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"