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-rw-r--r--lib/scudo/standalone/secondary.cpp135
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diff --git a/lib/scudo/standalone/secondary.cpp b/lib/scudo/standalone/secondary.cpp
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+//===-- secondary.cpp -------------------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "secondary.h"
+
+#include "string_utils.h"
+
+namespace scudo {
+
+// As with the Primary, the size passed to this function includes any desired
+// alignment, so that the frontend can align the user allocation. The hint
+// parameter allows us to unmap spurious memory when dealing with larger
+// (greater than a page) alignments on 32-bit platforms.
+// Due to the sparsity of address space available on those platforms, requesting
+// an allocation from the Secondary with a large alignment would end up wasting
+// VA space (even though we are not committing the whole thing), hence the need
+// to trim off some of the reserved space.
+// For allocations requested with an alignment greater than or equal to a page,
+// the committed memory will amount to something close to Size - AlignmentHint
+// (pending rounding and headers).
+void *MapAllocator::allocate(uptr Size, uptr AlignmentHint, uptr *BlockEnd) {
+ DCHECK_GT(Size, AlignmentHint);
+ const uptr PageSize = getPageSizeCached();
+ const uptr MapSize =
+ roundUpTo(Size + LargeBlock::getHeaderSize(), PageSize) + 2 * PageSize;
+ MapPlatformData Data = {};
+ uptr MapBase =
+ reinterpret_cast<uptr>(map(nullptr, MapSize, "scudo:secondary",
+ MAP_NOACCESS | MAP_ALLOWNOMEM, &Data));
+ if (UNLIKELY(!MapBase))
+ return nullptr;
+ uptr CommitBase = MapBase + PageSize;
+ uptr MapEnd = MapBase + MapSize;
+
+ // In the unlikely event of alignments larger than a page, adjust the amount
+ // of memory we want to commit, and trim the extra memory.
+ if (UNLIKELY(AlignmentHint >= PageSize)) {
+ // For alignments greater than or equal to a page, the user pointer (eg: the
+ // pointer that is returned by the C or C++ allocation APIs) ends up on a
+ // page boundary , and our headers will live in the preceding page.
+ CommitBase = roundUpTo(MapBase + PageSize + 1, AlignmentHint) - PageSize;
+ const uptr NewMapBase = CommitBase - PageSize;
+ DCHECK_GE(NewMapBase, MapBase);
+ // We only trim the extra memory on 32-bit platforms: 64-bit platforms
+ // are less constrained memory wise, and that saves us two syscalls.
+ if (SCUDO_WORDSIZE == 32U && NewMapBase != MapBase) {
+ unmap(reinterpret_cast<void *>(MapBase), NewMapBase - MapBase, 0, &Data);
+ MapBase = NewMapBase;
+ }
+ const uptr NewMapEnd = CommitBase + PageSize +
+ roundUpTo((Size - AlignmentHint), PageSize) +
+ PageSize;
+ DCHECK_LE(NewMapEnd, MapEnd);
+ if (SCUDO_WORDSIZE == 32U && NewMapEnd != MapEnd) {
+ unmap(reinterpret_cast<void *>(NewMapEnd), MapEnd - NewMapEnd, 0, &Data);
+ MapEnd = NewMapEnd;
+ }
+ }
+
+ const uptr CommitSize = MapEnd - PageSize - CommitBase;
+ const uptr Ptr =
+ reinterpret_cast<uptr>(map(reinterpret_cast<void *>(CommitBase),
+ CommitSize, "scudo:secondary", 0, &Data));
+ LargeBlock::Header *H = reinterpret_cast<LargeBlock::Header *>(Ptr);
+ H->MapBase = MapBase;
+ H->MapSize = MapEnd - MapBase;
+ H->BlockEnd = CommitBase + CommitSize;
+ H->Data = Data;
+ {
+ ScopedLock L(Mutex);
+ if (LIKELY(Tail)) {
+ Tail->Next = H;
+ H->Prev = Tail;
+ }
+ Tail = H;
+ AllocatedBytes += CommitSize;
+ if (LargestSize < CommitSize)
+ LargestSize = CommitSize;
+ NumberOfAllocs++;
+ Stats.add(StatAllocated, CommitSize);
+ Stats.add(StatMapped, H->MapSize);
+ }
+ if (BlockEnd)
+ *BlockEnd = CommitBase + CommitSize;
+ return reinterpret_cast<void *>(Ptr + LargeBlock::getHeaderSize());
+}
+
+void MapAllocator::deallocate(void *Ptr) {
+ LargeBlock::Header *H = LargeBlock::getHeader(Ptr);
+ {
+ ScopedLock L(Mutex);
+ LargeBlock::Header *Prev = H->Prev;
+ LargeBlock::Header *Next = H->Next;
+ if (Prev) {
+ CHECK_EQ(Prev->Next, H);
+ Prev->Next = Next;
+ }
+ if (Next) {
+ CHECK_EQ(Next->Prev, H);
+ Next->Prev = Prev;
+ }
+ if (UNLIKELY(Tail == H)) {
+ CHECK(!Next);
+ Tail = Prev;
+ } else {
+ CHECK(Next);
+ }
+ const uptr CommitSize = H->BlockEnd - reinterpret_cast<uptr>(H);
+ FreedBytes += CommitSize;
+ NumberOfFrees++;
+ Stats.sub(StatAllocated, CommitSize);
+ Stats.sub(StatMapped, H->MapSize);
+ }
+ void *Addr = reinterpret_cast<void *>(H->MapBase);
+ const uptr Size = H->MapSize;
+ MapPlatformData Data;
+ Data = H->Data;
+ unmap(Addr, Size, UNMAP_ALL, &Data);
+}
+
+void MapAllocator::getStats(ScopedString *Str) const {
+ Str->append(
+ "Stats: MapAllocator: allocated %zu times (%zuK), freed %zu times "
+ "(%zuK), remains %zu (%zuK) max %zuM\n",
+ NumberOfAllocs, AllocatedBytes >> 10, NumberOfFrees, FreedBytes >> 10,
+ NumberOfAllocs - NumberOfFrees, (AllocatedBytes - FreedBytes) >> 10,
+ LargestSize >> 20);
+}
+
+} // namespace scudo