DolphinQt: Properly lock CPU before accessing emulated memory

This fixes a problem I was having where using frame advance with the
debugger open would frequently cause panic alerts about invalid addresses
due to the CPU thread changing MSR.DR while the host thread was trying
to access memory.

To aid in tracking down all the places where we weren't properly locking
the CPU, I've created a new type (in Core.h) that you have to pass as a
reference or pointer to functions that require running as the CPU thread.

2 files changed, 36 insertions, 26 deletions

diff --git a/Source/Core/DiscIO/RiivolutionPatcher.cpp b/Source/Core/DiscIO/RiivolutionPatcher.cpp
index 6469607cc1..4b265599d8 100644
--- a/Source/Core/DiscIO/RiivolutionPatcher.cpp
+++ b/Source/Core/DiscIO/RiivolutionPatcher.cpp
@@ -477,30 +477,31 @@ void ApplyPatchesToFiles(const std::vector<Patch>& patches, PatchIndex index,
   }
 }
 
-static bool MemoryMatchesAt(u32 offset, const std::vector<u8>& value)
+static bool MemoryMatchesAt(const Core::CPUThreadGuard& guard, u32 offset,
+                            const std::vector<u8>& value)
 {
   for (u32 i = 0; i < value.size(); ++i)
   {
-    auto result = PowerPC::HostTryReadU8(offset + i);
+    auto result = PowerPC::HostTryReadU8(guard, offset + i);
     if (!result || result->value != value[i])
       return false;
   }
   return true;
 }
 
-static void ApplyMemoryPatch(u32 offset, const std::vector<u8>& value,
-                             const std::vector<u8>& original)
+static void ApplyMemoryPatch(const Core::CPUThreadGuard& guard, u32 offset,
+                             const std::vector<u8>& value, const std::vector<u8>& original)
 {
   if (value.empty())
     return;
 
-  if (!original.empty() && !MemoryMatchesAt(offset, original))
+  if (!original.empty() && !MemoryMatchesAt(guard, offset, original))
     return;
 
   auto& system = Core::System::GetInstance();
   const u32 size = static_cast<u32>(value.size());
   for (u32 i = 0; i < size; ++i)
-    PowerPC::HostTryWriteU8(value[i], offset + i);
+    PowerPC::HostTryWriteU8(guard, value[i], offset + i);
   const u32 overlapping_hook_count = HLE::UnpatchRange(system, offset, offset + size);
   if (overlapping_hook_count != 0)
   {
@@ -516,17 +517,18 @@ static std::vector<u8> GetMemoryPatchValue(const Patch& patch, const Memory& mem
   return memory_patch.m_value;
 }
 
-static void ApplyMemoryPatch(const Patch& patch, const Memory& memory_patch)
+static void ApplyMemoryPatch(const Core::CPUThreadGuard& guard, const Patch& patch,
+                             const Memory& memory_patch)
 {
   if (memory_patch.m_offset == 0)
     return;
 
-  ApplyMemoryPatch(memory_patch.m_offset | 0x80000000, GetMemoryPatchValue(patch, memory_patch),
-                   memory_patch.m_original);
+  ApplyMemoryPatch(guard, memory_patch.m_offset | 0x80000000,
+                   GetMemoryPatchValue(patch, memory_patch), memory_patch.m_original);
 }
 
-static void ApplySearchMemoryPatch(const Patch& patch, const Memory& memory_patch, u32 ram_start,
-                                   u32 length)
+static void ApplySearchMemoryPatch(const Core::CPUThreadGuard& guard, const Patch& patch,
+                                   const Memory& memory_patch, u32 ram_start, u32 length)
 {
   if (memory_patch.m_original.empty() || memory_patch.m_align == 0)
     return;
@@ -535,16 +537,16 @@ static void ApplySearchMemoryPatch(const Patch& patch, const Memory& memory_patc
   for (u32 i = 0; i < length - (stride - 1); i += stride)
   {
     const u32 address = ram_start + i;
-    if (MemoryMatchesAt(address, memory_patch.m_original))
+    if (MemoryMatchesAt(guard, address, memory_patch.m_original))
     {
-      ApplyMemoryPatch(address, GetMemoryPatchValue(patch, memory_patch), {});
+      ApplyMemoryPatch(guard, address, GetMemoryPatchValue(patch, memory_patch), {});
       break;
     }
   }
 }
 
-static void ApplyOcarinaMemoryPatch(const Patch& patch, const Memory& memory_patch, u32 ram_start,
-                                    u32 length)
+static void ApplyOcarinaMemoryPatch(const Core::CPUThreadGuard& guard, const Patch& patch,
+                                    const Memory& memory_patch, u32 ram_start, u32 length)
 {
   if (memory_patch.m_offset == 0)
     return;
@@ -557,19 +559,19 @@ static void ApplyOcarinaMemoryPatch(const Patch& patch, const Memory& memory_pat
   {
     // first find the pattern
     const u32 address = ram_start + i;
-    if (MemoryMatchesAt(address, value))
+    if (MemoryMatchesAt(guard, address, value))
     {
       for (; i < length; i += 4)
       {
         // from the pattern find the next blr instruction
         const u32 blr_address = ram_start + i;
-        auto blr = PowerPC::HostTryReadU32(blr_address);
+        auto blr = PowerPC::HostTryReadU32(guard, blr_address);
         if (blr && blr->value == 0x4e800020)
         {
           // and replace it with a jump to the given offset
           const u32 target = memory_patch.m_offset | 0x80000000;
           const u32 jmp = ((target - blr_address) & 0x03fffffc) | 0x48000000;
-          PowerPC::HostTryWriteU32(jmp, blr_address);
+          PowerPC::HostTryWriteU32(guard, jmp, blr_address);
           const u32 overlapping_hook_count =
               HLE::UnpatchRange(system, blr_address, blr_address + 4);
           if (overlapping_hook_count != 0)
@@ -584,7 +586,7 @@ static void ApplyOcarinaMemoryPatch(const Patch& patch, const Memory& memory_pat
   }
 }
 
-void ApplyGeneralMemoryPatches(const std::vector<Patch>& patches)
+void ApplyGeneralMemoryPatches(const Core::CPUThreadGuard& guard, const std::vector<Patch>& patches)
 {
   auto& system = Core::System::GetInstance();
   auto& system_memory = system.GetMemory();
@@ -597,14 +599,15 @@ void ApplyGeneralMemoryPatches(const std::vector<Patch>& patches)
         continue;
 
       if (memory.m_search)
-        ApplySearchMemoryPatch(patch, memory, 0x80000000, system_memory.GetRamSize());
+        ApplySearchMemoryPatch(guard, patch, memory, 0x80000000, system_memory.GetRamSize());
       else
-        ApplyMemoryPatch(patch, memory);
+        ApplyMemoryPatch(guard, patch, memory);
     }
   }
 }
 
-void ApplyApploaderMemoryPatches(const std::vector<Patch>& patches, u32 ram_address, u32 ram_length)
+void ApplyApploaderMemoryPatches(const Core::CPUThreadGuard& guard,
+                                 const std::vector<Patch>& patches, u32 ram_address, u32 ram_length)
 {
   for (const auto& patch : patches)
   {
@@ -614,9 +617,9 @@ void ApplyApploaderMemoryPatches(const std::vector<Patch>& patches, u32 ram_addr
         continue;
 
       if (memory.m_ocarina)
-        ApplyOcarinaMemoryPatch(patch, memory, ram_address, ram_length);
+        ApplyOcarinaMemoryPatch(guard, patch, memory, ram_address, ram_length);
       else
-        ApplySearchMemoryPatch(patch, memory, ram_address, ram_length);
+        ApplySearchMemoryPatch(guard, patch, memory, ram_address, ram_length);
     }
   }
 }
diff --git a/Source/Core/DiscIO/RiivolutionPatcher.h b/Source/Core/DiscIO/RiivolutionPatcher.h
index 0a83ba9d13..d83c51d686 100644
--- a/Source/Core/DiscIO/RiivolutionPatcher.h
+++ b/Source/Core/DiscIO/RiivolutionPatcher.h
@@ -11,6 +11,11 @@
 #include "DiscIO/DirectoryBlob.h"
 #include "DiscIO/RiivolutionParser.h"
 
+namespace Core
+{
+class CPUThreadGuard;
+}
+
 namespace DiscIO::Riivolution
 {
 struct SavegameRedirect
@@ -74,8 +79,10 @@ enum class PatchIndex
 void ApplyPatchesToFiles(const std::vector<Patch>& patches, PatchIndex index,
                          std::vector<DiscIO::FSTBuilderNode>* fst,
                          DiscIO::FSTBuilderNode* dol_node);
-void ApplyGeneralMemoryPatches(const std::vector<Patch>& patches);
-void ApplyApploaderMemoryPatches(const std::vector<Patch>& patches, u32 ram_address,
+void ApplyGeneralMemoryPatches(const Core::CPUThreadGuard& guard,
+                               const std::vector<Patch>& patches);
+void ApplyApploaderMemoryPatches(const Core::CPUThreadGuard& guard,
+                                 const std::vector<Patch>& patches, u32 ram_address,
                                  u32 ram_length);
 std::optional<SavegameRedirect>
 ExtractSavegameRedirect(const std::vector<Patch>& riivolution_patches);