add minimal plugin system

Author: fogInSingularity

.gitignore

@@ -33,5 +33,9 @@
 
 # Directories
 build/
+
+# IDEs and LSP specific
 .vscode/
 __pycache__/
+.cache/
+compile_commands.json

CMakeLists.txt

@@ -8,6 +8,7 @@ include(cmake/defaults.cmake)
 
 add_subdirectory(third_party)
 add_subdirectory(scripts)
+add_subdirectory(plugins)
 
 set(hSIM_LIB
     src/memory.cc src/machine.cc

include/machine.hh

@@ -2,12 +2,14 @@
 #define HSIM_MACHINE_INCLUDED
 
 #include <memory>
+#include <string>
 
 #include "config.hh"
 #include "cpu_state.hh"
 #include "elf_loader.hh"
 #include "executors.hh"
 #include "memory.hh"
+#include "plugin_manager.hh"
 
 namespace hsim {
 
@@ -32,9 +34,14 @@ class Machine final {
         }
     }
 
+    void loadPlugin(const std::string& pluginPath, const std::string& options = "") {
+        m_plugins.loadPlugin(pluginPath, options);
+    }
+
   private:
     std::unique_ptr<CpuState> m_state;
     Memory m_mem{};
+    PluginManager m_plugins;
 };
 
 } // namespace hsim

include/plugin.hh

@@ -0,0 +1,60 @@
+#ifndef HSIM_PLUGIN_INCLUDED
+#define HSIM_PLUGIN_INCLUDED
+
+#include <stdexcept>
+#include <string>
+
+#include <dlfcn.h>
+
+#include "plugin_api.hh"
+
+namespace hsim {
+
+class Plugin final {
+  public:
+    Plugin(const std::string &pluginPath, const std::string &options = "")
+        : m_pluginName{pluginPath}, m_options{options} {
+        m_dlhandle = dlopen(pluginPath.c_str(), RTLD_NOW);
+        if (m_dlhandle == nullptr) {
+            std::string dlErrorMsg = dlerror();
+            std::string fullErrorMsg = "Unable to load plugin: " + pluginPath +
+                                       ". Error: " + dlErrorMsg;
+            throw std::runtime_error(fullErrorMsg);
+        }
+
+        auto loadFunc = reinterpret_cast<LoadFunc>(
+            dlsym(m_dlhandle, kLoadFuncName.c_str()));
+        if (loadFunc == nullptr) {
+            std::string dlErrorMsg = dlerror();
+            std::string fullErrorMsg =
+                "Unable to load : " + pluginPath + ". Error: " + dlErrorMsg;
+            throw std::runtime_error(fullErrorMsg);
+        }
+
+        LoadablePlugin plugin = loadFunc(options.c_str());
+        m_pluginMem = plugin.pluginMem;
+        m_notify = plugin.notify;
+        m_unload = plugin.unload;
+    }
+
+    ~Plugin() {
+        m_unload(m_pluginMem);
+
+        dlclose(m_dlhandle);
+    }
+
+    void notify() { m_notify(m_pluginMem); }
+
+  private:
+    std::string m_pluginName;
+    std::string m_options;
+
+    void *m_dlhandle;
+    void *m_pluginMem;
+    NotifyFunc m_notify;
+    UnloadFunc m_unload;
+};
+
+} // namespace hsim
+
+#endif // HSIM_PLUGIN_INCLUDED

include/plugin_api.hh

@@ -0,0 +1,30 @@
+#ifndef HSIM_PLUGIN_API_INCLUDED
+#define HSIM_PLUGIN_API_INCLUDED
+
+#include <string>
+
+#define PLUGIN_API_ATTR extern "C"
+
+namespace hsim {
+
+static const std::string kLoadFuncName = "loadPlugin";
+
+struct LoadablePlugin;
+
+extern "C" {
+
+using LoadFunc = LoadablePlugin (*)(const char *options);
+using NotifyFunc = void (*)(void *pluginMem);
+using UnloadFunc = void (*)(void *pluginMem);
+
+} // extern "C"
+
+struct LoadablePlugin {
+    void *pluginMem;
+    NotifyFunc notify;
+    UnloadFunc unload;
+};
+
+}; // namespace hsim
+
+#endif // HSIM_PLUGIN_API_INCLUDED

include/plugin_manager.hh

@@ -0,0 +1,30 @@
+#ifndef HSIM_PLUGIN_MANAGER_INCLUDED
+#define HSIM_PLUGIN_MANAGER_INCLUDED
+
+#include <string>
+#include <vector>
+
+#include "plugin.hh"
+
+namespace hsim {
+
+class PluginManager final {
+  public:
+    void loadPlugin(const std::string &pluginPath,
+                    const std::string &options = "") {
+        m_plugins.emplace_back(pluginPath, options);
+    }
+
+    void notify() {
+        for (auto &plugin : m_plugins) {
+            plugin.notify();
+        }
+    }
+
+  private:
+    std::vector<Plugin> m_plugins;
+};
+
+} // namespace hsim
+
+#endif // HSIM_PLUGIN_MANAGER_INCLUDED

plugins/CMakeLists.txt

@@ -0,0 +1,14 @@
+include_directories(
+    ${CMAKE_SOURCE_DIR}/include
+)
+
+set(PLUGIN_OUTPUT_DIR "${CMAKE_BINARY_DIR}/plugins")
+file(MAKE_DIRECTORY ${PLUGIN_OUTPUT_DIR})
+
+add_library(simple_plugin SHARED
+    simple_plugin.cc
+)
+
+set_target_properties(simple_plugin PROPERTIES
+    LIBRARY_OUTPUT_DIRECTORY ${PLUGIN_OUTPUT_DIR}
+)

plugins/simple_plugin.cc

@@ -0,0 +1,25 @@
+#include "plugin_api.hh"
+
+#include <iostream>
+
+void notify(void* pluginMem);
+void unload(void* pluginMem);
+
+PLUGIN_API_ATTR hsim::LoadablePlugin loadPlugin([[maybe_unused]] const char* options) {
+    hsim::LoadablePlugin plugin = {};
+    plugin.pluginMem = nullptr;
+    plugin.notify = notify;
+    plugin.unload = unload;
+
+    std::cout << "load plugin" << std::endl;
+
+    return plugin;
+}
+
+void notify([[maybe_unused]] void* pluginMem) {
+    std::cout << "notify plugin" << std::endl;   
+}
+
+void unload([[maybe_unused]] void* pluginMem) {
+    std::cout << "unload plugin" << std::endl;
+} 

src/main.cc

@@ -30,6 +30,8 @@ int main(int argc, char **argv) try {
     //
     hsim::Machine machine{config};
 
+    // machine.loadPlugin("./build/plugins/libsimple_plugin.so");
+
     machine.run();
 
     return 0;