1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include <limits.h> 18 #include <errno.h> 19 #include <pthread.h> 20 #include <unistd.h> 21 #include <string.h> 22 23 #include <sys/mman.h> 24 #include <sys/stat.h> 25 #include <sys/types.h> 26 27 #include <cutils/log.h> 28 #include <cutils/atomic.h> 29 30 #include <hardware/hardware.h> 31 #include <hardware/gralloc.h> 32 33 #include "gralloc_priv.h" 34 35 36 /* desktop Linux needs a little help with gettid() */ 37 #if defined(ARCH_X86) && !defined(HAVE_ANDROID_OS) 38 #define __KERNEL__ 39 # include <linux/unistd.h> 40 pid_t gettid() { return syscall(__NR_gettid);} 41 #undef __KERNEL__ 42 #endif 43 44 /*****************************************************************************/ 45 46 static int gralloc_map(gralloc_module_t const* module, 47 buffer_handle_t handle, 48 void** vaddr) 49 { 50 private_handle_t* hnd = (private_handle_t*)handle; 51 if (!(hnd->flags & private_handle_t::PRIV_FLAGS_FRAMEBUFFER)) { 52 size_t size = hnd->size; 53 void* mappedAddress = mmap(0, size, 54 PROT_READ|PROT_WRITE, MAP_SHARED, hnd->fd, 0); 55 if (mappedAddress == MAP_FAILED) { 56 ALOGE("Could not mmap %s", strerror(errno)); 57 return -errno; 58 } 59 hnd->base = intptr_t(mappedAddress) + hnd->offset; 60 //ALOGD("gralloc_map() succeeded fd=%d, off=%d, size=%d, vaddr=%p", 61 // hnd->fd, hnd->offset, hnd->size, mappedAddress); 62 } 63 *vaddr = (void*)hnd->base; 64 return 0; 65 } 66 67 static int gralloc_unmap(gralloc_module_t const* module, 68 buffer_handle_t handle) 69 { 70 private_handle_t* hnd = (private_handle_t*)handle; 71 if (!(hnd->flags & private_handle_t::PRIV_FLAGS_FRAMEBUFFER)) { 72 void* base = (void*)hnd->base; 73 size_t size = hnd->size; 74 //ALOGD("unmapping from %p, size=%d", base, size); 75 if (munmap(base, size) < 0) { 76 ALOGE("Could not unmap %s", strerror(errno)); 77 } 78 } 79 hnd->base = 0; 80 return 0; 81 } 82 83 /*****************************************************************************/ 84 85 static pthread_mutex_t sMapLock = PTHREAD_MUTEX_INITIALIZER; 86 87 /*****************************************************************************/ 88 89 int gralloc_register_buffer(gralloc_module_t const* module, 90 buffer_handle_t handle) 91 { 92 if (private_handle_t::validate(handle) < 0) 93 return -EINVAL; 94 95 // *** WARNING WARNING WARNING *** 96 // 97 // If a buffer handle is passed from the process that allocated it to a 98 // different process, and then back to the allocator process, we will 99 // create a second mapping of the buffer. If the process reads and writes 100 // through both mappings, normal memory ordering guarantees may be 101 // violated, depending on the processor cache implementation*. 102 // 103 // If you are deriving a new gralloc implementation from this code, don't 104 // do this. A "real" gralloc should provide a single reference-counted 105 // mapping for each buffer in a process. 106 // 107 // In the current system, there is one case that needs a buffer to be 108 // registered in the same process that allocated it. The SurfaceFlinger 109 // process acts as the IGraphicBufferAlloc Binder provider, so all gralloc 110 // allocations happen in its process. After returning the buffer handle to 111 // the IGraphicBufferAlloc client, SurfaceFlinger free's its handle to the 112 // buffer (unmapping it from the SurfaceFlinger process). If 113 // SurfaceFlinger later acts as the producer end of the buffer queue the 114 // buffer belongs to, it will get a new handle to the buffer in response 115 // to IGraphicBufferProducer::requestBuffer(). Like any buffer handle 116 // received through Binder, the SurfaceFlinger process will register it. 117 // Since it already freed its original handle, it will only end up with 118 // one mapping to the buffer and there will be no problem. 119 // 120 // Currently SurfaceFlinger only acts as a buffer producer for a remote 121 // consumer when taking screenshots and when using virtual displays. 122 // 123 // Eventually, each application should be allowed to make its own gralloc 124 // allocations, solving the problem. Also, this ashmem-based gralloc 125 // should go away, replaced with a real ion-based gralloc. 126 // 127 // * Specifically, associative virtually-indexed caches are likely to have 128 // problems. Most modern L1 caches fit that description. 129 130 private_handle_t* hnd = (private_handle_t*)handle; 131 ALOGD_IF(hnd->pid == getpid(), 132 "Registering a buffer in the process that created it. " 133 "This may cause memory ordering problems."); 134 135 void *vaddr; 136 return gralloc_map(module, handle, &vaddr); 137 } 138 139 int gralloc_unregister_buffer(gralloc_module_t const* module, 140 buffer_handle_t handle) 141 { 142 if (private_handle_t::validate(handle) < 0) 143 return -EINVAL; 144 145 private_handle_t* hnd = (private_handle_t*)handle; 146 if (hnd->base) 147 gralloc_unmap(module, handle); 148 149 return 0; 150 } 151 152 int mapBuffer(gralloc_module_t const* module, 153 private_handle_t* hnd) 154 { 155 void* vaddr; 156 return gralloc_map(module, hnd, &vaddr); 157 } 158 159 int terminateBuffer(gralloc_module_t const* module, 160 private_handle_t* hnd) 161 { 162 if (hnd->base) { 163 // this buffer was mapped, unmap it now 164 gralloc_unmap(module, hnd); 165 } 166 167 return 0; 168 } 169 170 int gralloc_lock(gralloc_module_t const* module, 171 buffer_handle_t handle, int usage, 172 int l, int t, int w, int h, 173 void** vaddr) 174 { 175 // this is called when a buffer is being locked for software 176 // access. in thin implementation we have nothing to do since 177 // not synchronization with the h/w is needed. 178 // typically this is used to wait for the h/w to finish with 179 // this buffer if relevant. the data cache may need to be 180 // flushed or invalidated depending on the usage bits and the 181 // hardware. 182 183 if (private_handle_t::validate(handle) < 0) 184 return -EINVAL; 185 186 private_handle_t* hnd = (private_handle_t*)handle; 187 *vaddr = (void*)hnd->base; 188 return 0; 189 } 190 191 int gralloc_unlock(gralloc_module_t const* module, 192 buffer_handle_t handle) 193 { 194 // we're done with a software buffer. nothing to do in this 195 // implementation. typically this is used to flush the data cache. 196 197 if (private_handle_t::validate(handle) < 0) 198 return -EINVAL; 199 return 0; 200 } 201
