mapper.cpp revision a4b587cb063dfd1b11f0006b0149e5e3045cc873 
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// we need this for now because pmem cannot mmap at an offset
37#define PMEM_HACK   1
38
39/* desktop Linux needs a little help with gettid() */
40#if defined(ARCH_X86) && !defined(HAVE_ANDROID_OS)
41#define __KERNEL__
42# include <linux/unistd.h>
43pid_t gettid() { return syscall(__NR_gettid);}
44#undef __KERNEL__
45#endif
46
47/*****************************************************************************/
48
49static int gralloc_map(gralloc_module_t const* module,
50        buffer_handle_t handle,
51        void** vaddr)
52{
53    private_handle_t* hnd = (private_handle_t*)handle;
54    if (!(hnd->flags & private_handle_t::PRIV_FLAGS_FRAMEBUFFER)) {
55        size_t size = hnd->size;
56#if PMEM_HACK
57        size += hnd->offset;
58#endif
59        void* mappedAddress = mmap(0, size,
60                PROT_READ|PROT_WRITE, MAP_SHARED, hnd->fd, 0);
61        if (mappedAddress == MAP_FAILED) {
62            LOGE("Could not mmap %s", strerror(errno));
63            return -errno;
64        }
65        hnd->base = intptr_t(mappedAddress) + hnd->offset;
66        //LOGD("gralloc_map() succeeded fd=%d, off=%d, size=%d, vaddr=%p",
67        //        hnd->fd, hnd->offset, hnd->size, mappedAddress);
68    }
69    *vaddr = (void*)hnd->base;
70    return 0;
71}
72
73static int gralloc_unmap(gralloc_module_t const* module,
74        buffer_handle_t handle)
75{
76    private_handle_t* hnd = (private_handle_t*)handle;
77    if (!(hnd->flags & private_handle_t::PRIV_FLAGS_FRAMEBUFFER)) {
78        if (munmap((void*)hnd->base, hnd->size) < 0) {
79            LOGE("Could not unmap %s", strerror(errno));
80        }
81    }
82    hnd->base = 0;
83    return 0;
84}
85
86/*****************************************************************************/
87
88static pthread_mutex_t sMapLock = PTHREAD_MUTEX_INITIALIZER;
89
90/*****************************************************************************/
91
92int gralloc_register_buffer(gralloc_module_t const* module,
93        buffer_handle_t handle)
94{
95    if (private_handle_t::validate(handle) < 0)
96        return -EINVAL;
97
98    // In this implementation, we don't need to do anything here
99
100    /* NOTE: we need to initialize the buffer as not mapped/not locked
101     * because it shouldn't when this function is called the first time
102     * in a new process. Ideally these flags shouldn't be part of the
103     * handle, but instead maintained in the kernel or at least
104     * out-of-line
105     */
106
107    // if this handle was created in this process, then we keep it as is.
108    private_handle_t* hnd = (private_handle_t*)handle;
109    if (hnd->pid != getpid()) {
110        hnd->base = 0;
111        hnd->lockState  = 0;
112        hnd->writeOwner = 0;
113    }
114    return 0;
115}
116
117int gralloc_unregister_buffer(gralloc_module_t const* module,
118        buffer_handle_t handle)
119{
120    if (private_handle_t::validate(handle) < 0)
121        return -EINVAL;
122
123    /*
124     * If the buffer has been mapped during a lock operation, it's time
125     * to un-map it. It's an error to be here with a locked buffer.
126     * NOTE: the framebuffer is handled differently and is never unmapped.
127     */
128
129    private_handle_t* hnd = (private_handle_t*)handle;
130
131    LOGE_IF(hnd->lockState & private_handle_t::LOCK_STATE_READ_MASK,
132            "handle %p still locked (state=%08x)",
133            hnd, hnd->lockState);
134
135    // never unmap buffers that were created in this process
136    if (hnd->pid != getpid()) {
137        if (hnd->lockState & private_handle_t::LOCK_STATE_MAPPED) {
138            gralloc_unmap(module, handle);
139        }
140        hnd->base = 0;
141        hnd->lockState  = 0;
142        hnd->writeOwner = 0;
143    }
144    return 0;
145}
146
147int gralloc_lock(gralloc_module_t const* module,
148        buffer_handle_t handle, int usage,
149        int l, int t, int w, int h,
150        void** vaddr)
151{
152    if (private_handle_t::validate(handle) < 0)
153        return -EINVAL;
154
155    int err = 0;
156    private_handle_t* hnd = (private_handle_t*)handle;
157    int32_t current_value, new_value;
158    int retry;
159
160    do {
161        current_value = hnd->lockState;
162        new_value = current_value;
163
164        if (current_value & private_handle_t::LOCK_STATE_WRITE) {
165            // already locked for write
166            LOGE("handle %p already locked for write", handle);
167            return -EBUSY;
168        } else if (current_value & private_handle_t::LOCK_STATE_READ_MASK) {
169            // already locked for read
170            if (usage & (GRALLOC_USAGE_SW_WRITE_MASK | GRALLOC_USAGE_HW_RENDER)) {
171                LOGE("handle %p already locked for read", handle);
172                return -EBUSY;
173            } else {
174                // this is not an error
175                //LOGD("%p already locked for read... count = %d",
176                //        handle, (current_value & ~(1<<31)));
177            }
178        }
179
180        // not currently locked
181        if (usage & (GRALLOC_USAGE_SW_WRITE_MASK | GRALLOC_USAGE_HW_RENDER)) {
182            // locking for write
183            new_value |= private_handle_t::LOCK_STATE_WRITE;
184        }
185        new_value++;
186
187        retry = android_atomic_cmpxchg(current_value, new_value,
188                (volatile int32_t*)&hnd->lockState);
189    } while (retry);
190
191    if (new_value & private_handle_t::LOCK_STATE_WRITE) {
192        // locking for write, store the tid
193        hnd->writeOwner = gettid();
194    }
195
196    if (usage & (GRALLOC_USAGE_SW_READ_MASK | GRALLOC_USAGE_SW_WRITE_MASK)) {
197        if (!(current_value & private_handle_t::LOCK_STATE_MAPPED)) {
198            // we need to map for real
199            pthread_mutex_t* const lock = &sMapLock;
200            pthread_mutex_lock(lock);
201            if (!(hnd->lockState & private_handle_t::LOCK_STATE_MAPPED)) {
202                err = gralloc_map(module, handle, vaddr);
203                if (err == 0) {
204                    android_atomic_or(private_handle_t::LOCK_STATE_MAPPED,
205                            (volatile int32_t*)&(hnd->lockState));
206                }
207            }
208            pthread_mutex_unlock(lock);
209        }
210        *vaddr = (void*)hnd->base;
211    }
212
213    return err;
214}
215
216int gralloc_unlock(gralloc_module_t const* module,
217        buffer_handle_t handle)
218{
219    if (private_handle_t::validate(handle) < 0)
220        return -EINVAL;
221
222    private_handle_t* hnd = (private_handle_t*)handle;
223    int32_t current_value, new_value;
224
225    do {
226        current_value = hnd->lockState;
227        new_value = current_value;
228
229        if (current_value & private_handle_t::LOCK_STATE_WRITE) {
230            // locked for write
231            if (hnd->writeOwner == gettid()) {
232                hnd->writeOwner = 0;
233                new_value &= ~private_handle_t::LOCK_STATE_WRITE;
234            }
235        }
236
237        if ((new_value & private_handle_t::LOCK_STATE_READ_MASK) == 0) {
238            LOGE("handle %p not locked", handle);
239            return -EINVAL;
240        }
241
242        new_value--;
243
244    } while (android_atomic_cmpxchg(current_value, new_value,
245            (volatile int32_t*)&hnd->lockState));
246
247    return 0;
248}
249