[deliverable/linux.git] / arch / s390 / kernel / process.c

/*
 *  arch/s390/kernel/process.c
 *
 *  S390 version
 *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
 *               Hartmut Penner (hp@de.ibm.com),
 *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
 *
 *  Derived from "arch/i386/kernel/process.c"
 *    Copyright (C) 1995, Linus Torvalds
 */

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

#include <linux/compiler.h>
#include <linux/cpu.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/user.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/utsname.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/irq.h>
#include <asm/timer.h>
#include <asm/cpu.h>

asmlinkage void ret_from_fork(void) asm ("ret_from_fork");

/*
 * Return saved PC of a blocked thread. used in kernel/sched.
 * resume in entry.S does not create a new stack frame, it
 * just stores the registers %r6-%r15 to the frame given by
 * schedule. We want to return the address of the caller of
 * schedule, so we have to walk the backchain one time to
 * find the frame schedule() store its return address.
 */
unsigned long thread_saved_pc(struct task_struct *tsk)
{
	struct stack_frame *sf, *low, *high;

	if (!tsk || !task_stack_page(tsk))
		return 0;
	low = task_stack_page(tsk);
	high = (struct stack_frame *) task_pt_regs(tsk);
	sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
	if (sf <= low || sf > high)
		return 0;
	sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
	if (sf <= low || sf > high)
		return 0;
	return sf->gprs[8];
}

/*
 * Need to know about CPUs going idle?
 */
static ATOMIC_NOTIFIER_HEAD(idle_chain);

int register_idle_notifier(struct notifier_block *nb)
{
	return atomic_notifier_chain_register(&idle_chain, nb);
}
EXPORT_SYMBOL(register_idle_notifier);

int unregister_idle_notifier(struct notifier_block *nb)
{
	return atomic_notifier_chain_unregister(&idle_chain, nb);
}
EXPORT_SYMBOL(unregister_idle_notifier);

void do_monitor_call(struct pt_regs *regs, long interruption_code)
{
#ifdef CONFIG_SMP
	struct s390_idle_data *idle;

	idle = &__get_cpu_var(s390_idle);
	spin_lock(&idle->lock);
	idle->idle_time += get_clock() - idle->idle_enter;
	idle->in_idle = 0;
	spin_unlock(&idle->lock);
#endif
	/* disable monitor call class 0 */
	__ctl_clear_bit(8, 15);

	atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
				   (void *)(long) smp_processor_id());
}

extern void s390_handle_mcck(void);
/*
 * The idle loop on a S390...
 */
static void default_idle(void)
{
	int cpu, rc;
	int nr_calls = 0;
	void *hcpu;
#ifdef CONFIG_SMP
	struct s390_idle_data *idle;
#endif

	/* CPU is going idle. */
	cpu = smp_processor_id();
	hcpu = (void *)(long)cpu;
	local_irq_disable();
	if (need_resched()) {
		local_irq_enable();
		return;
	}

	rc = __atomic_notifier_call_chain(&idle_chain, S390_CPU_IDLE, hcpu, -1,
					  &nr_calls);
	if (rc == NOTIFY_BAD) {
		nr_calls--;
		__atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
					     hcpu, nr_calls, NULL);
		local_irq_enable();
		return;
	}

	/* enable monitor call class 0 */
	__ctl_set_bit(8, 15);

#ifdef CONFIG_HOTPLUG_CPU
	if (cpu_is_offline(cpu)) {
		preempt_enable_no_resched();
		cpu_die();
	}
#endif

	local_mcck_disable();
	if (test_thread_flag(TIF_MCCK_PENDING)) {
		local_mcck_enable();
		/* disable monitor call class 0 */
		__ctl_clear_bit(8, 15);
		atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
					   hcpu);
		local_irq_enable();
		s390_handle_mcck();
		return;
	}
#ifdef CONFIG_SMP
	idle = &__get_cpu_var(s390_idle);
	spin_lock(&idle->lock);
	idle->idle_count++;
	idle->in_idle = 1;
	idle->idle_enter = get_clock();
	spin_unlock(&idle->lock);
#endif
	trace_hardirqs_on();
	/* Wait for external, I/O or machine check interrupt. */
	__load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
			PSW_MASK_IO | PSW_MASK_EXT);
}

void cpu_idle(void)
{
	for (;;) {
		while (!need_resched())
			default_idle();

		preempt_enable_no_resched();
		schedule();
		preempt_disable();
	}
}

void show_regs(struct pt_regs *regs)
{
	print_modules();
	printk("CPU: %d %s %s %.*s\n",
	       task_thread_info(current)->cpu, print_tainted(),
	       init_utsname()->release,
	       (int)strcspn(init_utsname()->version, " "),
	       init_utsname()->version);
	printk("Process %s (pid: %d, task: %p, ksp: %p)\n",
	       current->comm, current->pid, current,
	       (void *) current->thread.ksp);
	show_registers(regs);
	/* Show stack backtrace if pt_regs is from kernel mode */
	if (!(regs->psw.mask & PSW_MASK_PSTATE))
		show_trace(NULL, (unsigned long *) regs->gprs[15]);
}

extern void kernel_thread_starter(void);

asm(
	".align 4\n"
	"kernel_thread_starter:\n"
	"    la    2,0(10)\n"
	"    basr  14,9\n"
	"    la    2,0\n"
	"    br    11\n");

int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
	struct pt_regs regs;

	memset(&regs, 0, sizeof(regs));
	regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
	regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
	regs.gprs[9] = (unsigned long) fn;
	regs.gprs[10] = (unsigned long) arg;
	regs.gprs[11] = (unsigned long) do_exit;
	regs.orig_gpr2 = -1;

	/* Ok, create the new process.. */
	return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
		       0, &regs, 0, NULL, NULL);
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
}

void flush_thread(void)
{
	clear_used_math();
	clear_tsk_thread_flag(current, TIF_USEDFPU);
}

void release_thread(struct task_struct *dead_task)
{
}

int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp,
	unsigned long unused,
        struct task_struct * p, struct pt_regs * regs)
{
        struct fake_frame
          {
	    struct stack_frame sf;
            struct pt_regs childregs;
          } *frame;

        frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
        p->thread.ksp = (unsigned long) frame;
	/* Store access registers to kernel stack of new process. */
        frame->childregs = *regs;
	frame->childregs.gprs[2] = 0;	/* child returns 0 on fork. */
        frame->childregs.gprs[15] = new_stackp;
        frame->sf.back_chain = 0;

        /* new return point is ret_from_fork */
        frame->sf.gprs[8] = (unsigned long) ret_from_fork;

        /* fake return stack for resume(), don't go back to schedule */
        frame->sf.gprs[9] = (unsigned long) frame;

	/* Save access registers to new thread structure. */
	save_access_regs(&p->thread.acrs[0]);

#ifndef CONFIG_64BIT
        /*
	 * save fprs to current->thread.fp_regs to merge them with
	 * the emulated registers and then copy the result to the child.
	 */
	save_fp_regs(&current->thread.fp_regs);
	memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
	       sizeof(s390_fp_regs));
	/* Set a new TLS ?  */
	if (clone_flags & CLONE_SETTLS)
		p->thread.acrs[0] = regs->gprs[6];
#else /* CONFIG_64BIT */
	/* Save the fpu registers to new thread structure. */
	save_fp_regs(&p->thread.fp_regs);
	/* Set a new TLS ?  */
	if (clone_flags & CLONE_SETTLS) {
		if (test_thread_flag(TIF_31BIT)) {
			p->thread.acrs[0] = (unsigned int) regs->gprs[6];
		} else {
			p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
			p->thread.acrs[1] = (unsigned int) regs->gprs[6];
		}
	}
#endif /* CONFIG_64BIT */
	/* start new process with ar4 pointing to the correct address space */
	p->thread.mm_segment = get_fs();
        /* Don't copy debug registers */
        memset(&p->thread.per_info,0,sizeof(p->thread.per_info));

        return 0;
}

asmlinkage long sys_fork(void)
{
	struct pt_regs *regs = task_pt_regs(current);
	return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
}

asmlinkage long sys_clone(void)
{
	struct pt_regs *regs = task_pt_regs(current);
	unsigned long clone_flags;
	unsigned long newsp;
	int __user *parent_tidptr, *child_tidptr;

	clone_flags = regs->gprs[3];
	newsp = regs->orig_gpr2;
	parent_tidptr = (int __user *) regs->gprs[4];
	child_tidptr = (int __user *) regs->gprs[5];
	if (!newsp)
		newsp = regs->gprs[15];
	return do_fork(clone_flags, newsp, regs, 0,
		       parent_tidptr, child_tidptr);
}

/*
 * This is trivial, and on the face of it looks like it
 * could equally well be done in user mode.
 *
 * Not so, for quite unobvious reasons - register pressure.
 * In user mode vfork() cannot have a stack frame, and if
 * done by calling the "clone()" system call directly, you
 * do not have enough call-clobbered registers to hold all
 * the information you need.
 */
asmlinkage long sys_vfork(void)
{
	struct pt_regs *regs = task_pt_regs(current);
	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
		       regs->gprs[15], regs, 0, NULL, NULL);
}

asmlinkage void execve_tail(void)
{
	task_lock(current);
	current->ptrace &= ~PT_DTRACE;
	task_unlock(current);
	current->thread.fp_regs.fpc = 0;
	if (MACHINE_HAS_IEEE)
		asm volatile("sfpc %0,%0" : : "d" (0));
}

/*
 * sys_execve() executes a new program.
 */
asmlinkage long sys_execve(void)
{
	struct pt_regs *regs = task_pt_regs(current);
	char *filename;
	unsigned long result;
	int rc;

	filename = getname((char __user *) regs->orig_gpr2);
	if (IS_ERR(filename)) {
		result = PTR_ERR(filename);
		goto out;
	}
	rc = do_execve(filename, (char __user * __user *) regs->gprs[3],
		       (char __user * __user *) regs->gprs[4], regs);
	if (rc) {
		result = rc;
		goto out_putname;
	}
	execve_tail();
	result = regs->gprs[2];
out_putname:
	putname(filename);
out:
	return result;
}

/*
 * fill in the FPU structure for a core dump.
 */
int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
{
#ifndef CONFIG_64BIT
        /*
	 * save fprs to current->thread.fp_regs to merge them with
	 * the emulated registers and then copy the result to the dump.
	 */
	save_fp_regs(&current->thread.fp_regs);
	memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
#else /* CONFIG_64BIT */
	save_fp_regs(fpregs);
#endif /* CONFIG_64BIT */
	return 1;
}

unsigned long get_wchan(struct task_struct *p)
{
	struct stack_frame *sf, *low, *high;
	unsigned long return_address;
	int count;

	if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
		return 0;
	low = task_stack_page(p);
	high = (struct stack_frame *) task_pt_regs(p);
	sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
	if (sf <= low || sf > high)
		return 0;
	for (count = 0; count < 16; count++) {
		sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
		if (sf <= low || sf > high)
			return 0;
		return_address = sf->gprs[8] & PSW_ADDR_INSN;
		if (!in_sched_functions(return_address))
			return return_address;
	}
	return 0;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* arch/s390/kernel/process.c
	3	*
	4	* S390 version
	5	* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
	6	* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
	7	* Hartmut Penner (hp@de.ibm.com),
	8	* Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
	9	*
	10	* Derived from "arch/i386/kernel/process.c"
	11	* Copyright (C) 1995, Linus Torvalds
	12	*/
	13
	14	/*
	15	* This file handles the architecture-dependent parts of process handling..
	16	*/
	17
1da177e4 LT	18	#include <linux/compiler.h>
	19	#include <linux/cpu.h>
	20	#include <linux/errno.h>
	21	#include <linux/sched.h>
	22	#include <linux/kernel.h>
	23	#include <linux/mm.h>
4e950f6f	24	#include <linux/fs.h>
1da177e4	25	#include <linux/smp.h>
1da177e4 LT	26	#include <linux/stddef.h>
	27	#include <linux/unistd.h>
	28	#include <linux/ptrace.h>
	29	#include <linux/slab.h>
	30	#include <linux/vmalloc.h>
	31	#include <linux/user.h>
1da177e4 LT	32	#include <linux/interrupt.h>
	33	#include <linux/delay.h>
	34	#include <linux/reboot.h>
	35	#include <linux/init.h>
	36	#include <linux/module.h>
	37	#include <linux/notifier.h>
5c699714	38	#include <linux/utsname.h>
1da177e4 LT	39	#include <asm/uaccess.h>
	40	#include <asm/pgtable.h>
	41	#include <asm/system.h>
	42	#include <asm/io.h>
	43	#include <asm/processor.h>
	44	#include <asm/irq.h>
	45	#include <asm/timer.h>
fae8b22d	46	#include <asm/cpu.h>
1da177e4	47
94c12cc7	48	asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
1da177e4 LT	49
	50	/*
	51	* Return saved PC of a blocked thread. used in kernel/sched.
	52	* resume in entry.S does not create a new stack frame, it
	53	* just stores the registers %r6-%r15 to the frame given by
	54	* schedule. We want to return the address of the caller of
	55	* schedule, so we have to walk the backchain one time to
	56	* find the frame schedule() store its return address.
	57	*/
	58	unsigned long thread_saved_pc(struct task_struct *tsk)
	59	{
eb33c190	60	struct stack_frame sf, low, *high;
1da177e4	61
eb33c190 HC	62	if (!tsk \|\| !task_stack_page(tsk))
	63	return 0;
	64	low = task_stack_page(tsk);
	65	high = (struct stack_frame *) task_pt_regs(tsk);
	66	sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
	67	if (sf <= low \|\| sf > high)
	68	return 0;
	69	sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
	70	if (sf <= low \|\| sf > high)
	71	return 0;
1da177e4 LT	72	return sf->gprs[8];
	73	}
	74
	75	/*
	76	* Need to know about CPUs going idle?
	77	*/
e041c683	78	static ATOMIC_NOTIFIER_HEAD(idle_chain);
1da177e4 LT	79
	80	int register_idle_notifier(struct notifier_block *nb)
	81	{
e041c683	82	return atomic_notifier_chain_register(&idle_chain, nb);
1da177e4 LT	83	}
	84	EXPORT_SYMBOL(register_idle_notifier);
	85
	86	int unregister_idle_notifier(struct notifier_block *nb)
	87	{
e041c683	88	return atomic_notifier_chain_unregister(&idle_chain, nb);
1da177e4 LT	89	}
	90	EXPORT_SYMBOL(unregister_idle_notifier);
	91
	92	void do_monitor_call(struct pt_regs *regs, long interruption_code)
	93	{
0d2be088	94	#ifdef CONFIG_SMP
fae8b22d HC	95	struct s390_idle_data *idle;
	96
	97	idle = &__get_cpu_var(s390_idle);
	98	spin_lock(&idle->lock);
	99	idle->idle_time += get_clock() - idle->idle_enter;
	100	idle->in_idle = 0;
	101	spin_unlock(&idle->lock);
0d2be088	102	#endif
1da177e4 LT	103	/* disable monitor call class 0 */
	104	__ctl_clear_bit(8, 15);
	105
dce55470 HC	106	atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
dce55470 HC	107	(void *)(long) smp_processor_id());
1da177e4 LT	108	}
1da177e4 LT	109
77fa2245	110	extern void s390_handle_mcck(void);
1da177e4 LT	111	/*
	112	* The idle loop on a S390...
	113	*/
cdb04527	114	static void default_idle(void)
1da177e4	115	{
1da177e4	116	int cpu, rc;
11ab244c HC	117	int nr_calls = 0;
11ab244c HC	118	void *hcpu;
0d2be088	119	#ifdef CONFIG_SMP
fae8b22d	120	struct s390_idle_data *idle;
0d2be088	121	#endif
1da177e4	122
64c7c8f8 NP	123	/* CPU is going idle. */
64c7c8f8 NP	124	cpu = smp_processor_id();
11ab244c	125	hcpu = (void *)(long)cpu;
1da177e4	126	local_irq_disable();
64c7c8f8	127	if (need_resched()) {
1da177e4	128	local_irq_enable();
64c7c8f8 NP	129	return;
64c7c8f8 NP	130	}
1da177e4	131
11ab244c HC	132	rc = __atomic_notifier_call_chain(&idle_chain, S390_CPU_IDLE, hcpu, -1,
	133	&nr_calls);
	134	if (rc == NOTIFY_BAD) {
	135	nr_calls--;
	136	__atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
	137	hcpu, nr_calls, NULL);
1da177e4 LT	138	local_irq_enable();
	139	return;
	140	}
	141
	142	/* enable monitor call class 0 */
	143	__ctl_set_bit(8, 15);
	144
	145	#ifdef CONFIG_HOTPLUG_CPU
1fca251f HC	146	if (cpu_is_offline(cpu)) {
1fca251f HC	147	preempt_enable_no_resched();
1da177e4	148	cpu_die();
1fca251f	149	}
1da177e4 LT	150	#endif
1da177e4 LT	151
77fa2245 HC	152	local_mcck_disable();
	153	if (test_thread_flag(TIF_MCCK_PENDING)) {
	154	local_mcck_enable();
5ccd0e43 HC	155	/* disable monitor call class 0 */
	156	__ctl_clear_bit(8, 15);
	157	atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
	158	hcpu);
77fa2245 HC	159	local_irq_enable();
	160	s390_handle_mcck();
	161	return;
	162	}
0d2be088	163	#ifdef CONFIG_SMP
fae8b22d HC	164	idle = &__get_cpu_var(s390_idle);
	165	spin_lock(&idle->lock);
	166	idle->idle_count++;
	167	idle->in_idle = 1;
	168	idle->idle_enter = get_clock();
	169	spin_unlock(&idle->lock);
0d2be088	170	#endif
1f194a4c	171	trace_hardirqs_on();
77fa2245	172	/* Wait for external, I/O or machine check interrupt. */
c1821c2e	173	__load_psw_mask(psw_kernel_bits \| PSW_MASK_WAIT \|
77fa2245	174	PSW_MASK_IO \| PSW_MASK_EXT);
1da177e4 LT	175	}
	176
	177	void cpu_idle(void)
	178	{
5bfb5d69 NP	179	for (;;) {
	180	while (!need_resched())
	181	default_idle();
	182
	183	preempt_enable_no_resched();
	184	schedule();
	185	preempt_disable();
	186	}
1da177e4 LT	187	}
	188
	189	void show_regs(struct pt_regs *regs)
	190	{
5c699714 HC	191	print_modules();
	192	printk("CPU: %d %s %s %.*s\n",
	193	task_thread_info(current)->cpu, print_tainted(),
	194	init_utsname()->release,
	195	(int)strcspn(init_utsname()->version, " "),
	196	init_utsname()->version);
	197	printk("Process %s (pid: %d, task: %p, ksp: %p)\n",
	198	current->comm, current->pid, current,
	199	(void *) current->thread.ksp);
1da177e4 LT	200	show_registers(regs);
	201	/* Show stack backtrace if pt_regs is from kernel mode */
	202	if (!(regs->psw.mask & PSW_MASK_PSTATE))
d2c993d8	203	show_trace(NULL, (unsigned long *) regs->gprs[15]);
1da177e4 LT	204	}
	205
	206	extern void kernel_thread_starter(void);
	207
94c12cc7 MS	208	asm(
94c12cc7 MS	209	".align 4\n"
1da177e4 LT	210	"kernel_thread_starter:\n"
	211	" la 2,0(10)\n"
	212	" basr 14,9\n"
	213	" la 2,0\n"
	214	" br 11\n");
	215
	216	int kernel_thread(int (fn)(void ), void * arg, unsigned long flags)
	217	{
	218	struct pt_regs regs;
	219
	220	memset(&regs, 0, sizeof(regs));
c1821c2e	221	regs.psw.mask = psw_kernel_bits \| PSW_MASK_IO \| PSW_MASK_EXT;
1da177e4 LT	222	regs.psw.addr = (unsigned long) kernel_thread_starter \| PSW_ADDR_AMODE;
	223	regs.gprs[9] = (unsigned long) fn;
	224	regs.gprs[10] = (unsigned long) arg;
	225	regs.gprs[11] = (unsigned long) do_exit;
	226	regs.orig_gpr2 = -1;
	227
	228	/* Ok, create the new process.. */
	229	return do_fork(flags \| CLONE_VM \| CLONE_UNTRACED,
	230	0, &regs, 0, NULL, NULL);
	231	}
	232
	233	/*
	234	* Free current thread data structures etc..
	235	*/
	236	void exit_thread(void)
	237	{
	238	}
	239
	240	void flush_thread(void)
	241	{
	242	clear_used_math();
	243	clear_tsk_thread_flag(current, TIF_USEDFPU);
	244	}
	245
	246	void release_thread(struct task_struct *dead_task)
	247	{
	248	}
	249
	250	int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp,
	251	unsigned long unused,
	252	struct task_struct * p, struct pt_regs * regs)
	253	{
	254	struct fake_frame
	255	{
	256	struct stack_frame sf;
	257	struct pt_regs childregs;
	258	} *frame;
	259
c7584fb6	260	frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
1da177e4 LT	261	p->thread.ksp = (unsigned long) frame;
	262	/* Store access registers to kernel stack of new process. */
	263	frame->childregs = *regs;
	264	frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */
	265	frame->childregs.gprs[15] = new_stackp;
	266	frame->sf.back_chain = 0;
	267
	268	/* new return point is ret_from_fork */
	269	frame->sf.gprs[8] = (unsigned long) ret_from_fork;
	270
	271	/* fake return stack for resume(), don't go back to schedule */
	272	frame->sf.gprs[9] = (unsigned long) frame;
	273
	274	/* Save access registers to new thread structure. */
	275	save_access_regs(&p->thread.acrs[0]);
	276
347a8dc3	277	#ifndef CONFIG_64BIT
1da177e4 LT	278	/*
	279	* save fprs to current->thread.fp_regs to merge them with
	280	* the emulated registers and then copy the result to the child.
	281	*/
	282	save_fp_regs(&current->thread.fp_regs);
	283	memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
	284	sizeof(s390_fp_regs));
1da177e4 LT	285	/* Set a new TLS ? */
	286	if (clone_flags & CLONE_SETTLS)
	287	p->thread.acrs[0] = regs->gprs[6];
347a8dc3	288	#else /* CONFIG_64BIT */
1da177e4 LT	289	/* Save the fpu registers to new thread structure. */
1da177e4 LT	290	save_fp_regs(&p->thread.fp_regs);
1da177e4 LT	291	/* Set a new TLS ? */
	292	if (clone_flags & CLONE_SETTLS) {
	293	if (test_thread_flag(TIF_31BIT)) {
	294	p->thread.acrs[0] = (unsigned int) regs->gprs[6];
	295	} else {
	296	p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
	297	p->thread.acrs[1] = (unsigned int) regs->gprs[6];
	298	}
	299	}
347a8dc3	300	#endif /* CONFIG_64BIT */
1da177e4 LT	301	/* start new process with ar4 pointing to the correct address space */
	302	p->thread.mm_segment = get_fs();
	303	/* Don't copy debug registers */
	304	memset(&p->thread.per_info,0,sizeof(p->thread.per_info));
	305
	306	return 0;
	307	}
	308
03ff9a23	309	asmlinkage long sys_fork(void)
1da177e4	310	{
03ff9a23 MS	311	struct pt_regs *regs = task_pt_regs(current);
03ff9a23 MS	312	return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
1da177e4 LT	313	}
1da177e4 LT	314
03ff9a23	315	asmlinkage long sys_clone(void)
1da177e4	316	{
03ff9a23 MS	317	struct pt_regs *regs = task_pt_regs(current);
	318	unsigned long clone_flags;
	319	unsigned long newsp;
1da177e4 LT	320	int __user parent_tidptr, child_tidptr;
1da177e4 LT	321
03ff9a23 MS	322	clone_flags = regs->gprs[3];
	323	newsp = regs->orig_gpr2;
	324	parent_tidptr = (int __user *) regs->gprs[4];
	325	child_tidptr = (int __user *) regs->gprs[5];
	326	if (!newsp)
	327	newsp = regs->gprs[15];
	328	return do_fork(clone_flags, newsp, regs, 0,
1da177e4 LT	329	parent_tidptr, child_tidptr);
	330	}
	331
	332	/*
	333	* This is trivial, and on the face of it looks like it
	334	* could equally well be done in user mode.
	335	*
	336	* Not so, for quite unobvious reasons - register pressure.
	337	* In user mode vfork() cannot have a stack frame, and if
	338	* done by calling the "clone()" system call directly, you
	339	* do not have enough call-clobbered registers to hold all
	340	* the information you need.
	341	*/
03ff9a23	342	asmlinkage long sys_vfork(void)
1da177e4	343	{
03ff9a23	344	struct pt_regs *regs = task_pt_regs(current);
1da177e4	345	return do_fork(CLONE_VFORK \| CLONE_VM \| SIGCHLD,
03ff9a23 MS	346	regs->gprs[15], regs, 0, NULL, NULL);
	347	}
	348
	349	asmlinkage void execve_tail(void)
	350	{
	351	task_lock(current);
	352	current->ptrace &= ~PT_DTRACE;
	353	task_unlock(current);
	354	current->thread.fp_regs.fpc = 0;
	355	if (MACHINE_HAS_IEEE)
	356	asm volatile("sfpc %0,%0" : : "d" (0));
1da177e4 LT	357	}
	358
	359	/*
	360	* sys_execve() executes a new program.
	361	*/
03ff9a23	362	asmlinkage long sys_execve(void)
1da177e4	363	{
03ff9a23 MS	364	struct pt_regs *regs = task_pt_regs(current);
	365	char *filename;
	366	unsigned long result;
	367	int rc;
	368
	369	filename = getname((char __user *) regs->orig_gpr2);
	370	if (IS_ERR(filename)) {
	371	result = PTR_ERR(filename);
	372	goto out;
1da177e4	373	}
03ff9a23 MS	374	rc = do_execve(filename, (char __user * __user *) regs->gprs[3],
	375	(char __user * __user *) regs->gprs[4], regs);
	376	if (rc) {
	377	result = rc;
	378	goto out_putname;
	379	}
	380	execve_tail();
	381	result = regs->gprs[2];
	382	out_putname:
	383	putname(filename);
1da177e4	384	out:
03ff9a23	385	return result;
1da177e4 LT	386	}
1da177e4 LT	387
1da177e4 LT	388	/*
	389	* fill in the FPU structure for a core dump.
	390	*/
	391	int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
	392	{
347a8dc3	393	#ifndef CONFIG_64BIT
1da177e4 LT	394	/*
	395	* save fprs to current->thread.fp_regs to merge them with
	396	* the emulated registers and then copy the result to the dump.
	397	*/
	398	save_fp_regs(&current->thread.fp_regs);
	399	memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
347a8dc3	400	#else /* CONFIG_64BIT */
1da177e4	401	save_fp_regs(fpregs);
347a8dc3	402	#endif /* CONFIG_64BIT */
1da177e4 LT	403	return 1;
	404	}
	405
1da177e4 LT	406	unsigned long get_wchan(struct task_struct *p)
	407	{
	408	struct stack_frame sf, low, *high;
	409	unsigned long return_address;
	410	int count;
	411
30af7120	412	if (!p \|\| p == current \|\| p->state == TASK_RUNNING \|\| !task_stack_page(p))
1da177e4	413	return 0;
30af7120 AV	414	low = task_stack_page(p);
30af7120 AV	415	high = (struct stack_frame *) task_pt_regs(p);
1da177e4 LT	416	sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
	417	if (sf <= low \|\| sf > high)
	418	return 0;
	419	for (count = 0; count < 16; count++) {
	420	sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
	421	if (sf <= low \|\| sf > high)
	422	return 0;
	423	return_address = sf->gprs[8] & PSW_ADDR_INSN;
	424	if (!in_sched_functions(return_address))
	425	return return_address;
	426	}
	427	return 0;
	428	}
	429