[Lldb-commits] [lldb] d742903 - Delegate to ABI plugin to check if call frame addresses are valid (#161398)

[via lldb-commits]

Author: pveras
Date: 2025-10-13T18:11:10Z
New Revision: d74290319e3db3425bf2f0f87ef6c32f1078371f

URL: https://github.com/llvm/llvm-project/commit/d74290319e3db3425bf2f0f87ef6c32f1078371f
DIFF: https://github.com/llvm/llvm-project/commit/d74290319e3db3425bf2f0f87ef6c32f1078371f.diff

LOG: Delegate to ABI plugin to check if call frame addresses are valid (#161398)

Specially when dealing with different address spaces, CFAs could start
from addresses like 0. For instance, Nvidia GPUs have instructions to
read from local memory that use 0-based offsets and stack memory can be
referenced by these offsets rather than global addresses. Note that ABIs
could already specify what they consider to be valid CFA values but this
was never used in these parts of the unwinder code. For most ABIs, this
makes the validation more strict, as they already used to discard 0s and
then checked for alignment which would discard 1s. There a few
exceptions where 0s were possible and this makes it less strict, like
the RISCV and ARC ABIs.

@jasonmolenda Would you be the appropriate reviewer for this?
Also cc. @clayborg @walter-erquinigo

Added: 
    

Modified: 
    lldb/source/Target/RegisterContextUnwind.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/source/Target/RegisterContextUnwind.cpp b/lldb/source/Target/RegisterContextUnwind.cpp
index c6d15fc6be0a6..252bee2b5d72a 100644
--- a/lldb/source/Target/RegisterContextUnwind.cpp
+++ b/lldb/source/Target/RegisterContextUnwind.cpp
@@ -52,6 +52,14 @@ static ConstString GetSymbolOrFunctionName(const SymbolContext &sym_ctx) {
   return ConstString();
 }
 
+static bool CallFrameAddressIsValid(ABISP abi_sp, lldb::addr_t cfa) {
+  if (cfa == LLDB_INVALID_ADDRESS)
+    return false;
+  if (abi_sp)
+    return abi_sp->CallFrameAddressIsValid(cfa);
+  return cfa != 0 && cfa != 1;
+}
+
 RegisterContextUnwind::RegisterContextUnwind(Thread &thread,
                                              const SharedPtr &next_frame,
                                              SymbolContext &sym_ctx,
@@ -448,7 +456,7 @@ void RegisterContextUnwind::InitializeNonZerothFrame() {
         ReadFrameAddress(row_register_kind, row->GetAFAValue(), m_afa);
 
         // A couple of sanity checks..
-        if (m_cfa == LLDB_INVALID_ADDRESS || m_cfa == 0 || m_cfa == 1) {
+        if (!CallFrameAddressIsValid(abi_sp, m_cfa)) {
           UnwindLogMsg("could not find a valid cfa address");
           m_frame_type = eNotAValidFrame;
           return;
@@ -1847,9 +1855,11 @@ bool RegisterContextUnwind::TryFallbackUnwindPlan() {
       active_row->GetCFAValue().GetValueType() !=
           UnwindPlan::Row::FAValue::unspecified) {
     addr_t new_cfa;
+    ProcessSP process_sp = m_thread.GetProcess();
+    ABISP abi_sp = process_sp ? process_sp->GetABI() : nullptr;
     if (!ReadFrameAddress(m_fallback_unwind_plan_sp->GetRegisterKind(),
-                            active_row->GetCFAValue(), new_cfa) ||
-        new_cfa == 0 || new_cfa == 1 || new_cfa == LLDB_INVALID_ADDRESS) {
+                          active_row->GetCFAValue(), new_cfa) ||
+        !CallFrameAddressIsValid(abi_sp, new_cfa)) {
       UnwindLogMsg("failed to get cfa with fallback unwindplan");
       m_fallback_unwind_plan_sp.reset();
       m_full_unwind_plan_sp = original_full_unwind_plan_sp;
@@ -1870,10 +1880,9 @@ bool RegisterContextUnwind::TryFallbackUnwindPlan() {
         if (ReadRegisterValueFromRegisterLocation(regloc, reg_info,
                                                   reg_value)) {
           new_caller_pc_value = reg_value.GetAsUInt64();
-          if (ProcessSP process_sp = m_thread.GetProcess()) {
-            if (ABISP abi_sp = process_sp->GetABI())
-              new_caller_pc_value = abi_sp->FixCodeAddress(new_caller_pc_value);
-          }
+          if (process_sp)
+            new_caller_pc_value =
+                process_sp->FixCodeAddress(new_caller_pc_value);
         }
       }
     }
@@ -1932,9 +1941,11 @@ bool RegisterContextUnwind::ForceSwitchToFallbackUnwindPlan() {
       active_row->GetCFAValue().GetValueType() !=
           UnwindPlan::Row::FAValue::unspecified) {
     addr_t new_cfa;
+    ProcessSP process_sp = m_thread.GetProcess();
+    ABISP abi_sp = process_sp ? process_sp->GetABI() : nullptr;
     if (!ReadFrameAddress(m_fallback_unwind_plan_sp->GetRegisterKind(),
-                            active_row->GetCFAValue(), new_cfa) ||
-        new_cfa == 0 || new_cfa == 1 || new_cfa == LLDB_INVALID_ADDRESS) {
+                          active_row->GetCFAValue(), new_cfa) ||
+        !CallFrameAddressIsValid(abi_sp, new_cfa)) {
       UnwindLogMsg("failed to get cfa with fallback unwindplan");
       m_fallback_unwind_plan_sp.reset();
       return false;
@@ -2055,8 +2066,7 @@ bool RegisterContextUnwind::ReadFrameAddress(
     RegisterNumber cfa_reg(m_thread, row_register_kind,
                            fa.GetRegisterNumber());
     if (ReadGPRValue(cfa_reg, cfa_reg_contents)) {
-      if (cfa_reg_contents == LLDB_INVALID_ADDRESS || cfa_reg_contents == 0 ||
-          cfa_reg_contents == 1) {
+      if (!CallFrameAddressIsValid(abi_sp, cfa_reg_contents)) {
         UnwindLogMsg(
             "Got an invalid CFA register value - reg %s (%d), value 0x%" PRIx64,
             cfa_reg.GetName(), cfa_reg.GetAsKind(eRegisterKindLLDB),