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
37static 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
58static 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
76int 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
126int 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
139int mapBuffer(gralloc_module_t const* module,
140        private_handle_t* hnd)
141{
142    void* vaddr;
143    return gralloc_map(module, hnd, &vaddr);
144}
145
146int 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
157int 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
178int 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