From 20331d52c30014df1a56d18d8599af52d60d1bb2 Mon Sep 17 00:00:00 2001
From: Billy Laws <blaws05@gmail.com>
Date: Wed, 30 Jul 2025 00:05:46 +0100
Subject: [PATCH] LinuxSyscalls: Always reconstruct RIP and EFLAGS when
 spilling from the JIT

---
 .../LinuxEmulation/LinuxSyscalls/GdbServer.cpp   | 16 ++--------------
 .../LinuxSyscalls/SignalDelegator.cpp            | 13 ++++++++-----
 .../LinuxEmulation/LinuxSyscalls/ThreadManager.h |  3 ---
 3 files changed, 10 insertions(+), 22 deletions(-)

diff --git a/Source/Tools/LinuxEmulation/LinuxSyscalls/GdbServer.cpp b/Source/Tools/LinuxEmulation/LinuxSyscalls/GdbServer.cpp
index ae0015d80..91f099f40 100644
--- a/Source/Tools/LinuxEmulation/LinuxSyscalls/GdbServer.cpp
+++ b/Source/Tools/LinuxEmulation/LinuxSyscalls/GdbServer.cpp
@@ -108,12 +108,8 @@ GdbServer::GdbServer(FEXCore::Context::Context* ctx, FEX::HLE::SignalDelegator*
         ThreadObject->GdbInfo = {};
         ThreadObject->GdbInfo->Signal = Signal;
 
-        ThreadObject->GdbInfo->SignalPC = ArchHelpers::Context::GetPc(ucontext);
         this->SignalDelegation->SpillSRA(Thread, ucontext, Thread->CurrentFrame->InSyscallInfo);
 
-        memcpy(ThreadObject->GdbInfo->GPRs, ArchHelpers::Context::GetArmGPRs(ucontext), sizeof(ThreadObject->GdbInfo->GPRs));
-        ThreadObject->GdbInfo->PState = ArchHelpers::Context::GetArmPState(ucontext);
-
         // Let GDB know that we have a signal
         this->Break(Thread, Signal);
 
@@ -304,16 +300,8 @@ GdbServer::GDBContextDefinition GdbServer::GenerateContextDefinition(const FEX::
 
   // Encode the GDB context definition
   memcpy(&GDB.gregs[0], &state.gregs[0], sizeof(GDB.gregs));
-  if (ThreadObject->GdbInfo.has_value()) {
-    GDB.rip = CTX->RestoreRIPFromHostPC(ThreadObject->Thread, ThreadObject->GdbInfo->SignalPC);
-
-    const bool WasInJIT = CTX->IsAddressInCodeBuffer(ThreadObject->Thread, ThreadObject->GdbInfo->SignalPC);
-    GDB.eflags = CTX->ReconstructCompactedEFLAGS(ThreadObject->Thread, WasInJIT, const_cast<uint64_t*>(ThreadObject->GdbInfo->GPRs),
-                                                 ThreadObject->GdbInfo->PState);
-  } else {
-    GDB.rip = ThreadObject->Thread->CurrentFrame->State.rip;
-    GDB.eflags = CTX->ReconstructCompactedEFLAGS(ThreadObject->Thread, false, nullptr, 0);
-  }
+  GDB.rip = ThreadObject->Thread->CurrentFrame->State.rip;
+  GDB.eflags = CTX->ReconstructCompactedEFLAGS(ThreadObject->Thread, false, nullptr, 0);
 
   for (size_t i = 0; i < FEXCore::Core::CPUState::NUM_MMS; ++i) {
     memcpy(&GDB.mm[i], &state.mm[i], sizeof(GDB.mm[i]));
diff --git a/Source/Tools/LinuxEmulation/LinuxSyscalls/SignalDelegator.cpp b/Source/Tools/LinuxEmulation/LinuxSyscalls/SignalDelegator.cpp
index 4984205dd..2666c7bd2 100644
--- a/Source/Tools/LinuxEmulation/LinuxSyscalls/SignalDelegator.cpp
+++ b/Source/Tools/LinuxEmulation/LinuxSyscalls/SignalDelegator.cpp
@@ -110,6 +110,8 @@ void SignalDelegator::RegisterHostSignalHandler(int Signal, HostSignalDelegatorF
 
 void SignalDelegator::SpillSRA(FEXCore::Core::InternalThreadState* Thread, void* ucontext, uint32_t IgnoreMask) {
 #ifdef _M_ARM_64
+  Thread->CurrentFrame->State.rip = CTX->RestoreRIPFromHostPC(Thread, ArchHelpers::Context::GetPc(ucontext));
+
   for (size_t i = 0; i < Config.SRAGPRCount; i++) {
     const uint8_t SRAIdxMap = Config.SRAGPRMapping[i];
     if (IgnoreMask & (1U << SRAIdxMap)) {
@@ -132,6 +134,10 @@ void SignalDelegator::SpillSRA(FEXCore::Core::InternalThreadState* Thread, void*
       memcpy(&Thread->CurrentFrame->State.xmm.sse.data[i][0], &FPR, sizeof(__uint128_t));
     }
   }
+
+  uint32_t EFlags =
+    CTX->ReconstructCompactedEFLAGS(Thread, true, ArchHelpers::Context::GetArmGPRs(ucontext), ArchHelpers::Context::GetArmPState(ucontext));
+  CTX->SetFlagsFromCompactedEFLAGS(Thread, EFlags);
 #endif
 }
 
@@ -354,11 +360,8 @@ bool SignalDelegator::HandleDispatcherGuestSignal(FEXCore::Core::InternalThreadS
   // siginfo_t
   siginfo_t* HostSigInfo = reinterpret_cast<siginfo_t*>(info);
 
-  // Backup where we think the RIP currently is
-  ContextBackup->OriginalRIP = CTX->RestoreRIPFromHostPC(Thread, ArchHelpers::Context::GetPc(ucontext));
-  // Calculate eflags upfront.
-  uint32_t eflags = CTX->ReconstructCompactedEFLAGS(Thread, WasInJIT, ArchHelpers::Context::GetArmGPRs(ucontext),
-                                                    ArchHelpers::Context::GetArmPState(ucontext));
+  ContextBackup->OriginalRIP = Thread->CurrentFrame->State.rip;
+  uint32_t eflags = CTX->ReconstructCompactedEFLAGS(Thread, false, nullptr, 0);
 
   if (Is64BitMode) {
     NewGuestSP = SetupFrame_x64(Thread, ContextBackup, Frame, Signal, HostSigInfo, ucontext, GuestAction, GuestStack, NewGuestSP, eflags);
diff --git a/Source/Tools/LinuxEmulation/LinuxSyscalls/ThreadManager.h b/Source/Tools/LinuxEmulation/LinuxSyscalls/ThreadManager.h
index 134578b72..cc595ab6a 100644
--- a/Source/Tools/LinuxEmulation/LinuxSyscalls/ThreadManager.h
+++ b/Source/Tools/LinuxEmulation/LinuxSyscalls/ThreadManager.h
@@ -92,9 +92,6 @@ struct ThreadStateObject : public FEXCore::Allocator::FEXAllocOperators {
   // GDB signal information
   struct GdbInfoStruct {
     int Signal {};
-    uint64_t SignalPC {};
-    uint64_t GPRs[32];
-    uint64_t PState {};
   };
   std::optional<GdbInfoStruct> GdbInfo;