Fixes and workarounds to make UBSan happier on macOS

There are still some other issues not addressed here, but it's a start.

Workarounds for false-positive reports:

- `RasterizerAccelerated`: Put a gigantic array behind a `unique_ptr`,
  because UBSan has a [hardcoded limit](https://stackoverflow.com/questions/64531383/c-runtime-error-using-fsanitize-undefined-object-has-a-possibly-invalid-vp)
  of how big it thinks objects can be, specifically when dealing with
  offset-to-top values used with multiple inheritance.  Hopefully this
  doesn't have a performance impact.

- `QueryCacheBase::QueryCacheBase`: Avoid an operation that UBSan thinks
  is UB even though it at least arguably isn't.  See the link in the
  comment for more information.

Fixes for correct reports:

- `PageTable`, `Memory`: Use `uintptr_t` values instead of pointers to
  avoid UB from pointer overflow (when pointer arithmetic wraps around
  the address space).

- `KScheduler::Reload`: `thread->GetOwnerProcess()` can be `nullptr`;
  avoid calling methods on it in this case.  (The existing code returns
  a garbage reference to a field, which is then passed into
  `LoadWatchpointArray`, and apparently it's never used, so it's
  harmless in practice but still triggers UBSan.)

- `KAutoObject::Close`: This function calls `this->Destroy()`, which
  overwrites the beginning of the object with junk (specifically a free
  list pointer).  Then it calls `this->UnregisterWithKernel()`.  UBSan
  complains about a type mismatch because the vtable has been
  overwritten, and I believe this is indeed UB.  `UnregisterWithKernel`
  also loads `m_kernel` from the 'freed' object, which seems to be
  technically safe (the overwriting doesn't extend as far as that
  field), but seems dubious.  Switch to a `static` method and load
  `m_kernel` in advance.

4 files changed, 8 insertions, 6 deletions

diff --git a/src/core/hle/kernel/k_auto_object.cpp b/src/core/hle/kernel/k_auto_object.cpp
index 0ae42c95c..9cd7a9fd5 100644
--- a/src/core/hle/kernel/k_auto_object.cpp
+++ b/src/core/hle/kernel/k_auto_object.cpp
@@ -15,8 +15,8 @@ void KAutoObject::RegisterWithKernel() {
     m_kernel.RegisterKernelObject(this);
 }
 
-void KAutoObject::UnregisterWithKernel() {
-    m_kernel.UnregisterKernelObject(this);
+void KAutoObject::UnregisterWithKernel(KernelCore& kernel, KAutoObject* self) {
+    kernel.UnregisterKernelObject(self);
 }
 
 } // namespace Kernel
diff --git a/src/core/hle/kernel/k_auto_object.h b/src/core/hle/kernel/k_auto_object.h
index f384b1568..8d4e0df44 100644
--- a/src/core/hle/kernel/k_auto_object.h
+++ b/src/core/hle/kernel/k_auto_object.h
@@ -159,14 +159,15 @@ public:
 
         // If ref count hits zero, destroy the object.
         if (cur_ref_count - 1 == 0) {
+            KernelCore& kernel = m_kernel;
             this->Destroy();
-            this->UnregisterWithKernel();
+            KAutoObject::UnregisterWithKernel(kernel, this);
         }
     }
 
 private:
     void RegisterWithKernel();
-    void UnregisterWithKernel();
+    static void UnregisterWithKernel(KernelCore& kernel, KAutoObject* self);
 
 protected:
     KernelCore& m_kernel;
diff --git a/src/core/hle/kernel/k_scheduler.cpp b/src/core/hle/kernel/k_scheduler.cpp
index 75ce5a23c..d8143c650 100644
--- a/src/core/hle/kernel/k_scheduler.cpp
+++ b/src/core/hle/kernel/k_scheduler.cpp
@@ -510,11 +510,12 @@ void KScheduler::Unload(KThread* thread) {
 
 void KScheduler::Reload(KThread* thread) {
     auto& cpu_core = m_kernel.System().ArmInterface(m_core_id);
+    auto* process = thread->GetOwnerProcess();
     cpu_core.LoadContext(thread->GetContext32());
     cpu_core.LoadContext(thread->GetContext64());
     cpu_core.SetTlsAddress(GetInteger(thread->GetTlsAddress()));
     cpu_core.SetTPIDR_EL0(thread->GetTpidrEl0());
-    cpu_core.LoadWatchpointArray(thread->GetOwnerProcess()->GetWatchpoints());
+    cpu_core.LoadWatchpointArray(process ? &process->GetWatchpoints() : nullptr);
     cpu_core.ClearExclusiveState();
 }
 
diff --git a/src/core/hle/kernel/k_thread.cpp b/src/core/hle/kernel/k_thread.cpp
index adb6ec581..2a105a762 100644
--- a/src/core/hle/kernel/k_thread.cpp
+++ b/src/core/hle/kernel/k_thread.cpp
@@ -129,7 +129,7 @@ Result KThread::Initialize(KThreadFunction func, uintptr_t arg, KProcessAddress
     case ThreadType::User:
         ASSERT(((owner == nullptr) ||
                 (owner->GetCoreMask() | (1ULL << virt_core)) == owner->GetCoreMask()));
-        ASSERT(((owner == nullptr) ||
+        ASSERT(((owner == nullptr) || (prio > Svc::LowestThreadPriority) ||
                 (owner->GetPriorityMask() | (1ULL << prio)) == owner->GetPriorityMask()));
         break;
     case ThreadType::Kernel: