From 41d5b41523247a11f3c13ff055bdd1e37bec896e Mon Sep 17 00:00:00 2001
From: "Dr. Chat" <arkolbed@gmail.com>
Date: Fri, 27 Nov 2015 23:00:38 -0600
Subject: [PATCH] Automatically install any CPU breakpoints in any
 newly-defined functions if necessary.

---
 src/xenia/cpu/backend/backend.h          |  2 ++
 src/xenia/cpu/backend/x64/x64_backend.cc | 24 +++++++++++++++++++++++-
 src/xenia/cpu/backend/x64/x64_backend.h  |  1 +
 src/xenia/cpu/function.h                 | 12 ++++++++++++
 src/xenia/cpu/processor.cc               | 12 ++++++++++++
 src/xenia/cpu/processor.h                |  3 +--
 6 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/src/xenia/cpu/backend/backend.h b/src/xenia/cpu/backend/backend.h
index 86389f2fe..1f0c540a6 100644
--- a/src/xenia/cpu/backend/backend.h
+++ b/src/xenia/cpu/backend/backend.h
@@ -17,6 +17,7 @@
 namespace xe {
 namespace cpu {
 class Breakpoint;
+class Function;
 class GuestFunction;
 class Module;
 class Processor;
@@ -53,6 +54,7 @@ class Backend {
       Module* module, uint32_t address) = 0;
 
   virtual bool InstallBreakpoint(Breakpoint* bp) { return false; }
+  virtual bool InstallBreakpoint(Breakpoint* bp, Function* func) { return false; }
   virtual bool UninstallBreakpoint(Breakpoint* bp) { return false; }
 
  protected:
diff --git a/src/xenia/cpu/backend/x64/x64_backend.cc b/src/xenia/cpu/backend/x64/x64_backend.cc
index dca4addbb..021fe4a13 100644
--- a/src/xenia/cpu/backend/x64/x64_backend.cc
+++ b/src/xenia/cpu/backend/x64/x64_backend.cc
@@ -133,7 +133,11 @@ bool X64Backend::InstallBreakpoint(Breakpoint* bp) {
     assert_true(function->is_guest());
     auto guest_function = reinterpret_cast<cpu::GuestFunction*>(function);
     auto code = guest_function->MapGuestAddressToMachineCode(bp->address());
-    assert_not_zero(code);
+    if (!code) {
+      // This should not happen.
+      assert_always();
+      return false;
+    }
 
     auto orig_bytes =
         xe::load_and_swap<uint16_t>(reinterpret_cast<void*>(code + 0x0));
@@ -145,6 +149,24 @@ bool X64Backend::InstallBreakpoint(Breakpoint* bp) {
   return true;
 }
 
+bool X64Backend::InstallBreakpoint(Breakpoint* bp, Function* func) {
+  assert_true(func->is_guest());
+  auto guest_function = reinterpret_cast<cpu::GuestFunction*>(func);
+  auto code = guest_function->MapGuestAddressToMachineCode(bp->address());
+  if (!code) {
+    assert_always();
+    return false;
+  }
+
+  // Assume we haven't already installed a breakpoint in this spot.
+  auto orig_bytes =
+      xe::load_and_swap<uint16_t>(reinterpret_cast<void*>(code + 0x0));
+  bp->backend_data().push_back({code, orig_bytes});
+
+  xe::store_and_swap<uint16_t>(reinterpret_cast<void*>(code + 0x0), 0x0F0C);
+  return true;
+}
+
 bool X64Backend::UninstallBreakpoint(Breakpoint* bp) {
   for (auto pair : bp->backend_data()) {
     xe::store_and_swap<uint16_t>(reinterpret_cast<void*>(pair.first),
diff --git a/src/xenia/cpu/backend/x64/x64_backend.h b/src/xenia/cpu/backend/x64/x64_backend.h
index e1aadd9e1..02748d71f 100644
--- a/src/xenia/cpu/backend/x64/x64_backend.h
+++ b/src/xenia/cpu/backend/x64/x64_backend.h
@@ -63,6 +63,7 @@ class X64Backend : public Backend {
                                                      uint32_t address) override;
 
   bool InstallBreakpoint(Breakpoint* bp) override;
+  bool InstallBreakpoint(Breakpoint* bp, Function* func) override;
   bool UninstallBreakpoint(Breakpoint* bp) override;
 
  private:
diff --git a/src/xenia/cpu/function.h b/src/xenia/cpu/function.h
index 29160c4da..802241133 100644
--- a/src/xenia/cpu/function.h
+++ b/src/xenia/cpu/function.h
@@ -49,6 +49,18 @@ class Function : public Symbol {
   void set_behavior(Behavior value) { behavior_ = value; }
   bool is_guest() const { return behavior_ != Behavior::kBuiltin; }
 
+  bool ContainsAddress(uint32_t address) const {
+    if (!address_ || !end_address_) {
+      return false;
+    }
+
+    if (address >= address_ && address < end_address_) {
+      return true;
+    }
+
+    return false;
+  }
+
   virtual bool Call(ThreadState* thread_state, uint32_t return_address) = 0;
 
  protected:
diff --git a/src/xenia/cpu/processor.cc b/src/xenia/cpu/processor.cc
index bd85cfba9..c2a31affa 100644
--- a/src/xenia/cpu/processor.cc
+++ b/src/xenia/cpu/processor.cc
@@ -274,6 +274,8 @@ bool Processor::DemandFunction(Function* function) {
       debugger_->OnFunctionDefined(function);
     }
 
+    BreakpointFunctionDefined(function);
+
     function->set_status(Symbol::Status::kDefined);
     symbol_status = function->status();
   }
@@ -402,6 +404,16 @@ void Processor::LowerIrql(Irql old_value) {
                       reinterpret_cast<volatile uint32_t*>(&irql_));
 }
 
+void Processor::BreakpointFunctionDefined(Function* function) {
+  std::lock_guard<std::recursive_mutex> lock(breakpoint_lock_);
+
+  for (auto it = breakpoints_.begin(); it != breakpoints_.end(); it++) {
+    if (function->ContainsAddress((*it)->address())) {
+      backend_->InstallBreakpoint(*it, function);
+    }
+  }
+}
+
 bool Processor::InstallBreakpoint(Breakpoint* bp) {
   std::lock_guard<std::recursive_mutex> lock(breakpoint_lock_);
 
diff --git a/src/xenia/cpu/processor.h b/src/xenia/cpu/processor.h
index ef5790dc4..ca5296e99 100644
--- a/src/xenia/cpu/processor.h
+++ b/src/xenia/cpu/processor.h
@@ -101,8 +101,7 @@ class Processor {
   std::vector<Breakpoint*> breakpoints() const { return breakpoints_; }
 
  private:
-  static bool ExceptionCallbackThunk(Exception* ex, void* data);
-  bool ExceptionCallback(Exception* ex);
+  void BreakpointFunctionDefined(Function* function);
 
   bool DemandFunction(Function* function);