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 /*****************************************************************************/ 37 38 static int gralloc_map(gralloc_module_t const* /*module*/, 39 buffer_handle_t handle, 40 void** vaddr) 41 { 42 private_handle_t* hnd = (private_handle_t*)handle; 43 if (!(hnd->flags & private_handle_t::PRIV_FLAGS_FRAMEBUFFER)) { 44 size_t size = hnd->size; 45 void* mappedAddress = mmap(0, size, 46 PROT_READ|PROT_WRITE, MAP_SHARED, hnd->fd, 0); 47 if (mappedAddress == MAP_FAILED) { 48 ALOGE("Could not mmap %s", strerror(errno)); 49 return -errno; 50 } 51 hnd->base = uintptr_t(mappedAddress) + hnd->offset; 52 //ALOGD("gralloc_map() succeeded fd=%d, off=%d, size=%d, vaddr=%p", 53 // hnd->fd, hnd->offset, hnd->size, mappedAddress); 54 } 55 *vaddr = (void*)hnd->base; 56 return 0; 57 } 58 59 static int gralloc_unmap(gralloc_module_t const* /*module*/, 60 buffer_handle_t handle) 61 { 62 private_handle_t* hnd = (private_handle_t*)handle; 63 if (!(hnd->flags & private_handle_t::PRIV_FLAGS_FRAMEBUFFER)) { 64 void* base = (void*)hnd->base; 65 size_t size = hnd->size; 66 //ALOGD("unmapping from %p, size=%d", base, size); 67 if (munmap(base, size) < 0) { 68 ALOGE("Could not unmap %s", strerror(errno)); 69 } 70 } 71 hnd->base = 0; 72 return 0; 73 } 74 75 /*****************************************************************************/ 76 77 int gralloc_register_buffer(gralloc_module_t const* module, 78 buffer_handle_t handle) 79 { 80 if (private_handle_t::validate(handle) < 0) 81 return -EINVAL; 82 83 // *** WARNING WARNING WARNING *** 84 // 85 // If a buffer handle is passed from the process that allocated it to a 86 // different process, and then back to the allocator process, we will 87 // create a second mapping of the buffer. If the process reads and writes 88 // through both mappings, normal memory ordering guarantees may be 89 // violated, depending on the processor cache implementation*. 90 // 91 // If you are deriving a new gralloc implementation from this code, don't 92 // do this. A "real" gralloc should provide a single reference-counted 93 // mapping for each buffer in a process. 94 // 95 // In the current system, there is one case that needs a buffer to be 96 // registered in the same process that allocated it. The SurfaceFlinger 97 // process acts as the IGraphicBufferAlloc Binder provider, so all gralloc 98 // allocations happen in its process. After returning the buffer handle to 99 // the IGraphicBufferAlloc client, SurfaceFlinger free's its handle to the 100 // buffer (unmapping it from the SurfaceFlinger process). If 101 // SurfaceFlinger later acts as the producer end of the buffer queue the 102 // buffer belongs to, it will get a new handle to the buffer in response 103 // to IGraphicBufferProducer::requestBuffer(). Like any buffer handle 104 // received through Binder, the SurfaceFlinger process will register it. 105 // Since it already freed its original handle, it will only end up with 106 // one mapping to the buffer and there will be no problem. 107 // 108 // Currently SurfaceFlinger only acts as a buffer producer for a remote 109 // consumer when taking screenshots and when using virtual displays. 110 // 111 // Eventually, each application should be allowed to make its own gralloc 112 // allocations, solving the problem. Also, this ashmem-based gralloc 113 // should go away, replaced with a real ion-based gralloc. 114 // 115 // * Specifically, associative virtually-indexed caches are likely to have 116 // problems. Most modern L1 caches fit that description. 117 118 private_handle_t* hnd = (private_handle_t*)handle; 119 ALOGD_IF(hnd->pid == getpid(), 120 "Registering a buffer in the process that created it. " 121 "This may cause memory ordering problems."); 122 123 void *vaddr; 124 return gralloc_map(module, handle, &vaddr); 125 } 126 127 int gralloc_unregister_buffer(gralloc_module_t const* module, 128 buffer_handle_t handle) 129 { 130 if (private_handle_t::validate(handle) < 0) 131 return -EINVAL; 132 133 private_handle_t* hnd = (private_handle_t*)handle; 134 if (hnd->base) 135 gralloc_unmap(module, handle); 136 137 return 0; 138 } 139 140 int mapBuffer(gralloc_module_t const* module, 141 private_handle_t* hnd) 142 { 143 void* vaddr; 144 return gralloc_map(module, hnd, &vaddr); 145 } 146 147 int terminateBuffer(gralloc_module_t const* module, 148 private_handle_t* hnd) 149 { 150 if (hnd->base) { 151 // this buffer was mapped, unmap it now 152 gralloc_unmap(module, hnd); 153 } 154 155 return 0; 156 } 157 158 int gralloc_lock(gralloc_module_t const* /*module*/, 159 buffer_handle_t handle, int /*usage*/, 160 int /*l*/, int /*t*/, int /*w*/, int /*h*/, 161 void** vaddr) 162 { 163 // this is called when a buffer is being locked for software 164 // access. in thin implementation we have nothing to do since 165 // not synchronization with the h/w is needed. 166 // typically this is used to wait for the h/w to finish with 167 // this buffer if relevant. the data cache may need to be 168 // flushed or invalidated depending on the usage bits and the 169 // hardware. 170 171 if (private_handle_t::validate(handle) < 0) 172 return -EINVAL; 173 174 private_handle_t* hnd = (private_handle_t*)handle; 175 *vaddr = (void*)hnd->base; 176 return 0; 177 } 178 179 int gralloc_unlock(gralloc_module_t const* /*module*/, 180 buffer_handle_t handle) 181 { 182 // we're done with a software buffer. nothing to do in this 183 // implementation. typically this is used to flush the data cache. 184 185 if (private_handle_t::validate(handle) < 0) 186 return -EINVAL; 187 return 0; 188 } 189
