[core, am] stub SetGpuTimeSliceBoost & fix ExitProcessAndReturn (#3475)

A few things noticed on "Super Mario Allstars", this stubs SetGpuTimeSliceBoost and adds a fix for the "Return to title selection" menü.

Basically ExitProcessAndReturn now starts/restarts the process on program_index 0 (main menu / title screen) and fixes a device memory clear when using that method.

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3475
Reviewed-by: Lizzie <lizzie@eden-emu.dev>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Co-authored-by: Maufeat <sahyno1996@gmail.com>
Co-committed-by: Maufeat <sahyno1996@gmail.com>

src/core/core.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 #include <array>
@@ -142,6 +142,7 @@ struct System::Impl {
 
     void ReinitializeIfNecessary(System& system) {
         const bool must_reinitialize =
+            !device_memory.has_value() ||
             is_multicore != Settings::values.use_multi_core.GetValue() ||
             extended_memory_layout != (Settings::values.memory_layout_mode.GetValue() !=
                                        Settings::MemoryLayout::Memory_4Gb);
@@ -414,6 +415,7 @@ struct System::Impl {
         cpu_manager.Shutdown();
         debugger.reset();
         kernel.Shutdown();
+        device_memory.reset();
         stop_event = {};
         Network::RestartSocketOperations();
 

src/core/hle/service/am/service/applet_common_functions.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2024 yuzu Emulator Project
@@ -36,7 +36,7 @@ IAppletCommonFunctions::IAppletCommonFunctions(Core::System& system_,
         {100, nullptr, "SetApplicationCoreUsageMode"},
         {300, D<&IAppletCommonFunctions::GetCurrentApplicationId>, "GetCurrentApplicationId"},
         {310, nullptr, "IsSystemAppletHomeMenu"}, //19.0.0+
-        {320, nullptr, "SetGpuTimeSliceBoost"}, //19.0.0+
+        {320, D<&IAppletCommonFunctions::SetGpuTimeSliceBoost>, "SetGpuTimeSliceBoost"}, //19.0.0+
         {321, nullptr, "SetGpuTimeSliceBoostDueToApplication"}, //19.0.0+
         {350, D<&IAppletCommonFunctions::Unknown350>, "Unknown350"} //20.0.0+
     };
@@ -82,6 +82,11 @@ Result IAppletCommonFunctions::GetCurrentApplicationId(Out<u64> out_application_
     R_SUCCEED();
 }
 
+Result IAppletCommonFunctions::SetGpuTimeSliceBoost(s64 time_span) {
+    LOG_WARNING(Service_AM, "(STUBBED) called, time_span={}", time_span);
+    R_SUCCEED();
+}
+
 Result IAppletCommonFunctions::Unknown350(Out<u16> out_unknown) {
     LOG_WARNING(Service_AM, "(STUBBED) called");
     *out_unknown = 0;

src/core/hle/service/am/service/applet_common_functions.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2024 yuzu Emulator Project
@@ -24,6 +24,7 @@ private:
     Result SetDisplayMagnification(f32 x, f32 y, f32 width, f32 height);
     Result SetCpuBoostRequestPriority(s32 priority);
     Result GetCurrentApplicationId(Out<u64> out_application_id);
+    Result SetGpuTimeSliceBoost(s64 time_span);
     Result Unknown350(Out<u16> out_unknown);
 
     const std::shared_ptr<Applet> applet;

src/core/hle/service/am/service/library_applet_self_accessor.cpp

@@ -179,7 +179,14 @@ Result ILibraryAppletSelfAccessor::GetMainAppletStorageId(Out<FileSys::StorageId
 
 Result ILibraryAppletSelfAccessor::ExitProcessAndReturn() {
     LOG_INFO(Service_AM, "called");
-    m_applet->process->Terminate();
+
+    if (const auto caller_applet = m_applet->caller_applet.lock(); caller_applet) {
+        system.GetUserChannel() = caller_applet->user_channel_launch_parameter;
+    } else {
+        system.GetUserChannel() = m_applet->user_channel_launch_parameter;
+    }
+
+    system.ExecuteProgram(0);
     R_SUCCEED();
 }