Kernel: Expose CPU load information under /proc/cpu/<index>

kernel/include/kernel/FS/ProcFS/FileSystem.h

@@ -13,6 +13,8 @@ namespace Kernel
 		static void initialize();
 		static ProcFileSystem& get();
 
+		void post_scheduler_initialize();
+
 		BAN::ErrorOr<void> on_process_create(Process&);
 		void on_process_delete(Process&);
 

kernel/kernel/FS/ProcFS/FileSystem.cpp

@@ -49,6 +49,35 @@ namespace Kernel
 		MUST(static_cast<TmpDirectoryInode*>(s_instance->root_inode().ptr())->link_inode(*self_inode, "self"_sv));
 	}
 
+	void ProcFileSystem::post_scheduler_initialize()
+	{
+		MUST(s_instance->root_inode()->create_directory("cpu"_sv, Inode::Mode::IFDIR | 0555, 0, 0));
+		auto cpu_directory = MUST(s_instance->root_inode()->find_inode("cpu"_sv));
+
+		for (size_t i = 0; i < Processor::count(); i++)
+		{
+			auto cpu_inode = MUST(ProcROInode::create_new(
+				[](off_t offset, BAN::ByteSpan buffer, void* index_ptr) -> BAN::ErrorOr<size_t>
+				{
+					ASSERT(offset >= 0);
+
+					const size_t index = reinterpret_cast<uintptr_t>(index_ptr);
+					const auto load_stats = Processor::get_load_stats(index);
+
+					auto string = TRY(BAN::String::formatted("{} {}", load_stats.ns_idle, load_stats.ns_total));
+					if (static_cast<size_t>(offset) >= string.size())
+						return 0;
+
+					const size_t bytes = BAN::Math::min<size_t>(string.size() - offset, buffer.size());
+					memcpy(buffer.data(), string.data() + offset, bytes);
+					return bytes;
+				},
+				*s_instance, reinterpret_cast<void*>(i), 0444, 0, 0
+			));
+			MUST(cpu_directory->link_inode(MUST(BAN::String::formatted("{}", i)), cpu_inode));
+		}
+	}
+
 	ProcFileSystem& ProcFileSystem::get()
 	{
 		ASSERT(s_instance);

kernel/kernel/kernel.cpp

@@ -211,6 +211,8 @@ static void init2(void*)
 
 	SystemTimer::get().initialize_tsc();
 
+	ProcFileSystem::get().post_scheduler_initialize();
+
 	auto console = MUST(DevFileSystem::get().root_inode()->find_inode(cmdline.console));
 	ASSERT(console->is_tty());
 	static_cast<Kernel::TTY*>(console.ptr())->set_as_current();