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//===-- sanitizer_allocator_secondary.h -------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Part of the Sanitizer Allocator.
//
//===----------------------------------------------------------------------===//
#ifndef SANITIZER_ALLOCATOR_H
#error This file must be included inside sanitizer_allocator.h
#endif
// Fixed array to store LargeMmapAllocator chunks list, limited to 32K total
// allocated chunks. To be used in memory constrained or not memory hungry cases
// (currently, 32 bits and internal allocator).
class LargeMmapAllocatorPtrArrayStatic {
public:
inline void *Init() { return &p_[0]; }
inline void EnsureSpace(uptr n) { CHECK_LT(n, kMaxNumChunks); }
private:
static const int kMaxNumChunks = 1 << 15;
uptr p_[kMaxNumChunks];
};
// Much less restricted LargeMmapAllocator chunks list (comparing to
// PtrArrayStatic). Backed by mmaped memory region and can hold up to 1M chunks.
// ReservedAddressRange was used instead of just MAP_NORESERVE to achieve the
// same functionality in Fuchsia case, which does not support MAP_NORESERVE.
class LargeMmapAllocatorPtrArrayDynamic {
public:
inline void *Init() {
uptr p = address_range_.Init(kMaxNumChunks * sizeof(uptr),
SecondaryAllocatorName);
CHECK(p);
return reinterpret_cast<void*>(p);
}
inline void EnsureSpace(uptr n) {
CHECK_LT(n, kMaxNumChunks);
DCHECK(n <= n_reserved_);
if (UNLIKELY(n == n_reserved_)) {
address_range_.MapOrDie(
reinterpret_cast<uptr>(address_range_.base()) +
n_reserved_ * sizeof(uptr),
kChunksBlockCount * sizeof(uptr));
n_reserved_ += kChunksBlockCount;
}
}
private:
static const int kMaxNumChunks = 1 << 20;
static const int kChunksBlockCount = 1 << 14;
ReservedAddressRange address_range_;
uptr n_reserved_;
};
#if SANITIZER_WORDSIZE == 32
typedef LargeMmapAllocatorPtrArrayStatic DefaultLargeMmapAllocatorPtrArray;
#else
typedef LargeMmapAllocatorPtrArrayDynamic DefaultLargeMmapAllocatorPtrArray;
#endif
// This class can (de)allocate only large chunks of memory using mmap/unmap.
// The main purpose of this allocator is to cover large and rare allocation
// sizes not covered by more efficient allocators (e.g. SizeClassAllocator64).
template <class MapUnmapCallback = NoOpMapUnmapCallback,
class PtrArrayT = DefaultLargeMmapAllocatorPtrArray,
class AddressSpaceViewTy = LocalAddressSpaceView>
class LargeMmapAllocator {
public:
using AddressSpaceView = AddressSpaceViewTy;
void InitLinkerInitialized() {
page_size_ = GetPageSizeCached();
chunks_ = reinterpret_cast<Header**>(ptr_array_.Init());
}
void Init() {
internal_memset(this, 0, sizeof(*this));
InitLinkerInitialized();
}
void *Allocate(AllocatorStats *stat, uptr size, uptr alignment) {
CHECK(IsPowerOfTwo(alignment));
uptr map_size = RoundUpMapSize(size);
if (alignment > page_size_)
map_size += alignment;
// Overflow.
if (map_size < size) {
Report("WARNING: %s: LargeMmapAllocator allocation overflow: "
"0x%zx bytes with 0x%zx alignment requested\n",
SanitizerToolName, map_size, alignment);
return nullptr;
}
uptr map_beg = reinterpret_cast<uptr>(
MmapOrDieOnFatalError(map_size, SecondaryAllocatorName));
if (!map_beg)
return nullptr;
CHECK(IsAligned(map_beg, page_size_));
MapUnmapCallback().OnMap(map_beg, map_size);
uptr map_end = map_beg + map_size;
uptr res = map_beg + page_size_;
if (res & (alignment - 1)) // Align.
res += alignment - (res & (alignment - 1));
CHECK(IsAligned(res, alignment));
CHECK(IsAligned(res, page_size_));
CHECK_GE(res + size, map_beg);
CHECK_LE(res + size, map_end);
Header *h = GetHeader(res);
h->size = size;
h->map_beg = map_beg;
h->map_size = map_size;
uptr size_log = MostSignificantSetBitIndex(map_size);
CHECK_LT(size_log, ARRAY_SIZE(stats.by_size_log));
{
SpinMutexLock l(&mutex_);
ptr_array_.EnsureSpace(n_chunks_);
uptr idx = n_chunks_++;
h->chunk_idx = idx;
chunks_[idx] = h;
chunks_sorted_ = false;
stats.n_allocs++;
stats.currently_allocated += map_size;
stats.max_allocated = Max(stats.max_allocated, stats.currently_allocated);
stats.by_size_log[size_log]++;
stat->Add(AllocatorStatAllocated, map_size);
stat->Add(AllocatorStatMapped, map_size);
}
return reinterpret_cast<void*>(res);
}
void Deallocate(AllocatorStats *stat, void *p) {
Header *h = GetHeader(p);
{
SpinMutexLock l(&mutex_);
uptr idx = h->chunk_idx;
CHECK_EQ(chunks_[idx], h);
CHECK_LT(idx, n_chunks_);
chunks_[idx] = chunks_[--n_chunks_];
chunks_[idx]->chunk_idx = idx;
chunks_sorted_ = false;
stats.n_frees++;
stats.currently_allocated -= h->map_size;
stat->Sub(AllocatorStatAllocated, h->map_size);
stat->Sub(AllocatorStatMapped, h->map_size);
}
MapUnmapCallback().OnUnmap(h->map_beg, h->map_size);
UnmapOrDie(reinterpret_cast<void*>(h->map_beg), h->map_size);
}
uptr TotalMemoryUsed() {
SpinMutexLock l(&mutex_);
uptr res = 0;
for (uptr i = 0; i < n_chunks_; i++) {
Header *h = chunks_[i];
CHECK_EQ(h->chunk_idx, i);
res += RoundUpMapSize(h->size);
}
return res;
}
bool PointerIsMine(const void *p) const {
return GetBlockBegin(p) != nullptr;
}
uptr GetActuallyAllocatedSize(void *p) {
return RoundUpTo(GetHeader(p)->size, page_size_);
}
// At least page_size_/2 metadata bytes is available.
void *GetMetaData(const void *p) {
// Too slow: CHECK_EQ(p, GetBlockBegin(p));
if (!IsAligned(reinterpret_cast<uptr>(p), page_size_)) {
Printf("%s: bad pointer %p\n", SanitizerToolName, p);
CHECK(IsAligned(reinterpret_cast<uptr>(p), page_size_));
}
return GetHeader(p) + 1;
}
void *GetBlockBegin(const void *ptr) const {
uptr p = reinterpret_cast<uptr>(ptr);
SpinMutexLock l(&mutex_);
uptr nearest_chunk = 0;
Header *const *chunks = AddressSpaceView::Load(chunks_, n_chunks_);
// Cache-friendly linear search.
for (uptr i = 0; i < n_chunks_; i++) {
uptr ch = reinterpret_cast<uptr>(chunks[i]);
if (p < ch) continue; // p is at left to this chunk, skip it.
if (p - ch < p - nearest_chunk)
nearest_chunk = ch;
}
if (!nearest_chunk)
return nullptr;
const Header *h =
AddressSpaceView::Load(reinterpret_cast<Header *>(nearest_chunk));
Header *h_ptr = reinterpret_cast<Header *>(nearest_chunk);
CHECK_GE(nearest_chunk, h->map_beg);
CHECK_LT(nearest_chunk, h->map_beg + h->map_size);
CHECK_LE(nearest_chunk, p);
if (h->map_beg + h->map_size <= p)
return nullptr;
return GetUser(h_ptr);
}
void EnsureSortedChunks() {
if (chunks_sorted_) return;
Header **chunks = AddressSpaceView::LoadWritable(chunks_, n_chunks_);
Sort(reinterpret_cast<uptr *>(chunks), n_chunks_);
for (uptr i = 0; i < n_chunks_; i++)
AddressSpaceView::LoadWritable(chunks[i])->chunk_idx = i;
chunks_sorted_ = true;
}
// This function does the same as GetBlockBegin, but is much faster.
// Must be called with the allocator locked.
void *GetBlockBeginFastLocked(void *ptr) {
mutex_.CheckLocked();
uptr p = reinterpret_cast<uptr>(ptr);
uptr n = n_chunks_;
if (!n) return nullptr;
EnsureSortedChunks();
Header *const *chunks = AddressSpaceView::Load(chunks_, n_chunks_);
auto min_mmap_ = reinterpret_cast<uptr>(chunks[0]);
auto max_mmap_ = reinterpret_cast<uptr>(chunks[n - 1]) +
AddressSpaceView::Load(chunks[n - 1])->map_size;
if (p < min_mmap_ || p >= max_mmap_)
return nullptr;
uptr beg = 0, end = n - 1;
// This loop is a log(n) lower_bound. It does not check for the exact match
// to avoid expensive cache-thrashing loads.
while (end - beg >= 2) {
uptr mid = (beg + end) / 2; // Invariant: mid >= beg + 1
if (p < reinterpret_cast<uptr>(chunks[mid]))
end = mid - 1; // We are not interested in chunks[mid].
else
beg = mid; // chunks[mid] may still be what we want.
}
if (beg < end) {
CHECK_EQ(beg + 1, end);
// There are 2 chunks left, choose one.
if (p >= reinterpret_cast<uptr>(chunks[end]))
beg = end;
}
const Header *h = AddressSpaceView::Load(chunks[beg]);
Header *h_ptr = chunks[beg];
if (h->map_beg + h->map_size <= p || p < h->map_beg)
return nullptr;
return GetUser(h_ptr);
}
void PrintStats() {
Printf("Stats: LargeMmapAllocator: allocated %zd times, "
"remains %zd (%zd K) max %zd M; by size logs: ",
stats.n_allocs, stats.n_allocs - stats.n_frees,
stats.currently_allocated >> 10, stats.max_allocated >> 20);
for (uptr i = 0; i < ARRAY_SIZE(stats.by_size_log); i++) {
uptr c = stats.by_size_log[i];
if (!c) continue;
Printf("%zd:%zd; ", i, c);
}
Printf("\n");
}
// ForceLock() and ForceUnlock() are needed to implement Darwin malloc zone
// introspection API.
void ForceLock() ACQUIRE(mutex_) { mutex_.Lock(); }
void ForceUnlock() RELEASE(mutex_) { mutex_.Unlock(); }
// Iterate over all existing chunks.
// The allocator must be locked when calling this function.
void ForEachChunk(ForEachChunkCallback callback, void *arg) {
EnsureSortedChunks(); // Avoid doing the sort while iterating.
const Header *const *chunks = AddressSpaceView::Load(chunks_, n_chunks_);
for (uptr i = 0; i < n_chunks_; i++) {
const Header *t = chunks[i];
callback(reinterpret_cast<uptr>(GetUser(t)), arg);
// Consistency check: verify that the array did not change.
CHECK_EQ(chunks[i], t);
CHECK_EQ(AddressSpaceView::Load(chunks[i])->chunk_idx, i);
}
}
private:
struct Header {
uptr map_beg;
uptr map_size;
uptr size;
uptr chunk_idx;
};
Header *GetHeader(uptr p) {
CHECK(IsAligned(p, page_size_));
return reinterpret_cast<Header*>(p - page_size_);
}
Header *GetHeader(const void *p) {
return GetHeader(reinterpret_cast<uptr>(p));
}
void *GetUser(const Header *h) const {
CHECK(IsAligned((uptr)h, page_size_));
return reinterpret_cast<void*>(reinterpret_cast<uptr>(h) + page_size_);
}
uptr RoundUpMapSize(uptr size) {
return RoundUpTo(size, page_size_) + page_size_;
}
uptr page_size_;
Header **chunks_;
PtrArrayT ptr_array_;
uptr n_chunks_;
bool chunks_sorted_;
struct Stats {
uptr n_allocs, n_frees, currently_allocated, max_allocated, by_size_log[64];
} stats;
mutable StaticSpinMutex mutex_;
};