Correct mprotect page boundries to round up end page. Fixes PR30905.

Summary:
Update the boundries for mprotect.
Patch by Andrew Adams. Fixes PR30905.

Reviewers: loladiro, andrew.w.kaylor, chandlerc

Subscribers: abadams, llvm-commits

Differential Revision: https://reviews.llvm.org/D26312

llvm-svn: 286032

diff --git a/llvm/lib/Support/Unix/Memory.inc b/llvm/lib/Support/Unix/Memory.inc
index 6bbaf50..edbc793 100644 (file)
--- a/llvm/lib/Support/Unix/Memory.inc
+++ b/llvm/lib/Support/Unix/Memory.inc
@@ -153,7 +153,10 @@ Memory::protectMappedMemory(const MemoryBlock &M, unsigned Flags) {
 
   int Protect = getPosixProtectionFlags(Flags);
 
-  int Result = ::mprotect((void*)((uintptr_t)M.Address & ~(PageSize-1)), PageSize*((M.Size+PageSize-1)/PageSize), Protect);
+  uintptr_t Start = alignAddr((uint8_t *)M.Address - PageSize + 1, PageSize);
+  uintptr_t End = alignAddr((uint8_t *)M.Address + M.Size, PageSize);
+  int Result = ::mprotect((void *)Start, End - Start, Protect);
+
   if (Result != 0)
     return std::error_code(errno, std::generic_category());