path: root/gralloc_buffer_priv.cpp (plain)
blob: 71773eb0f59bb747507412b7f2d20ff3d5523fd2

1	/*
2	* Copyright (C) 2014 ARM Limited. All rights reserved.
3	*
4	* Copyright (C) 2008 The Android Open Source Project
5	*
6	* Licensed under the Apache License, Version 2.0 (the "License");
7	* you may not use this file except in compliance with the License.
8	* You may obtain a copy of the License at
9	*
10	* http://www.apache.org/licenses/LICENSE-2.0
11	*
12	* Unless required by applicable law or agreed to in writing, software
13	* distributed under the License is distributed on an "AS IS" BASIS,
14	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15	* See the License for the specific language governing permissions and
16	* limitations under the License.
17	*/
18
19	#include <cutils/ashmem.h>
20	#include <cutils/log.h>
21	#include <sys/mman.h>
22	#include "gralloc_priv.h"
23	#include "gralloc_buffer_priv.h"
24
25
26	/*
27	* Allocate shared memory for attribute storage. Only to be
28	* used by gralloc internally.
29	*
30	* Return 0 on success.
31	*/
32	int gralloc_buffer_attr_allocate( private_handle_t *hnd )
33	{
34	int rval = -1;
35
36	if ( !hnd )
37	goto out;
38
39	if ( hnd->share_attr_fd >= 0 )
40	{
41	ALOGW("Warning share attribute fd already exists during create. Closing.");
42	close( hnd->share_attr_fd );
43	}
44
45	hnd->share_attr_fd = ashmem_create_region( "gralloc_shared_attr", PAGE_SIZE );
46	if (hnd->share_attr_fd < 0)
47	{
48	ALOGE("Failed to allocate page for shared attribute region");
49	goto err_ashmem;
50	}
51
52	/*
53	* Default protection on the shm region is PROT_EXEC | PROT_READ | PROT_WRITE.
54	*
55	* Personality flag READ_IMPLIES_EXEC which is used by some processes, namely gdbserver,
56	* causes a mmap with PROT_READ to be translated to PROT_READ | PROT_EXEC.
57	*
58	* If we were to drop PROT_EXEC here with a call to ashmem_set_prot_region()
59	* this can potentially cause clients to fail importing this gralloc attribute buffer
60	* with EPERM error since PROT_EXEC is not allowed.
61	*
62	* Because of this we keep the PROT_EXEC flag.
63	*/
64
65	hnd->attr_base = mmap( NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, hnd->share_attr_fd, 0 );
66	if (hnd->attr_base != MAP_FAILED)
67	{
68	/* The attribute region contains signed integers only.
69	* The reason for this is because we can set a value less than 0 for
70	* not-initialized values.
71	*/
72	attr_region *region = (attr_region *) hnd->attr_base;
73
74	memset(hnd->attr_base, 0xff, PAGE_SIZE);
75	munmap( hnd->attr_base, PAGE_SIZE );
76	hnd->attr_base = MAP_FAILED;
77	}
78	else
79	{
80	ALOGE("Failed to mmap shared attribute region");
81	goto err_ashmem;
82	}
83
84	rval = 0;
85	goto out;
86
87	err_ashmem:
88	if ( hnd->share_attr_fd >= 0 )
89	{
90	close( hnd->share_attr_fd );
91	hnd->share_attr_fd = -1;
92	}
93
94	out:
95	return rval;
96	}
97
98	/*
99	* Frees the shared memory allocated for attribute storage.
100	* Only to be used by gralloc internally.
101
102	* Return 0 on success.
103	*/
104	int gralloc_buffer_attr_free( private_handle_t *hnd )
105	{
106	int rval = -1;
107
108	if ( !hnd )
109	goto out;
110
111	if ( hnd->share_attr_fd < 0 )
112	{
113	ALOGE("Shared attribute region not avail to free");
114	goto out;
115	}
116	if ( hnd->attr_base != MAP_FAILED )
117	{
118	ALOGW("Warning shared attribute region mapped at free. Unmapping");
119	munmap( hnd->attr_base, PAGE_SIZE );
120	hnd->attr_base = MAP_FAILED;
121	}
122
123	close( hnd->share_attr_fd );
124	hnd->share_attr_fd = -1;
125	rval = 0;
126
127	out:
128	return rval;
129	}
130