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/*
* Copyright (C) 2016 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 <errno.h>
#include <inttypes.h>
#include <sys/mman.h>
#include <unistd.h>
#include <map>
#include <utility>
#include "Allocator.h"
#include "HeapWalker.h"
#include "LeakFolding.h"
#include "ScopedSignalHandler.h"
#include "log.h"
namespace android {
bool HeapWalker::Allocation(uintptr_t begin, uintptr_t end) {
if (end == begin) {
end = begin + 1;
}
Range range{begin, end};
auto inserted = allocations_.insert(std::pair<Range, AllocationInfo>(range, AllocationInfo{}));
if (inserted.second) {
valid_allocations_range_.begin = std::min(valid_allocations_range_.begin, begin);
valid_allocations_range_.end = std::max(valid_allocations_range_.end, end);
allocation_bytes_ += range.size();
return true;
} else {
Range overlap = inserted.first->first;
if (overlap != range) {
MEM_ALOGE("range %p-%p overlaps with existing range %p-%p", reinterpret_cast<void*>(begin),
reinterpret_cast<void*>(end), reinterpret_cast<void*>(overlap.begin),
reinterpret_cast<void*>(overlap.end));
}
return false;
}
}
bool HeapWalker::WordContainsAllocationPtr(uintptr_t word_ptr, Range* range, AllocationInfo** info) {
walking_ptr_ = word_ptr;
// This access may segfault if the process under test has done something strange,
// for example mprotect(PROT_NONE) on a native heap page. If so, it will be
// caught and handled by mmaping a zero page over the faulting page.
uintptr_t value = *reinterpret_cast<uintptr_t*>(word_ptr);
walking_ptr_ = 0;
if (value >= valid_allocations_range_.begin && value < valid_allocations_range_.end) {
AllocationMap::iterator it = allocations_.find(Range{value, value + 1});
if (it != allocations_.end()) {
*range = it->first;
*info = &it->second;
return true;
}
}
return false;
}
void HeapWalker::RecurseRoot(const Range& root) {
allocator::vector<Range> to_do(1, root, allocator_);
while (!to_do.empty()) {
Range range = to_do.back();
to_do.pop_back();
ForEachPtrInRange(range, [&](Range& ref_range, AllocationInfo* ref_info) {
if (!ref_info->referenced_from_root) {
ref_info->referenced_from_root = true;
to_do.push_back(ref_range);
}
});
}
}
void HeapWalker::Root(uintptr_t begin, uintptr_t end) {
roots_.push_back(Range{begin, end});
}
void HeapWalker::Root(const allocator::vector<uintptr_t>& vals) {
root_vals_.insert(root_vals_.end(), vals.begin(), vals.end());
}
size_t HeapWalker::Allocations() {
return allocations_.size();
}
size_t HeapWalker::AllocationBytes() {
return allocation_bytes_;
}
bool HeapWalker::DetectLeaks() {
// Recursively walk pointers from roots to mark referenced allocations
for (auto it = roots_.begin(); it != roots_.end(); it++) {
RecurseRoot(*it);
}
Range vals;
vals.begin = reinterpret_cast<uintptr_t>(root_vals_.data());
vals.end = vals.begin + root_vals_.size() * sizeof(uintptr_t);
RecurseRoot(vals);
return true;
}
bool HeapWalker::Leaked(allocator::vector<Range>& leaked, size_t limit, size_t* num_leaks_out,
size_t* leak_bytes_out) {
leaked.clear();
size_t num_leaks = 0;
size_t leak_bytes = 0;
for (auto it = allocations_.begin(); it != allocations_.end(); it++) {
if (!it->second.referenced_from_root) {
num_leaks++;
leak_bytes += it->first.end - it->first.begin;
}
}
size_t n = 0;
for (auto it = allocations_.begin(); it != allocations_.end(); it++) {
if (!it->second.referenced_from_root) {
if (n++ < limit) {
leaked.push_back(it->first);
}
}
}
if (num_leaks_out) {
*num_leaks_out = num_leaks;
}
if (leak_bytes_out) {
*leak_bytes_out = leak_bytes;
}
return true;
}
static bool MapOverPage(void* addr) {
const size_t page_size = sysconf(_SC_PAGE_SIZE);
void* page = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(addr) & ~(page_size - 1));
void* ret = mmap(page, page_size, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
if (ret == MAP_FAILED) {
MEM_ALOGE("failed to map page at %p: %s", page, strerror(errno));
return false;
}
return true;
}
void HeapWalker::HandleSegFault(ScopedSignalHandler& handler, int signal, siginfo_t* si,
void* /*uctx*/) {
uintptr_t addr = reinterpret_cast<uintptr_t>(si->si_addr);
if (addr != walking_ptr_) {
handler.reset();
return;
}
MEM_ALOGW("failed to read page at %p, signal %d", si->si_addr, signal);
if (!MapOverPage(si->si_addr)) {
handler.reset();
}
}
ScopedSignalHandler::SignalFn ScopedSignalHandler::handler_;
} // namespace android
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