--- /dev/null
+/*
+ * Stack-less Just-In-Time compiler
+ *
+ * Copyright 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(NULL, 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
+
+static SLJIT_INLINE void* alloc_chunk(sljit_uw size)
+{
+ void *retval;
+
+#ifdef MAP_ANON
+
+ int flags = MAP_PRIVATE | MAP_ANON;
+
+#ifdef MAP_JIT
+ flags |= MAP_JIT;
+#endif
+
+ retval = mmap(NULL, size, PROT_READ | PROT_WRITE | PROT_EXEC, flags, -1, 0);
+#else
+ if (dev_zero < 0) {
+ if (open_dev_zero())
+ return NULL;
+ }
+ retval = mmap(NULL, size, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, dev_zero, 0);
+#endif
+
+ 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_u8*)base) + offset))
+#define AS_FREE_BLOCK(base, offset) \
+ ((struct free_block*)(((sljit_u8*)base) + offset))
+#define MEM_START(base) ((void*)(((sljit_u8*)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 = NULL;
+ 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 < (64 - sizeof(struct block_header)))
+ size = (64 - sizeof(struct block_header));
+ 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);
+ if (!header) {
+ allocator_release_lock();
+ return NULL;
+ }
+
+ 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_sw)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_sw)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();
+}
+
+SLJIT_API_FUNC_ATTRIBUTE void sljit_free_unused_memory_exec(void)
+{
+ struct free_block* free_block;
+ struct free_block* next_free_block;
+
+ allocator_grab_lock();
+
+ free_block = free_blocks;
+ while (free_block) {
+ next_free_block = free_block->next;
+ if (!free_block->header.prev_size &&
+ AS_BLOCK_HEADER(free_block, free_block->size)->size == 1) {
+ total_size -= free_block->size;
+ sljit_remove_free_block(free_block);
+ free_chunk(free_block, free_block->size + sizeof(struct block_header));
+ }
+ free_block = next_free_block;
+ }
+
+ SLJIT_ASSERT((total_size && free_blocks) || (!total_size && !free_blocks));
+ allocator_release_lock();
+}
projects / ossec-hids.git / blobdiff