1 use core::{intrinsics::unlikely, sync::atomic::Ordering}; 2 3 use alloc::{string::ToString, sync::Arc}; 4 use log::error; 5 use system_error::SystemError; 6 7 use crate::{ 8 arch::{interrupt::TrapFrame, ipc::signal::Signal}, 9 filesystem::procfs::procfs_register_pid, 10 ipc::signal::flush_signal_handlers, 11 libs::rwlock::RwLock, 12 mm::VirtAddr, 13 process::ProcessFlags, 14 sched::{sched_cgroup_fork, sched_fork}, 15 smp::core::smp_get_processor_id, 16 syscall::user_access::UserBufferWriter, 17 }; 18 19 use super::{ 20 kthread::{KernelThreadPcbPrivate, WorkerPrivate}, 21 KernelStack, Pid, ProcessControlBlock, ProcessManager, 22 }; 23 24 bitflags! { 25 /// 进程克隆标志 26 pub struct CloneFlags: u64 { 27 /// 在进程间共享虚拟内存空间 28 const CLONE_VM = 0x00000100; 29 /// 在进程间共享文件系统信息 30 const CLONE_FS = 0x00000200; 31 /// 共享打开的文件 32 const CLONE_FILES = 0x00000400; 33 /// 克隆时，与父进程共享信号处理结构体 34 const CLONE_SIGHAND = 0x00000800; 35 /// 返回进程的文件描述符 36 const CLONE_PIDFD = 0x00001000; 37 /// 使克隆对象成为父进程的跟踪对象 38 const CLONE_PTRACE = 0x00002000; 39 /// 在执行 exec() 或 _exit() 之前挂起父进程的执行 40 const CLONE_VFORK = 0x00004000; 41 /// 使克隆对象的父进程为调用进程的父进程 42 const CLONE_PARENT = 0x00008000; 43 /// 拷贝线程 44 const CLONE_THREAD = 0x00010000; 45 /// 创建一个新的命名空间，其中包含独立的文件系统挂载点层次结构。 46 const CLONE_NEWNS = 0x00020000; 47 /// 与父进程共享 System V 信号量。 48 const CLONE_SYSVSEM = 0x00040000; 49 /// 设置其线程本地存储 50 const CLONE_SETTLS = 0x00080000; 51 /// 设置partent_tid地址为子进程线程 ID 52 const CLONE_PARENT_SETTID = 0x00100000; 53 /// 在子进程中设置一个清除线程 ID 的用户空间地址 54 const CLONE_CHILD_CLEARTID = 0x00200000; 55 /// 创建一个新线程，将其设置为分离状态 56 const CLONE_DETACHED = 0x00400000; 57 /// 使其在创建者进程或线程视角下成为无法跟踪的。 58 const CLONE_UNTRACED = 0x00800000; 59 /// 设置其子进程线程 ID 60 const CLONE_CHILD_SETTID = 0x01000000; 61 /// 将其放置在一个新的 cgroup 命名空间中 62 const CLONE_NEWCGROUP = 0x02000000; 63 /// 将其放置在一个新的 UTS 命名空间中 64 const CLONE_NEWUTS = 0x04000000; 65 /// 将其放置在一个新的 IPC 命名空间中 66 const CLONE_NEWIPC = 0x08000000; 67 /// 将其放置在一个新的用户命名空间中 68 const CLONE_NEWUSER = 0x10000000; 69 /// 将其放置在一个新的 PID 命名空间中 70 const CLONE_NEWPID = 0x20000000; 71 /// 将其放置在一个新的网络命名空间中 72 const CLONE_NEWNET = 0x40000000; 73 /// 在新的 I/O 上下文中运行它 74 const CLONE_IO = 0x80000000; 75 /// 克隆时，与父进程共享信号结构体 76 const CLONE_SIGNAL = 0x00010000 | 0x00000800; 77 /// 克隆时，将原本被设置为SIG_IGNORE的信号，设置回SIG_DEFAULT 78 const CLONE_CLEAR_SIGHAND = 0x100000000; 79 } 80 } 81 82 /// ## clone与clone3系统调用的参数载体 83 /// 84 /// 因为这两个系统调用的参数很多，所以有这样一个载体更灵活 85 /// 86 /// 仅仅作为参数传递 87 #[derive(Debug, Clone, Copy)] 88 #[allow(dead_code)] 89 pub struct KernelCloneArgs { 90 pub flags: CloneFlags, 91 92 // 下列属性均来自用户空间 93 pub pidfd: VirtAddr, 94 pub child_tid: VirtAddr, 95 pub parent_tid: VirtAddr, 96 pub set_tid: VirtAddr, 97 98 /// 进程退出时发送的信号 99 pub exit_signal: Signal, 100 101 pub stack: usize, 102 // clone3用到 103 pub stack_size: usize, 104 pub tls: usize, 105 106 pub set_tid_size: usize, 107 pub cgroup: i32, 108 109 pub io_thread: bool, 110 pub kthread: bool, 111 pub idle: bool, 112 pub func: VirtAddr, 113 pub fn_arg: VirtAddr, 114 // cgrp 和 cset? 115 } 116 117 impl KernelCloneArgs { new() -> Self118 pub fn new() -> Self { 119 let null_addr = VirtAddr::new(0); 120 Self { 121 flags: unsafe { CloneFlags::from_bits_unchecked(0) }, 122 pidfd: null_addr, 123 child_tid: null_addr, 124 parent_tid: null_addr, 125 set_tid: null_addr, 126 exit_signal: Signal::SIGCHLD, 127 stack: 0, 128 stack_size: 0, 129 tls: 0, 130 set_tid_size: 0, 131 cgroup: 0, 132 io_thread: false, 133 kthread: false, 134 idle: false, 135 func: null_addr, 136 fn_arg: null_addr, 137 } 138 } 139 } 140 141 impl ProcessManager { 142 /// 创建一个新进程 143 /// 144 /// ## 参数 145 /// 146 /// - `current_trapframe`: 当前进程的trapframe 147 /// - `clone_flags`: 进程克隆标志 148 /// 149 /// ## 返回值 150 /// 151 /// - 成功：返回新进程的pid 152 /// - 失败：返回Err(SystemError)，fork失败的话，子线程不会执行。 153 /// 154 /// ## Safety 155 /// 156 /// - fork失败的话，子线程不会执行。 fork( current_trapframe: &TrapFrame, clone_flags: CloneFlags, ) -> Result<Pid, SystemError>157 pub fn fork( 158 current_trapframe: &TrapFrame, 159 clone_flags: CloneFlags, 160 ) -> Result<Pid, SystemError> { 161 let current_pcb = ProcessManager::current_pcb(); 162 163 let new_kstack: KernelStack = KernelStack::new()?; 164 165 let name = current_pcb.basic().name().to_string(); 166 167 let pcb = ProcessControlBlock::new(name, new_kstack); 168 169 let mut args = KernelCloneArgs::new(); 170 args.flags = clone_flags; 171 args.exit_signal = Signal::SIGCHLD; 172 Self::copy_process(¤t_pcb, &pcb, args, current_trapframe).map_err(|e| { 173 error!( 174 "fork: Failed to copy process, current pid: [{:?}], new pid: [{:?}]. Error: {:?}", 175 current_pcb.pid(), 176 pcb.pid(), 177 e 178 ); 179 e 180 })?; 181 ProcessManager::add_pcb(pcb.clone()); 182 183 // 向procfs注册进程 184 procfs_register_pid(pcb.pid()).unwrap_or_else(|e| { 185 panic!( 186 "fork: Failed to register pid to procfs, pid: [{:?}]. Error: {:?}", 187 pcb.pid(), 188 e 189 ) 190 }); 191 192 pcb.sched_info().set_on_cpu(Some(smp_get_processor_id())); 193 194 ProcessManager::wakeup(&pcb).unwrap_or_else(|e| { 195 panic!( 196 "fork: Failed to wakeup new process, pid: [{:?}]. Error: {:?}", 197 pcb.pid(), 198 e 199 ) 200 }); 201 202 return Ok(pcb.pid()); 203 } 204 copy_flags( clone_flags: &CloneFlags, new_pcb: &Arc<ProcessControlBlock>, ) -> Result<(), SystemError>205 fn copy_flags( 206 clone_flags: &CloneFlags, 207 new_pcb: &Arc<ProcessControlBlock>, 208 ) -> Result<(), SystemError> { 209 if clone_flags.contains(CloneFlags::CLONE_VM) { 210 new_pcb.flags().insert(ProcessFlags::VFORK); 211 } 212 *new_pcb.flags.get_mut() = *ProcessManager::current_pcb().flags(); 213 return Ok(()); 214 } 215 216 /// 拷贝进程的地址空间 217 /// 218 /// ## 参数 219 /// 220 /// - `clone_vm`: 是否与父进程共享地址空间。true表示共享 221 /// - `new_pcb`: 新进程的pcb 222 /// 223 /// ## 返回值 224 /// 225 /// - 成功：返回Ok(()) 226 /// - 失败：返回Err(SystemError) 227 /// 228 /// ## Panic 229 /// 230 /// - 如果当前进程没有用户地址空间，则panic 231 #[inline(never)] copy_mm( clone_flags: &CloneFlags, current_pcb: &Arc<ProcessControlBlock>, new_pcb: &Arc<ProcessControlBlock>, ) -> Result<(), SystemError>232 fn copy_mm( 233 clone_flags: &CloneFlags, 234 current_pcb: &Arc<ProcessControlBlock>, 235 new_pcb: &Arc<ProcessControlBlock>, 236 ) -> Result<(), SystemError> { 237 let old_address_space = current_pcb.basic().user_vm().unwrap_or_else(|| { 238 panic!( 239 "copy_mm: Failed to get address space of current process, current pid: [{:?}]", 240 current_pcb.pid() 241 ) 242 }); 243 244 if clone_flags.contains(CloneFlags::CLONE_VM) { 245 unsafe { new_pcb.basic_mut().set_user_vm(Some(old_address_space)) }; 246 return Ok(()); 247 } 248 let new_address_space = old_address_space.write_irqsave().try_clone().unwrap_or_else(|e| { 249 panic!( 250 "copy_mm: Failed to clone address space of current process, current pid: [{:?}], new pid: [{:?}]. Error: {:?}", 251 current_pcb.pid(), new_pcb.pid(), e 252 ) 253 }); 254 unsafe { new_pcb.basic_mut().set_user_vm(Some(new_address_space)) }; 255 return Ok(()); 256 } 257 258 #[inline(never)] copy_files( clone_flags: &CloneFlags, current_pcb: &Arc<ProcessControlBlock>, new_pcb: &Arc<ProcessControlBlock>, ) -> Result<(), SystemError>259 fn copy_files( 260 clone_flags: &CloneFlags, 261 current_pcb: &Arc<ProcessControlBlock>, 262 new_pcb: &Arc<ProcessControlBlock>, 263 ) -> Result<(), SystemError> { 264 // 如果不共享文件描述符表，则拷贝文件描述符表 265 if !clone_flags.contains(CloneFlags::CLONE_FILES) { 266 let new_fd_table = current_pcb.basic().fd_table().unwrap().read().clone(); 267 let new_fd_table = Arc::new(RwLock::new(new_fd_table)); 268 new_pcb.basic_mut().set_fd_table(Some(new_fd_table)); 269 } else { 270 // 如果共享文件描述符表，则直接拷贝指针 271 new_pcb 272 .basic_mut() 273 .set_fd_table(current_pcb.basic().fd_table().clone()); 274 } 275 276 return Ok(()); 277 } 278 279 #[allow(dead_code)] copy_sighand( clone_flags: &CloneFlags, current_pcb: &Arc<ProcessControlBlock>, new_pcb: &Arc<ProcessControlBlock>, ) -> Result<(), SystemError>280 fn copy_sighand( 281 clone_flags: &CloneFlags, 282 current_pcb: &Arc<ProcessControlBlock>, 283 new_pcb: &Arc<ProcessControlBlock>, 284 ) -> Result<(), SystemError> { 285 // // 将信号的处理函数设置为default(除了那些被手动屏蔽的) 286 if clone_flags.contains(CloneFlags::CLONE_CLEAR_SIGHAND) { 287 flush_signal_handlers(new_pcb.clone(), false); 288 } 289 290 if clone_flags.contains(CloneFlags::CLONE_SIGHAND) { 291 new_pcb.sig_struct_irqsave().handlers = current_pcb.sig_struct_irqsave().handlers; 292 } 293 return Ok(()); 294 } 295 296 /// 拷贝进程信息 297 /// 298 /// ## panic: 299 /// 某一步拷贝失败时会引发panic 300 /// 例如：copy_mm等失败时会触发panic 301 /// 302 /// ## 参数 303 /// 304 /// - clone_flags 标志位 305 /// - current_pcb 拷贝源pcb 306 /// - pcb 目标pcb 307 /// 308 /// ## return 309 /// - 发生错误时返回Err(SystemError) 310 #[inline(never)] copy_process( current_pcb: &Arc<ProcessControlBlock>, pcb: &Arc<ProcessControlBlock>, clone_args: KernelCloneArgs, current_trapframe: &TrapFrame, ) -> Result<(), SystemError>311 pub fn copy_process( 312 current_pcb: &Arc<ProcessControlBlock>, 313 pcb: &Arc<ProcessControlBlock>, 314 clone_args: KernelCloneArgs, 315 current_trapframe: &TrapFrame, 316 ) -> Result<(), SystemError> { 317 let clone_flags = clone_args.flags; 318 // 不允许与不同namespace的进程共享根目录 319 if (clone_flags == (CloneFlags::CLONE_NEWNS | CloneFlags::CLONE_FS)) 320 || clone_flags == (CloneFlags::CLONE_NEWUSER | CloneFlags::CLONE_FS) 321 { 322 return Err(SystemError::EINVAL); 323 } 324 325 // 线程组必须共享信号，分离线程只能在线程组内启动。 326 if clone_flags.contains(CloneFlags::CLONE_THREAD) 327 && !clone_flags.contains(CloneFlags::CLONE_SIGHAND) 328 { 329 return Err(SystemError::EINVAL); 330 } 331 332 // 共享信号处理器意味着共享vm。 333 // 线程组也意味着共享vm。阻止这种情况可以简化其他代码。 334 if clone_flags.contains(CloneFlags::CLONE_SIGHAND) 335 && !clone_flags.contains(CloneFlags::CLONE_VM) 336 { 337 return Err(SystemError::EINVAL); 338 } 339 340 // TODO: 处理CLONE_PARENT 与 SIGNAL_UNKILLABLE的情况 341 342 // 如果新进程使用不同的 pid 或 namespace， 343 // 则不允许它与分叉任务共享线程组。 344 if clone_flags.contains(CloneFlags::CLONE_THREAD) 345 && clone_flags.contains(CloneFlags::CLONE_NEWUSER | CloneFlags::CLONE_NEWPID) 346 { 347 return Err(SystemError::EINVAL); 348 // TODO: 判断新进程与当前进程namespace是否相同，不同则返回错误 349 } 350 351 // 如果新进程将处于不同的time namespace， 352 // 则不能让它共享vm或线程组。 353 if clone_flags.contains(CloneFlags::CLONE_THREAD | CloneFlags::CLONE_VM) { 354 // TODO: 判断time namespace，不同则返回错误 355 } 356 357 if clone_flags.contains(CloneFlags::CLONE_PIDFD) 358 && clone_flags.contains(CloneFlags::CLONE_DETACHED | CloneFlags::CLONE_THREAD) 359 { 360 return Err(SystemError::EINVAL); 361 } 362 363 // TODO: 克隆前应该锁信号处理，等待克隆完成后再处理 364 365 // 克隆架构相关 366 let guard = current_pcb.arch_info_irqsave(); 367 unsafe { pcb.arch_info().clone_from(&guard) }; 368 drop(guard); 369 370 // 为内核线程设置WorkerPrivate 371 if current_pcb.flags().contains(ProcessFlags::KTHREAD) { 372 *pcb.worker_private() = 373 Some(WorkerPrivate::KernelThread(KernelThreadPcbPrivate::new())); 374 } 375 376 // 设置clear_child_tid，在线程结束时将其置0以通知父进程 377 if clone_flags.contains(CloneFlags::CLONE_CHILD_CLEARTID) { 378 pcb.thread.write_irqsave().clear_child_tid = Some(clone_args.child_tid); 379 } 380 381 // 设置child_tid，意味着子线程能够知道自己的id 382 if clone_flags.contains(CloneFlags::CLONE_CHILD_SETTID) { 383 pcb.thread.write_irqsave().set_child_tid = Some(clone_args.child_tid); 384 } 385 386 // 将子进程/线程的id存储在用户态传进的地址中 387 if clone_flags.contains(CloneFlags::CLONE_PARENT_SETTID) { 388 let mut writer = UserBufferWriter::new( 389 clone_args.parent_tid.data() as *mut i32, 390 core::mem::size_of::<i32>(), 391 true, 392 )?; 393 394 writer.copy_one_to_user(&(pcb.pid().0 as i32), 0)?; 395 } 396 397 sched_fork(pcb).unwrap_or_else(|e| { 398 panic!( 399 "fork: Failed to set sched info from current process, current pid: [{:?}], new pid: [{:?}]. Error: {:?}", 400 current_pcb.pid(), pcb.pid(), e 401 ) 402 }); 403 404 // 拷贝标志位 405 Self::copy_flags(&clone_flags, pcb).unwrap_or_else(|e| { 406 panic!( 407 "fork: Failed to copy flags from current process, current pid: [{:?}], new pid: [{:?}]. Error: {:?}", 408 current_pcb.pid(), pcb.pid(), e 409 ) 410 }); 411 412 // 拷贝用户地址空间 413 Self::copy_mm(&clone_flags, current_pcb, pcb).unwrap_or_else(|e| { 414 panic!( 415 "fork: Failed to copy mm from current process, current pid: [{:?}], new pid: [{:?}]. Error: {:?}", 416 current_pcb.pid(), pcb.pid(), e 417 ) 418 }); 419 420 // 拷贝文件描述符表 421 Self::copy_files(&clone_flags, current_pcb, pcb).unwrap_or_else(|e| { 422 panic!( 423 "fork: Failed to copy files from current process, current pid: [{:?}], new pid: [{:?}]. Error: {:?}", 424 current_pcb.pid(), pcb.pid(), e 425 ) 426 }); 427 428 // 拷贝信号相关数据 429 Self::copy_sighand(&clone_flags, current_pcb, pcb).unwrap_or_else(|e| { 430 panic!( 431 "fork: Failed to copy sighand from current process, current pid: [{:?}], new pid: [{:?}]. Error: {:?}", 432 current_pcb.pid(), pcb.pid(), e 433 ) 434 }); 435 436 // 拷贝线程 437 Self::copy_thread(current_pcb, pcb, clone_args,current_trapframe).unwrap_or_else(|e| { 438 panic!( 439 "fork: Failed to copy thread from current process, current pid: [{:?}], new pid: [{:?}]. Error: {:?}", 440 current_pcb.pid(), pcb.pid(), e 441 ) 442 }); 443 444 // 设置线程组id、组长 445 if clone_flags.contains(CloneFlags::CLONE_THREAD) { 446 pcb.thread.write_irqsave().group_leader = 447 current_pcb.thread.read_irqsave().group_leader.clone(); 448 unsafe { 449 let ptr = pcb.as_ref() as *const ProcessControlBlock as *mut ProcessControlBlock; 450 (*ptr).tgid = current_pcb.tgid; 451 } 452 } else { 453 pcb.thread.write_irqsave().group_leader = Arc::downgrade(pcb); 454 unsafe { 455 let ptr = pcb.as_ref() as *const ProcessControlBlock as *mut ProcessControlBlock; 456 (*ptr).tgid = pcb.tgid; 457 } 458 } 459 460 // CLONE_PARENT re-uses the old parent 461 if clone_flags.contains(CloneFlags::CLONE_PARENT | CloneFlags::CLONE_THREAD) { 462 *pcb.real_parent_pcb.write_irqsave() = 463 current_pcb.real_parent_pcb.read_irqsave().clone(); 464 465 if clone_flags.contains(CloneFlags::CLONE_THREAD) { 466 pcb.exit_signal.store(Signal::INVALID, Ordering::SeqCst); 467 } else { 468 let leader = current_pcb.thread.read_irqsave().group_leader(); 469 if unlikely(leader.is_none()) { 470 panic!( 471 "fork: Failed to get leader of current process, current pid: [{:?}]", 472 current_pcb.pid() 473 ); 474 } 475 476 pcb.exit_signal.store( 477 leader.unwrap().exit_signal.load(Ordering::SeqCst), 478 Ordering::SeqCst, 479 ); 480 } 481 } else { 482 // 新创建的进程，设置其父进程为当前进程 483 *pcb.real_parent_pcb.write_irqsave() = Arc::downgrade(current_pcb); 484 pcb.exit_signal 485 .store(clone_args.exit_signal, Ordering::SeqCst); 486 } 487 488 // todo: 增加线程组相关的逻辑。 参考 https://code.dragonos.org.cn/xref/linux-6.1.9/kernel/fork.c#2437 489 490 sched_cgroup_fork(pcb); 491 492 Ok(()) 493 } 494 } 495