Add barebones of MiMalloc WinDbg extension

CMakeLists.txt

@@ -74,6 +74,10 @@ set(mi_sources
     src/stats.c
     src/prim/prim.c)
 
+if(WIN32 AND MI_WIN_DBG_EXTS)
+  list(APPEND mi_sources src/prim/windows/windbg/mimalloc_dbg.cpp)
+endif()
+
 set(mi_cflags "")
 set(mi_cflags_static "")            # extra flags for a static library build
 set(mi_cflags_dynamic "")           # extra flags for a shared-object library build
@@ -255,6 +259,17 @@ if(MI_TRACK_ETW)
   endif()
 endif()
 
+if(MI_WIN_DBG_EXTS)
+  if(NOT WIN32)
+    set(MI_WIN_DBG_EXTS OFF)
+    message(WARNING "Can only enable Windows debbuger extension support on Windows (MI_WIN_DBG_EXTS=OFF)")
+  endif()
+  if(MI_WIN_DBG_EXTS)
+    message(STATUS "Compile with Windows debbuger extension support (MI_WIN_DBG_EXTS=ON)")
+    list(APPEND mi_defines MI_WIN_DBG_EXTS=1)
+  endif()
+endif()
+
 if(MI_GUARDED)
   message(STATUS "Compile guard pages behind certain object allocations (MI_GUARDED=ON)")
   list(APPEND mi_defines MI_GUARDED=1)

ide/vs2022/mimalloc-lib.vcxproj

@@ -211,8 +211,7 @@
     <Lib>
       <AdditionalLibraryDirectories>
       </AdditionalLibraryDirectories>
-      <AdditionalDependencies>
+      <AdditionalDependencies>dbgeng.lib</AdditionalDependencies>
-      </AdditionalDependencies>
     </Lib>
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|ARM64'">
@@ -477,6 +476,7 @@
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release|ARM64EC'">true</ExcludedFromBuild>
     </ClCompile>
     <ClCompile Include="..\..\src\page.c" />
+    <ClCompile Include="..\..\src\prim\windows\windbg\mimalloc_dbg.cpp" />
     <ClCompile Include="..\..\src\random.c" />
     <ClCompile Include="..\..\src\os.c" />
     <ClCompile Include="..\..\src\stats.c" />
@@ -493,6 +493,7 @@
     <ClInclude Include="..\..\include\mimalloc\track.h" />
     <ClInclude Include="..\..\include\mimalloc\types.h" />
     <ClInclude Include="..\..\src\bitmap.h" />
+    <ClInclude Include="..\..\src\prim\windows\windbg\mimalloc_dbg.h" />
   </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">

ide/vs2022/mimalloc-lib.vcxproj.filters

@@ -61,6 +61,9 @@
     <ClCompile Include="..\..\src\arena-meta.c">
       <Filter>Sources</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\src\prim\windows\windbg\mimalloc_dbg.cpp">
+      <Filter>Sources</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="..\..\include\mimalloc\atomic.h">

ide/vs2022/mimalloc-override-dll.vcxproj

@@ -208,7 +208,7 @@
       <AdditionalOptions>/Zc:__cplusplus %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <Link>
-      <AdditionalDependencies>$(ProjectDir)\..\..\bin\mimalloc-redirect.lib;%(AdditionalDependencies)</AdditionalDependencies>
+      <AdditionalDependencies>$(ProjectDir)\..\..\bin\mimalloc-redirect.lib;dbgeng.lib;%(AdditionalDependencies)</AdditionalDependencies>
       <IgnoreSpecificDefaultLibraries>
       </IgnoreSpecificDefaultLibraries>
       <ModuleDefinitionFile>
@@ -441,6 +441,7 @@
     <ClInclude Include="..\..\include\mimalloc\track.h" />
     <ClInclude Include="..\..\include\mimalloc\types.h" />
     <ClInclude Include="..\..\src\bitmap.h" />
+    <ClInclude Include="..\..\src\prim\windows\windbg\mimalloc_dbg.h" />
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="..\..\src\alloc-aligned.c">
@@ -506,6 +507,7 @@
       <ExcludedFromBuild Condition="'$(Configuration)|$(Platform)'=='Release|ARM64EC'">true</ExcludedFromBuild>
     </ClCompile>
     <ClCompile Include="..\..\src\page.c" />
+    <ClCompile Include="..\..\src\prim\windows\windbg\mimalloc_dbg.cpp" />
     <ClCompile Include="..\..\src\random.c" />
     <ClCompile Include="..\..\src\stats.c" />
   </ItemGroup>

ide/vs2022/mimalloc-override-dll.vcxproj.filters

@@ -61,6 +61,9 @@
     <ClCompile Include="..\..\src\arena-meta.c">
       <Filter>Sources</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\src\prim\windows\windbg\mimalloc_dbg.cpp">
+      <Filter>Sources</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="..\..\include\mimalloc\atomic.h">

src/prim/windows/windbg/mimalloc_dbg.cpp

@@ -0,0 +1,146 @@
+/* ----------------------------------------------------------------------------
+Copyright (c) Microsoft Research
+This is free software; you can redistribute it and/or modify it under the
+terms of the MIT license. A copy of the license can be found in the file
+"LICENSE" at the root of this distribution.
+-----------------------------------------------------------------------------*/
+
+#include <atomic>
+#include <DbgEng.h>
+#include <map>
+#include <string>
+#include <vector>
+#include <Windows.h>
+
+#include "mimalloc.h"
+#include "mimalloc/internal.h"
+
+ULONG64 g_MiMallocBase = 0;
+IDebugClient* g_DebugClient = nullptr;
+IDebugControl* g_DebugControl = nullptr;
+IDebugSymbols3* g_DebugSymbols = nullptr;
+IDebugDataSpaces* g_DataSpaces = nullptr;
+
+// Function to find mimalloc.dll base address at startup
+HRESULT FindMimallocBase()
+{
+    if (g_DebugSymbols == nullptr)
+    {
+        return E_FAIL;
+    }
+
+    return g_DebugSymbols->GetModuleByModuleName("mimalloc", 0, NULL, &g_MiMallocBase);
+}
+
+// Entry point for the extension
+extern "C" __declspec(dllexport) HRESULT CALLBACK DebugExtensionInitialize(PULONG version, PULONG flags)
+{
+    UNREFERENCED_PARAMETER(flags);
+
+    // Ensure Version is valid
+    if (!version)
+    {
+        return E_INVALIDARG;
+    }
+
+    // Set the version
+    *version = DEBUG_EXTENSION_VERSION(1, 0);
+
+    HRESULT hr = DebugCreate(__uuidof(IDebugClient), (void**)&g_DebugClient);
+    if (FAILED(hr))
+    {
+        return hr;
+    }
+
+    // Query for the IDebugControl interface
+    hr = g_DebugClient->QueryInterface(__uuidof(IDebugControl), (void**)&g_DebugControl);
+    if (FAILED(hr))
+    {
+        g_DebugClient->Release();
+
+        return hr;
+    }
+
+    hr = g_DebugClient->QueryInterface(__uuidof(IDebugSymbols3), (void**)&g_DebugSymbols);
+    if (FAILED(hr))
+    {
+        g_DebugControl->Release();
+        g_DebugClient->Release();
+
+        return hr;
+    }
+
+    hr = g_DebugClient->QueryInterface(__uuidof(IDebugDataSpaces), (void**)&g_DataSpaces);
+    if (FAILED(hr))
+    {
+        g_DebugSymbols->Release();
+        g_DebugControl->Release();
+        g_DebugClient->Release();
+
+        return hr;
+    }
+
+    // Find mimalloc base address at startup
+    hr = FindMimallocBase();
+    if (FAILED(hr) || g_MiMallocBase == 0)
+    {
+        return E_FAIL;  // Prevent extension from loading
+    }
+
+    mi_register_output(
+        [](const char* msg, void* arg) {
+            g_DebugControl->Output(DEBUG_OUTPUT_ERROR, msg);
+            g_DebugControl->Output(DEBUG_OUTPUT_ERROR, "\n");
+        },
+        nullptr);
+
+    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "mimalloc.dll base address found: 0x%llx\n", g_MiMallocBase);
+
+    return S_OK;
+}
+
+// Notifies the extension that a debug event has occurred
+extern "C" __declspec(dllexport) void CALLBACK DebugExtensionNotify(ULONG notify, ULONG64 argument)
+{
+    UNREFERENCED_PARAMETER(notify);
+    UNREFERENCED_PARAMETER(argument);
+}
+
+// Uninitializes the extension
+extern "C" __declspec(dllexport) void CALLBACK DebugExtensionUninitialize()
+{
+    if (g_DebugSymbols)
+    {
+        g_DebugSymbols->Release();
+        g_DebugSymbols = nullptr;
+    }
+
+    if (g_DebugControl)
+    {
+        g_DebugControl->Release();
+        g_DebugControl = nullptr;
+    }
+
+    if (g_DebugClient)
+    {
+        g_DebugClient->Release();
+        g_DebugClient = nullptr;
+    }
+}
+
+// Sample command: !mi_help
+extern "C" __declspec(dllexport) HRESULT CALLBACK mi_help(PDEBUG_CLIENT Client, PCSTR args)
+{
+    UNREFERENCED_PARAMETER(args);
+
+    // Print Help
+    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "Hello from MiMalloc WinDbg Extension!\n");
+
+    return S_OK;
+}
+
+extern "C" __declspec(dllexport) HRESULT CALLBACK mi_dump_arenas(PDEBUG_CLIENT client, PCSTR args)
+{
+    mi_debug_show_arenas();
+    return S_OK;
+}