process.c

优龙2410linux2.6.8内核源代码

void prepare_to_copy(struct task_struct *tsk)
{
	struct pt_regs *regs = tsk->thread.regs;

	if (regs == NULL)
		return;
	preempt_disable();
	if (regs->msr & MSR_FP)
		giveup_fpu(current);
#ifdef CONFIG_ALTIVEC
	if (regs->msr & MSR_VEC)
		giveup_altivec(current);
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
	if (regs->msr & MSR_SPE)
		giveup_spe(current);
#endif /* CONFIG_SPE */
	preempt_enable();
}

/*
 * 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;
	unsigned long childframe;

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

	CHECK_FULL_REGS(regs);
	/* Copy registers */
	sp -= sizeof(struct pt_regs);
	childregs = (struct pt_regs *) sp;
	*childregs = *regs;
	if ((childregs->msr & MSR_PR) == 0) {
		/* for kernel thread, set `current' and stackptr in new task */
		childregs->gpr[1] = sp + sizeof(struct pt_regs);
		childregs->gpr[2] = (unsigned long) p;
		p->thread.regs = NULL;	/* no user register state */
	} else {
		childregs->gpr[1] = usp;
		p->thread.regs = childregs;
		if (clone_flags & CLONE_SETTLS)
			childregs->gpr[2] = childregs->gpr[6];
	}
	childregs->gpr[3] = 0;  /* Result from fork() */
	sp -= STACK_FRAME_OVERHEAD;
	childframe = sp;

	/*
	 * 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;
	kregs->nip = (unsigned long)ret_from_fork;

	p->thread.last_syscall = -1;

	return 0;
}

/*
 * Set up a thread for executing a new program
 */
void start_thread(struct pt_regs *regs, unsigned long nip, unsigned long sp)
{
	set_fs(USER_DS);
	memset(regs->gpr, 0, sizeof(regs->gpr));
	regs->ctr = 0;
	regs->link = 0;
	regs->xer = 0;
	regs->ccr = 0;
	regs->mq = 0;
	regs->nip = nip;
	regs->gpr[1] = sp;
	regs->msr = MSR_USER;
	if (last_task_used_math == current)
		last_task_used_math = NULL;
	if (last_task_used_altivec == current)
		last_task_used_altivec = NULL;
	memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
	current->thread.fpscr = 0;
#ifdef CONFIG_ALTIVEC
	memset(current->thread.vr, 0, sizeof(current->thread.vr));
	memset(&current->thread.vscr, 0, sizeof(current->thread.vscr));
	current->thread.vrsave = 0;
	current->thread.used_vr = 0;
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
	memset(current->thread.evr, 0, sizeof(current->thread.evr));
	current->thread.acc = 0;
	current->thread.spefscr = 0;
	current->thread.used_spe = 0;
#endif /* CONFIG_SPE */
}

#define PR_FP_ALL_EXCEPT (PR_FP_EXC_DIV | PR_FP_EXC_OVF | PR_FP_EXC_UND \
		| PR_FP_EXC_RES | PR_FP_EXC_INV)

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

	/* This is a bit hairy.  If we are an SPE enabled  processor
	 * (have embedded fp) we store the IEEE exception enable flags in
	 * fpexc_mode.  fpexc_mode is also used for setting FP exception
	 * mode (asyn, precise, disabled) for 'Classic' FP. */
	if (val & PR_FP_EXC_SW_ENABLE) {
#ifdef CONFIG_SPE
		tsk->thread.fpexc_mode = val &
			(PR_FP_EXC_SW_ENABLE | PR_FP_ALL_EXCEPT);
#else
		return -EINVAL;
#endif
	} else {
		/* on a CONFIG_SPE this does not hurt us.  The bits that
		 * __pack_fe01 use do not overlap with bits used for
		 * PR_FP_EXC_SW_ENABLE.  Additionally, the MSR[FE0,FE1] bits
		 * on CONFIG_SPE implementations are reserved so writing to
		 * them does not change anything */
		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;

	if (tsk->thread.fpexc_mode & PR_FP_EXC_SW_ENABLE)
#ifdef CONFIG_SPE
		val = tsk->thread.fpexc_mode;
#else
		return -EINVAL;
#endif
	else
		val = __unpack_fe01(tsk->thread.fpexc_mode);
	return put_user(val, (unsigned int __user *) adr);
}

int sys_clone(unsigned long clone_flags, unsigned long usp,
	      int __user *parent_tidp, void __user *child_threadptr,
	      int __user *child_tidp, int p6,
	      struct pt_regs *regs)
{
	CHECK_FULL_REGS(regs);
	if (usp == 0)
		usp = regs->gpr[1];	/* stack pointer for child */
 	return do_fork(clone_flags & ~CLONE_IDLETASK, usp, regs, 0,
			parent_tidp, child_tidp);
}

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

int sys_vfork(int p1, int p2, int p3, int p4, int p5, int p6,
	      struct pt_regs *regs)
{
	CHECK_FULL_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;
	preempt_disable();
	if (regs->msr & MSR_FP)
		giveup_fpu(current);
#ifdef CONFIG_ALTIVEC
	if (regs->msr & MSR_VEC)
		giveup_altivec(current);
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
	if (regs->msr & MSR_SPE)
		giveup_spe(current);
#endif /* CONFIG_SPE */
	preempt_enable();
	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;
}

void dump_stack(void)
{
	show_stack(current, NULL);
}

EXPORT_SYMBOL(dump_stack);

void show_stack(struct task_struct *tsk, unsigned long *stack)
{
	unsigned long sp, stack_top, prev_sp, ret;
	int count = 0;
	unsigned long next_exc = 0;
	struct pt_regs *regs;
	extern char ret_from_except, ret_from_except_full, ret_from_syscall;

	sp = (unsigned long) stack;
	if (tsk == NULL)
		tsk = current;
	if (sp == 0) {
		if (tsk == current)
			asm("mr %0,1" : "=r" (sp));
		else
			sp = tsk->thread.ksp;
	}

	prev_sp = (unsigned long) (tsk->thread_info + 1);
	stack_top = (unsigned long) tsk->thread_info + THREAD_SIZE;
	while (count < 16 && sp > prev_sp && sp < stack_top && (sp & 3) == 0) {
		if (count == 0) {
			printk("Call trace:");
#ifdef CONFIG_KALLSYMS
			printk("\n");
#endif
		} else {
			if (next_exc) {
				ret = next_exc;
				next_exc = 0;
			} else
				ret = *(unsigned long *)(sp + 4);
			printk(" [%08lx] ", ret);
#ifdef CONFIG_KALLSYMS
			print_symbol("%s", ret);
			printk("\n");
#endif
			if (ret == (unsigned long) &ret_from_except
			    || ret == (unsigned long) &ret_from_except_full
			    || ret == (unsigned long) &ret_from_syscall) {
				/* sp + 16 points to an exception frame */
				regs = (struct pt_regs *) (sp + 16);
				if (sp + 16 + sizeof(*regs) <= stack_top)
					next_exc = regs->nip;
			}
		}
		++count;
		sp = *(unsigned long *)sp;
	}
#if !CONFIG_KALLSYMS
	if (count > 0)
		printk("\n");
#endif
}

#if 0
/*
 * Low level print for debugging - Cort
 */
int __init ll_printk(const char *fmt, ...)
{
        va_list args;
	char buf[256];
        int i;

        va_start(args, fmt);
        i=vsprintf(buf,fmt,args);
	ll_puts(buf);
        va_end(args);
        return i;
}

int lines = 24, cols = 80;
int orig_x = 0, orig_y = 0;

void puthex(unsigned long val)
{
	unsigned char buf[10];
	int i;
	for (i = 7;  i >= 0;  i--)
	{
		buf[i] = "0123456789ABCDEF"[val & 0x0F];
		val >>= 4;
	}
	buf[8] = '\0';
	prom_print(buf);
}

void __init ll_puts(const char *s)
{
	int x,y;
	char *vidmem = (char *)/*(_ISA_MEM_BASE + 0xB8000) */0xD00B8000;
	char c;
	extern int mem_init_done;

	if ( mem_init_done ) /* assume this means we can printk */
	{
		printk(s);
		return;
	}

#if 0
	if ( have_of )
	{
		prom_print(s);
		return;
	}
#endif

	/*
	 * can't ll_puts on chrp without openfirmware yet.
	 * vidmem just needs to be setup for it.
	 * -- Cort
	 */
	if ( _machine != _MACH_prep )
		return;
	x = orig_x;
	y = orig_y;

	while ( ( c = *s++ ) != '\0' ) {
		if ( c == '\n' ) {
			x = 0;
			if ( ++y >= lines ) {
				/*scroll();*/
				/*y--;*/
				y = 0;
			}
		} else {
			vidmem [ ( x + cols * y ) * 2 ] = c;
			if ( ++x >= cols ) {
				x = 0;
				if ( ++y >= lines ) {
					/*scroll();*/
					/*y--;*/
					y = 0;
				}
			}
		}
	}

	orig_x = x;
	orig_y = y;
}
#endif

unsigned long get_wchan(struct task_struct *p)
{
	unsigned long ip, sp;
	unsigned long stack_page = (unsigned long) p->thread_info;
	int count = 0;
	if (!p || p == current || p->state == TASK_RUNNING)
		return 0;
	sp = p->thread.ksp;
	do {
		sp = *(unsigned long *)sp;
		if (sp < stack_page || sp >= stack_page + 8188)
			return 0;
		if (count > 0) {
			ip = *(unsigned long *)(sp + 4);
			if (!in_sched_functions(ip))
				return ip;
		}
	} while (count++ < 16);
	return 0;
}