dmnt-cheat: Implement real workaround for 6.0.0+ kernel bug

stratosphere/dmnt/source/dmnt_cheat_debug_events_manager.cpp

@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2018 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+ 
+#include <map>
+#include <switch.h>
+#include "dmnt_config.hpp"
+#include "dmnt_cheat_debug_events_manager.hpp"
+
+
+/* WORKAROUND: This design prevents a kernel deadlock from occurring on 6.0.0+ */
+
+static HosThread g_per_core_threads[DmntCheatDebugEventsManager::NumCores];
+static HosMessageQueue *g_per_core_queues[DmntCheatDebugEventsManager::NumCores];
+static HosSignal g_continued_signal;
+
+void DmntCheatDebugEventsManager::PerCoreThreadFunc(void *arg) {
+    /* This thread will simply wait on the appropriate message queue. */
+    size_t current_core = reinterpret_cast<size_t>(arg);
+    while (true) {
+        Handle debug_handle = 0;
+        /* Get the debug handle. */
+        {
+            uintptr_t x = 0;
+            g_per_core_queues[current_core]->Receive(&x);
+            debug_handle = static_cast<Handle>(x);
+        }
+        
+        /* Continue the process, if needed. */
+        if (kernelAbove300()) {
+            svcContinueDebugEvent(debug_handle, 5, nullptr, 0);
+        } else {
+            svcLegacyContinueDebugEvent(debug_handle, 5, 0);
+        }
+        
+        g_continued_signal.Signal();
+    }
+}
+
+void DmntCheatDebugEventsManager::ContinueCheatProcess(Handle cheat_dbg_hnd) {
+    /* Loop getting debug events. */
+    DebugEventInfo dbg_event;
+    while (R_SUCCEEDED(svcGetDebugEvent((u8 *)&dbg_event, cheat_dbg_hnd))) {
+        /* ... */
+    }
+    
+    size_t target_core = DmntCheatDebugEventsManager::NumCores - 1;
+    /* Retrieve correct core for new thread event. */
+    if (dbg_event.type == DebugEventType::AttachThread) {
+        u64 out64;
+        u32 out32;
+        Result rc = svcGetDebugThreadParam(&out64, &out32, cheat_dbg_hnd, dbg_event.info.attach_thread.thread_id, DebugThreadParam_CurrentCore);
+        if (R_FAILED(rc)) {
+            fatalSimple(rc);
+        }
+        
+        
+        target_core = out32;
+    }
+    
+    /* Make appropriate thread continue. */
+    g_per_core_queues[target_core]->Send(static_cast<uintptr_t>(cheat_dbg_hnd));
+    
+    /* Wait. */
+    g_continued_signal.Wait();
+    g_continued_signal.Reset();
+}
+
+void DmntCheatDebugEventsManager::Initialize() {
+    /* Spawn per core resources. */
+    for (size_t i = 0; i < DmntCheatDebugEventsManager::NumCores; i++) {
+        /* Create queue. */
+        g_per_core_queues[i] = new HosMessageQueue(1);
+        
+        /* Create thread. */
+        if (R_FAILED(g_per_core_threads[i].Initialize(&DmntCheatDebugEventsManager::PerCoreThreadFunc, reinterpret_cast<void *>(i), 0x1000, 24, i))) {
+            std::abort();
+        }
+        
+        /* Set core mask. */
+        if (R_FAILED(svcSetThreadCoreMask(g_per_core_threads[i].GetHandle(), i, (1u << i)))) {
+            std::abort();
+        }
+        
+        /* Start thread. */
+        if (R_FAILED(g_per_core_threads[i].Start())) {
+            std::abort();
+        }
+    }
+}

stratosphere/dmnt/source/dmnt_cheat_debug_events_manager.hpp

@@ -0,0 +1,131 @@
+/*
+ * Copyright (c) 2018 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+ 
+#pragma once
+#include <switch.h>
+#include <stratosphere.hpp>
+
+#include "dmnt_cheat_types.hpp"
+
+struct StackFrame {
+    u64 fp;
+    u64 lr;
+};
+
+struct AttachProcessInfo {
+    u64 title_id;
+    u64 process_id;
+    char name[0xC];
+    u32 flags;
+    u64 user_exception_context_address; /* 5.0.0+ */
+};
+
+struct AttachThreadInfo {
+    u64 thread_id;
+    u64 tls_address;
+    u64 entrypoint;
+};
+
+/* TODO: ExitProcessInfo */
+/* TODO: ExitThreadInfo */
+
+enum class DebugExceptionType : u32 {
+    UndefinedInstruction = 0,
+    InstructionAbort = 1,
+    DataAbort = 2,
+    AlignmentFault = 3,
+    DebuggerAttached = 4,
+    BreakPoint = 5,
+    UserBreak = 6,
+    DebuggerBreak = 7,
+    BadSvc = 8,
+    UnknownNine = 9,
+};
+
+struct UndefinedInstructionInfo {
+    u32 insn;
+};
+
+struct DataAbortInfo {
+    u64 address;
+};
+
+struct AlignmentFaultInfo {
+    u64 address;
+};
+
+struct UserBreakInfo {
+    u64 break_reason;
+    u64 address;
+    u64 size;
+};
+
+struct BadSvcInfo {
+    u32 id;
+};
+
+union SpecificExceptionInfo {
+    UndefinedInstructionInfo undefined_instruction;
+    DataAbortInfo data_abort;
+    AlignmentFaultInfo alignment_fault;
+    UserBreakInfo user_break;
+    BadSvcInfo bad_svc;
+    u64 raw;
+};
+
+struct ExceptionInfo {
+    DebugExceptionType type;
+    u64 address;
+    SpecificExceptionInfo specific;
+};
+
+
+enum class DebugEventType : u32 {
+    AttachProcess = 0,
+    AttachThread = 1,
+    ExitProcess = 2,
+    ExitThread = 3,
+    Exception = 4
+};
+
+union DebugInfo {
+    AttachProcessInfo attach_process;
+    AttachThreadInfo attach_thread;
+    ExceptionInfo exception;
+};
+
+struct DebugEventInfo {
+    DebugEventType type;
+    u32 flags;
+    u64 thread_id;
+    union {
+        DebugInfo info;
+        u64 _[0x40/sizeof(u64)];
+    };
+};
+
+static_assert(sizeof(DebugEventInfo) >= 0x50, "Incorrect DebugEventInfo definition!");
+
+class DmntCheatDebugEventsManager {
+    public:
+        static constexpr size_t NumCores = 4;
+    private:
+        static void PerCoreThreadFunc(void *arg);
+    public:
+        static void ContinueCheatProcess(Handle cheat_dbg_hnd);
+        
+        static void Initialize();
+};

stratosphere/dmnt/source/dmnt_cheat_manager.cpp

@@ -19,6 +19,7 @@
 #include "dmnt_cheat_manager.hpp"
 #include "dmnt_cheat_vm.hpp"
 #include "dmnt_config.hpp"
+#include "dmnt_cheat_debug_events_manager.hpp"
 #include "pm_shim.h"
 
 static HosMutex g_cheat_lock;
@@ -46,10 +47,6 @@ static CheatEntry g_cheat_entries[DmntCheatManager::MaxCheatCount];
 /* Global frozen address storage. */
 static std::map<u64, FrozenAddressValue> g_frozen_addresses_map;
 
-/* WORKAROUND: These prevent a kernel deadlock from occurring on 6.0.0+ */
-static HosThread g_workaround_threads[4];
-static void KernelWorkaroundThreadFunc(void *arg) { svcSleepThread(INT64_MAX); }
-
 void DmntCheatManager::StartDebugEventsThread() {
     std::scoped_lock<HosMutex> lk(g_debug_event_thread_lock);
     
@@ -122,21 +119,6 @@ bool DmntCheatManager::HasActiveCheatProcess() {
     return has_cheat_process;
 }
 
-void DmntCheatManager::ContinueCheatProcess() {
-    /* Loop getting debug events. */
-    u8 debug_event_buf[0x50];
-    while (R_SUCCEEDED(svcGetDebugEvent((u8 *)debug_event_buf, g_cheat_process_debug_hnd))) {
-        /* ... */
-    }
-
-    /* Continue the process, if needed. */
-    if (kernelAbove300()) {
-        svcContinueDebugEvent(g_cheat_process_debug_hnd, 5, nullptr, 0);
-    } else {
-        svcLegacyContinueDebugEvent(g_cheat_process_debug_hnd, 5, 0);
-    }
-}
-
 Result DmntCheatManager::ReadCheatProcessMemoryForVm(u64 proc_addr, void *out_data, size_t size) {
     if (HasActiveCheatProcess()) {
         return svcReadDebugProcessMemory(out_data, g_cheat_process_debug_hnd, proc_addr, size);
@@ -933,7 +915,7 @@ void DmntCheatManager::DebugEventsThread(void *arg) {
         
         /* Handle any pending debug events. */
         if (HasActiveCheatProcess()) {
-            ContinueCheatProcess();
+            DmntCheatDebugEventsManager::ContinueCheatProcess(g_cheat_process_debug_hnd);
         }
         
     }
@@ -975,19 +957,8 @@ void DmntCheatManager::InitializeCheatManager() {
         }
     }
     
-    /* WORKAROUND: On 6.0.0+, we must ensure that every core has at least one non-game thread. */
+    /* Initialize debug events manager. */
-    /* This prevents a kernel deadlock when continuing debug events. */
+    DmntCheatDebugEventsManager::Initialize();
-    if (kernelAbove600()) {
-        for (size_t i = 0; i < sizeof(g_workaround_threads) / sizeof(g_workaround_threads[0]); i++) {
-            if (R_FAILED(g_workaround_threads[i].Initialize(&KernelWorkaroundThreadFunc, nullptr, 0x1000, 0, i))) {
-                std::abort();
-            }
-            
-            if (R_FAILED(g_workaround_threads[i].Start())) {
-                std::abort();
-            }
-        }
-    }
     
     /* Spawn application detection thread, spawn cheat vm thread. */
     if (R_FAILED(g_detect_thread.Initialize(&DmntCheatManager::DetectThread, nullptr, 0x4000, 39))) {