From 3252d256ca4b8eabd292a7c8bf66cad5716fece1 Mon Sep 17 00:00:00 2001
From: Gliniak <Gliniak93@gmail.com>
Date: Mon, 3 Nov 2025 20:10:36 +0100
Subject: [PATCH] [Emulator] Removed windows rdrand ntdll patch

---
 src/xenia/ui/windowed_app_main_win.cc | 67 +--------------------------
 1 file changed, 2 insertions(+), 65 deletions(-)

diff --git a/src/xenia/ui/windowed_app_main_win.cc b/src/xenia/ui/windowed_app_main_win.cc
index 1aed7bf07..0baf4f5f4 100644
--- a/src/xenia/ui/windowed_app_main_win.cc
+++ b/src/xenia/ui/windowed_app_main_win.cc
@@ -19,69 +19,13 @@
 // Autogenerated by `xb premake`.
 #include "build/version.h"
 
+#include <Psapi.h>
+
 DEFINE_bool(enable_console, false, "Open a console window with the main window",
             "Logging");
 
 static uintptr_t g_xenia_exe_base = 0;
 static size_t g_xenia_exe_size = 0;
-#if XE_ARCH_AMD64 == 1
-DEFINE_bool(enable_rdrand_ntdll_patch, true,
-            "Hot-patches ntdll at the start of the process to not use rdrand "
-            "as part of the RNG for heap randomization. Can reduce CPU usage "
-            "significantly, but is untested on all Windows versions.",
-            "Win32");
-
-// begin ntdll hack
-#include <psapi.h>
-static bool g_didfailtowrite = false;
-static void write_process_memory(HANDLE process, uintptr_t offset,
-                                 unsigned size, const unsigned char* bvals) {
-  if (!WriteProcessMemory(process, (void*)offset, bvals, size, nullptr)) {
-    if (!g_didfailtowrite) {
-      MessageBoxA(nullptr, "Failed to write to process!", "Failed", MB_OK);
-      g_didfailtowrite = true;
-    }
-  }
-}
-
-static constexpr unsigned char pattern_cmp_processorfeature_28_[] = {
-    0x80, 0x3C, 0x25, 0x90,
-    0x02, 0xFE, 0x7F, 0x00};  // cmp     byte ptr ds:7FFE0290h, 0
-static constexpr unsigned char pattern_replacement[] = {
-    0x48, 0x39, 0xe4,             // cmp rsp, rsp = always Z
-    0x0F, 0x1F, 0x44, 0x00, 0x00  // 5byte nop
-};
-static void patch_ntdll_instance(HANDLE process, uintptr_t ntdll_base) {
-  MODULEINFO modinfo;
-
-  GetModuleInformation(process, (HMODULE)ntdll_base, &modinfo,
-                       sizeof(MODULEINFO));
-
-  std::vector<uintptr_t> possible_places{};
-
-  unsigned char* strt = (unsigned char*)modinfo.lpBaseOfDll;
-
-  for (unsigned i = 0; i < modinfo.SizeOfImage; ++i) {
-    for (unsigned j = 0; j < sizeof(pattern_cmp_processorfeature_28_); ++j) {
-      if (strt[i + j] != pattern_cmp_processorfeature_28_[j]) {
-        goto miss;
-      }
-    }
-    possible_places.push_back((uintptr_t)(&strt[i]));
-  miss:;
-  }
-
-  for (auto&& place : possible_places) {
-    write_process_memory(process, place, sizeof(pattern_replacement),
-                         pattern_replacement);
-  }
-}
-
-static void do_ntdll_hack_this_process() {
-  patch_ntdll_instance(GetCurrentProcess(),
-                       (uintptr_t)GetModuleHandleA("ntdll.dll"));
-}
-#endif
 
 static HMODULE probe_for_module(void* addr) {
   // get 65k aligned addr downwards to probe for MZ
@@ -107,8 +51,6 @@ static HMODULE probe_for_module(void* addr) {
   }
 }
 
-// end ntdll hack
-
 static constexpr auto XENIA_ERROR_LANGUAGE =
     MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT);
 
@@ -376,11 +318,6 @@ int WINAPI wWinMain(HINSTANCE hinstance, HINSTANCE hinstance_prev,
     xe::InitializeWin32App(app->GetName());
 
     if (app->OnInitialize()) {
-#if XE_ARCH_AMD64 == 1
-      if (cvars::enable_rdrand_ntdll_patch) {
-        do_ntdll_hack_this_process();
-      }
-#endif
       // TODO(Triang3l): Rework this, need to initialize the console properly,
       // disable has_console_attached_ by default in windowed apps, and attach
       // only if needed.