1 files changed, 136 insertions, 0 deletions
diff --git a/lib/scudo/standalone/secondary.cc b/lib/scudo/standalone/secondary.cc
new file mode 100644
index 0000000000000..75f9171f1617b
--- /dev/null
+++ b/lib/scudo/standalone/secondary.cc
@@ -0,0 +1,136 @@
+//===-- secondary.cc --------------------------------------------*- 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 (!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 (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 (!Tail) {
+      Tail = H;
+    } else {
+      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 (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::printStats() const {
+  Printf("Stats: MapAllocator: allocated %zd times (%zdK), freed %zd times "
+         "(%zdK), remains %zd (%zdK) max %zdM\n",
+         NumberOfAllocs, AllocatedBytes >> 10, NumberOfFrees, FreedBytes >> 10,
+         NumberOfAllocs - NumberOfFrees, (AllocatedBytes - FreedBytes) >> 10,
+         LargestSize >> 20);
+}
+
+} // namespace scudo