[mirror_ubuntu-bionic-kernel.git] / arch / arm / kernel / process.c

/*
 *  linux/arch/arm/kernel/process.c
 *
 *  Copyright (C) 1996-2000 Russell King - Converted to ARM.
 *  Original Copyright (C) 1995  Linus Torvalds
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <stdarg.h>

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/interrupt.h>
#include <linux/kallsyms.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/elfcore.h>
#include <linux/pm.h>
#include <linux/tick.h>
#include <linux/utsname.h>
#include <linux/uaccess.h>

#include <asm/leds.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/thread_notify.h>
#include <asm/stacktrace.h>
#include <asm/mach/time.h>

static const char *processor_modes[] = {
  "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
  "UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
  "USER_32", "FIQ_32" , "IRQ_32" , "SVC_32" , "UK4_32" , "UK5_32" , "UK6_32" , "ABT_32" ,
  "UK8_32" , "UK9_32" , "UK10_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
};

static const char *isa_modes[] = {
  "ARM" , "Thumb" , "Jazelle", "ThumbEE"
};

extern void setup_mm_for_reboot(char mode);

static volatile int hlt_counter;

#include <mach/system.h>

void disable_hlt(void)
{
	hlt_counter++;
}

EXPORT_SYMBOL(disable_hlt);

void enable_hlt(void)
{
	hlt_counter--;
}

EXPORT_SYMBOL(enable_hlt);

static int __init nohlt_setup(char *__unused)
{
	hlt_counter = 1;
	return 1;
}

static int __init hlt_setup(char *__unused)
{
	hlt_counter = 0;
	return 1;
}

__setup("nohlt", nohlt_setup);
__setup("hlt", hlt_setup);

void arm_machine_restart(char mode, const char *cmd)
{
	/*
	 * Clean and disable cache, and turn off interrupts
	 */
	cpu_proc_fin();

	/*
	 * Tell the mm system that we are going to reboot -
	 * we may need it to insert some 1:1 mappings so that
	 * soft boot works.
	 */
	setup_mm_for_reboot(mode);

	/*
	 * Now call the architecture specific reboot code.
	 */
	arch_reset(mode, cmd);

	/*
	 * Whoops - the architecture was unable to reboot.
	 * Tell the user!
	 */
	mdelay(1000);
	printk("Reboot failed -- System halted\n");
	while (1);
}

/*
 * Function pointers to optional machine specific functions
 */
void (*pm_idle)(void);
EXPORT_SYMBOL(pm_idle);

void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);

void (*arm_pm_restart)(char str, const char *cmd) = arm_machine_restart;
EXPORT_SYMBOL_GPL(arm_pm_restart);


/*
 * This is our default idle handler.  We need to disable
 * interrupts here to ensure we don't miss a wakeup call.
 */
static void default_idle(void)
{
	if (hlt_counter)
		cpu_relax();
	else {
		local_irq_disable();
		if (!need_resched())
			arch_idle();
		local_irq_enable();
	}
}

/*
 * The idle thread.  We try to conserve power, while trying to keep
 * overall latency low.  The architecture specific idle is passed
 * a value to indicate the level of "idleness" of the system.
 */
void cpu_idle(void)
{
	local_fiq_enable();

	/* endless idle loop with no priority at all */
	while (1) {
		void (*idle)(void) = pm_idle;

#ifdef CONFIG_HOTPLUG_CPU
		if (cpu_is_offline(smp_processor_id())) {
			leds_event(led_idle_start);
			cpu_die();
		}
#endif

		if (!idle)
			idle = default_idle;
		leds_event(led_idle_start);
		tick_nohz_stop_sched_tick(1);
		while (!need_resched())
			idle();
		leds_event(led_idle_end);
		tick_nohz_restart_sched_tick();
		preempt_enable_no_resched();
		schedule();
		preempt_disable();
	}
}

static char reboot_mode = 'h';

int __init reboot_setup(char *str)
{
	reboot_mode = str[0];
	return 1;
}

__setup("reboot=", reboot_setup);

void machine_halt(void)
{
}


void machine_power_off(void)
{
	if (pm_power_off)
		pm_power_off();
}

void machine_restart(char *cmd)
{
	arm_pm_restart(reboot_mode, cmd);
}

void __show_regs(struct pt_regs *regs)
{
	unsigned long flags;
	char buf[64];

	printk("CPU: %d    %s  (%s %.*s)\n",
		smp_processor_id(), print_tainted(), init_utsname()->release,
		(int)strcspn(init_utsname()->version, " "),
		init_utsname()->version);
	print_symbol("PC is at %s\n", instruction_pointer(regs));
	print_symbol("LR is at %s\n", regs->ARM_lr);
	printk("pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n"
	       "sp : %08lx  ip : %08lx  fp : %08lx\n",
		regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr,
		regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
	printk("r10: %08lx  r9 : %08lx  r8 : %08lx\n",
		regs->ARM_r10, regs->ARM_r9,
		regs->ARM_r8);
	printk("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
		regs->ARM_r7, regs->ARM_r6,
		regs->ARM_r5, regs->ARM_r4);
	printk("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
		regs->ARM_r3, regs->ARM_r2,
		regs->ARM_r1, regs->ARM_r0);

	flags = regs->ARM_cpsr;
	buf[0] = flags & PSR_N_BIT ? 'N' : 'n';
	buf[1] = flags & PSR_Z_BIT ? 'Z' : 'z';
	buf[2] = flags & PSR_C_BIT ? 'C' : 'c';
	buf[3] = flags & PSR_V_BIT ? 'V' : 'v';
	buf[4] = '\0';

	printk("Flags: %s  IRQs o%s  FIQs o%s  Mode %s  ISA %s  Segment %s\n",
		buf, interrupts_enabled(regs) ? "n" : "ff",
		fast_interrupts_enabled(regs) ? "n" : "ff",
		processor_modes[processor_mode(regs)],
		isa_modes[isa_mode(regs)],
		get_fs() == get_ds() ? "kernel" : "user");
#ifdef CONFIG_CPU_CP15
	{
		unsigned int ctrl;

		buf[0] = '\0';
#ifdef CONFIG_CPU_CP15_MMU
		{
			unsigned int transbase, dac;
			asm("mrc p15, 0, %0, c2, c0\n\t"
			    "mrc p15, 0, %1, c3, c0\n"
			    : "=r" (transbase), "=r" (dac));
			snprintf(buf, sizeof(buf), "  Table: %08x  DAC: %08x",
			  	transbase, dac);
		}
#endif
		asm("mrc p15, 0, %0, c1, c0\n" : "=r" (ctrl));

		printk("Control: %08x%s\n", ctrl, buf);
	}
#endif
}

void show_regs(struct pt_regs * regs)
{
	printk("\n");
	printk("Pid: %d, comm: %20s\n", task_pid_nr(current), current->comm);
	__show_regs(regs);
	__backtrace();
}

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

ATOMIC_NOTIFIER_HEAD(thread_notify_head);

EXPORT_SYMBOL_GPL(thread_notify_head);

void flush_thread(void)
{
	struct thread_info *thread = current_thread_info();
	struct task_struct *tsk = current;

	memset(thread->used_cp, 0, sizeof(thread->used_cp));
	memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
	memset(&thread->fpstate, 0, sizeof(union fp_state));

	thread_notify(THREAD_NOTIFY_FLUSH, thread);
}

void release_thread(struct task_struct *dead_task)
{
	struct thread_info *thread = task_thread_info(dead_task);

	thread_notify(THREAD_NOTIFY_RELEASE, thread);
}

asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");

int
copy_thread(unsigned long clone_flags, unsigned long stack_start,
	    unsigned long stk_sz, struct task_struct *p, struct pt_regs *regs)
{
	struct thread_info *thread = task_thread_info(p);
	struct pt_regs *childregs = task_pt_regs(p);

	*childregs = *regs;
	childregs->ARM_r0 = 0;
	childregs->ARM_sp = stack_start;

	memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
	thread->cpu_context.sp = (unsigned long)childregs;
	thread->cpu_context.pc = (unsigned long)ret_from_fork;

	if (clone_flags & CLONE_SETTLS)
		thread->tp_value = regs->ARM_r3;

	return 0;
}

/*
 * fill in the fpe structure for a core dump...
 */
int dump_fpu (struct pt_regs *regs, struct user_fp *fp)
{
	struct thread_info *thread = current_thread_info();
	int used_math = thread->used_cp[1] | thread->used_cp[2];

	if (used_math)
		memcpy(fp, &thread->fpstate.soft, sizeof (*fp));

	return used_math != 0;
}
EXPORT_SYMBOL(dump_fpu);

/*
 * Shuffle the argument into the correct register before calling the
 * thread function.  r1 is the thread argument, r2 is the pointer to
 * the thread function, and r3 points to the exit function.
 */
extern void kernel_thread_helper(void);
asm(	".section .text\n"
"	.align\n"
"	.type	kernel_thread_helper, #function\n"
"kernel_thread_helper:\n"
"	mov	r0, r1\n"
"	mov	lr, r3\n"
"	mov	pc, r2\n"
"	.size	kernel_thread_helper, . - kernel_thread_helper\n"
"	.previous");

/*
 * Create a kernel thread.
 */
pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
	struct pt_regs regs;

	memset(&regs, 0, sizeof(regs));

	regs.ARM_r1 = (unsigned long)arg;
	regs.ARM_r2 = (unsigned long)fn;
	regs.ARM_r3 = (unsigned long)do_exit;
	regs.ARM_pc = (unsigned long)kernel_thread_helper;
	regs.ARM_cpsr = SVC_MODE;

	return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
}
EXPORT_SYMBOL(kernel_thread);

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

	frame.fp = thread_saved_fp(p);
	frame.sp = thread_saved_sp(p);
	frame.lr = 0;			/* recovered from the stack */
	frame.pc = thread_saved_pc(p);
	do {
		int ret = unwind_frame(&frame);
		if (ret < 0)
			return 0;
		if (!in_sched_functions(frame.pc))
			return frame.pc;
	} while (count ++ < 16);
	return 0;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/arch/arm/kernel/process.c
	3	*
	4	* Copyright (C) 1996-2000 Russell King - Converted to ARM.
	5	* Original Copyright (C) 1995 Linus Torvalds
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*/
	11	#include <stdarg.h>
	12
1da177e4 LT	13	#include <linux/module.h>
	14	#include <linux/sched.h>
	15	#include <linux/kernel.h>
	16	#include <linux/mm.h>
	17	#include <linux/stddef.h>
	18	#include <linux/unistd.h>
1da177e4 LT	19	#include <linux/slab.h>
1da177e4 LT	20	#include <linux/user.h>
1da177e4 LT	21	#include <linux/delay.h>
	22	#include <linux/reboot.h>
	23	#include <linux/interrupt.h>
	24	#include <linux/kallsyms.h>
	25	#include <linux/init.h>
a054a811	26	#include <linux/cpu.h>
84dff1a7	27	#include <linux/elfcore.h>
74617fb6	28	#include <linux/pm.h>
9e4559dd	29	#include <linux/tick.h>
154c772e	30	#include <linux/utsname.h>
33fa9b13	31	#include <linux/uaccess.h>
1da177e4	32
1da177e4 LT	33	#include <asm/leds.h>
1da177e4 LT	34	#include <asm/processor.h>
78ff18a4	35	#include <asm/system.h>
d6551e88	36	#include <asm/thread_notify.h>
2d7c11bf	37	#include <asm/stacktrace.h>
2ea83398	38	#include <asm/mach/time.h>
1da177e4	39
ae0a846e RK	40	static const char *processor_modes[] = {
	41	"USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
	42	"UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
	43	"USER_32", "FIQ_32" , "IRQ_32" , "SVC_32" , "UK4_32" , "UK5_32" , "UK6_32" , "ABT_32" ,
	44	"UK8_32" , "UK9_32" , "UK10_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
	45	};
	46
909d6c6c GD	47	static const char *isa_modes[] = {
	48	"ARM" , "Thumb" , "Jazelle", "ThumbEE"
	49	};
	50
1da177e4 LT	51	extern void setup_mm_for_reboot(char mode);
	52
	53	static volatile int hlt_counter;
	54
a09e64fb	55	#include <mach/system.h>
1da177e4 LT	56
	57	void disable_hlt(void)
	58	{
	59	hlt_counter++;
	60	}
	61
	62	EXPORT_SYMBOL(disable_hlt);
	63
	64	void enable_hlt(void)
	65	{
	66	hlt_counter--;
	67	}
	68
	69	EXPORT_SYMBOL(enable_hlt);
	70
	71	static int __init nohlt_setup(char *__unused)
	72	{
	73	hlt_counter = 1;
	74	return 1;
	75	}
	76
	77	static int __init hlt_setup(char *__unused)
	78	{
	79	hlt_counter = 0;
	80	return 1;
	81	}
	82
	83	__setup("nohlt", nohlt_setup);
	84	__setup("hlt", hlt_setup);
	85
be093beb	86	void arm_machine_restart(char mode, const char *cmd)
74617fb6 RP	87	{
	88	/*
	89	* Clean and disable cache, and turn off interrupts
	90	*/
	91	cpu_proc_fin();
	92
	93	/*
	94	* Tell the mm system that we are going to reboot -
	95	* we may need it to insert some 1:1 mappings so that
	96	* soft boot works.
	97	*/
	98	setup_mm_for_reboot(mode);
	99
	100	/*
	101	* Now call the architecture specific reboot code.
	102	*/
be093beb	103	arch_reset(mode, cmd);
74617fb6 RP	104
	105	/*
	106	* Whoops - the architecture was unable to reboot.
	107	* Tell the user!
	108	*/
	109	mdelay(1000);
	110	printk("Reboot failed -- System halted\n");
	111	while (1);
	112	}
	113
1da177e4	114	/*
74617fb6	115	* Function pointers to optional machine specific functions
1da177e4 LT	116	*/
	117	void (*pm_idle)(void);
	118	EXPORT_SYMBOL(pm_idle);
	119
	120	void (*pm_power_off)(void);
	121	EXPORT_SYMBOL(pm_power_off);
	122
be093beb	123	void (arm_pm_restart)(char str, const char cmd) = arm_machine_restart;
74617fb6 RP	124	EXPORT_SYMBOL_GPL(arm_pm_restart);
	125
	126
1da177e4 LT	127	/*
	128	* This is our default idle handler. We need to disable
	129	* interrupts here to ensure we don't miss a wakeup call.
	130	*/
84dff1a7	131	static void default_idle(void)
1da177e4	132	{
64c7c8f8 NP	133	if (hlt_counter)
	134	cpu_relax();
	135	else {
	136	local_irq_disable();
205bee6a	137	if (!need_resched())
64c7c8f8	138	arch_idle();
64c7c8f8	139	local_irq_enable();
2ea83398	140	}
1da177e4 LT	141	}
	142
	143	/*
	144	* The idle thread. We try to conserve power, while trying to keep
	145	* overall latency low. The architecture specific idle is passed
	146	* a value to indicate the level of "idleness" of the system.
	147	*/
	148	void cpu_idle(void)
	149	{
	150	local_fiq_enable();
	151
	152	/* endless idle loop with no priority at all */
	153	while (1) {
	154	void (*idle)(void) = pm_idle;
a054a811 RK	155
	156	#ifdef CONFIG_HOTPLUG_CPU
	157	if (cpu_is_offline(smp_processor_id())) {
	158	leds_event(led_idle_start);
	159	cpu_die();
	160	}
	161	#endif
	162
1da177e4 LT	163	if (!idle)
1da177e4 LT	164	idle = default_idle;
1da177e4	165	leds_event(led_idle_start);
b8f8c3cf	166	tick_nohz_stop_sched_tick(1);
1da177e4 LT	167	while (!need_resched())
	168	idle();
	169	leds_event(led_idle_end);
9e4559dd	170	tick_nohz_restart_sched_tick();
5bfb5d69	171	preempt_enable_no_resched();
1da177e4	172	schedule();
5bfb5d69	173	preempt_disable();
1da177e4 LT	174	}
	175	}
	176
	177	static char reboot_mode = 'h';
	178
	179	int __init reboot_setup(char *str)
	180	{
	181	reboot_mode = str[0];
	182	return 1;
	183	}
	184
	185	__setup("reboot=", reboot_setup);
	186
	187	void machine_halt(void)
	188	{
	189	}
	190
1da177e4 LT	191
	192	void machine_power_off(void)
	193	{
	194	if (pm_power_off)
	195	pm_power_off();
	196	}
	197
be093beb	198	void machine_restart(char *cmd)
1da177e4	199	{
be093beb	200	arm_pm_restart(reboot_mode, cmd);
1da177e4 LT	201	}
1da177e4 LT	202
652a12ef	203	void __show_regs(struct pt_regs *regs)
1da177e4	204	{
154c772e RK	205	unsigned long flags;
154c772e RK	206	char buf[64];
1da177e4	207
154c772e RK	208	printk("CPU: %d %s (%s %.*s)\n",
	209	smp_processor_id(), print_tainted(), init_utsname()->release,
	210	(int)strcspn(init_utsname()->version, " "),
	211	init_utsname()->version);
1da177e4 LT	212	print_symbol("PC is at %s\n", instruction_pointer(regs));
1da177e4 LT	213	print_symbol("LR is at %s\n", regs->ARM_lr);
154c772e	214	printk("pc : [<%08lx>] lr : [<%08lx>] psr: %08lx\n"
1da177e4	215	"sp : %08lx ip : %08lx fp : %08lx\n",
154c772e RK	216	regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr,
154c772e RK	217	regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
1da177e4 LT	218	printk("r10: %08lx r9 : %08lx r8 : %08lx\n",
	219	regs->ARM_r10, regs->ARM_r9,
	220	regs->ARM_r8);
	221	printk("r7 : %08lx r6 : %08lx r5 : %08lx r4 : %08lx\n",
	222	regs->ARM_r7, regs->ARM_r6,
	223	regs->ARM_r5, regs->ARM_r4);
	224	printk("r3 : %08lx r2 : %08lx r1 : %08lx r0 : %08lx\n",
	225	regs->ARM_r3, regs->ARM_r2,
	226	regs->ARM_r1, regs->ARM_r0);
154c772e RK	227
	228	flags = regs->ARM_cpsr;
	229	buf[0] = flags & PSR_N_BIT ? 'N' : 'n';
	230	buf[1] = flags & PSR_Z_BIT ? 'Z' : 'z';
	231	buf[2] = flags & PSR_C_BIT ? 'C' : 'c';
	232	buf[3] = flags & PSR_V_BIT ? 'V' : 'v';
	233	buf[4] = '\0';
	234
909d6c6c	235	printk("Flags: %s IRQs o%s FIQs o%s Mode %s ISA %s Segment %s\n",
154c772e	236	buf, interrupts_enabled(regs) ? "n" : "ff",
1da177e4 LT	237	fast_interrupts_enabled(regs) ? "n" : "ff",
1da177e4 LT	238	processor_modes[processor_mode(regs)],
909d6c6c	239	isa_modes[isa_mode(regs)],
1da177e4	240	get_fs() == get_ds() ? "kernel" : "user");
154c772e	241	#ifdef CONFIG_CPU_CP15
1da177e4	242	{
f12d0d7c	243	unsigned int ctrl;
154c772e RK	244
154c772e RK	245	buf[0] = '\0';
f12d0d7c	246	#ifdef CONFIG_CPU_CP15_MMU
154c772e RK	247	{
	248	unsigned int transbase, dac;
	249	asm("mrc p15, 0, %0, c2, c0\n\t"
	250	"mrc p15, 0, %1, c3, c0\n"
	251	: "=r" (transbase), "=r" (dac));
	252	snprintf(buf, sizeof(buf), " Table: %08x DAC: %08x",
	253	transbase, dac);
	254	}
f12d0d7c	255	#endif
154c772e RK	256	asm("mrc p15, 0, %0, c1, c0\n" : "=r" (ctrl));
	257
	258	printk("Control: %08x%s\n", ctrl, buf);
	259	}
f12d0d7c	260	#endif
1da177e4 LT	261	}
1da177e4 LT	262
652a12ef RK	263	void show_regs(struct pt_regs * regs)
	264	{
	265	printk("\n");
19c5870c	266	printk("Pid: %d, comm: %20s\n", task_pid_nr(current), current->comm);
652a12ef RK	267	__show_regs(regs);
	268	__backtrace();
	269	}
	270
1da177e4 LT	271	/*
	272	* Free current thread data structures etc..
	273	*/
	274	void exit_thread(void)
	275	{
	276	}
	277
d6551e88	278	ATOMIC_NOTIFIER_HEAD(thread_notify_head);
1da177e4	279
d6551e88	280	EXPORT_SYMBOL_GPL(thread_notify_head);
1da177e4 LT	281
	282	void flush_thread(void)
	283	{
	284	struct thread_info *thread = current_thread_info();
	285	struct task_struct *tsk = current;
	286
	287	memset(thread->used_cp, 0, sizeof(thread->used_cp));
	288	memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
d6551e88 RK	289	memset(&thread->fpstate, 0, sizeof(union fp_state));
	290
	291	thread_notify(THREAD_NOTIFY_FLUSH, thread);
1da177e4 LT	292	}
	293
	294	void release_thread(struct task_struct *dead_task)
	295	{
d6551e88 RK	296	struct thread_info *thread = task_thread_info(dead_task);
	297
	298	thread_notify(THREAD_NOTIFY_RELEASE, thread);
1da177e4 LT	299	}
	300
	301	asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
	302
	303	int
6f2c55b8	304	copy_thread(unsigned long clone_flags, unsigned long stack_start,
1da177e4 LT	305	unsigned long stk_sz, struct task_struct p, struct pt_regs regs)
1da177e4 LT	306	{
815d5ec8 AV	307	struct thread_info *thread = task_thread_info(p);
815d5ec8 AV	308	struct pt_regs *childregs = task_pt_regs(p);
1da177e4	309
1da177e4 LT	310	childregs = regs;
	311	childregs->ARM_r0 = 0;
	312	childregs->ARM_sp = stack_start;
	313
	314	memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
	315	thread->cpu_context.sp = (unsigned long)childregs;
	316	thread->cpu_context.pc = (unsigned long)ret_from_fork;
	317
	318	if (clone_flags & CLONE_SETTLS)
	319	thread->tp_value = regs->ARM_r3;
	320
	321	return 0;
	322	}
	323
	324	/*
	325	* fill in the fpe structure for a core dump...
	326	*/
	327	int dump_fpu (struct pt_regs regs, struct user_fp fp)
	328	{
	329	struct thread_info *thread = current_thread_info();
	330	int used_math = thread->used_cp[1] \| thread->used_cp[2];
	331
	332	if (used_math)
	333	memcpy(fp, &thread->fpstate.soft, sizeof (*fp));
	334
	335	return used_math != 0;
	336	}
	337	EXPORT_SYMBOL(dump_fpu);
	338
1da177e4 LT	339	/*
	340	* Shuffle the argument into the correct register before calling the
	341	* thread function. r1 is the thread argument, r2 is the pointer to
	342	* the thread function, and r3 points to the exit function.
	343	*/
	344	extern void kernel_thread_helper(void);
	345	asm( ".section .text\n"
	346	" .align\n"
	347	" .type kernel_thread_helper, #function\n"
	348	"kernel_thread_helper:\n"
	349	" mov r0, r1\n"
	350	" mov lr, r3\n"
	351	" mov pc, r2\n"
	352	" .size kernel_thread_helper, . - kernel_thread_helper\n"
	353	" .previous");
	354
	355	/*
	356	* Create a kernel thread.
	357	*/
	358	pid_t kernel_thread(int (fn)(void ), void *arg, unsigned long flags)
	359	{
	360	struct pt_regs regs;
	361
	362	memset(&regs, 0, sizeof(regs));
	363
	364	regs.ARM_r1 = (unsigned long)arg;
	365	regs.ARM_r2 = (unsigned long)fn;
	366	regs.ARM_r3 = (unsigned long)do_exit;
	367	regs.ARM_pc = (unsigned long)kernel_thread_helper;
	368	regs.ARM_cpsr = SVC_MODE;
	369
	370	return do_fork(flags\|CLONE_VM\|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
	371	}
	372	EXPORT_SYMBOL(kernel_thread);
	373
	374	unsigned long get_wchan(struct task_struct *p)
	375	{
2d7c11bf	376	struct stackframe frame;
1da177e4 LT	377	int count = 0;
	378	if (!p \|\| p == current \|\| p->state == TASK_RUNNING)
	379	return 0;
	380
2d7c11bf CM	381	frame.fp = thread_saved_fp(p);
	382	frame.sp = thread_saved_sp(p);
	383	frame.lr = 0; /* recovered from the stack */
	384	frame.pc = thread_saved_pc(p);
1da177e4	385	do {
2d7c11bf CM	386	int ret = unwind_frame(&frame);
2d7c11bf CM	387	if (ret < 0)
1da177e4	388	return 0;
2d7c11bf CM	389	if (!in_sched_functions(frame.pc))
2d7c11bf CM	390	return frame.pc;
1da177e4 LT	391	} while (count ++ < 16);
	392	return 0;
	393	}