132 lines
3.5 KiB
C++
132 lines
3.5 KiB
C++
/*
|
|
* Copyright (C) 2014 The Android Open Source Project
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
#include "linker_allocator.h"
|
|
#include <inttypes.h>
|
|
#include <sys/mman.h>
|
|
#include <unistd.h>
|
|
|
|
#include "private/bionic_prctl.h"
|
|
|
|
struct LinkerAllocatorPage {
|
|
LinkerAllocatorPage* next;
|
|
uint8_t bytes[PAGE_SIZE-sizeof(LinkerAllocatorPage*)];
|
|
};
|
|
|
|
struct FreeBlockInfo {
|
|
void* next_block;
|
|
size_t num_free_blocks;
|
|
};
|
|
|
|
LinkerBlockAllocator::LinkerBlockAllocator(size_t block_size)
|
|
: block_size_(block_size < sizeof(FreeBlockInfo) ? sizeof(FreeBlockInfo) : block_size),
|
|
page_list_(nullptr),
|
|
free_block_list_(nullptr)
|
|
{}
|
|
|
|
void* LinkerBlockAllocator::alloc() {
|
|
if (free_block_list_ == nullptr) {
|
|
create_new_page();
|
|
}
|
|
|
|
FreeBlockInfo* block_info = reinterpret_cast<FreeBlockInfo*>(free_block_list_);
|
|
if (block_info->num_free_blocks > 1) {
|
|
FreeBlockInfo* next_block_info = reinterpret_cast<FreeBlockInfo*>(
|
|
reinterpret_cast<char*>(free_block_list_) + block_size_);
|
|
next_block_info->next_block = block_info->next_block;
|
|
next_block_info->num_free_blocks = block_info->num_free_blocks - 1;
|
|
free_block_list_ = next_block_info;
|
|
} else {
|
|
free_block_list_ = block_info->next_block;
|
|
}
|
|
|
|
memset(block_info, 0, block_size_);
|
|
|
|
return block_info;
|
|
}
|
|
|
|
void LinkerBlockAllocator::free(void* block) {
|
|
if (block == nullptr) {
|
|
return;
|
|
}
|
|
|
|
LinkerAllocatorPage* page = find_page(block);
|
|
|
|
if (page == nullptr) {
|
|
abort();
|
|
}
|
|
|
|
ssize_t offset = reinterpret_cast<uint8_t*>(block) - page->bytes;
|
|
|
|
if (offset % block_size_ != 0) {
|
|
abort();
|
|
}
|
|
|
|
memset(block, 0, block_size_);
|
|
|
|
FreeBlockInfo* block_info = reinterpret_cast<FreeBlockInfo*>(block);
|
|
|
|
block_info->next_block = free_block_list_;
|
|
block_info->num_free_blocks = 1;
|
|
|
|
free_block_list_ = block_info;
|
|
}
|
|
|
|
void LinkerBlockAllocator::protect_all(int prot) {
|
|
for (LinkerAllocatorPage* page = page_list_; page != nullptr; page = page->next) {
|
|
if (mprotect(page, PAGE_SIZE, prot) == -1) {
|
|
abort();
|
|
}
|
|
}
|
|
}
|
|
|
|
void LinkerBlockAllocator::create_new_page() {
|
|
LinkerAllocatorPage* page = reinterpret_cast<LinkerAllocatorPage*>(mmap(nullptr, PAGE_SIZE,
|
|
PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0));
|
|
if (page == MAP_FAILED) {
|
|
abort(); // oom
|
|
}
|
|
|
|
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, page, PAGE_SIZE, "linker_alloc");
|
|
|
|
memset(page, 0, PAGE_SIZE);
|
|
|
|
FreeBlockInfo* first_block = reinterpret_cast<FreeBlockInfo*>(page->bytes);
|
|
first_block->next_block = free_block_list_;
|
|
first_block->num_free_blocks = (PAGE_SIZE - sizeof(LinkerAllocatorPage*))/block_size_;
|
|
|
|
free_block_list_ = first_block;
|
|
|
|
page->next = page_list_;
|
|
page_list_ = page;
|
|
}
|
|
|
|
LinkerAllocatorPage* LinkerBlockAllocator::find_page(void* block) {
|
|
if (block == nullptr) {
|
|
abort();
|
|
}
|
|
|
|
LinkerAllocatorPage* page = page_list_;
|
|
while (page != nullptr) {
|
|
const uint8_t* page_ptr = reinterpret_cast<const uint8_t*>(page);
|
|
if (block >= (page_ptr + sizeof(page->next)) && block < (page_ptr + PAGE_SIZE)) {
|
|
return page;
|
|
}
|
|
|
|
page = page->next;
|
|
}
|
|
|
|
abort();
|
|
}
|