gdb: Remove all stepping support and full CPU halt

src/core/arm/skyeye_common/armstate.cpp

@@ -612,7 +612,7 @@ void ARMul_State::ServeBreak() {
     Kernel::Thread* thread = system.Kernel().GetCurrentThreadManager().GetCurrentThread();
     system.GetRunningCore().SaveContext(thread->context);
 
-    if (last_bkpt_hit || GDBStub::IsMemoryBreak() || GDBStub::GetCpuStepFlag()) {
+    if (last_bkpt_hit || GDBStub::IsMemoryBreak()) {
         last_bkpt_hit = false;
         GDBStub::Break();
         GDBStub::SendTrap(thread, 5);

src/core/core.cpp

@@ -89,16 +89,6 @@ System::ResultStatus System::RunLoop(bool tight_loop) {
             running_core->SaveContext(thread->context);
         }
         GDBStub::HandlePacket(*this);
-
-        // If the loop is halted and we want to step, use a tiny (1) number of instructions to
-        // execute. Otherwise, get out of the loop function.
-        if (GDBStub::GetCpuHaltFlag()) {
-            if (GDBStub::GetCpuStepFlag()) {
-                tight_loop = false;
-            } else {
-                return ResultStatus::Success;
-            }
-        }
     }
 
     Signal signal{Signal::None};
@@ -269,10 +259,6 @@ System::ResultStatus System::RunLoop(bool tight_loop) {
         }
     }
 
-    if (GDBStub::IsServerEnabled()) {
-        GDBStub::SetCpuStepFlag(false);
-    }
-
     Reschedule();
 
     return status;

src/core/gdbstub/gdbstub.cpp

@@ -137,8 +137,6 @@ static Kernel::Thread* current_thread = nullptr;
 // so default to a port outside of that range.
 u16 gdbstub_port = 24689;
 
-bool halt_loop = true;
-bool step_loop = false;
 bool send_trap = false;
 
 // If set to false, the server will never be started and no
@@ -666,7 +664,6 @@ static void ReadCommand() {
         return;
     } else if (c == 0x03) {
         LOG_INFO(Debug_GDBStub, "gdb: found break command\n");
-        halt_loop = true;
         SendSignal(current_thread, SIGTRAP);
         return;
     } else if (c != GDB_STUB_START) {
@@ -916,18 +913,6 @@ void Break(bool is_memory_break) {
     memory_break = is_memory_break;
 }
 
-/// Tell the CPU that it should perform a single step.
-static void Step() {
-    if (command_length > 1) {
-        RegWrite(PC_REGISTER, GdbHexToInt(command_buffer + 1), current_thread);
-        UpdateCPUThreadContext();
-    }
-    step_loop = true;
-    halt_loop = true;
-    send_trap = true;
-    ClearAllInstructionCache();
-}
-
 bool IsMemoryBreak() {
     if (!IsConnected()) {
         return false;
@@ -939,8 +924,6 @@ bool IsMemoryBreak() {
 /// Tell the CPU to continue executing.
 static void Continue() {
     memory_break = false;
-    step_loop = false;
-    halt_loop = false;
     ClearAllInstructionCache();
 }
 
@@ -1132,7 +1115,8 @@ void HandlePacket(Core::System& system) {
         WriteMemory();
         break;
     case 's':
-        Step();
+        // Single step, return ENOTSUP
+        SendReply("E5F");
         return;
     case 'C':
     case 'c':
@@ -1181,17 +1165,9 @@ void DeferStart() {
 
 static void Init(u16 port) {
     if (!server_enabled) {
-        // Set the halt loop to false in case the user enabled the gdbstub mid-execution.
-        // This way the CPU can still execute normally.
-        halt_loop = false;
-        step_loop = false;
         return;
     }
 
-    // Setup initial gdbstub status
-    halt_loop = true;
-    step_loop = false;
-
     breakpoints_execute.clear();
     breakpoints_read.clear();
     breakpoints_write.clear();
@@ -1239,9 +1215,6 @@ static void Init(u16 port) {
     if (gdbserver_socket < 0) {
         // In the case that we couldn't start the server for whatever reason, just start CPU
         // execution like normal.
-        halt_loop = false;
-        step_loop = false;
-
         LOG_ERROR(Debug_GDBStub, "Failed to accept gdb client");
     } else {
         LOG_INFO(Debug_GDBStub, "Client connected.\n");
@@ -1285,22 +1258,6 @@ bool IsConnected() {
     return IsServerEnabled() && gdbserver_socket != -1;
 }
 
-bool GetCpuHaltFlag() {
-    return halt_loop;
-}
-
-void SetCpuHaltFlag(bool halt) {
-    halt_loop = halt;
-}
-
-bool GetCpuStepFlag() {
-    return step_loop;
-}
-
-void SetCpuStepFlag(bool is_step) {
-    step_loop = is_step;
-}
-
 void SendTrap(Kernel::Thread* thread, int trap) {
     if (!send_trap) {
         return;
@@ -1310,7 +1267,6 @@ void SendTrap(Kernel::Thread* thread, int trap) {
 
     SendSignal(thread, trap);
 
-    halt_loop = true;
     send_trap = false;
 }
 }; // namespace GDBStub

src/core/gdbstub/gdbstub.h

@@ -92,26 +92,6 @@ BreakpointAddress GetNextBreakpointFromAddress(VAddr addr, GDBStub::BreakpointTy
  */
 bool CheckBreakpoint(VAddr addr, GDBStub::BreakpointType type);
 
-// If set to true, the CPU will halt at the beginning of the next CPU loop.
-bool GetCpuHaltFlag();
-
-/**
- * If set to true, the CPU will halt at the beginning of the next CPU loop.
- *
- * @param halt whether to halt on the next loop
- */
-void SetCpuHaltFlag(bool halt);
-
-// If set to true and the CPU is halted, the CPU will step one instruction.
-bool GetCpuStepFlag();
-
-/**
- * When set to true, the CPU will step one instruction when the CPU is halted next.
- *
- * @param is_step
- */
-void SetCpuStepFlag(bool is_step);
-
 /**
  * Send trap signal from thread back to the gdbstub server.
  *

src/core/gdbstub/hio.cpp

@@ -23,9 +23,6 @@ enum class Status {
 
 static std::atomic<Status> request_status{Status::NoRequest};
 
-static std::atomic<bool> was_halted = false;
-static std::atomic<bool> was_stepping = false;
-
 } // namespace
 
 /**
@@ -97,14 +94,9 @@ void SetHioRequest(Core::System& system, const VAddr addr) {
     current_hio_request_addr = addr;
     request_status = Status::NotSent;
 
-    was_halted = GetCpuHaltFlag();
-    was_stepping = GetCpuStepFlag();
-
     // Now halt, so that no further instructions are executed until the request
     // is processed by the client. We will continue after the reply comes back
     Break();
-    SetCpuHaltFlag(true);
-    SetCpuStepFlag(false);
     system.GetRunningCore().ClearInstructionCache();
 }
 
@@ -195,8 +187,6 @@ void HandleHioReply(Core::System& system, const u8* const command_buffer,
     request_status = Status::NoRequest;
 
     // Restore state from before the request came in
-    SetCpuStepFlag(was_stepping);
-    SetCpuHaltFlag(was_halted);
     system.GetRunningCore().ClearInstructionCache();
 }