[sanitizer] Introduce ReservedAddressRange to sanitizer_common

In Fuchsia, MmapNoAccess/MmapFixedOrDie are implemented using a global
VMAR, which means that MmapNoAccess can only be called once. This works
for the sanitizer allocator but *not* for the Scudo allocator.

Hence, this changeset introduces a new ReservedAddressRange object to
serve as the new API for these calls. In this changeset, the object
still calls into the old Mmap implementations.

The next changeset two changesets will convert the sanitizer and scudo
allocators to use the new APIs, respectively. (ReservedAddressRange will
replace the SecondaryHeader in Scudo.)

Finally, a last changeset will update the Fuchsia implementation.

Patch by Julia Hansbrough

Differential Revision: https://reviews.llvm.org/D38759

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@315493 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 180 insertions, 0 deletions

diff --git a/lib/sanitizer_common/sanitizer_common.h b/lib/sanitizer_common/sanitizer_common.h
index ee5eca516..f29420c68 100644
--- a/lib/sanitizer_common/sanitizer_common.h
+++ b/lib/sanitizer_common/sanitizer_common.h
@@ -128,6 +128,20 @@ void CheckVMASize();
 void RunMallocHooks(const void *ptr, uptr size);
 void RunFreeHooks(const void *ptr);
 
+class ReservedAddressRange {
+ public:
+  uptr Init(uptr size, const char *name = nullptr, uptr fixed_addr = 0);
+  uptr Map(uptr fixed_addr, uptr size, bool tolerate_enomem = false);
+  void Unmap(uptr addr, uptr size);
+  const void *base() { return base_; }
+  const uptr size() { return size_; }
+
+ private:
+  void* base_;
+  uptr size_;
+  const char* name_;
+};
+
 typedef void (*fill_profile_f)(uptr start, uptr rss, bool file,
                                /*out*/uptr *stats, uptr stats_size);
 
diff --git a/lib/sanitizer_common/sanitizer_fuchsia.cc b/lib/sanitizer_common/sanitizer_fuchsia.cc
index 21fabddb1..00a8aabbf 100644
--- a/lib/sanitizer_common/sanitizer_fuchsia.cc
+++ b/lib/sanitizer_common/sanitizer_fuchsia.cc
@@ -236,6 +236,37 @@ void *MmapOrDieOnFatalError(uptr size, const char *mem_type) {
   return DoAnonymousMmapOrDie(size, mem_type, false, false);
 }
 
+uptr ReservedAddressRange::Init(uptr init_size, const char* name = nullptr,
+                                uptr fixed_addr = uptr(0)) {
+  base_ = MmapNoAccess(init_size);
+  size_ = size;
+  name_ = name;
+  return reinterpret_cast<uptr>(base_);
+}
+
+// Uses fixed_addr for now.
+// Will use offset instead once we've implemented this function for real.
+uptr ReservedAddressRange::Map(uptr fixed_addr, uptr map_size,
+                               bool tolerate_enomem = true) {
+  return reinterpret_cast<uptr>(MmapFixedOrDie(fixed_addr, size,
+                                               tolerate_enomem));
+}
+
+void ReservedAddressRange::Unmap(uptr addr, uptr size) {
+  void* addr_as_void = reinterpret_cast<void*>(addr);
+  uptr base_as_uptr = reinterpret_cast<uptr>(base_);
+  // Only unmap at the beginning or end of the range.
+  CHECK_EQ((addr_as_void == base_) || (addr + size == base_as_uptr + size_),
+           true);
+  // Detect overflows.
+  CHECK_LE(size, (base_as_uptr + size_) - addr);
+  UnmapOrDie(reinterpret_cast<void*>(addr), size);
+  if (addr_as_void == base_) {
+    base_ = reinterpret_cast<void*>(addr + size);
+  }
+  size_ = size_ - size;
+}
+
 // MmapNoAccess and MmapFixedOrDie are used only by sanitizer_allocator.
 // Instead of doing exactly what they say, we make MmapNoAccess actually
 // just allocate a VMAR to reserve the address space.  Then MmapFixedOrDie
diff --git a/lib/sanitizer_common/sanitizer_posix_libcdep.cc b/lib/sanitizer_common/sanitizer_posix_libcdep.cc
index 4214d91c5..b6b09b5e4 100644
--- a/lib/sanitizer_common/sanitizer_posix_libcdep.cc
+++ b/lib/sanitizer_common/sanitizer_posix_libcdep.cc
@@ -337,6 +337,42 @@ void *MmapFixedNoReserve(uptr fixed_addr, uptr size, const char *name) {
   return (void *)p;
 }
 
+uptr ReservedAddressRange::Init(uptr size, const char *name, uptr fixed_addr) {
+  if (fixed_addr) {
+    base_ = MmapFixedNoAccess(fixed_addr, size, name);
+  } else {
+    base_ = MmapNoAccess(size);
+  }
+  size_ = size;
+  name_ = name;
+  return reinterpret_cast<uptr>(base_);
+}
+
+// Uses fixed_addr for now.
+// Will use offset instead once we've implemented this function for real.
+uptr ReservedAddressRange::Map(uptr fixed_addr, uptr size,
+                               bool tolerate_enomem) {
+  if (tolerate_enomem) {
+    return reinterpret_cast<uptr>(MmapFixedOrDieOnFatalError(fixed_addr, size));
+  }
+  return reinterpret_cast<uptr>(MmapFixedOrDie(fixed_addr, size));
+}
+
+void ReservedAddressRange::Unmap(uptr addr, uptr size) {
+  void* addr_as_void = reinterpret_cast<void*>(addr);
+  uptr base_as_uptr = reinterpret_cast<uptr>(base_);
+  // Only unmap at the beginning or end of the range.
+  CHECK_EQ((addr_as_void == base_) || (addr + size == base_as_uptr + size_),
+           true);
+  // Detect overflows.
+  CHECK_LE(size, (base_as_uptr + size_) - addr);
+  UnmapOrDie(reinterpret_cast<void*>(addr), size);
+  if (addr_as_void == base_) {
+    base_ = reinterpret_cast<void*>(addr + size);
+  }
+  size_ = size_ - size;
+}
+
 void *MmapFixedNoAccess(uptr fixed_addr, uptr size, const char *name) {
   int fd = name ? GetNamedMappingFd(name, size) : -1;
   unsigned flags = MAP_PRIVATE | MAP_FIXED | MAP_NORESERVE;
diff --git a/lib/sanitizer_common/sanitizer_win.cc b/lib/sanitizer_common/sanitizer_win.cc
index f1a74d3f2..762ba46cc 100644
--- a/lib/sanitizer_common/sanitizer_win.cc
+++ b/lib/sanitizer_common/sanitizer_win.cc
@@ -235,6 +235,31 @@ void *MmapFixedOrDie(uptr fixed_addr, uptr size) {
   return p;
 }
 
+// Uses fixed_addr for now.
+// Will use offset instead once we've implemented this function for real.
+uptr ReservedAddressRange::Map(uptr fixed_addr, uptr size,
+                               bool tolerate_enomem) {
+  if (tolerate_enomem) {
+    return reinterpret_cast<uptr>(MmapFixedOrDieOnFatalError(fixed_addr, size));
+  }
+  return reinterpret_cast<uptr>(MmapFixedOrDie(uptr fixed_addr, uptr size));
+}
+
+void ReservedAddressRange::Unmap(uptr addr, uptr size) {
+  void* addr_as_void = reinterpret_cast<void*>(addr);
+  uptr base_as_uptr = reinterpret_cast<uptr>(base_);
+  // Only unmap at the beginning or end of the range.
+  CHECK_EQ((addr_as_void == base_) || (addr + size == base_as_uptr + size_),
+           true);
+  // Detect overflows.
+  CHECK_LE(size, (base_as_uptr + size_) - addr);
+  UnmapOrDie(reinterpret_cast<void*>(addr), size);
+  if (addr_as_void == base_) {
+    base_ = reinterpret_cast<void*>(addr + size);
+  }
+  size_ = size_ - size;
+}
+
 void *MmapFixedOrDieOnFatalError(uptr fixed_addr, uptr size) {
   void *p = VirtualAlloc((LPVOID)fixed_addr, size,
       MEM_COMMIT, PAGE_READWRITE);
@@ -252,6 +277,18 @@ void *MmapNoReserveOrDie(uptr size, const char *mem_type) {
   return MmapOrDie(size, mem_type);
 }
 
+uptr ReservedAddressRange::Init(uptr size, const char *name, uptr fixed_addr) {
+  if (fixed_addr) {
+    base_ = MmapFixedNoAccess(fixed_addr, size, name);
+  } else {
+    base_ = MmapNoAccess(size);
+  }
+  size_ = size;
+  name_ = name;
+  return reinterpret_cast<uptr>(base_);
+}
+
+
 void *MmapFixedNoAccess(uptr fixed_addr, uptr size, const char *name) {
   (void)name; // unsupported
   void *res = VirtualAlloc((LPVOID)fixed_addr, size,
diff --git a/lib/sanitizer_common/tests/sanitizer_common_test.cc b/lib/sanitizer_common/tests/sanitizer_common_test.cc
index 9c62b4593..5efce86ce 100644
--- a/lib/sanitizer_common/tests/sanitizer_common_test.cc
+++ b/lib/sanitizer_common/tests/sanitizer_common_test.cc
@@ -320,4 +320,66 @@ TEST(SanitizerCommon, GetRandom) {
 }
 #endif
 
+TEST(SanitizerCommon, ReservedAddressRangeInit) {
+  uptr init_size = 0xffff;
+  ReservedAddressRange address_range;
+  uptr res = address_range.Init(init_size);
+  CHECK_NE(res, (void*)-1);
+  UnmapOrDie((void*)res, init_size);
+  // Should be able to map into the same space now.
+  ReservedAddressRange address_range2;
+  uptr res2 = address_range2.Init(init_size, nullptr, res);
+  CHECK_EQ(res, res2);
+
+  // TODO(flowerhack): Once this is switched to the "real" implementation
+  // (rather than passing through to MmapNoAccess*), enforce and test "no
+  // double initializations allowed"
+}
+
+TEST(SanitizerCommon, ReservedAddressRangeMap) {
+  constexpr uptr init_size = 0xffff;
+  ReservedAddressRange address_range;
+  uptr res = address_range.Init(init_size);
+  CHECK_NE(res, (void*) -1);
+
+  // Valid mappings should succeed.
+  CHECK_EQ(res, address_range.Map(res, init_size));
+
+  // Valid mappings should be readable.
+  unsigned char buffer[init_size];
+  memcpy(buffer, &res, sizeof(buffer));
+
+  // Invalid mappings should fail.
+  EXPECT_DEATH(address_range.Map(res, 0), ".*");
+
+  // TODO(flowerhack): Once this is switched to the "real" implementation, make
+  // sure you can only mmap into offsets in the Init range.
+}
+
+TEST(SanitizerCommon, ReservedAddressRangeUnmap) {
+  uptr PageSize = GetPageSizeCached();
+  uptr init_size = PageSize * 4;
+  ReservedAddressRange address_range;
+  uptr base_addr = address_range.Init(init_size);
+  CHECK_NE(base_addr, (void*)-1);
+  CHECK_EQ(base_addr, address_range.Map(base_addr, init_size));
+
+  // Unmapping at the beginning should succeed.
+  address_range.Unmap(base_addr, PageSize);
+  CHECK_EQ(base_addr + PageSize, address_range.base());
+  CHECK_EQ(init_size - PageSize, address_range.size());
+
+  // Unmapping at the end should succeed.
+  uptr old_size = address_range.size();
+  void* old_base = address_range.base();
+  uptr new_start = reinterpret_cast<uptr>(address_range.base()) +
+                   address_range.size() - PageSize;
+  address_range.Unmap(new_start, PageSize);
+  CHECK_EQ(old_size - PageSize, address_range.size());
+  CHECK_EQ(old_base, address_range.base());
+
+  // Unmapping in the middle of the ReservedAddressRange should fail.
+  EXPECT_DEATH(address_range.Unmap(base_addr + 0xf, 0xff), ".*");
+}
+
 }  // namespace __sanitizer