2 * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
3 * Licensed under the GPL
6 #include "linux/sched.h"
7 #include "linux/signal.h"
8 #include "linux/kernel.h"
9 #include "linux/interrupt.h"
10 #include "linux/ptrace.h"
11 #include "asm/system.h"
12 #include "asm/pgalloc.h"
13 #include "asm/ptrace.h"
14 #include "asm/tlbflush.h"
16 #include "signal_user.h"
17 #include "kern_util.h"
18 #include "user_util.h"
21 #include "sigcontext.h"
22 #include "time_user.h"
29 void *switch_to_tt(void *prev, void *next, void *last)
31 struct task_struct *from, *to, *prev_sched;
33 int err, vtalrm, alrm, prof, cpu;
35 /* jailing and SMP are incompatible, so this doesn't need to be
43 to->thread.prev_sched = from;
45 cpu = from->thread_info->cpu;
47 forward_interrupts(to->thread.mode.tt.extern_pid);
49 forward_ipi(cpu_data[cpu].ipi_pipe[0], to->thread.mode.tt.extern_pid);
51 local_irq_save(flags);
53 vtalrm = change_sig(SIGVTALRM, 0);
54 alrm = change_sig(SIGALRM, 0);
55 prof = change_sig(SIGPROF, 0);
57 forward_pending_sigio(to->thread.mode.tt.extern_pid);
63 err = os_write_file(to->thread.mode.tt.switch_pipe[1], &c, sizeof(c));
65 panic("write of switch_pipe failed, err = %d", -err);
68 if((from->exit_state == EXIT_ZOMBIE) ||
69 (from->exit_state == EXIT_DEAD))
70 os_kill_process(os_getpid(), 0);
72 err = os_read_file(from->thread.mode.tt.switch_pipe[0], &c, sizeof(c));
74 panic("read of switch_pipe failed, errno = %d", -err);
76 /* If the process that we have just scheduled away from has exited,
77 * then it needs to be killed here. The reason is that, even though
78 * it will kill itself when it next runs, that may be too late. Its
79 * stack will be freed, possibly before then, and if that happens,
80 * we have a use-after-free situation. So, it gets killed here
81 * in case it has not already killed itself.
83 prev_sched = current->thread.prev_sched;
84 if((prev_sched->exit_state == EXIT_ZOMBIE) ||
85 (prev_sched->exit_state == EXIT_DEAD))
86 os_kill_process(prev_sched->thread.mode.tt.extern_pid, 1);
88 change_sig(SIGVTALRM, vtalrm);
89 change_sig(SIGALRM, alrm);
90 change_sig(SIGPROF, prof);
95 local_irq_restore(flags);
97 return(current->thread.prev_sched);
100 void release_thread_tt(struct task_struct *task)
102 int pid = task->thread.mode.tt.extern_pid;
104 if(os_getpid() != pid)
105 os_kill_process(pid, 0);
108 void exit_thread_tt(void)
110 os_close_file(current->thread.mode.tt.switch_pipe[0]);
111 os_close_file(current->thread.mode.tt.switch_pipe[1]);
114 void suspend_new_thread(int fd)
119 os_stop_process(os_getpid());
120 err = os_read_file(fd, &c, sizeof(c));
122 panic("read failed in suspend_new_thread, err = %d", -err);
125 void schedule_tail(task_t *prev);
127 static void new_thread_handler(int sig)
129 unsigned long disable;
133 fn = current->thread.request.u.thread.proc;
134 arg = current->thread.request.u.thread.arg;
136 UPT_SC(¤t->thread.regs.regs) = (void *) (&sig + 1);
137 disable = (1 << (SIGVTALRM - 1)) | (1 << (SIGALRM - 1)) |
138 (1 << (SIGIO - 1)) | (1 << (SIGPROF - 1));
139 SC_SIGMASK(UPT_SC(¤t->thread.regs.regs)) &= ~disable;
141 suspend_new_thread(current->thread.mode.tt.switch_pipe[0]);
144 if(current->thread.prev_sched != NULL)
145 schedule_tail(current->thread.prev_sched);
146 current->thread.prev_sched = NULL;
148 init_new_thread_signals(1);
150 free_page(current->thread.temp_stack);
151 set_cmdline("(kernel thread)");
153 change_sig(SIGUSR1, 1);
154 change_sig(SIGVTALRM, 1);
155 change_sig(SIGPROF, 1);
157 if(!run_kernel_thread(fn, arg, ¤t->thread.exec_buf))
160 /* XXX No set_user_mode here because a newly execed process will
161 * immediately segfault on its non-existent IP, coming straight back
162 * to the signal handler, which will call set_user_mode on its way
163 * out. This should probably change since it's confusing.
167 static int new_thread_proc(void *stack)
169 /* local_irq_disable is needed to block out signals until this thread is
170 * properly scheduled. Otherwise, the tracing thread will get mighty
171 * upset about any signals that arrive before that.
172 * This has the complication that it sets the saved signal mask in
173 * the sigcontext to block signals. This gets restored when this
174 * thread (or a descendant, since they get a copy of this sigcontext)
175 * returns to userspace.
176 * So, this is compensated for elsewhere.
177 * XXX There is still a small window until local_irq_disable() actually
178 * finishes where signals are possible - shouldn't be a problem in
179 * practice since SIGIO hasn't been forwarded here yet, and the
180 * local_irq_disable should finish before a SIGVTALRM has time to be
185 init_new_thread_stack(stack, new_thread_handler);
186 os_usr1_process(os_getpid());
187 change_sig(SIGUSR1, 1);
191 /* Signal masking - signals are blocked at the start of fork_tramp. They
192 * are re-enabled when finish_fork_handler is entered by fork_tramp hitting
193 * itself with a SIGUSR1. set_user_mode has to be run with SIGUSR1 off,
194 * so it is blocked before it's called. They are re-enabled on sigreturn
195 * despite the fact that they were blocked when the SIGUSR1 was issued because
196 * copy_thread copies the parent's sigcontext, including the signal mask
197 * onto the signal frame.
200 void finish_fork_handler(int sig)
202 UPT_SC(¤t->thread.regs.regs) = (void *) (&sig + 1);
203 suspend_new_thread(current->thread.mode.tt.switch_pipe[0]);
206 if(current->thread.prev_sched != NULL)
207 schedule_tail(current->thread.prev_sched);
208 current->thread.prev_sched = NULL;
211 change_sig(SIGVTALRM, 1);
213 if(current->mm != current->parent->mm)
214 protect_memory(uml_reserved, high_physmem - uml_reserved, 1,
216 task_protections((unsigned long) current_thread);
218 free_page(current->thread.temp_stack);
220 change_sig(SIGUSR1, 0);
221 set_user_mode(current);
224 int fork_tramp(void *stack)
228 init_new_thread_stack(stack, finish_fork_handler);
230 os_usr1_process(os_getpid());
231 change_sig(SIGUSR1, 1);
235 int copy_thread_tt(int nr, unsigned long clone_flags, unsigned long sp,
236 unsigned long stack_top, struct task_struct * p,
237 struct pt_regs *regs)
239 int (*tramp)(void *);
243 if(current->thread.forking)
246 tramp = new_thread_proc;
247 p->thread.request.u.thread = current->thread.request.u.thread;
250 err = os_pipe(p->thread.mode.tt.switch_pipe, 1, 1);
252 printk("copy_thread : pipe failed, err = %d\n", -err);
256 stack = alloc_stack(0, 0);
258 printk(KERN_ERR "copy_thread : failed to allocate "
259 "temporary stack\n");
263 clone_flags &= CLONE_VM;
264 p->thread.temp_stack = stack;
265 new_pid = start_fork_tramp(p->thread_info, stack, clone_flags, tramp);
267 printk(KERN_ERR "copy_thread : clone failed - errno = %d\n",
272 if(current->thread.forking){
273 sc_to_sc(UPT_SC(&p->thread.regs.regs),
274 UPT_SC(¤t->thread.regs.regs));
275 SC_SET_SYSCALL_RETURN(UPT_SC(&p->thread.regs.regs), 0);
276 if(sp != 0) SC_SP(UPT_SC(&p->thread.regs.regs)) = sp;
278 p->thread.mode.tt.extern_pid = new_pid;
280 current->thread.request.op = OP_FORK;
281 current->thread.request.u.fork.pid = new_pid;
282 os_usr1_process(os_getpid());
284 /* Enable the signal and then disable it to ensure that it is handled
285 * here, and nowhere else.
287 change_sig(SIGUSR1, 1);
289 change_sig(SIGUSR1, 0);
296 current->thread.request.op = OP_REBOOT;
297 os_usr1_process(os_getpid());
298 change_sig(SIGUSR1, 1);
303 current->thread.request.op = OP_HALT;
304 os_usr1_process(os_getpid());
305 change_sig(SIGUSR1, 1);
308 void kill_off_processes_tt(void)
310 struct task_struct *p;
315 if(p->thread.mode.tt.extern_pid != me)
316 os_kill_process(p->thread.mode.tt.extern_pid, 0);
318 if(init_task.thread.mode.tt.extern_pid != me)
319 os_kill_process(init_task.thread.mode.tt.extern_pid, 0);
322 void initial_thread_cb_tt(void (*proc)(void *), void *arg)
324 if(os_getpid() == tracing_pid){
328 current->thread.request.op = OP_CB;
329 current->thread.request.u.cb.proc = proc;
330 current->thread.request.u.cb.arg = arg;
331 os_usr1_process(os_getpid());
332 change_sig(SIGUSR1, 1);
334 change_sig(SIGUSR1, 0);
338 int do_proc_op(void *t, int proc_id)
340 struct task_struct *task;
341 struct thread_struct *thread;
345 thread = &task->thread;
346 op = thread->request.op;
352 pid = thread->request.u.exec.pid;
353 do_exec(thread->mode.tt.extern_pid, pid);
354 thread->mode.tt.extern_pid = pid;
355 cpu_tasks[task->thread_info->cpu].pid = pid;
358 attach_process(thread->request.u.fork.pid);
361 (*thread->request.u.cb.proc)(thread->request.u.cb.arg);
367 tracer_panic("Bad op in do_proc_op");
370 thread->request.op = OP_NONE;
374 void init_idle_tt(void)
379 extern void start_kernel(void);
381 static int start_kernel_proc(void *unused)
388 cpu_tasks[0].pid = pid;
389 cpu_tasks[0].task = current;
391 cpu_online_map = cpumask_of_cpu(0);
393 if(debug) os_stop_process(pid);
398 void set_tracing(void *task, int tracing)
400 ((struct task_struct *) task)->thread.mode.tt.tracing = tracing;
403 int is_tracing(void *t)
405 return (((struct task_struct *) t)->thread.mode.tt.tracing);
408 int set_user_mode(void *t)
410 struct task_struct *task;
412 task = t ? t : current;
413 if(task->thread.mode.tt.tracing)
415 task->thread.request.op = OP_TRACE_ON;
416 os_usr1_process(os_getpid());
420 void set_init_pid(int pid)
424 init_task.thread.mode.tt.extern_pid = pid;
425 err = os_pipe(init_task.thread.mode.tt.switch_pipe, 1, 1);
427 panic("Can't create switch pipe for init_task, errno = %d",
431 int start_uml_tt(void)
436 pages = (1 << CONFIG_KERNEL_STACK_ORDER);
437 sp = (void *) ((unsigned long) init_task.thread_info) +
438 pages * PAGE_SIZE - sizeof(unsigned long);
439 return(tracer(start_kernel_proc, sp));
442 int external_pid_tt(struct task_struct *task)
444 return(task->thread.mode.tt.extern_pid);
447 int thread_pid_tt(struct task_struct *task)
449 return(task->thread.mode.tt.extern_pid);
452 int is_valid_pid(int pid)
454 struct task_struct *task;
456 read_lock(&tasklist_lock);
457 for_each_process(task){
458 if(task->thread.mode.tt.extern_pid == pid){
459 read_unlock(&tasklist_lock);
463 read_unlock(&tasklist_lock);
468 * Overrides for Emacs so that we follow Linus's tabbing style.
469 * Emacs will notice this stuff at the end of the file and automatically
470 * adjust the settings for this buffer only. This must remain at the end
472 * ---------------------------------------------------------------------------
474 * c-file-style: "linux"