riscv: Support -mstack-protector-guard=tls

Add support for using a thread-local variable with a specified offset
for holding the stack guard canary value.

Signed-off-by: Keith Packard <[email protected]>

Author: keith-packard

clang/lib/Driver/ToolChains/Clang.cpp

@@ -3604,7 +3604,8 @@ static void RenderSSPOptions(const Driver &D, const ToolChain &TC,
   if (Arg *A = Args.getLastArg(options::OPT_mstack_protector_guard_EQ)) {
     StringRef Value = A->getValue();
     if (!EffectiveTriple.isX86() && !EffectiveTriple.isAArch64() &&
-        !EffectiveTriple.isARM() && !EffectiveTriple.isThumb())
+        !EffectiveTriple.isARM() && !EffectiveTriple.isThumb() &&
+        !EffectiveTriple.isRISCV())
       D.Diag(diag::err_drv_unsupported_opt_for_target)
           << A->getAsString(Args) << TripleStr;
     if ((EffectiveTriple.isX86() || EffectiveTriple.isARM() ||
@@ -3644,13 +3645,28 @@ static void RenderSSPOptions(const Driver &D, const ToolChain &TC,
           << A->getOption().getName() << Value << "sysreg global";
       return;
     }
+    if (EffectiveTriple.isRISCV()) {
+      if (Value != "tls" && Value != "global") {
+        D.Diag(diag::err_drv_invalid_value_with_suggestion)
+            << A->getOption().getName() << Value << "tls global";
+        return;
+      }
+      if (Value == "tls") {
+        if (!Args.hasArg(options::OPT_mstack_protector_guard_offset_EQ)) {
+          D.Diag(diag::err_drv_ssp_missing_offset_argument)
+              << A->getAsString(Args);
+          return;
+        }
+      }
+    }
     A->render(Args, CmdArgs);
   }
 
   if (Arg *A = Args.getLastArg(options::OPT_mstack_protector_guard_offset_EQ)) {
     StringRef Value = A->getValue();
     if (!EffectiveTriple.isX86() && !EffectiveTriple.isAArch64() &&
-        !EffectiveTriple.isARM() && !EffectiveTriple.isThumb())
+        !EffectiveTriple.isARM() && !EffectiveTriple.isThumb() &&
+        !EffectiveTriple.isRISCV())
       D.Diag(diag::err_drv_unsupported_opt_for_target)
           << A->getAsString(Args) << TripleStr;
     int Offset;
@@ -3669,7 +3685,8 @@ static void RenderSSPOptions(const Driver &D, const ToolChain &TC,
 
   if (Arg *A = Args.getLastArg(options::OPT_mstack_protector_guard_reg_EQ)) {
     StringRef Value = A->getValue();
-    if (!EffectiveTriple.isX86() && !EffectiveTriple.isAArch64())
+    if (!EffectiveTriple.isX86() && !EffectiveTriple.isAArch64() &&
+        !EffectiveTriple.isRISCV())
       D.Diag(diag::err_drv_unsupported_opt_for_target)
           << A->getAsString(Args) << TripleStr;
     if (EffectiveTriple.isX86() && (Value != "fs" && Value != "gs")) {
@@ -3681,6 +3698,11 @@ static void RenderSSPOptions(const Driver &D, const ToolChain &TC,
       D.Diag(diag::err_drv_invalid_value) << A->getOption().getName() << Value;
       return;
     }
+    if (EffectiveTriple.isRISCV() && Value != "tp") {
+      D.Diag(diag::err_drv_invalid_value_with_suggestion)
+          << A->getOption().getName() << Value << "tp";
+      return;
+    }
     A->render(Args, CmdArgs);
   }
 

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -21228,6 +21228,14 @@ Value *RISCVTargetLowering::getIRStackGuard(IRBuilderBase &IRB) const {
   if (Subtarget.isTargetAndroid())
     return useTpOffset(IRB, -0x18);
 
+  Module *M = IRB.GetInsertBlock()->getModule();
+
+  if (M->getStackProtectorGuard() == "tls") {
+    // Users must specify the offset explicitly
+    int Offset = M->getStackProtectorGuardOffset();
+    return useTpOffset(IRB, Offset);
+  }
+
   return TargetLowering::getIRStackGuard(IRB);
 }