[deliverable/linux.git] / arch / m68k / kernel / process.c

/*
 *  linux/arch/m68k/kernel/process.c
 *
 *  Copyright (C) 1995  Hamish Macdonald
 *
 *  68060 fixes by Jesper Skov
 */

/*
 * This file handles the architecture-dependent parts of process handling..
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/reboot.h>
#include <linux/init_task.h>
#include <linux/mqueue.h>
#include <linux/rcupdate.h>

#include <asm/uaccess.h>
#include <asm/traps.h>
#include <asm/machdep.h>
#include <asm/setup.h>
#include <asm/pgtable.h>


asmlinkage void ret_from_fork(void);


/*
 * Return saved PC from a blocked thread
 */
unsigned long thread_saved_pc(struct task_struct *tsk)
{
	struct switch_stack *sw = (struct switch_stack *)tsk->thread.ksp;
	/* Check whether the thread is blocked in resume() */
	if (in_sched_functions(sw->retpc))
		return ((unsigned long *)sw->a6)[1];
	else
		return sw->retpc;
}

/*
 * The idle loop on an m68k..
 */
static void default_idle(void)
{
	if (!need_resched())
#if defined(MACH_ATARI_ONLY)
		/* block out HSYNC on the atari (falcon) */
		__asm__("stop #0x2200" : : : "cc");
#else
		__asm__("stop #0x2000" : : : "cc");
#endif
}

void (*idle)(void) = default_idle;

/*
 * The idle thread. There's no useful work to be
 * done, so just try to conserve power and have a
 * low exit latency (ie sit in a loop waiting for
 * somebody to say that they'd like to reschedule)
 */
void cpu_idle(void)
{
	/* endless idle loop with no priority at all */
	while (1) {
		rcu_idle_enter();
		while (!need_resched())
			idle();
		rcu_idle_exit();
		schedule_preempt_disabled();
	}
}

void machine_restart(char * __unused)
{
	if (mach_reset)
		mach_reset();
	for (;;);
}

void machine_halt(void)
{
	if (mach_halt)
		mach_halt();
	for (;;);
}

void machine_power_off(void)
{
	if (mach_power_off)
		mach_power_off();
	for (;;);
}

void (*pm_power_off)(void) = machine_power_off;
EXPORT_SYMBOL(pm_power_off);

void show_regs(struct pt_regs * regs)
{
	printk("\n");
	printk("Format %02x  Vector: %04x  PC: %08lx  Status: %04x    %s\n",
	       regs->format, regs->vector, regs->pc, regs->sr, print_tainted());
	printk("ORIG_D0: %08lx  D0: %08lx  A2: %08lx  A1: %08lx\n",
	       regs->orig_d0, regs->d0, regs->a2, regs->a1);
	printk("A0: %08lx  D5: %08lx  D4: %08lx\n",
	       regs->a0, regs->d5, regs->d4);
	printk("D3: %08lx  D2: %08lx  D1: %08lx\n",
	       regs->d3, regs->d2, regs->d1);
	if (!(regs->sr & PS_S))
		printk("USP: %08lx\n", rdusp());
}

/*
 * Create a kernel thread
 */
int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
	int pid;
	mm_segment_t fs;

	fs = get_fs();
	set_fs (KERNEL_DS);

	{
	register long retval __asm__ ("d0");
	register long clone_arg __asm__ ("d1") = flags | CLONE_VM | CLONE_UNTRACED;

	retval = __NR_clone;
	__asm__ __volatile__
	  ("clrl %%d2\n\t"
	   "trap #0\n\t"		/* Linux/m68k system call */
	   "tstl %0\n\t"		/* child or parent */
	   "jne 1f\n\t"			/* parent - jump */
#ifdef CONFIG_MMU
	   "lea %%sp@(%c7),%6\n\t"	/* reload current */
	   "movel %6@,%6\n\t"
#endif
	   "movel %3,%%sp@-\n\t"	/* push argument */
	   "jsr %4@\n\t"		/* call fn */
	   "movel %0,%%d1\n\t"		/* pass exit value */
	   "movel %2,%%d0\n\t"		/* exit */
	   "trap #0\n"
	   "1:"
	   : "+d" (retval)
	   : "i" (__NR_clone), "i" (__NR_exit),
	     "r" (arg), "a" (fn), "d" (clone_arg), "r" (current),
	     "i" (-THREAD_SIZE)
	   : "d2");

	pid = retval;
	}

	set_fs (fs);
	return pid;
}
EXPORT_SYMBOL(kernel_thread);

void flush_thread(void)
{
	current->thread.fs = __USER_DS;
#ifdef CONFIG_FPU
	if (!FPU_IS_EMU) {
		unsigned long zero = 0;
		asm volatile("frestore %0": :"m" (zero));
	}
#endif
}

/*
 * "m68k_fork()".. By the time we get here, the
 * non-volatile registers have also been saved on the
 * stack. We do some ugly pointer stuff here.. (see
 * also copy_thread)
 */

asmlinkage int m68k_fork(struct pt_regs *regs)
{
#ifdef CONFIG_MMU
	return do_fork(SIGCHLD, rdusp(), regs, 0, NULL, NULL);
#else
	return -EINVAL;
#endif
}

asmlinkage int m68k_vfork(struct pt_regs *regs)
{
	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), regs, 0,
		       NULL, NULL);
}

asmlinkage int m68k_clone(struct pt_regs *regs)
{
	unsigned long clone_flags;
	unsigned long newsp;
	int __user *parent_tidptr, *child_tidptr;

	/* syscall2 puts clone_flags in d1 and usp in d2 */
	clone_flags = regs->d1;
	newsp = regs->d2;
	parent_tidptr = (int __user *)regs->d3;
	child_tidptr = (int __user *)regs->d4;
	if (!newsp)
		newsp = rdusp();
	return do_fork(clone_flags, newsp, regs, 0,
		       parent_tidptr, child_tidptr);
}

int copy_thread(unsigned long clone_flags, unsigned long usp,
		 unsigned long unused,
		 struct task_struct * p, struct pt_regs * regs)
{
	struct pt_regs * childregs;
	struct switch_stack * childstack, *stack;
	unsigned long *retp;

	childregs = (struct pt_regs *) (task_stack_page(p) + THREAD_SIZE) - 1;

	*childregs = *regs;
	childregs->d0 = 0;

	retp = ((unsigned long *) regs);
	stack = ((struct switch_stack *) retp) - 1;

	childstack = ((struct switch_stack *) childregs) - 1;
	*childstack = *stack;
	childstack->retpc = (unsigned long)ret_from_fork;

	p->thread.usp = usp;
	p->thread.ksp = (unsigned long)childstack;

	if (clone_flags & CLONE_SETTLS)
		task_thread_info(p)->tp_value = regs->d5;

	/*
	 * Must save the current SFC/DFC value, NOT the value when
	 * the parent was last descheduled - RGH  10-08-96
	 */
	p->thread.fs = get_fs().seg;

#ifdef CONFIG_FPU
	if (!FPU_IS_EMU) {
		/* Copy the current fpu state */
		asm volatile ("fsave %0" : : "m" (p->thread.fpstate[0]) : "memory");

		if (!CPU_IS_060 ? p->thread.fpstate[0] : p->thread.fpstate[2]) {
			if (CPU_IS_COLDFIRE) {
				asm volatile ("fmovemd %/fp0-%/fp7,%0\n\t"
					      "fmovel %/fpiar,%1\n\t"
					      "fmovel %/fpcr,%2\n\t"
					      "fmovel %/fpsr,%3"
					      :
					      : "m" (p->thread.fp[0]),
						"m" (p->thread.fpcntl[0]),
						"m" (p->thread.fpcntl[1]),
						"m" (p->thread.fpcntl[2])
					      : "memory");
			} else {
				asm volatile ("fmovemx %/fp0-%/fp7,%0\n\t"
					      "fmoveml %/fpiar/%/fpcr/%/fpsr,%1"
					      :
					      : "m" (p->thread.fp[0]),
						"m" (p->thread.fpcntl[0])
					      : "memory");
			}
		}

		/* Restore the state in case the fpu was busy */
		asm volatile ("frestore %0" : : "m" (p->thread.fpstate[0]));
	}
#endif /* CONFIG_FPU */

	return 0;
}

/* Fill in the fpu structure for a core dump.  */
#ifdef CONFIG_FPU
int dump_fpu (struct pt_regs *regs, struct user_m68kfp_struct *fpu)
{
	char fpustate[216];

	if (FPU_IS_EMU) {
		int i;

		memcpy(fpu->fpcntl, current->thread.fpcntl, 12);
		memcpy(fpu->fpregs, current->thread.fp, 96);
		/* Convert internal fpu reg representation
		 * into long double format
		 */
		for (i = 0; i < 24; i += 3)
			fpu->fpregs[i] = ((fpu->fpregs[i] & 0xffff0000) << 15) |
			                 ((fpu->fpregs[i] & 0x0000ffff) << 16);
		return 1;
	}

	/* First dump the fpu context to avoid protocol violation.  */
	asm volatile ("fsave %0" :: "m" (fpustate[0]) : "memory");
	if (!CPU_IS_060 ? !fpustate[0] : !fpustate[2])
		return 0;

	if (CPU_IS_COLDFIRE) {
		asm volatile ("fmovel %/fpiar,%0\n\t"
			      "fmovel %/fpcr,%1\n\t"
			      "fmovel %/fpsr,%2\n\t"
			      "fmovemd %/fp0-%/fp7,%3"
			      :
			      : "m" (fpu->fpcntl[0]),
				"m" (fpu->fpcntl[1]),
				"m" (fpu->fpcntl[2]),
				"m" (fpu->fpregs[0])
			      : "memory");
	} else {
		asm volatile ("fmovem %/fpiar/%/fpcr/%/fpsr,%0"
			      :
			      : "m" (fpu->fpcntl[0])
			      : "memory");
		asm volatile ("fmovemx %/fp0-%/fp7,%0"
			      :
			      : "m" (fpu->fpregs[0])
			      : "memory");
	}

	return 1;
}
EXPORT_SYMBOL(dump_fpu);
#endif /* CONFIG_FPU */

/*
 * sys_execve() executes a new program.
 */
asmlinkage int sys_execve(const char __user *name,
			  const char __user *const __user *argv,
			  const char __user *const __user *envp)
{
	int error;
	char * filename;
	struct pt_regs *regs = (struct pt_regs *) &name;

	filename = getname(name);
	error = PTR_ERR(filename);
	if (IS_ERR(filename))
		return error;
	error = do_execve(filename, argv, envp, regs);
	putname(filename);
	return error;
}

unsigned long get_wchan(struct task_struct *p)
{
	unsigned long fp, pc;
	unsigned long stack_page;
	int count = 0;
	if (!p || p == current || p->state == TASK_RUNNING)
		return 0;

	stack_page = (unsigned long)task_stack_page(p);
	fp = ((struct switch_stack *)p->thread.ksp)->a6;
	do {
		if (fp < stack_page+sizeof(struct thread_info) ||
		    fp >= 8184+stack_page)
			return 0;
		pc = ((unsigned long *)fp)[1];
		if (!in_sched_functions(pc))
			return pc;
		fp = *(unsigned long *) fp;
	} while (count++ < 16);
	return 0;
}
Commit	Line	Data
fde39441 GU	1	/*
	2	* linux/arch/m68k/kernel/process.c
	3	*
	4	* Copyright (C) 1995 Hamish Macdonald
	5	*
	6	* 68060 fixes by Jesper Skov
	7	*/
	8
	9	/*
	10	* This file handles the architecture-dependent parts of process handling..
	11	*/
	12
	13	#include <linux/errno.h>
	14	#include <linux/module.h>
	15	#include <linux/sched.h>
	16	#include <linux/kernel.h>
	17	#include <linux/mm.h>
	18	#include <linux/slab.h>
	19	#include <linux/fs.h>
	20	#include <linux/smp.h>
	21	#include <linux/stddef.h>
	22	#include <linux/unistd.h>
	23	#include <linux/ptrace.h>
	24	#include <linux/user.h>
	25	#include <linux/reboot.h>
	26	#include <linux/init_task.h>
	27	#include <linux/mqueue.h>
5b57ba37	28	#include <linux/rcupdate.h>
fde39441 GU	29
fde39441 GU	30	#include <asm/uaccess.h>
fde39441 GU	31	#include <asm/traps.h>
	32	#include <asm/machdep.h>
	33	#include <asm/setup.h>
	34	#include <asm/pgtable.h>
	35
	36
	37	asmlinkage void ret_from_fork(void);
	38
	39
	40	/*
	41	* Return saved PC from a blocked thread
	42	*/
	43	unsigned long thread_saved_pc(struct task_struct *tsk)
	44	{
	45	struct switch_stack sw = (struct switch_stack )tsk->thread.ksp;
	46	/* Check whether the thread is blocked in resume() */
	47	if (in_sched_functions(sw->retpc))
	48	return ((unsigned long *)sw->a6)[1];
	49	else
	50	return sw->retpc;
	51	}
	52
	53	/*
	54	* The idle loop on an m68k..
	55	*/
	56	static void default_idle(void)
	57	{
	58	if (!need_resched())
	59	#if defined(MACH_ATARI_ONLY)
	60	/* block out HSYNC on the atari (falcon) */
	61	__asm__("stop #0x2200" : : : "cc");
	62	#else
	63	__asm__("stop #0x2000" : : : "cc");
	64	#endif
	65	}
	66
	67	void (*idle)(void) = default_idle;
	68
	69	/*
	70	* The idle thread. There's no useful work to be
	71	* done, so just try to conserve power and have a
	72	* low exit latency (ie sit in a loop waiting for
	73	* somebody to say that they'd like to reschedule)
	74	*/
	75	void cpu_idle(void)
	76	{
	77	/* endless idle loop with no priority at all */
	78	while (1) {
5b57ba37	79	rcu_idle_enter();
fde39441 GU	80	while (!need_resched())
fde39441 GU	81	idle();
5b57ba37	82	rcu_idle_exit();
b57cb723	83	schedule_preempt_disabled();
fde39441 GU	84	}
	85	}
	86
	87	void machine_restart(char * __unused)
	88	{
	89	if (mach_reset)
	90	mach_reset();
	91	for (;;);
	92	}
	93
	94	void machine_halt(void)
	95	{
	96	if (mach_halt)
	97	mach_halt();
	98	for (;;);
	99	}
	100
	101	void machine_power_off(void)
	102	{
	103	if (mach_power_off)
	104	mach_power_off();
	105	for (;;);
	106	}
	107
	108	void (*pm_power_off)(void) = machine_power_off;
	109	EXPORT_SYMBOL(pm_power_off);
	110
	111	void show_regs(struct pt_regs * regs)
	112	{
	113	printk("\n");
	114	printk("Format %02x Vector: %04x PC: %08lx Status: %04x %s\n",
	115	regs->format, regs->vector, regs->pc, regs->sr, print_tainted());
	116	printk("ORIG_D0: %08lx D0: %08lx A2: %08lx A1: %08lx\n",
	117	regs->orig_d0, regs->d0, regs->a2, regs->a1);
	118	printk("A0: %08lx D5: %08lx D4: %08lx\n",
	119	regs->a0, regs->d5, regs->d4);
	120	printk("D3: %08lx D2: %08lx D1: %08lx\n",
	121	regs->d3, regs->d2, regs->d1);
	122	if (!(regs->sr & PS_S))
	123	printk("USP: %08lx\n", rdusp());
	124	}
	125
	126	/*
	127	* Create a kernel thread
	128	*/
	129	int kernel_thread(int (fn)(void ), void * arg, unsigned long flags)
	130	{
	131	int pid;
	132	mm_segment_t fs;
	133
	134	fs = get_fs();
	135	set_fs (KERNEL_DS);
	136
	137	{
	138	register long retval __asm__ ("d0");
	139	register long clone_arg __asm__ ("d1") = flags \| CLONE_VM \| CLONE_UNTRACED;
	140
	141	retval = __NR_clone;
	142	__asm__ __volatile__
	143	("clrl %%d2\n\t"
	144	"trap #0\n\t" /* Linux/m68k system call */
	145	"tstl %0\n\t" /* child or parent */
	146	"jne 1f\n\t" /* parent - jump */
	147	#ifdef CONFIG_MMU
148	"lea %%sp@(%c7),%6\n\t" /* reload current */
149	"movel %6@,%6\n\t"
150	#endif
151	"movel %3,%%sp@-\n\t" /* push argument */
152	"jsr %4@\n\t" /* call fn */
153	"movel %0,%%d1\n\t" /* pass exit value */
154	"movel %2,%%d0\n\t" /* exit */
155	"trap #0\n"
156	"1:"
157	: "+d" (retval)
158	: "i" (__NR_clone), "i" (__NR_exit),
159	"r" (arg), "a" (fn), "d" (clone_arg), "r" (current),
160	"i" (-THREAD_SIZE)
161	: "d2");
162
163	pid = retval;
164	}
165
166	set_fs (fs);
167	return pid;
168	}
169	EXPORT_SYMBOL(kernel_thread);
170
171	void flush_thread(void)
172	{
173	current->thread.fs = __USER_DS;
174	#ifdef CONFIG_FPU
175	if (!FPU_IS_EMU) {
176	unsigned long zero = 0;
177	asm volatile("frestore %0": :"m" (zero));
178	}
179	#endif
180	}
181
182	/*
183	* "m68k_fork()".. By the time we get here, the
184	* non-volatile registers have also been saved on the
185	* stack. We do some ugly pointer stuff here.. (see
186	* also copy_thread)
187	*/
188
189	asmlinkage int m68k_fork(struct pt_regs *regs)
190	{
66d857b0	191	#ifdef CONFIG_MMU
fde39441	192	return do_fork(SIGCHLD, rdusp(), regs, 0, NULL, NULL);
1da177e4	193	#else
fde39441	194	return -EINVAL;
1da177e4	195	#endif
fde39441 GU	196	}
	197
	198	asmlinkage int m68k_vfork(struct pt_regs *regs)
	199	{
	200	return do_fork(CLONE_VFORK \| CLONE_VM \| SIGCHLD, rdusp(), regs, 0,
	201	NULL, NULL);
	202	}
	203
	204	asmlinkage int m68k_clone(struct pt_regs *regs)
	205	{
	206	unsigned long clone_flags;
	207	unsigned long newsp;
	208	int __user parent_tidptr, child_tidptr;
	209
	210	/* syscall2 puts clone_flags in d1 and usp in d2 */
	211	clone_flags = regs->d1;
	212	newsp = regs->d2;
	213	parent_tidptr = (int __user *)regs->d3;
	214	child_tidptr = (int __user *)regs->d4;
	215	if (!newsp)
	216	newsp = rdusp();
	217	return do_fork(clone_flags, newsp, regs, 0,
	218	parent_tidptr, child_tidptr);
	219	}
	220
	221	int copy_thread(unsigned long clone_flags, unsigned long usp,
	222	unsigned long unused,
	223	struct task_struct * p, struct pt_regs * regs)
	224	{
	225	struct pt_regs * childregs;
	226	struct switch_stack * childstack, *stack;
	227	unsigned long *retp;
	228
	229	childregs = (struct pt_regs *) (task_stack_page(p) + THREAD_SIZE) - 1;
	230
	231	childregs = regs;
	232	childregs->d0 = 0;
	233
	234	retp = ((unsigned long *) regs);
	235	stack = ((struct switch_stack *) retp) - 1;
	236
	237	childstack = ((struct switch_stack *) childregs) - 1;
	238	childstack = stack;
	239	childstack->retpc = (unsigned long)ret_from_fork;
	240
	241	p->thread.usp = usp;
	242	p->thread.ksp = (unsigned long)childstack;
	243
	244	if (clone_flags & CLONE_SETTLS)
	245	task_thread_info(p)->tp_value = regs->d5;
	246
	247	/*
	248	* Must save the current SFC/DFC value, NOT the value when
	249	* the parent was last descheduled - RGH 10-08-96
	250	*/
	251	p->thread.fs = get_fs().seg;
	252
	253	#ifdef CONFIG_FPU
	254	if (!FPU_IS_EMU) {
	255	/* Copy the current fpu state */
	256	asm volatile ("fsave %0" : : "m" (p->thread.fpstate[0]) : "memory");
	257
	258	if (!CPU_IS_060 ? p->thread.fpstate[0] : p->thread.fpstate[2]) {
	259	if (CPU_IS_COLDFIRE) {
260	asm volatile ("fmovemd %/fp0-%/fp7,%0\n\t"
261	"fmovel %/fpiar,%1\n\t"
262	"fmovel %/fpcr,%2\n\t"
263	"fmovel %/fpsr,%3"
264	:
265	: "m" (p->thread.fp[0]),
266	"m" (p->thread.fpcntl[0]),
267	"m" (p->thread.fpcntl[1]),
268	"m" (p->thread.fpcntl[2])
269	: "memory");
270	} else {
271	asm volatile ("fmovemx %/fp0-%/fp7,%0\n\t"
272	"fmoveml %/fpiar/%/fpcr/%/fpsr,%1"
273	:
274	: "m" (p->thread.fp[0]),
275	"m" (p->thread.fpcntl[0])
276	: "memory");
277	}
278	}
279
280	/* Restore the state in case the fpu was busy */
281	asm volatile ("frestore %0" : : "m" (p->thread.fpstate[0]));
282	}
283	#endif /* CONFIG_FPU */
284
285	return 0;
286	}
287
288	/* Fill in the fpu structure for a core dump. */
289	#ifdef CONFIG_FPU
290	int dump_fpu (struct pt_regs regs, struct user_m68kfp_struct fpu)
291	{
292	char fpustate[216];
293
294	if (FPU_IS_EMU) {
295	int i;
296
297	memcpy(fpu->fpcntl, current->thread.fpcntl, 12);
298	memcpy(fpu->fpregs, current->thread.fp, 96);
299	/* Convert internal fpu reg representation
300	* into long double format
301	*/
302	for (i = 0; i < 24; i += 3)
303	fpu->fpregs[i] = ((fpu->fpregs[i] & 0xffff0000) << 15) \|
304	((fpu->fpregs[i] & 0x0000ffff) << 16);
305	return 1;
306	}
307
308	/* First dump the fpu context to avoid protocol violation. */
309	asm volatile ("fsave %0" :: "m" (fpustate[0]) : "memory");
310	if (!CPU_IS_060 ? !fpustate[0] : !fpustate[2])
311	return 0;
312
313	if (CPU_IS_COLDFIRE) {
314	asm volatile ("fmovel %/fpiar,%0\n\t"
315	"fmovel %/fpcr,%1\n\t"
316	"fmovel %/fpsr,%2\n\t"
317	"fmovemd %/fp0-%/fp7,%3"
318	:
319	: "m" (fpu->fpcntl[0]),
320	"m" (fpu->fpcntl[1]),
321	"m" (fpu->fpcntl[2]),
322	"m" (fpu->fpregs[0])
323	: "memory");
324	} else {
325	asm volatile ("fmovem %/fpiar/%/fpcr/%/fpsr,%0"
326	:
327	: "m" (fpu->fpcntl[0])
328	: "memory");
329	asm volatile ("fmovemx %/fp0-%/fp7,%0"
330	:
331	: "m" (fpu->fpregs[0])
332	: "memory");
333	}
334
335	return 1;
336	}
337	EXPORT_SYMBOL(dump_fpu);
338	#endif /* CONFIG_FPU */
339
340	/*
341	* sys_execve() executes a new program.
342	*/
343	asmlinkage int sys_execve(const char __user *name,
344	const char __user const __user argv,
345	const char __user const __user envp)
346	{
347	int error;
348	char * filename;
349	struct pt_regs regs = (struct pt_regs ) &name;
350
351	filename = getname(name);
352	error = PTR_ERR(filename);
353	if (IS_ERR(filename))
354	return error;
355	error = do_execve(filename, argv, envp, regs);
356	putname(filename);
357	return error;
358	}
359
360	unsigned long get_wchan(struct task_struct *p)
361	{
362	unsigned long fp, pc;
363	unsigned long stack_page;
364	int count = 0;
365	if (!p \|\| p == current \|\| p->state == TASK_RUNNING)
366	return 0;
367
368	stack_page = (unsigned long)task_stack_page(p);
369	fp = ((struct switch_stack *)p->thread.ksp)->a6;
370	do {
371	if (fp < stack_page+sizeof(struct thread_info) \|\|
372	fp >= 8184+stack_page)
373	return 0;
374	pc = ((unsigned long *)fp)[1];
375	if (!in_sched_functions(pc))
376	return pc;
377	fp = (unsigned long ) fp;
378	} while (count++ < 16);
379	return 0;
380	}