[RISC-V][HWASAN] Support tagging global variables for RISC-V HWASAN

Reviewed by: luismarques Differential Revision: https://reviews.llvm.org/D132995
llvm · Dec 13, 2022 · 11937ca · 11937ca
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commit 11937ca
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Showing 4 changed files with 103 additions and 3 deletions.
diff --git a/llvm/lib/Target/RISCV/RISCV.td b/llvm/lib/Target/RISCV/RISCV.td
@@ -525,6 +525,11 @@ def FeatureForcedAtomics : SubtargetFeature<
 def HasAtomicLdSt
     : Predicate<"Subtarget->hasStdExtA() || Subtarget->hasForcedAtomics()">;
 
+def FeatureTaggedGlobals : SubtargetFeature<"tagged-globals",
+    "AllowTaggedGlobals",
+    "true", "Use an instruction sequence for taking the address of a global "
+    "that allows a memory tag in the upper address bits">;
+
 //===----------------------------------------------------------------------===//
 // Named operands for CSR instructions.
 //===----------------------------------------------------------------------===//

diff --git a/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp b/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp
@@ -333,8 +333,12 @@ bool RISCVPreRAExpandPseudo::expandLoadAddress(
     MachineBasicBlock::iterator &NextMBBI) {
   MachineFunction *MF = MBB.getParent();
 
-  assert(MF->getTarget().isPositionIndependent());
   const auto &STI = MF->getSubtarget<RISCVSubtarget>();
+  // When HWASAN is used and tagging of global variables is enabled
+  // they should be accessed via the GOT, since the tagged address of a global
+  // is incompatible with existing code models. This also applies to non-pic
+  // mode.
+  assert(MF->getTarget().isPositionIndependent() || STI.allowTaggedGlobals());
   unsigned SecondOpcode = STI.is64Bit() ? RISCV::LD : RISCV::LW;
   return expandAuipcInstPair(MBB, MBBI, NextMBBI, RISCVII::MO_GOT_HI,
                              SecondOpcode);

diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -4230,9 +4230,13 @@ SDValue RISCVTargetLowering::getAddr(NodeTy *N, SelectionDAG &DAG,
   SDLoc DL(N);
   EVT Ty = getPointerTy(DAG.getDataLayout());
 
-  if (isPositionIndependent()) {
+  // When HWASAN is used and tagging of global variables is enabled
+  // they should be accessed via the GOT, since the tagged address of a global
+  // is incompatible with existing code models. This also applies to non-pic
+  // mode.
+  if (isPositionIndependent() || Subtarget.allowTaggedGlobals()) {
     SDValue Addr = getTargetNode(N, DL, Ty, DAG, 0);
-    if (IsLocal)
+    if (IsLocal && !Subtarget.allowTaggedGlobals())
       // Use PC-relative addressing to access the symbol. This generates the
       // pattern (PseudoLLA sym), which expands to (addi (auipc %pcrel_hi(sym))
       // %pcrel_lo(auipc)).

diff --git a/llvm/test/CodeGen/RISCV/tagged-globals.ll b/llvm/test/CodeGen/RISCV/tagged-globals.ll
@@ -0,0 +1,87 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --no-generate-body-for-unused-prefixes
+; RUN: llc --relocation-model=pic < %s | FileCheck %s
+; RUN: llc --relocation-model=static < %s | FileCheck %s
+
+@global_ext = external global i32
+@global_int = internal global i32 0
+declare void @func()
+
+define i32* @global_addr() #0 {
+; CHECK-LABEL: global_addr:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:  .Lpcrel_hi0:
+; CHECK-NEXT:    auipc a0, %got_pcrel_hi(global_ext)
+; CHECK-NEXT:    ld a0, %pcrel_lo(.Lpcrel_hi0)(a0)
+; CHECK-NEXT:    ret
+  ret i32* @global_ext
+}
+
+define i32 @global_load() #0 {
+; CHECK-LABEL: global_load:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:  .Lpcrel_hi1:
+; CHECK-NEXT:    auipc a0, %got_pcrel_hi(global_ext)
+; CHECK-NEXT:    ld a0, %pcrel_lo(.Lpcrel_hi1)(a0)
+; CHECK-NEXT:    lw a0, 0(a0)
+; CHECK-NEXT:    ret
+  %load = load i32, i32* @global_ext
+  ret i32 %load
+}
+
+define void @global_store() #0 {
+; CHECK-LABEL: global_store:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:  .Lpcrel_hi2:
+; CHECK-NEXT:    auipc a0, %got_pcrel_hi(global_ext)
+; CHECK-NEXT:    ld a0, %pcrel_lo(.Lpcrel_hi2)(a0)
+; CHECK-NEXT:    sw zero, 0(a0)
+; CHECK-NEXT:    ret
+  store i32 0, i32* @global_ext
+  ret void
+}
+
+define i32* @global_int_addr() #0 {
+; CHECK-LABEL: global_int_addr:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:  .Lpcrel_hi3:
+; CHECK-NEXT:    auipc a0, %got_pcrel_hi(global_int)
+; CHECK-NEXT:    ld a0, %pcrel_lo(.Lpcrel_hi3)(a0)
+; CHECK-NEXT:    ret
+  ret i32* @global_int
+}
+
+define i32 @global_int_load() #0 {
+; CHECK-LABEL: global_int_load:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:  .Lpcrel_hi4:
+; CHECK-NEXT:    auipc a0, %got_pcrel_hi(global_int)
+; CHECK-NEXT:    ld a0, %pcrel_lo(.Lpcrel_hi4)(a0)
+; CHECK-NEXT:    lw a0, 0(a0)
+; CHECK-NEXT:    ret
+  %load = load i32, i32* @global_int
+  ret i32 %load
+}
+
+define void @global_int_store() #0 {
+; CHECK-LABEL: global_int_store:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:  .Lpcrel_hi5:
+; CHECK-NEXT:    auipc a0, %got_pcrel_hi(global_int)
+; CHECK-NEXT:    ld a0, %pcrel_lo(.Lpcrel_hi5)(a0)
+; CHECK-NEXT:    sw zero, 0(a0)
+; CHECK-NEXT:    ret
+  store i32 0, i32* @global_int
+  ret void
+}
+
+define void ()* @func_addr() #0 {
+; CHECK-LABEL: func_addr:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:  .Lpcrel_hi6:
+; CHECK-NEXT:    auipc a0, %got_pcrel_hi(func)
+; CHECK-NEXT:    ld a0, %pcrel_lo(.Lpcrel_hi6)(a0)
+; CHECK-NEXT:    ret
+  ret void ()* @func
+}
+
+attributes #0 = { "target-features"="+tagged-globals" }