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 = uintptr_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 int gralloc_register_buffer(gralloc_module_t const* module, 86 buffer_handle_t handle) 87 { 88 if (private_handle_t::validate(handle) < 0) 89 return -EINVAL; 90 91 // *** WARNING WARNING WARNING *** 92 // 93 // If a buffer handle is passed from the process that allocated it to a 94 // different process, and then back to the allocator process, we will 95 // create a second mapping of the buffer. If the process reads and writes 96 // through both mappings, normal memory ordering guarantees may be 97 // violated, depending on the processor cache implementation*. 98 // 99 // If you are deriving a new gralloc implementation from this code, don't 100 // do this. A "real" gralloc should provide a single reference-counted 101 // mapping for each buffer in a process. 102 // 103 // In the current system, there is one case that needs a buffer to be 104 // registered in the same process that allocated it. The SurfaceFlinger 105 // process acts as the IGraphicBufferAlloc Binder provider, so all gralloc 106 // allocations happen in its process. After returning the buffer handle to 107 // the IGraphicBufferAlloc client, SurfaceFlinger free's its handle to the 108 // buffer (unmapping it from the SurfaceFlinger process). If 109 // SurfaceFlinger later acts as the producer end of the buffer queue the 110 // buffer belongs to, it will get a new handle to the buffer in response 111 // to IGraphicBufferProducer::requestBuffer(). Like any buffer handle 112 // received through Binder, the SurfaceFlinger process will register it. 113 // Since it already freed its original handle, it will only end up with 114 // one mapping to the buffer and there will be no problem. 115 // 116 // Currently SurfaceFlinger only acts as a buffer producer for a remote 117 // consumer when taking screenshots and when using virtual displays. 118 // 119 // Eventually, each application should be allowed to make its own gralloc 120 // allocations, solving the problem. Also, this ashmem-based gralloc 121 // should go away, replaced with a real ion-based gralloc. 122 // 123 // * Specifically, associative virtually-indexed caches are likely to have 124 // problems. Most modern L1 caches fit that description. 125 126 private_handle_t* hnd = (private_handle_t*)handle; 127 ALOGD_IF(hnd->pid == getpid(), 128 "Registering a buffer in the process that created it. " 129 "This may cause memory ordering problems."); 130 131 void *vaddr; 132 return gralloc_map(module, handle, &vaddr); 133 } 134 135 int gralloc_unregister_buffer(gralloc_module_t const* module, 136 buffer_handle_t handle) 137 { 138 if (private_handle_t::validate(handle) < 0) 139 return -EINVAL; 140 141 private_handle_t* hnd = (private_handle_t*)handle; 142 if (hnd->base) 143 gralloc_unmap(module, handle); 144 145 return 0; 146 } 147 148 int mapBuffer(gralloc_module_t const* module, 149 private_handle_t* hnd) 150 { 151 void* vaddr; 152 return gralloc_map(module, hnd, &vaddr); 153 } 154 155 int terminateBuffer(gralloc_module_t const* module, 156 private_handle_t* hnd) 157 { 158 if (hnd->base) { 159 // this buffer was mapped, unmap it now 160 gralloc_unmap(module, hnd); 161 } 162 163 return 0; 164 } 165 166 int gralloc_lock(gralloc_module_t const* /*module*/, 167 buffer_handle_t handle, int /*usage*/, 168 int /*l*/, int /*t*/, int /*w*/, int /*h*/, 169 void** vaddr) 170 { 171 // this is called when a buffer is being locked for software 172 // access. in thin implementation we have nothing to do since 173 // not synchronization with the h/w is needed. 174 // typically this is used to wait for the h/w to finish with 175 // this buffer if relevant. the data cache may need to be 176 // flushed or invalidated depending on the usage bits and the 177 // hardware. 178 179 if (private_handle_t::validate(handle) < 0) 180 return -EINVAL; 181 182 private_handle_t* hnd = (private_handle_t*)handle; 183 *vaddr = (void*)hnd->base; 184 return 0; 185 } 186 187 int gralloc_unlock(gralloc_module_t const* /*module*/, 188 buffer_handle_t handle) 189 { 190 // we're done with a software buffer. nothing to do in this 191 // implementation. typically this is used to flush the data cache. 192 193 if (private_handle_t::validate(handle) < 0) 194 return -EINVAL; 195 return 0; 196 } 197
