Introduce ReservedAddressRange to sanitizer_common.

Summary:
Fixed version of https://reviews.llvm.org/D38437 (fixes Win/Fuchsia failures).

Creating a new revision, since the old one was getting a bit old/crowded.

    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.


Reviewers: alekseyshl, cryptoad, phosek

Reviewed By: alekseyshl, cryptoad

Subscribers: kubamracek

Differential Revision: https://reviews.llvm.org/D39072

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@316934 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 24 insertions, 0 deletions

diff --git a/lib/sanitizer_common/sanitizer_fuchsia.cc b/lib/sanitizer_common/sanitizer_fuchsia.cc
index 21fabddb1..7d3729c68 100644
--- a/lib/sanitizer_common/sanitizer_fuchsia.cc
+++ b/lib/sanitizer_common/sanitizer_fuchsia.cc
@@ -236,6 +236,30 @@ void *MmapOrDieOnFatalError(uptr size, const char *mem_type) {
   return DoAnonymousMmapOrDie(size, mem_type, false, false);
 }
 
+uptr ReservedAddressRange::Init(uptr init_size, const char* name,
+                                uptr fixed_addr) {
+  base_ = MmapNoAccess(init_size);
+  size_ = init_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) {
+  return reinterpret_cast<uptr>(MmapFixedOrDie(fixed_addr, map_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((addr_as_void == base_) || (addr + size == base_as_uptr + size_))
+  CHECK_LE(size, size_);
+  UnmapOrDie(reinterpret_cast<void*>(addr), 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