process.c

优龙2410linux2.6.8内核源代码

/*
 * Copy a thread..
 */
int
copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
	    unsigned long unused, struct task_struct *p, struct pt_regs *regs)
{
	struct pt_regs *childregs, *kregs;
	extern void ret_from_fork(void);
	unsigned long sp = (unsigned long)p->thread_info + THREAD_SIZE;

	p->set_child_tid = p->clear_child_tid = NULL;

	/* Copy registers */
	sp -= sizeof(struct pt_regs);
	childregs = (struct pt_regs *) sp;
	*childregs = *regs;
	if ((childregs->msr & MSR_PR) == 0) {
		/* for kernel thread, set stackptr in new task */
		childregs->gpr[1] = sp + sizeof(struct pt_regs);
		p->thread.regs = NULL;	/* no user register state */
		clear_ti_thread_flag(p->thread_info, TIF_32BIT);
#ifdef CONFIG_PPC_ISERIES
		set_ti_thread_flag(p->thread_info, TIF_RUN_LIGHT);
#endif
	} else {
		childregs->gpr[1] = usp;
		p->thread.regs = childregs;
		if (clone_flags & CLONE_SETTLS) {
			if (test_thread_flag(TIF_32BIT))
				childregs->gpr[2] = childregs->gpr[6];
			else
				childregs->gpr[13] = childregs->gpr[6];
		}
	}
	childregs->gpr[3] = 0;  /* Result from fork() */
	sp -= STACK_FRAME_OVERHEAD;

	/*
	 * The way this works is that at some point in the future
	 * some task will call _switch to switch to the new task.
	 * That will pop off the stack frame created below and start
	 * the new task running at ret_from_fork.  The new task will
	 * do some house keeping and then return from the fork or clone
	 * system call, using the stack frame created above.
	 */
	sp -= sizeof(struct pt_regs);
	kregs = (struct pt_regs *) sp;
	sp -= STACK_FRAME_OVERHEAD;
	p->thread.ksp = sp;

	/*
	 * The PPC64 ABI makes use of a TOC to contain function 
	 * pointers.  The function (ret_from_except) is actually a pointer
	 * to the TOC entry.  The first entry is a pointer to the actual
	 * function.
 	 */
	kregs->nip = *((unsigned long *)ret_from_fork);

	return 0;
}

/*
 * Set up a thread for executing a new program
 */
void start_thread(struct pt_regs *regs, unsigned long fdptr, unsigned long sp)
{
	unsigned long entry, toc, load_addr = regs->gpr[2];

	/* fdptr is a relocated pointer to the function descriptor for
         * the elf _start routine.  The first entry in the function
         * descriptor is the entry address of _start and the second
         * entry is the TOC value we need to use.
         */
	set_fs(USER_DS);
	__get_user(entry, (unsigned long __user *)fdptr);
	__get_user(toc, (unsigned long __user *)fdptr+1);

	/* Check whether the e_entry function descriptor entries
	 * need to be relocated before we can use them.
	 */
	if ( load_addr != 0 ) {
		entry += load_addr;
		toc   += load_addr;
	}

	regs->nip = entry;
	regs->gpr[1] = sp;
	regs->gpr[2] = toc;
	regs->msr = MSR_USER64;
#ifndef CONFIG_SMP
	if (last_task_used_math == current)
		last_task_used_math = 0;
#endif /* CONFIG_SMP */
	memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
	current->thread.fpscr = 0;
#ifdef CONFIG_ALTIVEC
#ifndef CONFIG_SMP
	if (last_task_used_altivec == current)
		last_task_used_altivec = 0;
#endif /* CONFIG_SMP */
	memset(current->thread.vr, 0, sizeof(current->thread.vr));
	current->thread.vscr.u[0] = 0;
	current->thread.vscr.u[1] = 0;
	current->thread.vscr.u[2] = 0;
	current->thread.vscr.u[3] = 0x00010000; /* Java mode disabled */
	current->thread.vrsave = 0;
	current->thread.used_vr = 0;
#endif /* CONFIG_ALTIVEC */
}

int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
{
	struct pt_regs *regs = tsk->thread.regs;

	if (val > PR_FP_EXC_PRECISE)
		return -EINVAL;
	tsk->thread.fpexc_mode = __pack_fe01(val);
	if (regs != NULL && (regs->msr & MSR_FP) != 0)
		regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
			| tsk->thread.fpexc_mode;
	return 0;
}

int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
{
	unsigned int val;

	val = __unpack_fe01(tsk->thread.fpexc_mode);
	return put_user(val, (unsigned int __user *) adr);
}

int sys_clone(unsigned long clone_flags, unsigned long p2, unsigned long p3,
	      unsigned long p4, unsigned long p5, unsigned long p6,
	      struct pt_regs *regs)
{
	unsigned long parent_tidptr = 0;
	unsigned long child_tidptr = 0;

	if (p2 == 0)
		p2 = regs->gpr[1];	/* stack pointer for child */

	if (clone_flags & (CLONE_PARENT_SETTID | CLONE_CHILD_SETTID |
			   CLONE_CHILD_CLEARTID)) {
		parent_tidptr = p3;
		child_tidptr = p5;
		if (test_thread_flag(TIF_32BIT)) {
			parent_tidptr &= 0xffffffff;
			child_tidptr &= 0xffffffff;
		}
	}

	return do_fork(clone_flags & ~CLONE_IDLETASK, p2, regs, 0,
		    (int __user *)parent_tidptr, (int __user *)child_tidptr);
}

int sys_fork(unsigned long p1, unsigned long p2, unsigned long p3,
	     unsigned long p4, unsigned long p5, unsigned long p6,
	     struct pt_regs *regs)
{
	return do_fork(SIGCHLD, regs->gpr[1], regs, 0, NULL, NULL);
}

int sys_vfork(unsigned long p1, unsigned long p2, unsigned long p3,
	      unsigned long p4, unsigned long p5, unsigned long p6,
	      struct pt_regs *regs)
{
	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->gpr[1], regs, 0,
	            NULL, NULL);
}

int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
	       unsigned long a3, unsigned long a4, unsigned long a5,
	       struct pt_regs *regs)
{
	int error;
	char * filename;
	
	filename = getname((char __user *) a0);
	error = PTR_ERR(filename);
	if (IS_ERR(filename))
		goto out;
	flush_fp_to_thread(current);
	flush_altivec_to_thread(current);
	error = do_execve(filename, (char __user * __user *) a1,
				    (char __user * __user *) a2, regs);
  
	if (error == 0)
		current->ptrace &= ~PT_DTRACE;
	putname(filename);

out:
	return error;
}

static int kstack_depth_to_print = 64;

static int validate_sp(unsigned long sp, struct task_struct *p,
		       unsigned long nbytes)
{
	unsigned long stack_page = (unsigned long)p->thread_info;

	if (sp >= stack_page + sizeof(struct thread_struct)
	    && sp <= stack_page + THREAD_SIZE - nbytes)
		return 1;

#ifdef CONFIG_IRQSTACKS
	stack_page = (unsigned long) hardirq_ctx[task_cpu(p)];
	if (sp >= stack_page + sizeof(struct thread_struct)
	    && sp <= stack_page + THREAD_SIZE - nbytes)
		return 1;

	stack_page = (unsigned long) softirq_ctx[task_cpu(p)];
	if (sp >= stack_page + sizeof(struct thread_struct)
	    && sp <= stack_page + THREAD_SIZE - nbytes)
		return 1;
#endif

	return 0;
}

unsigned long get_wchan(struct task_struct *p)
{
	unsigned long ip, sp;
	int count = 0;

	if (!p || p == current || p->state == TASK_RUNNING)
		return 0;

	sp = p->thread.ksp;
	if (!validate_sp(sp, p, 112))
		return 0;

	do {
		sp = *(unsigned long *)sp;
		if (!validate_sp(sp, p, 112))
			return 0;
		if (count > 0) {
			ip = *(unsigned long *)(sp + 16);
			if (!in_sched_functions(ip))
				return ip;
		}
	} while (count++ < 16);
	return 0;
}

void show_stack(struct task_struct *p, unsigned long *_sp)
{
	unsigned long ip, newsp, lr;
	int count = 0;
	unsigned long sp = (unsigned long)_sp;
	int firstframe = 1;

	if (sp == 0) {
		if (p) {
			sp = p->thread.ksp;
		} else {
			sp = __get_SP();
			p = current;
		}
	}

	lr = 0;
	printk("Call Trace:\n");
	do {
		if (!validate_sp(sp, p, 112))
			return;

		_sp = (unsigned long *) sp;
		newsp = _sp[0];
		ip = _sp[2];
		if (!firstframe || ip != lr) {
			printk("[%016lx] [%016lx] ", sp, ip);
			print_symbol("%s", ip);
			if (firstframe)
				printk(" (unreliable)");
			printk("\n");
		}
		firstframe = 0;

		/*
		 * See if this is an exception frame.
		 * We look for the "regshere" marker in the current frame.
		 */
		if (validate_sp(sp, p, sizeof(struct pt_regs) + 400)
		    && _sp[12] == 0x7265677368657265ul) {
			struct pt_regs *regs = (struct pt_regs *)
				(sp + STACK_FRAME_OVERHEAD);
			printk("--- Exception: %lx", regs->trap);
			print_symbol(" at %s\n", regs->nip);
			lr = regs->link;
			print_symbol("    LR = %s\n", lr);
			firstframe = 1;
		}

		sp = newsp;
	} while (count++ < kstack_depth_to_print);
}

void dump_stack(void)
{
	show_stack(current, (unsigned long *)__get_SP());
}
EXPORT_SYMBOL(dump_stack);