svn commit: r312891 - projects/clang400-import/contrib/llvm/tools/lld/ELF

[Ed Maste]

Author: emaste
Date: Fri Jan 27 16:53:53 2017
New Revision: 312891
URL: https://svnweb.freebsd.org/changeset/base/312891

Log:
  lld: do not round up PT_GNU_RELRO p_memsz
  
  The change was made to support glibc and believed to be a no-op on
  FreeBSD, but that is not the case for architectures with multiple page
  sizes, such as arm64. The relro p_memsz header was rounded up to the
  default maximum page size (64K). When 4K pages are in use, multiple
  pages beyond the final PT_LOAD segment had their permissions changed to
  read-only after application of relocations and copy relocations, which
  led to a segfault in certain cases.
  
  This reverts upstream r290986. I have started a discussion about the
  upstream fix on the LLVM mailing list.
  
  Reported by:	andrew
  Sponsored by:	The FreeBSD Foundation

Modified:
  projects/clang400-import/contrib/llvm/tools/lld/ELF/Writer.cpp

Modified: projects/clang400-import/contrib/llvm/tools/lld/ELF/Writer.cpp
==============================================================================
--- projects/clang400-import/contrib/llvm/tools/lld/ELF/Writer.cpp	Fri Jan 27 15:03:51 2017	(r312890)
+++ projects/clang400-import/contrib/llvm/tools/lld/ELF/Writer.cpp	Fri Jan 27 16:53:53 2017	(r312891)
@@ -1461,13 +1461,8 @@ template <class ELFT> void Writer<ELFT>:
     }
     if (P.p_type == PT_LOAD)
       P.p_align = Config->MaxPageSize;
-    else if (P.p_type == PT_GNU_RELRO) {
+    else if (P.p_type == PT_GNU_RELRO)
       P.p_align = 1;
-      // The glibc dynamic loader rounds the size down, so we need to round up
-      // to protect the last page. This is a no-op on FreeBSD which always
-      // rounds up.
-      P.p_memsz = alignTo(P.p_memsz, Config->MaxPageSize);
-    }
 
     // The TLS pointer goes after PT_TLS. At least glibc will align it,
     // so round up the size to make sure the offsets are correct.