[core/arm] introduce vtable bouncing (#2943)

Basically this just makes functions that go into zero-page or invalid addresses "bounce" back (with a return err of 0) such that it emulates a subroutine returning appropriatedly... this is mainly inspired by [this particular commit](fbb4f5c015); with the key difference of accounting for the scheduler fucking up some random bs.

I don't like this hack but anyways maybe it fixes something?

Signed-off-by: lizzie lizzie@eden-emu.dev

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/2943
Reviewed-by: Maufeat <sahyno1996@gmail.com>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Co-authored-by: lizzie <lizzie@eden-emu.dev>
Co-committed-by: lizzie <lizzie@eden-emu.dev>

src/common/settings.h

@@ -240,7 +240,7 @@ struct Values {
                                                     Category::Cpu};
     SwitchableSetting<CpuAccuracy, true> cpu_accuracy{linkage, CpuAccuracy::Auto,
                                                       "cpu_accuracy", Category::Cpu};
-
+    SwitchableSetting<bool> vtable_bouncing{linkage, true, "vtable_bouncing", Category::Cpu};
     SwitchableSetting<bool> use_fast_cpu_time{linkage,
                                               false,
                                               "use_fast_cpu_time",

src/core/hle/kernel/physical_core.cpp

@@ -103,12 +103,26 @@ void PhysicalCore::RunThread(Kernel::KThread* thread) {
         const bool data_abort = True(hr & Core::HaltReason::DataAbort);
         const bool interrupt = True(hr & Core::HaltReason::BreakLoop);
 
+        bool may_abort = true; // Ignore aborting virtual functions (for debugging)
+        if (prefetch_abort && ::Settings::values.vtable_bouncing) {
+            auto& lock = m_kernel.GlobalSchedulerContext().SchedulerLock();
+            lock.Lock();
+            Kernel::Svc::ThreadContext ctx;
+            interface->GetContext(ctx);
+            LOG_WARNING(Core_ARM, "vtable bouncing {:016X}", ctx.lr);
+            ctx.pc = ctx.lr;
+            ctx.r[0] = 0;
+            interface->SetContext(ctx);
+            lock.Unlock();
+            may_abort = false;
+        }
+
         // Since scheduling may occur here, we cannot use any cached
         // state after returning from calls we make.
 
         // Notify the debugger and go to sleep if a breakpoint was hit,
         // or if the thread is unable to continue for any reason.
-        if (breakpoint || prefetch_abort) {
+        if (breakpoint || (prefetch_abort && may_abort)) {
             if (breakpoint) {
                 interface->RewindBreakpointInstruction();
             }

src/qt_common/config/shared_translation.cpp

@@ -109,6 +109,10 @@ std::unique_ptr<TranslationMap> InitializeTranslations(QObject* parent)
               "cause deadlocks. A range of 77-21000 is recommended."));
     INSERT(Settings, cpu_backend, tr("Backend:"), QString());
 
+    INSERT(Settings, vtable_bouncing,
+        tr("Virtual Table Bouncing"),
+        tr("Bounces (by emulating a 0-valued return) any functions that triggers a prefetch abort"));
+
     // Cpu Debug
 
     // Cpu Unsafe