kern: Add real SvcBreak implementation

libraries/libmesosphere/include/mesosphere/arch/arm64/kern_k_debug.hpp

@@ -35,6 +35,10 @@ namespace ams::kern::arch::arm64 {
 
             static void PostDestroy(uintptr_t arg) { /* ... */ }
         public:
+            static uintptr_t GetProgramCounter(const KThread &thread);
+            static void SetPreviousProgramCounter();
+
+            static Result BreakIfAttached(ams::svc::BreakReason break_reason, uintptr_t address, size_t size);
             static Result SetHardwareBreakPoint(ams::svc::HardwareBreakPointRegisterName name, u64 flags, u64 value);
 
             /* TODO: This is a placeholder definition. */

libraries/libmesosphere/include/mesosphere/kern_k_process.hpp

@@ -193,6 +193,8 @@ namespace ams::kern {
             KProcess::State SetDebugObject(void *debug_object);
             void ClearDebugObject(KProcess::State state);
 
+            bool EnterJitDebug(ams::svc::DebugEvent event, ams::svc::DebugException exception, uintptr_t param1 = 0, uintptr_t param2 = 0, uintptr_t param3 = 0, uintptr_t param4 = 0);
+
             KEventInfo *GetJitDebugInfo();
             void ClearJitDebugInfo();
 

libraries/libmesosphere/source/arch/arm64/kern_k_debug.cpp

@@ -38,6 +38,36 @@ namespace ams::kern::arch::arm64 {
         static_assert(ForbiddenWatchPointFlagsMask == 0xFFFFFFFF00F0E006ul);
     }
 
+    uintptr_t KDebug::GetProgramCounter(const KThread &thread) {
+        return GetExceptionContext(std::addressof(thread))->pc;
+    }
+
+    void KDebug::SetPreviousProgramCounter() {
+        /* Get the current thread. */
+        KThread *thread = GetCurrentThreadPointer();
+        MESOSPHERE_ASSERT(thread->IsCallingSvc());
+
+        /* Get the exception context. */
+        KExceptionContext *e_ctx = GetExceptionContext(thread);
+
+        /* Set the previous pc. */
+        if (e_ctx->write == 0) {
+            /* Subtract from the program counter. */
+            if (thread->GetOwnerProcess()->Is64Bit()) {
+                e_ctx->pc -= sizeof(u32);
+            } else {
+                e_ctx->pc -= (e_ctx->psr & 0x20) ? sizeof(u16) : sizeof(u32);
+            }
+
+            /* Mark that we've set. */
+            e_ctx->write = 1;
+        }
+    }
+
+    Result KDebug::BreakIfAttached(ams::svc::BreakReason break_reason, uintptr_t address, size_t size) {
+        return KDebugBase::OnDebugEvent(ams::svc::DebugEvent_Exception, ams::svc::DebugException_UserBreak, GetProgramCounter(GetCurrentThread()), break_reason, address, size);
+    }
+
     #define MESOSPHERE_SET_HW_BREAK_POINT(ID, FLAGS, VALUE) \
         ({                                                  \
             cpu::SetDbgBcr##ID##El1(0);                     \

libraries/libmesosphere/source/kern_k_process.cpp

@@ -999,6 +999,90 @@ namespace ams::kern {
         }
     }
 
+    bool KProcess::EnterJitDebug(ams::svc::DebugEvent event, ams::svc::DebugException exception, uintptr_t param1, uintptr_t param2, uintptr_t param3, uintptr_t param4) {
+        /* Check that we're the current process. */
+        MESOSPHERE_ASSERT_THIS();
+        MESOSPHERE_ASSERT(this == GetCurrentProcessPointer());
+
+        /* If we aren't allowed to enter jit debug, don't. */
+        if ((this->flags & ams::svc::CreateProcessFlag_EnableDebug) == 0) {
+            return false;
+        }
+
+        /* We're the current process, so we should be some kind of running. */
+        MESOSPHERE_ASSERT(this->state != State_Created);
+        MESOSPHERE_ASSERT(this->state != State_CreatedAttached);
+        MESOSPHERE_ASSERT(this->state != State_Terminated);
+
+        /* Try to enter JIT debug. */
+        while (true) {
+            /* Lock ourselves and the scheduler. */
+            KScopedLightLock lk(this->state_lock);
+            KScopedLightLock list_lk(this->list_lock);
+            KScopedSchedulerLock sl;
+
+            /* If we're attached to a debugger, we're necessarily in debug. */
+            if (this->IsAttachedToDebugger()) {
+                return true;
+            }
+
+            /* If the current thread is terminating, we can't enter debug. */
+            if (GetCurrentThread().IsTerminationRequested()) {
+                return false;
+            }
+
+            /* We're not attached to debugger, so check that. */
+            MESOSPHERE_ASSERT(this->state != State_RunningAttached);
+            MESOSPHERE_ASSERT(this->state != State_DebugBreak);
+
+            /* If we're terminating, we can't enter debug. */
+            if (this->state != State_Running && this->state != State_Crashed) {
+                MESOSPHERE_ASSERT(this->state == State_Terminating);
+                return false;
+            }
+
+            /* If the current thread is suspended, retry. */
+            if (GetCurrentThread().IsSuspended()) {
+                continue;
+            }
+
+            /* Suspend all our threads. */
+            {
+                auto end = this->GetThreadList().end();
+                for (auto it = this->GetThreadList().begin(); it != end; ++it) {
+                    it->RequestSuspend(KThread::SuspendType_Debug);
+                }
+            }
+
+            /* Change our state to crashed. */
+            this->ChangeState(State_Crashed);
+
+            /* Enter jit debug. */
+            this->is_jit_debug             = true;
+            this->jit_debug_event_type     = event;
+            this->jit_debug_exception_type = exception;
+            this->jit_debug_params[0]      = param1;
+            this->jit_debug_params[1]      = param2;
+            this->jit_debug_params[2]      = param3;
+            this->jit_debug_params[3]      = param4;
+            this->jit_debug_thread_id      = GetCurrentThread().GetId();
+
+            /* Exit our retry loop. */
+            break;
+        }
+
+        /* Check if our state indicates we're in jit debug. */
+        {
+            KScopedSchedulerLock sl;
+
+            if (this->state == State_Running || this->state == State_RunningAttached || this->state == State_Crashed || this->state == State_DebugBreak) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     KEventInfo *KProcess::GetJitDebugInfo() {
         MESOSPHERE_ASSERT_THIS();
         MESOSPHERE_ASSERT(KScheduler::IsSchedulerLockedByCurrentThread());

libraries/libmesosphere/source/svc/kern_svc_exception.cpp

@@ -21,25 +21,54 @@ namespace ams::kern::svc {
 
     namespace {
 
-        void Break(ams::svc::BreakReason break_reason, uintptr_t address, size_t size) {
-            /* Log for debug that Break was called. */
-            MESOSPHERE_LOG("%s: Break(%08x, %016lx, %zu)\n", GetCurrentProcess().GetName(), static_cast<u32>(break_reason), address, size);
+        [[maybe_unused]] void PrintBreak(ams::svc::BreakReason break_reason) {
+            /* Print that break was called. */
+            MESOSPHERE_RELEASE_LOG("%s: svc::Break(%d) was called, pid=%ld, tid=%ld\n", GetCurrentProcess().GetName(), static_cast<s32>(break_reason), GetCurrentProcess().GetId(), GetCurrentThread().GetId());
 
-            /* If the current process is attached to debugger, notify it. */
+            /* Print the current thread's registers. */
+            /* TODO: KDebug::PrintRegisters(); */
+
+            /* Print a backtrace. */
+            /* TODO: KDebug::PrintBacktrace(); */
+        }
+
+        void Break(ams::svc::BreakReason break_reason, uintptr_t address, size_t size) {
+            /* Determine whether the break is only a notification. */
+            const bool is_notification = (break_reason & ams::svc::BreakReason_NotificationOnlyFlag) != 0;
+
+            /* If the break isn't a notification, print it. */
+            if (!is_notification) {
+                #ifdef MESOSPHERE_BUILD_FOR_DEBUGGING
+                PrintBreak(break_reason);
+                #endif
+            }
+
+            /* If the current process is attached to debugger, try to notify it. */
             if (GetCurrentProcess().IsAttachedToDebugger()) {
-                MESOSPHERE_UNIMPLEMENTED();
+                if (R_SUCCEEDED(KDebug::BreakIfAttached(break_reason, address, size))) {
+                    /* If we attached, set the pc to the instruction before the current one and return. */
+                    KDebug::SetPreviousProgramCounter();
+                    return;
+                }
             }
 
             /* If the break is only a notification, we're done. */
-            if ((break_reason & ams::svc::BreakReason_NotificationOnlyFlag) != 0) {
+            if (is_notification) {
                 return;
             }
 
-            /* TODO */
-            if (size == sizeof(u32)) {
-                MESOSPHERE_LOG("DEBUG: %08x\n", *reinterpret_cast<u32 *>(address));
+            /* Print that break was called. */
+            MESOSPHERE_RELEASE_LOG("Break() called. %016lx\n", GetCurrentProcess().GetProgramId());
+
+            /* Try to enter JIT debug state. */
+            if (GetCurrentProcess().EnterJitDebug(ams::svc::DebugEvent_Exception, ams::svc::DebugException_UserBreak, KDebug::GetProgramCounter(GetCurrentThread()), break_reason, address, size)) {
+                /* We entered JIT debug, so set the pc to the instruction before the current one and return. */
+                KDebug::SetPreviousProgramCounter();
+                return;
             }
-            MESOSPHERE_PANIC("Break was called\n");
+
+            /* Exit the current process. */
+            GetCurrentProcess().Exit();
         }
 
     }