From a30bd8631171a5d8ee6c96efafa522bb054874be Mon Sep 17 00:00:00 2001
From: Gregory Hainaut <gregory.hainaut@gmail.com>
Date: Fri, 14 Nov 2014 22:46:31 +0100
Subject: [PATCH] pcsx2: interpreter: add an exception for tlb miss

When a tlb miss is detected current instruction must be skipped. We need
to immediately switch to the handler

Typical instruction bug case:
 lw a0, 0x8(a0)

a0 mustn't be loaded if we have a miss

v2: create a dedicated exception for tlb miss

v3:
* rename exception to CancelInstruction
* add a basic state machine on the exec loop so we keep same behavior
  for eeloadReplaceOSDSYS and eeGameStarting

v4: remove assert
---
 pcsx2/Interpreter.cpp | 57 +++++++++++++++++++++++++++++++------------
 pcsx2/R5900.h         |  6 +++++
 pcsx2/vtlb.cpp        |  3 +++
 3 files changed, 50 insertions(+), 16 deletions(-)

diff --git a/pcsx2/Interpreter.cpp b/pcsx2/Interpreter.cpp
index 59a90181c1..60f2cb435c 100644
--- a/pcsx2/Interpreter.cpp
+++ b/pcsx2/Interpreter.cpp
@@ -479,23 +479,48 @@ static void intEventTest()
 
 static void intExecute()
 {
-	try {
-		if (g_SkipBiosHack) {
-			do
-				execI();
-			while (cpuRegs.pc != EELOAD_START);
-			eeloadReplaceOSDSYS();
+	bool instruction_was_cancelled;
+	enum ExecuteState {
+		RESET,
+		REPLACE_OSDSYS_DONE,
+		GAME_STARTING_DONE
+	};
+	ExecuteState state = RESET;
+	do {
+		instruction_was_cancelled = false;
+		try {
+			// The execution was splited in three parts so it is easier to
+			// resume it after a cancelled instruction.
+			switch (state) {
+				case RESET:
+					if (g_SkipBiosHack) {
+						do
+							execI();
+						while (cpuRegs.pc != EELOAD_START);
+						eeloadReplaceOSDSYS();
+					}
+					state = REPLACE_OSDSYS_DONE;
+
+				case REPLACE_OSDSYS_DONE:
+					if (ElfEntry != 0xFFFFFFFF) {
+						do
+							execI();
+						while (cpuRegs.pc != ElfEntry);
+						eeGameStarting();
+					}
+					state = GAME_STARTING_DONE;
+
+				case GAME_STARTING_DONE:
+					while (true)
+						execI();
+			}
 		}
-		if (ElfEntry != 0xFFFFFFFF) {
-			do
-				execI();
-			while (cpuRegs.pc != ElfEntry);
-			eeGameStarting();
-		} else {
-			while (true)
-				execI();
-		}
-	} catch( Exception::ExitCpuExecute& ) { }
+		catch( Exception::ExitCpuExecute& ) { }
+		catch( Exception::CancelInstruction& ) { instruction_was_cancelled = true; }
+
+		// For example a tlb miss will throw an exception. Cpu must be resumed
+		// to execute the handler
+	} while (instruction_was_cancelled);
 }
 
 static void intCheckExecutionState()
diff --git a/pcsx2/R5900.h b/pcsx2/R5900.h
index 4504a6fed7..cd027895a2 100644
--- a/pcsx2/R5900.h
+++ b/pcsx2/R5900.h
@@ -37,6 +37,12 @@ namespace Exception
 	public:
 		explicit ExitCpuExecute() { }
 	};
+
+	class CancelInstruction
+	{
+	public:
+		explicit CancelInstruction() { }
+	};
 }
 
 // --------------------------------------------------------------------------------------
diff --git a/pcsx2/vtlb.cpp b/pcsx2/vtlb.cpp
index a26ba37bac..da746654b9 100644
--- a/pcsx2/vtlb.cpp
+++ b/pcsx2/vtlb.cpp
@@ -376,6 +376,9 @@ static __ri void vtlb_Miss(u32 addr,u32 mode)
 			cpuTlbMissW(addr, cpuRegs.branch);
 		else
 			cpuTlbMissR(addr, cpuRegs.branch);
+
+		// Exception handled. Current instruction need to be stopped
+		throw Exception::CancelInstruction();
 	}
 
 	// The exception terminate the program on linux which is very annoying