From a5cc25e50f5be4b339f5da7cb5290f45ef59d172 Mon Sep 17 00:00:00 2001 From: Tim Shen Date: Mon, 22 Aug 2016 18:26:27 +0000 Subject: [PATCH] [SSP] Do not set __guard_local to hidden for OpenBSD SSP __guard_local is defined as long on OpenBSD. If the source file contains a definition of __guard_local, it mismatches with the int8 pointer type used in LLVM. In that case, Module::getOrInsertGlobal() returns a cast operation instead of a GlobalVariable. Trying to set the visibility on the cast operation leads to random segfaults (seen when compiling the OpenBSD kernel, which also runs with stack protection). In the kernel, the hidden attribute does not matter. For userspace code, __guard_local is defined as hidden in the startup code. If a program re-defines __guard_local, the definition from the startup code will either win or the linker complains about multiple definitions (depending on whether the re-defined __guard_local is placed in the common segment or not). It also matches what gcc on OpenBSD does. Thanks Stefan Kempf for the patch! Differential Revision: http://reviews.llvm.org/D23674 llvm-svn: 279449 --- llvm/lib/CodeGen/TargetLoweringBase.cpp | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp index 4bf0266..62a3499 100644 --- a/llvm/lib/CodeGen/TargetLoweringBase.cpp +++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp @@ -1817,9 +1817,7 @@ Value *TargetLoweringBase::getIRStackGuard(IRBuilder<> &IRB) const { if (getTargetMachine().getTargetTriple().isOSOpenBSD()) { Module &M = *IRB.GetInsertBlock()->getParent()->getParent(); PointerType *PtrTy = Type::getInt8PtrTy(M.getContext()); - auto Guard = cast(M.getOrInsertGlobal("__guard_local", PtrTy)); - Guard->setVisibility(GlobalValue::HiddenVisibility); - return Guard; + return M.getOrInsertGlobal("__guard_local", PtrTy); } return nullptr; } -- 2.7.4