trunk/sljit/sljitExecAllocator.c

/*
 *    Stack-less Just-In-Time compiler
 *
 *    Copyright 2009-2012 Zoltan Herczeg (hzmester@freemail.hu). All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are
 * permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright notice, this list of
 *      conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright notice, this list
 *      of conditions and the following disclaimer in the documentation and/or other materials
 *      provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) AND CONTRIBUTORS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE COPYRIGHT HOLDER(S) OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
   This file contains a simple executable memory allocator

   It is assumed, that executable code blocks are usually medium (or sometimes
   large) memory blocks, and the allocator is not too frequently called (less
   optimized than other allocators). Thus, using it as a generic allocator is
   not suggested.

   How does it work:
     Memory is allocated in continuous memory areas called chunks by alloc_chunk()
     Chunk format:
     [ block ][ block ] ... [ block ][ block terminator ]

   All blocks and the block terminator is started with block_header. The block
   header contains the size of the previous and the next block. These sizes
   can also contain special values.
     Block size:
       0 - The block is a free_block, with a different size member.
       1 - The block is a block terminator.
       n - The block is used at the moment, and the value contains its size.
     Previous block size:
       0 - This is the first block of the memory chunk.
       n - The size of the previous block.

   Using these size values we can go forward or backward on the block chain.
   The unused blocks are stored in a chain list pointed by free_blocks. This
   list is useful if we need to find a suitable memory area when the allocator
   is called.
 
   When a block is freed, the new free block is connected to its adjacent free
   blocks if possible.

     [ free block ][ used block ][ free block ]
   and "used block" is freed, the three blocks are connected together:
     [           one big free block           ]
*/

/* --------------------------------------------------------------------- */
/*  System (OS) functions                                                */
/* --------------------------------------------------------------------- */

/* 64 KByte. */
#define CHUNK_SIZE      0x10000

/*
   alloc_chunk / free_chunk :
     * allocate executable system memory chunks
     * the size is always divisible by CHUNK_SIZE
   allocator_grab_lock / allocator_release_lock :
     * make the allocator thread safe
     * can be empty if the OS (or the application) does not support threading
     * only the allocator requires this lock, sljit is fully thread safe
       as it only uses local variables
*/

#ifdef _WIN32

static SLJIT_INLINE void* alloc_chunk(sljit_uw size)
{
        return VirtualAlloc(0, size, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);
}

static SLJIT_INLINE void free_chunk(void* chunk, sljit_uw size)
{
        SLJIT_UNUSED_ARG(size);
        VirtualFree(chunk, 0, MEM_RELEASE);
}

#else

#include <sys/mman.h>

static SLJIT_INLINE void* alloc_chunk(sljit_uw size)
{
        void* retval = mmap(0, size, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANON, -1, 0);
        return (retval != MAP_FAILED) ? retval : NULL;
}

static SLJIT_INLINE void free_chunk(void* chunk, sljit_uw size)
{
        munmap(chunk, size);
}

#endif

/* --------------------------------------------------------------------- */
/*  Common functions                                                     */
/* --------------------------------------------------------------------- */

#define CHUNK_MASK      (~(CHUNK_SIZE - 1))

struct block_header {
        sljit_uw size;
        sljit_uw prev_size;
};

struct free_block {
        struct block_header header;
        struct free_block *next;
        struct free_block *prev;
        sljit_uw size;
};

#define AS_BLOCK_HEADER(base, offset) \
        ((struct block_header*)(((sljit_ub*)base) + offset))
#define AS_FREE_BLOCK(base, offset) \
        ((struct free_block*)(((sljit_ub*)base) + offset))
#define MEM_START(base)         ((void*)(((sljit_ub*)base) + sizeof(struct block_header)))
#define ALIGN_SIZE(size)        (((size) + sizeof(struct block_header) + 7) & ~7)

static struct free_block* free_blocks;
static sljit_uw allocated_size;
static sljit_uw total_size;

static SLJIT_INLINE void sljit_insert_free_block(struct free_block *free_block, sljit_uw size)
{
        free_block->header.size = 0;
        free_block->size = size;

        free_block->next = free_blocks;
        free_block->prev = 0;
        if (free_blocks)
                free_blocks->prev = free_block;
        free_blocks = free_block;
}

static SLJIT_INLINE void sljit_remove_free_block(struct free_block *free_block)
{
        if (free_block->next)
                free_block->next->prev = free_block->prev;

        if (free_block->prev)
                free_block->prev->next = free_block->next;
        else {
                SLJIT_ASSERT(free_blocks == free_block);
                free_blocks = free_block->next;
        }
}

SLJIT_API_FUNC_ATTRIBUTE void* sljit_malloc_exec(sljit_uw size)
{
        struct block_header *header;
        struct block_header *next_header;
        struct free_block *free_block;
        sljit_uw chunk_size;

        allocator_grab_lock();
        if (size < sizeof(struct free_block))
                size = sizeof(struct free_block);
        size = ALIGN_SIZE(size);

        free_block = free_blocks;
        while (free_block) {
                if (free_block->size >= size) {
                        chunk_size = free_block->size;
                        if (chunk_size > size + 64) {
                                /* We just cut a block from the end of the free block. */
                                chunk_size -= size;
                                free_block->size = chunk_size;
                                header = AS_BLOCK_HEADER(free_block, chunk_size);
                                header->prev_size = chunk_size;
                                AS_BLOCK_HEADER(header, size)->prev_size = size;
                        }
                        else {
                                sljit_remove_free_block(free_block);
                                header = (struct block_header*)free_block;
                                size = chunk_size;
                        }
                        allocated_size += size;
                        header->size = size;
                        allocator_release_lock();
                        return MEM_START(header);
                }
                free_block = free_block->next;
        }

        chunk_size = (size + sizeof(struct block_header) + CHUNK_SIZE - 1) & CHUNK_MASK;
        header = (struct block_header*)alloc_chunk(chunk_size);
        PTR_FAIL_IF(!header);

        chunk_size -= sizeof(struct block_header);
        total_size += chunk_size;

        header->prev_size = 0;
        if (chunk_size > size + 64) {
                /* Cut the allocated space into a free and a used block. */
                allocated_size += size;
                header->size = size;
                chunk_size -= size;

                free_block = AS_FREE_BLOCK(header, size);
                free_block->header.prev_size = size;
                sljit_insert_free_block(free_block, chunk_size);
                next_header = AS_BLOCK_HEADER(free_block, chunk_size);
        }
        else {
                /* All space belongs to this allocation. */
                allocated_size += chunk_size;
                header->size = chunk_size;
                next_header = AS_BLOCK_HEADER(header, chunk_size);
        }
        next_header->size = 1;
        next_header->prev_size = chunk_size;
        allocator_release_lock();
        return MEM_START(header);
}

SLJIT_API_FUNC_ATTRIBUTE void sljit_free_exec(void* ptr)
{
        struct block_header *header;
        struct free_block* free_block;

        allocator_grab_lock();
        header = AS_BLOCK_HEADER(ptr, -(sljit_w)sizeof(struct block_header));
        allocated_size -= header->size;

        /* Connecting free blocks together if possible. */

        /* If header->prev_size == 0, free_block will equal to header.
           In this case, free_block->header.size will be > 0. */
        free_block = AS_FREE_BLOCK(header, -(sljit_w)header->prev_size);
        if (SLJIT_UNLIKELY(!free_block->header.size)) {
                free_block->size += header->size;
                header = AS_BLOCK_HEADER(free_block, free_block->size);
                header->prev_size = free_block->size;
        }
        else {
                free_block = (struct free_block*)header;
                sljit_insert_free_block(free_block, header->size);
        }

        header = AS_BLOCK_HEADER(free_block, free_block->size);
        if (SLJIT_UNLIKELY(!header->size)) {
                free_block->size += ((struct free_block*)header)->size;
                sljit_remove_free_block((struct free_block*)header);
                header = AS_BLOCK_HEADER(free_block, free_block->size);
                header->prev_size = free_block->size;
        }

        /* The whole chunk is free. */
        if (SLJIT_UNLIKELY(!free_block->header.prev_size && header->size == 1)) {
                /* If this block is freed, we still have (allocated_size / 2) free space. */
                if (total_size - free_block->size > (allocated_size * 3 / 2)) {
                        total_size -= free_block->size;
                        sljit_remove_free_block(free_block);
                        free_chunk(free_block, free_block->size + sizeof(struct block_header));
                }
        }

        allocator_release_lock();
}
1	/*
2	* Stack-less Just-In-Time compiler
3	*
4	* Copyright 2009-2012 Zoltan Herczeg (hzmester@freemail.hu). All rights reserved.
5	*
6	* Redistribution and use in source and binary forms, with or without modification, are
7	* permitted provided that the following conditions are met:
8	*
9	* 1. Redistributions of source code must retain the above copyright notice, this list of
10	* conditions and the following disclaimer.
11	*
12	* 2. Redistributions in binary form must reproduce the above copyright notice, this list
13	* of conditions and the following disclaimer in the documentation and/or other materials
14	* provided with the distribution.
15	*
16	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) AND CONTRIBUTORS ``AS IS'' AND ANY
17	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
19	* SHALL THE COPYRIGHT HOLDER(S) OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
21	* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
22	* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
23	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
24	* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25	*/
26
27	/*
28	This file contains a simple executable memory allocator
29
30	It is assumed, that executable code blocks are usually medium (or sometimes
31	large) memory blocks, and the allocator is not too frequently called (less
32	optimized than other allocators). Thus, using it as a generic allocator is
33	not suggested.
34
35	How does it work:
36	Memory is allocated in continuous memory areas called chunks by alloc_chunk()
37	Chunk format:
38	[ block ][ block ] ... [ block ][ block terminator ]
39
40	All blocks and the block terminator is started with block_header. The block
41	header contains the size of the previous and the next block. These sizes
42	can also contain special values.
43	Block size:
44	0 - The block is a free_block, with a different size member.
45	1 - The block is a block terminator.
46	n - The block is used at the moment, and the value contains its size.
47	Previous block size:
48	0 - This is the first block of the memory chunk.
49	n - The size of the previous block.
50
51	Using these size values we can go forward or backward on the block chain.
52	The unused blocks are stored in a chain list pointed by free_blocks. This
53	list is useful if we need to find a suitable memory area when the allocator
54	is called.
55
56	When a block is freed, the new free block is connected to its adjacent free
57	blocks if possible.
58
59	[ free block ][ used block ][ free block ]
60	and "used block" is freed, the three blocks are connected together:
61	[ one big free block ]
62	*/
63
64	/* --------------------------------------------------------------------- */
65	/* System (OS) functions */
66	/* --------------------------------------------------------------------- */
67
68	/* 64 KByte. */
69	#define CHUNK_SIZE 0x10000
70
71	/*
72	alloc_chunk / free_chunk :
73	* allocate executable system memory chunks
74	* the size is always divisible by CHUNK_SIZE
75	allocator_grab_lock / allocator_release_lock :
76	* make the allocator thread safe
77	* can be empty if the OS (or the application) does not support threading
78	* only the allocator requires this lock, sljit is fully thread safe
79	as it only uses local variables
80	*/
81
82	#ifdef _WIN32
83
84	static SLJIT_INLINE void* alloc_chunk(sljit_uw size)
85	{
86	return VirtualAlloc(0, size, MEM_COMMIT \| MEM_RESERVE, PAGE_EXECUTE_READWRITE);
87	}
88
89	static SLJIT_INLINE void free_chunk(void* chunk, sljit_uw size)
90	{
91	SLJIT_UNUSED_ARG(size);
92	VirtualFree(chunk, 0, MEM_RELEASE);
93	}
94
95	#else
96
97	#include <sys/mman.h>
98
99	static SLJIT_INLINE void* alloc_chunk(sljit_uw size)
100	{
101	void* retval = mmap(0, size, PROT_READ \| PROT_WRITE \| PROT_EXEC, MAP_PRIVATE \| MAP_ANON, -1, 0);
102	return (retval != MAP_FAILED) ? retval : NULL;
103	}
104
105	static SLJIT_INLINE void free_chunk(void* chunk, sljit_uw size)
106	{
107	munmap(chunk, size);
108	}
109
110	#endif
111
112	/* --------------------------------------------------------------------- */
113	/* Common functions */
114	/* --------------------------------------------------------------------- */
115
116	#define CHUNK_MASK (~(CHUNK_SIZE - 1))
117
118	struct block_header {
119	sljit_uw size;
120	sljit_uw prev_size;
121	};
122
123	struct free_block {
124	struct block_header header;
125	struct free_block *next;
126	struct free_block *prev;
127	sljit_uw size;
128	};
129
130	#define AS_BLOCK_HEADER(base, offset) \
131	((struct block_header)(((sljit_ub)base) + offset))
132	#define AS_FREE_BLOCK(base, offset) \
133	((struct free_block)(((sljit_ub)base) + offset))
134	#define MEM_START(base) ((void)(((sljit_ub)base) + sizeof(struct block_header)))
135	#define ALIGN_SIZE(size) (((size) + sizeof(struct block_header) + 7) & ~7)
136
137	static struct free_block* free_blocks;
138	static sljit_uw allocated_size;
139	static sljit_uw total_size;
140
141	static SLJIT_INLINE void sljit_insert_free_block(struct free_block *free_block, sljit_uw size)
142	{
143	free_block->header.size = 0;
144	free_block->size = size;
145
146	free_block->next = free_blocks;
147	free_block->prev = 0;
148	if (free_blocks)
149	free_blocks->prev = free_block;
150	free_blocks = free_block;
151	}
152
153	static SLJIT_INLINE void sljit_remove_free_block(struct free_block *free_block)
154	{
155	if (free_block->next)
156	free_block->next->prev = free_block->prev;
157
158	if (free_block->prev)
159	free_block->prev->next = free_block->next;
160	else {
161	SLJIT_ASSERT(free_blocks == free_block);
162	free_blocks = free_block->next;
163	}
164	}
165
166	SLJIT_API_FUNC_ATTRIBUTE void* sljit_malloc_exec(sljit_uw size)
167	{
168	struct block_header *header;
169	struct block_header *next_header;
170	struct free_block *free_block;
171	sljit_uw chunk_size;
172
173	allocator_grab_lock();
174	if (size < sizeof(struct free_block))
175	size = sizeof(struct free_block);
176	size = ALIGN_SIZE(size);
177
178	free_block = free_blocks;
179	while (free_block) {
180	if (free_block->size >= size) {
181	chunk_size = free_block->size;
182	if (chunk_size > size + 64) {
183	/* We just cut a block from the end of the free block. */
184	chunk_size -= size;
185	free_block->size = chunk_size;
186	header = AS_BLOCK_HEADER(free_block, chunk_size);
187	header->prev_size = chunk_size;
188	AS_BLOCK_HEADER(header, size)->prev_size = size;
189	}
190	else {
191	sljit_remove_free_block(free_block);
192	header = (struct block_header*)free_block;
193	size = chunk_size;
194	}
195	allocated_size += size;
196	header->size = size;
197	allocator_release_lock();
198	return MEM_START(header);
199	}
200	free_block = free_block->next;
201	}
202
203	chunk_size = (size + sizeof(struct block_header) + CHUNK_SIZE - 1) & CHUNK_MASK;
204	header = (struct block_header*)alloc_chunk(chunk_size);
205	PTR_FAIL_IF(!header);
206
207	chunk_size -= sizeof(struct block_header);
208	total_size += chunk_size;
209
210	header->prev_size = 0;
211	if (chunk_size > size + 64) {
212	/* Cut the allocated space into a free and a used block. */
213	allocated_size += size;
214	header->size = size;
215	chunk_size -= size;
216
217	free_block = AS_FREE_BLOCK(header, size);
218	free_block->header.prev_size = size;
219	sljit_insert_free_block(free_block, chunk_size);
220	next_header = AS_BLOCK_HEADER(free_block, chunk_size);
221	}
222	else {
223	/* All space belongs to this allocation. */
224	allocated_size += chunk_size;
225	header->size = chunk_size;
226	next_header = AS_BLOCK_HEADER(header, chunk_size);
227	}
228	next_header->size = 1;
229	next_header->prev_size = chunk_size;
230	allocator_release_lock();
231	return MEM_START(header);
232	}
233
234	SLJIT_API_FUNC_ATTRIBUTE void sljit_free_exec(void* ptr)
235	{
236	struct block_header *header;
237	struct free_block* free_block;
238
239	allocator_grab_lock();
240	header = AS_BLOCK_HEADER(ptr, -(sljit_w)sizeof(struct block_header));
241	allocated_size -= header->size;
242
243	/* Connecting free blocks together if possible. */
244
245	/* If header->prev_size == 0, free_block will equal to header.
246	In this case, free_block->header.size will be > 0. */
247	free_block = AS_FREE_BLOCK(header, -(sljit_w)header->prev_size);
248	if (SLJIT_UNLIKELY(!free_block->header.size)) {
249	free_block->size += header->size;
250	header = AS_BLOCK_HEADER(free_block, free_block->size);
251	header->prev_size = free_block->size;
252	}
253	else {
254	free_block = (struct free_block*)header;
255	sljit_insert_free_block(free_block, header->size);
256	}
257
258	header = AS_BLOCK_HEADER(free_block, free_block->size);
259	if (SLJIT_UNLIKELY(!header->size)) {
260	free_block->size += ((struct free_block*)header)->size;
261	sljit_remove_free_block((struct free_block*)header);
262	header = AS_BLOCK_HEADER(free_block, free_block->size);
263	header->prev_size = free_block->size;
264	}
265
266	/* The whole chunk is free. */
267	if (SLJIT_UNLIKELY(!free_block->header.prev_size && header->size == 1)) {
268	/* If this block is freed, we still have (allocated_size / 2) free space. */
269	if (total_size - free_block->size > (allocated_size * 3 / 2)) {
270	total_size -= free_block->size;
271	sljit_remove_free_block(free_block);
272	free_chunk(free_block, free_block->size + sizeof(struct block_header));
273	}
274	}
275
276	allocator_release_lock();
277	}