[PATCH] D18846: [safestack] Add canary to unsafe stack frames

[Tim Shen via llvm-commits]

timshen added inline comments.

================
Comment at: lib/CodeGen/SafeStack.cpp:399
@@ +398,3 @@
+    StackGuardVar =
+        F.getParent()->getOrInsertGlobal("__stack_chk_guard", StackPtrTy);
+  return IRB.CreateLoad(StackGuardVar, "StackGuard");
----------------
timshen wrote:
> Is this going to work correctly, for say, PowerPC? As of my knowledge on powerpc64le-linux-gnu, there is no "__stack_chk_guard", but similarly has a data member in TCB.
> 
> On SSP side I'm actively working on supporting PowerPC - more generally, allowing backends to lower LOAD_STACK_GUARD node manually.
To be specific, powerpc64le-linux-gnu is similar to AArch64, which has a stack guard as data member in TCB.

================
Comment at: lib/CodeGen/SafeStack.cpp:504
@@ +503,3 @@
+  Constant *StackChkFail = F.getParent()->getOrInsertFunction(
+      "__stack_chk_fail", IRB.getVoidTy(), nullptr);
+  IRBFail.CreateCall(StackChkFail, {});
----------------
timshen wrote:
> OpenBSD doesn't have __stack_chk_fail. It has StackProtector::CreateFailBB.
> 
> I wonder if it's easy to share some code between SSP and safestack, though I have no idea what safestack is doing.
s/It has StackProtector::CreateFailBB/See StackProtector::CreateFailBB/.


Repository:
  rL LLVM

http://reviews.llvm.org/D18846