void *switch_to_tt(void *prev, void *next, void *last)
{
- struct task_struct *from, *to;
+ struct task_struct *from, *to, *prev_sched;
unsigned long flags;
int err, vtalrm, alrm, prof, cpu;
char c;
reading = 0;
err = os_write_file(to->thread.mode.tt.switch_pipe[1], &c, sizeof(c));
if(err != sizeof(c))
- panic("write of switch_pipe failed, errno = %d", -err);
+ panic("write of switch_pipe failed, err = %d", -err);
reading = 1;
if((from->state == TASK_ZOMBIE) || (from->state == TASK_DEAD))
if(err != sizeof(c))
panic("read of switch_pipe failed, errno = %d", -err);
+ /* If the process that we have just scheduled away from has exited,
+ * then it needs to be killed here. The reason is that, even though
+ * it will kill itself when it next runs, that may be too late. Its
+ * stack will be freed, possibly before then, and if that happens,
+ * we have a use-after-free situation. So, it gets killed here
+ * in case it has not already killed itself.
+ */
+ prev_sched = current->thread.prev_sched;
+ if((prev_sched->state == TASK_ZOMBIE) ||
+ (prev_sched->state == TASK_DEAD))
+ os_kill_process(prev_sched->thread.mode.tt.extern_pid, 1);
+
/* This works around a nasty race with 'jail'. If we are switching
* between two threads of a threaded app and the incoming process
* runs before the outgoing process reaches the read, and it makes
void release_thread_tt(struct task_struct *task)
{
- os_kill_process(task->thread.mode.tt.extern_pid, 0);
+ int pid = task->thread.mode.tt.extern_pid;
+
+ if(os_getpid() != pid)
+ os_kill_process(pid, 0);
}
void exit_thread_tt(void)
{
- close(current->thread.mode.tt.switch_pipe[0]);
- close(current->thread.mode.tt.switch_pipe[1]);
+ os_close_file(current->thread.mode.tt.switch_pipe[0]);
+ os_close_file(current->thread.mode.tt.switch_pipe[1]);
+}
+
+void suspend_new_thread(int fd)
+{
+ int err;
+ char c;
+
+ os_stop_process(os_getpid());
+ err = os_read_file(fd, &c, sizeof(c));
+ if(err != sizeof(c))
+ panic("read failed in suspend_new_thread, err = %d", -err);
}
void schedule_tail(task_t *prev);
static void new_thread_handler(int sig)
{
+ unsigned long disable;
int (*fn)(void *);
void *arg;
fn = current->thread.request.u.thread.proc;
arg = current->thread.request.u.thread.arg;
+
UPT_SC(¤t->thread.regs.regs) = (void *) (&sig + 1);
+ disable = (1 << (SIGVTALRM - 1)) | (1 << (SIGALRM - 1)) |
+ (1 << (SIGIO - 1)) | (1 << (SIGPROF - 1));
+ SC_SIGMASK(UPT_SC(¤t->thread.regs.regs)) &= ~disable;
+
suspend_new_thread(current->thread.mode.tt.switch_pipe[0]);
- block_signals();
+ force_flush_all();
+ if(current->thread.prev_sched != NULL)
+ schedule_tail(current->thread.prev_sched);
+ current->thread.prev_sched = NULL;
+
init_new_thread_signals(1);
-#ifdef CONFIG_SMP
- schedule_tail(current->thread.prev_sched);
-#endif
enable_timer();
free_page(current->thread.temp_stack);
set_cmdline("(kernel thread)");
- force_flush_all();
- current->thread.prev_sched = NULL;
change_sig(SIGUSR1, 1);
change_sig(SIGVTALRM, 1);
change_sig(SIGPROF, 1);
- unblock_signals();
+ local_irq_enable();
if(!run_kernel_thread(fn, arg, ¤t->thread.exec_buf))
do_exit(0);
+
+ /* XXX No set_user_mode here because a newly execed process will
+ * immediately segfault on its non-existent IP, coming straight back
+ * to the signal handler, which will call set_user_mode on its way
+ * out. This should probably change since it's confusing.
+ */
}
static int new_thread_proc(void *stack)
{
+ /* local_irq_disable is needed to block out signals until this thread is
+ * properly scheduled. Otherwise, the tracing thread will get mighty
+ * upset about any signals that arrive before that.
+ * This has the complication that it sets the saved signal mask in
+ * the sigcontext to block signals. This gets restored when this
+ * thread (or a descendant, since they get a copy of this sigcontext)
+ * returns to userspace.
+ * So, this is compensated for elsewhere.
+ * XXX There is still a small window until local_irq_disable() actually
+ * finishes where signals are possible - shouldn't be a problem in
+ * practice since SIGIO hasn't been forwarded here yet, and the
+ * local_irq_disable should finish before a SIGVTALRM has time to be
+ * delivered.
+ */
+
+ local_irq_disable();
init_new_thread_stack(stack, new_thread_handler);
os_usr1_process(os_getpid());
+ change_sig(SIGUSR1, 1);
return(0);
}
* itself with a SIGUSR1. set_user_mode has to be run with SIGUSR1 off,
* so it is blocked before it's called. They are re-enabled on sigreturn
* despite the fact that they were blocked when the SIGUSR1 was issued because
- * copy_thread copies the parent's signcontext, including the signal mask
+ * copy_thread copies the parent's sigcontext, including the signal mask
* onto the signal frame.
*/
UPT_SC(¤t->thread.regs.regs) = (void *) (&sig + 1);
suspend_new_thread(current->thread.mode.tt.switch_pipe[0]);
-#ifdef CONFIG_SMP
- schedule_tail(NULL);
-#endif
+ force_flush_all();
+ if(current->thread.prev_sched != NULL)
+ schedule_tail(current->thread.prev_sched);
+ current->thread.prev_sched = NULL;
+
enable_timer();
change_sig(SIGVTALRM, 1);
local_irq_enable();
- force_flush_all();
if(current->mm != current->parent->mm)
protect_memory(uml_reserved, high_physmem - uml_reserved, 1,
1, 0, 1);
- task_protections((unsigned long) current->thread_info);
-
- current->thread.prev_sched = NULL;
+ task_protections((unsigned long) current_thread);
free_page(current->thread.temp_stack);
+ local_irq_disable();
change_sig(SIGUSR1, 0);
set_user_mode(current);
}
-static int sigusr1 = SIGUSR1;
-
int fork_tramp(void *stack)
{
- int sig = sigusr1;
-
local_irq_disable();
+ arch_init_thread();
init_new_thread_stack(stack, finish_fork_handler);
- kill(os_getpid(), sig);
+ os_usr1_process(os_getpid());
+ change_sig(SIGUSR1, 1);
return(0);
}
}
err = os_pipe(p->thread.mode.tt.switch_pipe, 1, 1);
- if(err){
- printk("copy_thread : pipe failed, errno = %d\n", -err);
+ if(err < 0){
+ printk("copy_thread : pipe failed, err = %d\n", -err);
return(err);
}
clone_flags &= CLONE_VM;
p->thread.temp_stack = stack;
- new_pid = start_fork_tramp((void *) p->thread.kernel_stack, stack,
- clone_flags, tramp);
+ new_pid = start_fork_tramp(p->thread_info, stack, clone_flags, tramp);
if(new_pid < 0){
printk(KERN_ERR "copy_thread : clone failed - errno = %d\n",
-new_pid);
current->thread.request.op = OP_FORK;
current->thread.request.u.fork.pid = new_pid;
os_usr1_process(os_getpid());
- return(0);
+
+ /* Enable the signal and then disable it to ensure that it is handled
+ * here, and nowhere else.
+ */
+ change_sig(SIGUSR1, 1);
+
+ change_sig(SIGUSR1, 0);
+ err = 0;
+ out:
+ return(err);
}
void reboot_tt(void)
{
current->thread.request.op = OP_REBOOT;
os_usr1_process(os_getpid());
+ change_sig(SIGUSR1, 1);
}
void halt_tt(void)
{
current->thread.request.op = OP_HALT;
os_usr1_process(os_getpid());
+ change_sig(SIGUSR1, 1);
}
void kill_off_processes_tt(void)
current->thread.request.u.cb.proc = proc;
current->thread.request.u.cb.arg = arg;
os_usr1_process(os_getpid());
+ change_sig(SIGUSR1, 1);
+
+ change_sig(SIGUSR1, 0);
}
}
pages = (1 << CONFIG_KERNEL_STACK_ORDER);
- start = (unsigned long) current->thread_info + PAGE_SIZE;
- end = (unsigned long) current + PAGE_SIZE * pages;
+ start = (unsigned long) current_thread + PAGE_SIZE;
+ end = (unsigned long) current_thread + PAGE_SIZE * pages;
protect_memory(uml_reserved, start - uml_reserved, 1, w, 1, 1);
protect_memory(end, high_physmem - end, 1, w, 1, 1);
init_task.thread.mode.tt.extern_pid = pid;
err = os_pipe(init_task.thread.mode.tt.switch_pipe, 1, 1);
- if(err) panic("Can't create switch pipe for init_task, errno = %d",
- err);
+ if(err)
+ panic("Can't create switch pipe for init_task, errno = %d",
+ -err);
}
int singlestepping_tt(void *t)
void *sp;
int pages;
- pages = (1 << CONFIG_KERNEL_STACK_ORDER) - 2;
- sp = (void *) init_task.thread.kernel_stack + pages * PAGE_SIZE -
- sizeof(unsigned long);
+ pages = (1 << CONFIG_KERNEL_STACK_ORDER);
+ sp = (void *) ((unsigned long) init_task.thread_info) +
+ pages * PAGE_SIZE - sizeof(unsigned long);
return(tracer(start_kernel_proc, sp));
}
git://git.onelab.eu / linux-2.6.git / blobdiff