From de93a9492ca5a27b4e72320b0e7ad1ea5bee28ef Mon Sep 17 00:00:00 2001
From: Merijn <merijn.wayam@gmail.com>
Date: Mon, 5 Oct 2026 19:41:47 +0200
Subject: [PATCH] feat(libkernel): load the relinked module for a guest module
 path

dlopen and sceKernelLoadStartModule passed the guest path to the host
loader, which cannot load the original ELF module. When a relinked module
<path>.guest.prx exists beside it, that module is loaded instead; for a
module the executable already loaded at startup the host loader returns
the same module. PPSA12544 loads /app0/Media/Modules/Il2CppUserAssemblies.prx
at startup and resolves IL2CPP functions through it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../prx/libkernel/Module/src/DynamicLoader.cpp | 12 ++++++++++--
 core/libs/tests/GuestDynamicLoader.cpp         | 18 ++++++++++++++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/core/libs/prx/libkernel/Module/src/DynamicLoader.cpp b/core/libs/prx/libkernel/Module/src/DynamicLoader.cpp
index e1091def8..ef4790b78 100644
--- a/core/libs/prx/libkernel/Module/src/DynamicLoader.cpp
+++ b/core/libs/prx/libkernel/Module/src/DynamicLoader.cpp
@@ -1,6 +1,7 @@
 #include "prx/libc/include/General.hpp"
 #include <nid/NidCompute.hpp>
 #include <array>
+#include <filesystem>
 #include <cstdio>
 #include <map>
 #include <memory>
@@ -57,6 +58,13 @@ char* APS5_VABI dlerror_nid_postfix() {
     pendingError = false;
     return loaderError.data();
 }
+static std::filesystem::path RelinkedModulePath(const std::filesystem::path& path) {
+    auto relinked = path;
+    relinked += ".guest.prx";
+    std::error_code error;
+    return std::filesystem::is_regular_file(relinked, error) ? relinked : path;
+}
+
 void* APS5_VABI dlopen_nid_postfix(const char* path, int flags) {
     if ((flags & ~0x103) || (flags & 3) == 0 || (flags & 3) == 3) {
         Error("dlopen: unsupported flags"); return nullptr;
@@ -70,7 +78,7 @@ void* APS5_VABI dlopen_nid_postfix(const char* path, int flags) {
             module->owned = false;
         } else {
             if (!*path) { Error("dlopen: empty module path"); return nullptr; }
-            const auto resolved = ResolvePath_nid_no_patch(path);
+            const auto resolved = RelinkedModulePath(ResolvePath_nid_no_patch(path));
             module->native = LoadLibraryExW(resolved.c_str(), nullptr, LOAD_WITH_ALTERED_SEARCH_PATH);
         }
         if (!module->native) {
@@ -79,7 +87,7 @@ void* APS5_VABI dlopen_nid_postfix(const char* path, int flags) {
             Error(message); return nullptr;
         }
 #else
-        const auto resolved = path ? ResolvePath_nid_no_patch(path).string() : std::string{};
+        const auto resolved = path ? RelinkedModulePath(ResolvePath_nid_no_patch(path)).string() : std::string{};
         const int nativeFlags = ((flags & 3) == 1 ? RTLD_LAZY : RTLD_NOW) |
             ((flags & 0x100) ? RTLD_GLOBAL : RTLD_LOCAL);
         module->native = ::dlopen(path ? resolved.c_str() : nullptr, nativeFlags);
diff --git a/core/libs/tests/GuestDynamicLoader.cpp b/core/libs/tests/GuestDynamicLoader.cpp
index 2fa27e917..04b369b73 100644
--- a/core/libs/tests/GuestDynamicLoader.cpp
+++ b/core/libs/tests/GuestDynamicLoader.cpp
@@ -1,5 +1,7 @@
 #include "prx/libc/include/general/VabiMacros.hpp"
 #include <cstdlib>
+#include <filesystem>
+#include <fstream>
 #include <thread>
 extern "C" {
 void* APS5_VABI dlopen_nid_postfix(const char*, int);
@@ -37,4 +39,20 @@ int main(int argc, char** argv) {
     Require(add && add(2, 3) == 5);
     Require(dlclose_nid_postfix(second) == 0);
     Require(dlclose_nid_postfix(second) == -1);
+
+    const std::filesystem::path guest = "anyps5-relinked-module-for-test.prx";
+    auto relinked = guest;
+    relinked += ".guest.prx";
+    {
+        std::ofstream elf(guest, std::ios::binary);
+        elf.write("\x7f" "ELF", 4);
+    }
+    std::filesystem::copy_file(argv[1], relinked, std::filesystem::copy_options::overwrite_existing);
+    void* redirected = dlopen_nid_postfix(guest.string().c_str(), 2);
+    Require(redirected != nullptr);
+    add = reinterpret_cast<Add>(dlsym_nid_postfix(redirected, "GuestModuleAdd"));
+    Require(add && add(40, 2) == 42);
+    Require(dlclose_nid_postfix(redirected) == 0);
+    std::filesystem::remove(guest);
+    std::filesystem::remove(relinked);
 }