// Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "address_mapper.h"
#include "base/logging.h"
namespace quipper {
AddressMapper::AddressMapper(const AddressMapper& source) {
mappings_ = source.mappings_;
}
bool AddressMapper::Map(const uint64_t real_addr,
const uint64_t size,
const bool remove_existing_mappings) {
return MapWithID(real_addr, size, kuint64max, 0, remove_existing_mappings);
}
bool AddressMapper::MapWithID(const uint64_t real_addr,
const uint64_t size,
const uint64_t id,
const uint64_t offset_base,
bool remove_existing_mappings) {
MappedRange range;
range.real_addr = real_addr;
range.size = size;
range.id = id;
range.offset_base = offset_base;
if (size == 0) {
LOG(ERROR) << "Must allocate a nonzero-length address range.";
return false;
}
// Check that this mapping does not overflow the address space.
if (real_addr + size - 1 != kuint64max &&
!(real_addr + size > real_addr)) {
DumpToLog();
LOG(ERROR) << "Address mapping at " << std::hex << real_addr
<< " with size " << std::hex << size << " overflows.";
return false;
}
// Check for collision with an existing mapping. This must be an overlap that
// does not result in one range being completely covered by another
MappingList::iterator iter;
MappingList mappings_to_delete;
bool old_range_found = false;
MappedRange old_range;
for (iter = mappings_.begin(); iter != mappings_.end(); ++iter) {
if (!iter->Intersects(range))
continue;
// Quit if existing ranges that collide aren't supposed to be removed.
if (!remove_existing_mappings)
return false;
if (!old_range_found && iter->Covers(range) && iter->size > range.size) {
old_range_found = true;
old_range = *iter;
continue;
}
mappings_to_delete.push_back(*iter);
}
while (!mappings_to_delete.empty()) {
const MappedRange& range = mappings_to_delete.front();
CHECK(Unmap(range));
mappings_to_delete.pop_front();
}
// Otherwise check for this range being covered by another range. If that
// happens, split or reduce the existing range to make room.
if (old_range_found) {
CHECK(Unmap(old_range));
uint64_t gap_before = range.real_addr - old_range.real_addr;
uint64_t gap_after = (old_range.real_addr + old_range.size) -
(range.real_addr + range.size);
if (gap_before) {
CHECK(MapWithID(old_range.real_addr,
gap_before,
old_range.id,
old_range.offset_base,
false));
}
CHECK(MapWithID(range.real_addr, range.size, id, offset_base, false));
if (gap_after) {
CHECK(MapWithID(range.real_addr + range.size,
gap_after,
old_range.id,
old_range.offset_base + gap_before + range.size,
false));
}
return true;
}
// Now search for a location for the new range. It should be in the first
// free block in quipper space.
// If there is no existing mapping, add it to the beginning of quipper space.
if (mappings_.empty()) {
range.mapped_addr = 0;
range.unmapped_space_after = kuint64max - range.size;
mappings_.push_back(range);
return true;
}
// If there is space before the first mapped range in quipper space, use it.
if (mappings_.begin()->mapped_addr >= range.size) {
range.mapped_addr = 0;
range.unmapped_space_after = mappings_.begin()->mapped_addr - range.size;
mappings_.push_front(range);
return true;
}
// Otherwise, search through the existing mappings for a free block after one
// of them.
for (iter = mappings_.begin(); iter != mappings_.end(); ++iter) {
if (iter->unmapped_space_after < range.size)
continue;
range.mapped_addr = iter->mapped_addr + iter->size;
range.unmapped_space_after = iter->unmapped_space_after - range.size;
iter->unmapped_space_after = 0;
mappings_.insert(++iter, range);
return true;
}
// If it still hasn't succeeded in mapping, it means there is no free space in
// quipper space large enough for a mapping of this size.
DumpToLog();
LOG(ERROR) << "Could not find space to map addr=" << std::hex << real_addr
<< " with size " << std::hex << size;
return false;
}
void AddressMapper::DumpToLog() const {
MappingList::const_iterator it;
for (it = mappings_.begin(); it != mappings_.end(); ++it) {
LOG(INFO) << " real_addr: " << std::hex << it->real_addr
<< " mapped: " << std::hex << it->mapped_addr
<< " id: " << std::hex << it->id
<< " size: " << std::hex << it->size;
}
}
bool AddressMapper::GetMappedAddress(const uint64_t real_addr,
uint64_t* mapped_addr) const {
CHECK(mapped_addr);
MappingList::const_iterator iter;
for (iter = mappings_.begin(); iter != mappings_.end(); ++iter) {
if (!iter->ContainsAddress(real_addr))
continue;
*mapped_addr = iter->mapped_addr + real_addr - iter->real_addr;
return true;
}
return false;
}
bool AddressMapper::GetMappedIDAndOffset(const uint64_t real_addr,
uint64_t* id,
uint64_t* offset) const {
CHECK(id);
CHECK(offset);
MappingList::const_iterator iter;
for (iter = mappings_.begin(); iter != mappings_.end(); ++iter) {
if (!iter->ContainsAddress(real_addr))
continue;
*id = iter->id;
*offset = real_addr - iter->real_addr + iter->offset_base;
return true;
}
return false;
}
uint64_t AddressMapper::GetMaxMappedLength() const {
if (IsEmpty())
return 0;
uint64_t min = mappings_.begin()->mapped_addr;
MappingList::const_iterator iter = mappings_.end();
--iter;
uint64_t max = iter->mapped_addr + iter->size;
return max - min;
}
bool AddressMapper::Unmap(const MappedRange& range) {
MappingList::iterator iter;
// TODO(sque): this is highly inefficient since Unmap() is called from a
// function that has already iterated to the right place within |mappings_|.
// For a first revision, I am sacrificing efficiency for of clarity, due to
// the trickiness of removing elements using iterators.
for (iter = mappings_.begin(); iter != mappings_.end(); ++iter) {
if (range.real_addr == iter->real_addr && range.size == iter->size) {
// Add the freed up space to the free space counter of the previous
// mapped region, if it exists.
if (iter != mappings_.begin()) {
--iter;
iter->unmapped_space_after += range.size + range.unmapped_space_after;
++iter;
}
mappings_.erase(iter);
return true;
}
}
return false;
}
} // namespace quipper