[llvm-commits] [PATCH] Make use of OpenBSD's libc routines for stack protector

[Brad Smith]

On Thu, Aug 09, 2012 at 01:40:14AM -0700, Eli Friedman wrote:
> On Thu, Aug 9, 2012 at 12:52 AM, Brad Smith <brad at comstyle.com> wrote:
> > This makes LLVM use OpenBSD's libc routines for stack protector.
> 
> +#if defined(__OpenBSD__)
> 
> This is wrong; you want to check if the target is OpenBSD, not if the
> host is OpenBSD.

You're right. How about this?


Index: lib/CodeGen/StackProtector.cpp
===================================================================
--- lib/CodeGen/StackProtector.cpp	(revision 161304)
+++ lib/CodeGen/StackProtector.cpp	(working copy)
@@ -16,6 +16,7 @@
 
 #define DEBUG_TYPE "stack-protector"
 #include "llvm/CodeGen/Passes.h"
+#include "llvm/ADT/Triple.h"
 #include "llvm/Analysis/Dominators.h"
 #include "llvm/Attributes.h"
 #include "llvm/Constants.h"
@@ -169,7 +170,10 @@
         StackGuardVar = ConstantExpr::getIntToPtr(OffsetVal,
                                       PointerType::get(PtrTy, AddressSpace));
       } else {
-        StackGuardVar = M->getOrInsertGlobal("__stack_chk_guard", PtrTy); 
+        if (Triple(TLI->getTargetMachine().getTargetTriple()).getOS() == llvm::Triple::OpenBSD)
+          StackGuardVar = M->getOrInsertGlobal("__guard", PtrTy);
+        else
+          StackGuardVar = M->getOrInsertGlobal("__stack_chk_guard", PtrTy);
       }
 
       BasicBlock &Entry = F->getEntryBlock();
@@ -246,10 +250,24 @@
 BasicBlock *StackProtector::CreateFailBB() {
   BasicBlock *FailBB = BasicBlock::Create(F->getContext(),
                                           "CallStackCheckFailBlk", F);
-  Constant *StackChkFail =
-    M->getOrInsertFunction("__stack_chk_fail",
-                           Type::getVoidTy(F->getContext()), NULL);
-  CallInst::Create(StackChkFail, "", FailBB);
+  if (Triple(TLI->getTargetMachine().getTargetTriple()).getOS() == llvm::Triple::OpenBSD) {
+    Constant *StackChkFail =
+      M->getOrInsertFunction("__stack_smash_handler",
+                             Type::getVoidTy(F->getContext()), NULL);
+    Constant *G = new GlobalVariable(*M,
+                          ArrayType::get(Type::getInt1Ty(F->getContext()),
+                          F->getName().size() + 1),
+                          true, GlobalVariable::PrivateLinkage, 
+                          ConstantDataArray::getString(F->getContext(),
+                                  F->getName(), true),
+                           "SSH", false, 0);
+    CallInst::Create(StackChkFail, G, "", FailBB);
+  } else {
+    Constant *StackChkFail =
+      M->getOrInsertFunction("__stack_chk_fail",
+                             Type::getVoidTy(F->getContext()), NULL);
+    CallInst::Create(StackChkFail, "", FailBB);
+  }
   new UnreachableInst(F->getContext(), FailBB);
   return FailBB;
 }

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