (offset >= guardOffset && offset < guardOffset + fGuardedSize) { 137 TRACE(("stack overflow!\n")); 138 return B_BAD_ADDRESS; 139 } 140 } 141 142 if (fPrecommittedPages == 0) { 143 // never commit more than needed 144 if (committed_size / B_PAGE_SIZE > page_count) 145 return B_BAD_HANDLER; 146 147 // try to commit additional memory 148 int priority = aspace == VMAddressSpace::Kernel() 149 ? VM_PRIORITY_SYSTEM : VM_PRIORITY_USER; 150 if (vm_try_reserve_memory(B_PAGE_SIZE, priority, 0) != B_OK) { 151 dprintf("%p->VMAnonymousNoSwapCache::Fault(): Failed to " 152 "reserve %d bytes of RAM.\n", this, (int)B_PAGE_SIZE); 153 return B_NO_MEMORY; 154 } 155 156 committed_size += B_PAGE_SIZE; 157 } else 158 fPrecommittedPages--; 159 } 160 161 // This will cause vm_soft_fault() to handle the fault 162 return B_BAD_HANDLER; 163 } 164 165 166 void 167 VMAnonymousNoSwapCache::MergeStore(VMCache* _source) 168 { 169 VMAnonymousNoSwapCache* source 170 = dynamic_cast<VMAnonymousNoSwapCache*>(_source); 171 if (source == NULL) { 172 panic("VMAnonymousNoSwapCache::MergeStore(): merge with incompatible " 173 "cache %p requested", _source); 174 return; 175 } 176 177 // take over the source' committed size 178 committed_size += source->committed_size; 179 source->committed_size = 0; 180 181 off_t actualSize = virtual_end - virtual_base; 182 if (committed_size > actualSize) { 183 vm_unreserve_memory(committed_size - actualSize); 184 committed_size = actualSize; 185 } 186 } 187 188 189 void 190 VMAnonymousNoSwapCache::DeleteObject() 191 { 192 object_cache_delete(gAnonymousNoSwapCacheObjectCache, this); 193 } 194