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 <errno.h> 18 #include <limits.h> 19 #include <pthread.h> 20 #include <string.h> 21 #include <sys/mman.h> 22 #include <sys/stat.h> 23 #include <sys/types.h> 24 #include <unistd.h> 25 26 #include <cutils/atomic.h> 27 #include <log/log.h> 28 29 #include <hardware/hardware.h> 30 #include <hardware/gralloc.h> 31 32 #include "gralloc_priv.h" 33 34 35 /*****************************************************************************/ 36 37 static int gralloc_map(gralloc_module_t const* /*module*/, 38 buffer_handle_t handle, 39 void** vaddr) 40 { 41 private_handle_t* hnd = (private_handle_t*)handle; 42 if (!(hnd->flags & private_handle_t::PRIV_FLAGS_FRAMEBUFFER)) { 43 size_t size = hnd->size; 44 void* mappedAddress = mmap(0, size, 45 PROT_READ|PROT_WRITE, MAP_SHARED, hnd->fd, 0); 46 if (mappedAddress == MAP_FAILED) { 47 ALOGE("Could not mmap %s", strerror(errno)); 48 return -errno; 49 } 50 hnd->base = uintptr_t(mappedAddress) + hnd->offset; 51 //ALOGD("gralloc_map() succeeded fd=%d, off=%d, size=%d, vaddr=%p", 52 // hnd->fd, hnd->offset, hnd->size, mappedAddress); 53 } 54 *vaddr = (void*)hnd->base; 55 return 0; 56 } 57 58 static int gralloc_unmap(gralloc_module_t const* /*module*/, 59 buffer_handle_t handle) 60 { 61 private_handle_t* hnd = (private_handle_t*)handle; 62 if (!(hnd->flags & private_handle_t::PRIV_FLAGS_FRAMEBUFFER)) { 63 void* base = (void*)hnd->base; 64 size_t size = hnd->size; 65 //ALOGD("unmapping from %p, size=%d", base, size); 66 if (munmap(base, size) < 0) { 67 ALOGE("Could not unmap %s", strerror(errno)); 68 } 69 } 70 hnd->base = 0; 71 return 0; 72 } 73 74 /*****************************************************************************/ 75 76 int gralloc_register_buffer(gralloc_module_t const* module, 77 buffer_handle_t handle) 78 { 79 if (private_handle_t::validate(handle) < 0) 80 return -EINVAL; 81 82 // *** WARNING WARNING WARNING *** 83 // 84 // If a buffer handle is passed from the process that allocated it to a 85 // different process, and then back to the allocator process, we will 86 // create a second mapping of the buffer. If the process reads and writes 87 // through both mappings, normal memory ordering guarantees may be 88 // violated, depending on the processor cache implementation*. 89 // 90 // If you are deriving a new gralloc implementation from this code, don't 91 // do this. A "real" gralloc should provide a single reference-counted 92 // mapping for each buffer in a process. 93 // 94 // In the current system, there is one case that needs a buffer to be 95 // registered in the same process that allocated it. The SurfaceFlinger 96 // process acts as the IGraphicBufferAlloc Binder provider, so all gralloc 97 // allocations happen in its process. After returning the buffer handle to 98 // the IGraphicBufferAlloc client, SurfaceFlinger free's its handle to the 99 // buffer (unmapping it from the SurfaceFlinger process). If 100 // SurfaceFlinger later acts as the producer end of the buffer queue the 101 // buffer belongs to, it will get a new handle to the buffer in response 102 // to IGraphicBufferProducer::requestBuffer(). Like any buffer handle 103 // received through Binder, the SurfaceFlinger process will register it. 104 // Since it already freed its original handle, it will only end up with 105 // one mapping to the buffer and there will be no problem. 106 // 107 // Currently SurfaceFlinger only acts as a buffer producer for a remote 108 // consumer when taking screenshots and when using virtual displays. 109 // 110 // Eventually, each application should be allowed to make its own gralloc 111 // allocations, solving the problem. Also, this ashmem-based gralloc 112 // should go away, replaced with a real ion-based gralloc. 113 // 114 // * Specifically, associative virtually-indexed caches are likely to have 115 // problems. Most modern L1 caches fit that description. 116 117 private_handle_t* hnd = (private_handle_t*)handle; 118 ALOGD_IF(hnd->pid == getpid(), 119 "Registering a buffer in the process that created it. " 120 "This may cause memory ordering problems."); 121 122 void *vaddr; 123 return gralloc_map(module, handle, &vaddr); 124 } 125 126 int gralloc_unregister_buffer(gralloc_module_t const* module, 127 buffer_handle_t handle) 128 { 129 if (private_handle_t::validate(handle) < 0) 130 return -EINVAL; 131 132 private_handle_t* hnd = (private_handle_t*)handle; 133 if (hnd->base) 134 gralloc_unmap(module, handle); 135 136 return 0; 137 } 138 139 int mapBuffer(gralloc_module_t const* module, 140 private_handle_t* hnd) 141 { 142 void* vaddr; 143 return gralloc_map(module, hnd, &vaddr); 144 } 145 146 int terminateBuffer(gralloc_module_t const* module, 147 private_handle_t* hnd) 148 { 149 if (hnd->base) { 150 // this buffer was mapped, unmap it now 151 gralloc_unmap(module, hnd); 152 } 153 154 return 0; 155 } 156 157 int gralloc_lock(gralloc_module_t const* /*module*/, 158 buffer_handle_t handle, int /*usage*/, 159 int /*l*/, int /*t*/, int /*w*/, int /*h*/, 160 void** vaddr) 161 { 162 // this is called when a buffer is being locked for software 163 // access. in thin implementation we have nothing to do since 164 // not synchronization with the h/w is needed. 165 // typically this is used to wait for the h/w to finish with 166 // this buffer if relevant. the data cache may need to be 167 // flushed or invalidated depending on the usage bits and the 168 // hardware. 169 170 if (private_handle_t::validate(handle) < 0) 171 return -EINVAL; 172 173 private_handle_t* hnd = (private_handle_t*)handle; 174 *vaddr = (void*)hnd->base; 175 return 0; 176 } 177 178 int gralloc_unlock(gralloc_module_t const* /*module*/, 179 buffer_handle_t handle) 180 { 181 // we're done with a software buffer. nothing to do in this 182 // implementation. typically this is used to flush the data cache. 183 184 if (private_handle_t::validate(handle) < 0) 185 return -EINVAL; 186 return 0; 187 } 188
