General purpose memory allocator for linker.
Add basic general purpose memory allocator to
linker in order to enable usage of other libraries
like libziparchive.
Change-Id: I4a680ebb36ed5ba67c61249f81dba9f567808434
diff --git a/linker/linker_allocator.cpp b/linker/linker_allocator.cpp
new file mode 100644
index 0000000..1b16cf1
--- /dev/null
+++ b/linker/linker_allocator.cpp
@@ -0,0 +1,346 @@
+/*
+ * Copyright (C) 2015 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 "linker.h"
+
+#include <algorithm>
+#include <vector>
+
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include "private/bionic_prctl.h"
+
+//
+// LinkerMemeoryAllocator is general purpose allocator
+// designed to provide the same functionality as the malloc/free/realloc
+// libc functions.
+//
+// On alloc:
+// If size is >= 1k allocator proxies malloc call directly to mmap
+// If size < 1k allocator uses SmallObjectAllocator for the size
+// rounded up to the nearest power of two.
+//
+// On free:
+//
+// For a pointer allocated using proxy-to-mmap allocator unmaps
+// the memory.
+//
+// For a pointer allocated using SmallObjectAllocator it adds
+// the block to free_blocks_list_. If the number of free pages reaches 2,
+// SmallObjectAllocator munmaps one of the pages keeping the other one
+// in reserve.
+
+static const char kSignature[4] = {'L', 'M', 'A', 1};
+
+static const size_t kSmallObjectMaxSize = 1 << kSmallObjectMaxSizeLog2;
+
+// This type is used for large allocations (with size >1k)
+static const uint32_t kLargeObject = 111;
+
+bool operator<(const small_object_page_record& one, const small_object_page_record& two) {
+ return one.page_addr < two.page_addr;
+}
+
+static inline uint16_t log2(size_t number) {
+ uint16_t result = 0;
+ number--;
+
+ while (number != 0) {
+ result++;
+ number >>= 1;
+ }
+
+ return result;
+}
+
+LinkerSmallObjectAllocator::LinkerSmallObjectAllocator()
+ : type_(0), name_(nullptr), block_size_(0), free_pages_cnt_(0), free_blocks_list_(nullptr) {}
+
+void* LinkerSmallObjectAllocator::alloc() {
+ if (free_blocks_list_ == nullptr) {
+ alloc_page();
+ }
+
+ small_object_block_record* block_record = free_blocks_list_;
+ if (block_record->free_blocks_cnt > 1) {
+ small_object_block_record* next_free = reinterpret_cast<small_object_block_record*>(
+ reinterpret_cast<uint8_t*>(block_record) + block_size_);
+ next_free->next = block_record->next;
+ next_free->free_blocks_cnt = block_record->free_blocks_cnt - 1;
+ free_blocks_list_ = next_free;
+ } else {
+ free_blocks_list_ = block_record->next;
+ }
+
+ // bookkeeping...
+ auto page_record = find_page_record(block_record);
+
+ if (page_record->allocated_blocks_cnt == 0) {
+ free_pages_cnt_--;
+ }
+
+ page_record->free_blocks_cnt--;
+ page_record->allocated_blocks_cnt++;
+
+ memset(block_record, 0, block_size_);
+
+ return block_record;
+}
+
+void LinkerSmallObjectAllocator::free_page(linker_vector_t::iterator page_record) {
+ void* page_start = reinterpret_cast<void*>(page_record->page_addr);
+ void* page_end = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(page_start) + PAGE_SIZE);
+
+ while (free_blocks_list_ != nullptr &&
+ free_blocks_list_ > page_start &&
+ free_blocks_list_ < page_end) {
+ free_blocks_list_ = free_blocks_list_->next;
+ }
+
+ small_object_block_record* current = free_blocks_list_;
+
+ while (current != nullptr) {
+ while (current->next > page_start && current->next < page_end) {
+ current->next = current->next->next;
+ }
+
+ current = current->next;
+ }
+
+ munmap(page_start, PAGE_SIZE);
+ page_records_.erase(page_record);
+ free_pages_cnt_--;
+}
+
+void LinkerSmallObjectAllocator::free(void* ptr) {
+ auto page_record = find_page_record(ptr);
+
+ ssize_t offset = reinterpret_cast<uintptr_t>(ptr) - sizeof(page_info);
+
+ if (offset % block_size_ != 0) {
+ __libc_fatal("invalid pointer: %p (block_size=%zd)", ptr, block_size_);
+ }
+
+ memset(ptr, 0, block_size_);
+ small_object_block_record* block_record = reinterpret_cast<small_object_block_record*>(ptr);
+
+ block_record->next = free_blocks_list_;
+ block_record->free_blocks_cnt = 1;
+
+ free_blocks_list_ = block_record;
+
+ page_record->free_blocks_cnt++;
+ page_record->allocated_blocks_cnt--;
+
+ if (page_record->allocated_blocks_cnt == 0) {
+ if (free_pages_cnt_++ > 1) {
+ // if we already have a free page - unmap this one.
+ free_page(page_record);
+ }
+ }
+}
+
+void LinkerSmallObjectAllocator::init(uint32_t type, size_t block_size, const char* name) {
+ type_ = type;
+ block_size_ = block_size;
+ name_ = name;
+}
+
+linker_vector_t::iterator LinkerSmallObjectAllocator::find_page_record(void* ptr) {
+ void* addr = reinterpret_cast<void*>(PAGE_START(reinterpret_cast<uintptr_t>(ptr)));
+ small_object_page_record boundary;
+ boundary.page_addr = addr;
+ linker_vector_t::iterator it = std::lower_bound(
+ page_records_.begin(), page_records_.end(), boundary);
+
+ if (it == page_records_.end() || it->page_addr != addr) {
+ // not found...
+ __libc_fatal("page record for %p was not found (block_size=%zd)", ptr, block_size_);
+ }
+
+ return it;
+}
+
+void LinkerSmallObjectAllocator::create_page_record(void* page_addr, size_t free_blocks_cnt) {
+ small_object_page_record record;
+ record.page_addr = page_addr;
+ record.free_blocks_cnt = free_blocks_cnt;
+ record.allocated_blocks_cnt = 0;
+
+ linker_vector_t::iterator it = std::lower_bound(
+ page_records_.begin(), page_records_.end(), record);
+ page_records_.insert(it, record);
+}
+
+void LinkerSmallObjectAllocator::alloc_page() {
+ void* map_ptr = mmap(nullptr, PAGE_SIZE,
+ PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
+ if (map_ptr == MAP_FAILED) {
+ __libc_fatal("mmap failed");
+ }
+
+ prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, map_ptr, PAGE_SIZE, name_);
+
+ memset(map_ptr, 0, PAGE_SIZE);
+
+ page_info* info = reinterpret_cast<page_info*>(map_ptr);
+ memcpy(info->signature, kSignature, sizeof(kSignature));
+ info->type = type_;
+ info->allocator_addr = this;
+
+ size_t free_blocks_cnt = (PAGE_SIZE - sizeof(page_info))/block_size_;
+
+ create_page_record(map_ptr, free_blocks_cnt);
+
+ small_object_block_record* first_block = reinterpret_cast<small_object_block_record*>(info + 1);
+
+ first_block->next = free_blocks_list_;
+ first_block->free_blocks_cnt = free_blocks_cnt;
+
+ free_blocks_list_ = first_block;
+}
+
+
+LinkerMemoryAllocator::LinkerMemoryAllocator() {
+ static const char* allocator_names[kSmallObjectAllocatorsCount] = {
+ "linker_alloc_16", // 2^4
+ "linker_alloc_32", // 2^5
+ "linker_alloc_64", // and so on...
+ "linker_alloc_128",
+ "linker_alloc_256",
+ "linker_alloc_512",
+ "linker_alloc_1024", // 2^10
+ };
+
+ for (size_t i = 0; i < kSmallObjectAllocatorsCount; ++i) {
+ uint32_t type = i + kSmallObjectMinSizeLog2;
+ allocators_[i].init(type, 1 << type, allocator_names[i]);
+ }
+}
+
+void* LinkerMemoryAllocator::alloc_mmap(size_t size) {
+ size_t allocated_size = PAGE_END(size + sizeof(page_info));
+ void* map_ptr = mmap(nullptr, allocated_size,
+ PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
+
+ if (map_ptr == MAP_FAILED) {
+ __libc_fatal("mmap failed");
+ }
+
+ prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, map_ptr, allocated_size, "linker_alloc_lob");
+
+ memset(map_ptr, 0, allocated_size);
+
+ page_info* info = reinterpret_cast<page_info*>(map_ptr);
+ memcpy(info->signature, kSignature, sizeof(kSignature));
+ info->type = kLargeObject;
+ info->allocated_size = allocated_size;
+
+ return info + 1;
+}
+
+void* LinkerMemoryAllocator::alloc(size_t size) {
+ // treat alloc(0) as alloc(1)
+ if (size == 0) {
+ size = 1;
+ }
+
+ if (size > kSmallObjectMaxSize) {
+ return alloc_mmap(size);
+ }
+
+ uint16_t log2_size = log2(size);
+
+ if (log2_size < kSmallObjectMinSizeLog2) {
+ log2_size = kSmallObjectMinSizeLog2;
+ }
+
+ return get_small_object_allocator(log2_size)->alloc();
+}
+
+page_info* LinkerMemoryAllocator::get_page_info(void* ptr) {
+ page_info* info = reinterpret_cast<page_info*>(PAGE_START(reinterpret_cast<size_t>(ptr)));
+ if (memcmp(info->signature, kSignature, sizeof(kSignature)) != 0) {
+ __libc_fatal("invalid pointer %p (page signature mismatch)", ptr);
+ }
+
+ return info;
+}
+
+void* LinkerMemoryAllocator::realloc(void* ptr, size_t size) {
+ if (ptr == nullptr) {
+ return alloc(size);
+ }
+
+ if (size == 0) {
+ free(ptr);
+ return nullptr;
+ }
+
+ page_info* info = get_page_info(ptr);
+
+ size_t old_size = 0;
+
+ if (info->type == kLargeObject) {
+ old_size = info->allocated_size - sizeof(page_info);
+ } else {
+ LinkerSmallObjectAllocator* allocator = get_small_object_allocator(info->type);
+ if (allocator != info->allocator_addr) {
+ __libc_fatal("invalid pointer %p (page signature mismatch)", ptr);
+ }
+
+ old_size = allocator->get_block_size();
+ }
+
+ if (old_size < size) {
+ void *result = alloc(size);
+ memcpy(result, ptr, old_size);
+ free(ptr);
+ return result;
+ }
+
+ return ptr;
+}
+
+void LinkerMemoryAllocator::free(void* ptr) {
+ if (ptr == nullptr) {
+ return;
+ }
+
+ page_info* info = get_page_info(ptr);
+
+ if (info->type == kLargeObject) {
+ munmap(info, info->allocated_size);
+ } else {
+ LinkerSmallObjectAllocator* allocator = get_small_object_allocator(info->type);
+ if (allocator != info->allocator_addr) {
+ __libc_fatal("invalid pointer %p (invalid allocator address for the page)", ptr);
+ }
+
+ allocator->free(ptr);
+ }
+}
+
+LinkerSmallObjectAllocator* LinkerMemoryAllocator::get_small_object_allocator(uint32_t type) {
+ if (type < kSmallObjectMinSizeLog2 || type > kSmallObjectMaxSizeLog2) {
+ __libc_fatal("invalid type: %u", type);
+ }
+
+ return &allocators_[type - kSmallObjectMinSizeLog2];
+}