[people/arne_f/kernel.git] / arch / mips / kernel / process.c

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others.
 * Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org)
 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
 * Copyright (C) 2004 Thiemo Seufer
 */
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/tick.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/personality.h>
#include <linux/sys.h>
#include <linux/user.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <linux/kallsyms.h>
#include <linux/random.h>

#include <asm/asm.h>
#include <asm/bootinfo.h>
#include <asm/cpu.h>
#include <asm/dsp.h>
#include <asm/fpu.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/mipsregs.h>
#include <asm/processor.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/elf.h>
#include <asm/isadep.h>
#include <asm/inst.h>
#include <asm/stacktrace.h>

/*
 * 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 __noreturn cpu_idle(void)
{
	int cpu;

	/* CPU is going idle. */
	cpu = smp_processor_id();

	/* endless idle loop with no priority at all */
	while (1) {
		tick_nohz_stop_sched_tick(1);
		while (!need_resched() && cpu_online(cpu)) {
#ifdef CONFIG_MIPS_MT_SMTC
			extern void smtc_idle_loop_hook(void);

			smtc_idle_loop_hook();
#endif
			if (cpu_wait)
				(*cpu_wait)();
		}
#ifdef CONFIG_HOTPLUG_CPU
		if (!cpu_online(cpu) && !cpu_isset(cpu, cpu_callin_map) &&
		    (system_state == SYSTEM_RUNNING ||
		     system_state == SYSTEM_BOOTING))
			play_dead();
#endif
		tick_nohz_restart_sched_tick();
		preempt_enable_no_resched();
		schedule();
		preempt_disable();
	}
}

asmlinkage void ret_from_fork(void);

void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
{
	unsigned long status;

	/* New thread loses kernel privileges. */
	status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
#ifdef CONFIG_64BIT
	status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR;
#endif
	status |= KU_USER;
	regs->cp0_status = status;
	clear_used_math();
	clear_fpu_owner();
	if (cpu_has_dsp)
		__init_dsp();
	regs->cp0_epc = pc;
	regs->regs[29] = sp;
	current_thread_info()->addr_limit = USER_DS;
}

void exit_thread(void)
{
}

void flush_thread(void)
{
}

int copy_thread(unsigned long clone_flags, unsigned long usp,
	unsigned long unused, struct task_struct *p, struct pt_regs *regs)
{
	struct thread_info *ti = task_thread_info(p);
	struct pt_regs *childregs;
	unsigned long childksp;
	p->set_child_tid = p->clear_child_tid = NULL;

	childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;

	preempt_disable();

	if (is_fpu_owner())
		save_fp(p);

	if (cpu_has_dsp)
		save_dsp(p);

	preempt_enable();

	/* set up new TSS. */
	childregs = (struct pt_regs *) childksp - 1;
	/*  Put the stack after the struct pt_regs.  */
	childksp = (unsigned long) childregs;
	*childregs = *regs;
	childregs->regs[7] = 0;	/* Clear error flag */

	childregs->regs[2] = 0;	/* Child gets zero as return value */
	regs->regs[2] = p->pid;

	if (childregs->cp0_status & ST0_CU0) {
		childregs->regs[28] = (unsigned long) ti;
		childregs->regs[29] = childksp;
		ti->addr_limit = KERNEL_DS;
	} else {
		childregs->regs[29] = usp;
		ti->addr_limit = USER_DS;
	}
	p->thread.reg29 = (unsigned long) childregs;
	p->thread.reg31 = (unsigned long) ret_from_fork;

	/*
	 * New tasks lose permission to use the fpu. This accelerates context
	 * switching for most programs since they don't use the fpu.
	 */
	p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
	childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);

#ifdef CONFIG_MIPS_MT_SMTC
	/*
	 * SMTC restores TCStatus after Status, and the CU bits
	 * are aliased there.
	 */
	childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1);
#endif
	clear_tsk_thread_flag(p, TIF_USEDFPU);

#ifdef CONFIG_MIPS_MT_FPAFF
	clear_tsk_thread_flag(p, TIF_FPUBOUND);
#endif /* CONFIG_MIPS_MT_FPAFF */

	if (clone_flags & CLONE_SETTLS)
		ti->tp_value = regs->regs[7];

	return 0;
}

/* Fill in the fpu structure for a core dump.. */
int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
{
	memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));

	return 1;
}

void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs)
{
	int i;

	for (i = 0; i < EF_R0; i++)
		gp[i] = 0;
	gp[EF_R0] = 0;
	for (i = 1; i <= 31; i++)
		gp[EF_R0 + i] = regs->regs[i];
	gp[EF_R26] = 0;
	gp[EF_R27] = 0;
	gp[EF_LO] = regs->lo;
	gp[EF_HI] = regs->hi;
	gp[EF_CP0_EPC] = regs->cp0_epc;
	gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
	gp[EF_CP0_STATUS] = regs->cp0_status;
	gp[EF_CP0_CAUSE] = regs->cp0_cause;
#ifdef EF_UNUSED0
	gp[EF_UNUSED0] = 0;
#endif
}

int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
{
	elf_dump_regs(*regs, task_pt_regs(tsk));
	return 1;
}

int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr)
{
	memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));

	return 1;
}

/*
 * Create a kernel thread
 */
static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *))
{
	do_exit(fn(arg));
}

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

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

	regs.regs[4] = (unsigned long) arg;
	regs.regs[5] = (unsigned long) fn;
	regs.cp0_epc = (unsigned long) kernel_thread_helper;
	regs.cp0_status = read_c0_status();
#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
	regs.cp0_status = (regs.cp0_status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
			  ((regs.cp0_status & (ST0_KUC | ST0_IEC)) << 2);
#else
	regs.cp0_status |= ST0_EXL;
#endif

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

/*
 *
 */
struct mips_frame_info {
	void		*func;
	unsigned long	func_size;
	int		frame_size;
	int		pc_offset;
};

static inline int is_ra_save_ins(union mips_instruction *ip)
{
	/* sw / sd $ra, offset($sp) */
	return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
		ip->i_format.rs == 29 &&
		ip->i_format.rt == 31;
}

static inline int is_jal_jalr_jr_ins(union mips_instruction *ip)
{
	if (ip->j_format.opcode == jal_op)
		return 1;
	if (ip->r_format.opcode != spec_op)
		return 0;
	return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
}

static inline int is_sp_move_ins(union mips_instruction *ip)
{
	/* addiu/daddiu sp,sp,-imm */
	if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
		return 0;
	if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
		return 1;
	return 0;
}

static int get_frame_info(struct mips_frame_info *info)
{
	union mips_instruction *ip = info->func;
	unsigned max_insns = info->func_size / sizeof(union mips_instruction);
	unsigned i;

	info->pc_offset = -1;
	info->frame_size = 0;

	if (!ip)
		goto err;

	if (max_insns == 0)
		max_insns = 128U;	/* unknown function size */
	max_insns = min(128U, max_insns);

	for (i = 0; i < max_insns; i++, ip++) {

		if (is_jal_jalr_jr_ins(ip))
			break;
		if (!info->frame_size) {
			if (is_sp_move_ins(ip))
				info->frame_size = - ip->i_format.simmediate;
			continue;
		}
		if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
			info->pc_offset =
				ip->i_format.simmediate / sizeof(long);
			break;
		}
	}
	if (info->frame_size && info->pc_offset >= 0) /* nested */
		return 0;
	if (info->pc_offset < 0) /* leaf */
		return 1;
	/* prologue seems boggus... */
err:
	return -1;
}

static struct mips_frame_info schedule_mfi __read_mostly;

static int __init frame_info_init(void)
{
	unsigned long size = 0;
#ifdef CONFIG_KALLSYMS
	unsigned long ofs;

	kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs);
#endif
	schedule_mfi.func = schedule;
	schedule_mfi.func_size = size;

	get_frame_info(&schedule_mfi);

	/*
	 * Without schedule() frame info, result given by
	 * thread_saved_pc() and get_wchan() are not reliable.
	 */
	if (schedule_mfi.pc_offset < 0)
		printk("Can't analyze schedule() prologue at %p\n", schedule);

	return 0;
}

arch_initcall(frame_info_init);

/*
 * Return saved PC of a blocked thread.
 */
unsigned long thread_saved_pc(struct task_struct *tsk)
{
	struct thread_struct *t = &tsk->thread;

	/* New born processes are a special case */
	if (t->reg31 == (unsigned long) ret_from_fork)
		return t->reg31;
	if (schedule_mfi.pc_offset < 0)
		return 0;
	return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
}


#ifdef CONFIG_KALLSYMS
/* used by show_backtrace() */
unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
			   unsigned long pc, unsigned long *ra)
{
	unsigned long stack_page;
	struct mips_frame_info info;
	unsigned long size, ofs;
	int leaf;
	extern void ret_from_irq(void);
	extern void ret_from_exception(void);

	stack_page = (unsigned long)task_stack_page(task);
	if (!stack_page)
		return 0;

	/*
	 * If we reached the bottom of interrupt context,
	 * return saved pc in pt_regs.
	 */
	if (pc == (unsigned long)ret_from_irq ||
	    pc == (unsigned long)ret_from_exception) {
		struct pt_regs *regs;
		if (*sp >= stack_page &&
		    *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
			regs = (struct pt_regs *)*sp;
			pc = regs->cp0_epc;
			if (__kernel_text_address(pc)) {
				*sp = regs->regs[29];
				*ra = regs->regs[31];
				return pc;
			}
		}
		return 0;
	}
	if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
		return 0;
	/*
	 * Return ra if an exception occured at the first instruction
	 */
	if (unlikely(ofs == 0)) {
		pc = *ra;
		*ra = 0;
		return pc;
	}

	info.func = (void *)(pc - ofs);
	info.func_size = ofs;	/* analyze from start to ofs */
	leaf = get_frame_info(&info);
	if (leaf < 0)
		return 0;

	if (*sp < stack_page ||
	    *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
		return 0;

	if (leaf)
		/*
		 * For some extreme cases, get_frame_info() can
		 * consider wrongly a nested function as a leaf
		 * one. In that cases avoid to return always the
		 * same value.
		 */
		pc = pc != *ra ? *ra : 0;
	else
		pc = ((unsigned long *)(*sp))[info.pc_offset];

	*sp += info.frame_size;
	*ra = 0;
	return __kernel_text_address(pc) ? pc : 0;
}
#endif

/*
 * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
 */
unsigned long get_wchan(struct task_struct *task)
{
	unsigned long pc = 0;
#ifdef CONFIG_KALLSYMS
	unsigned long sp;
	unsigned long ra = 0;
#endif

	if (!task || task == current || task->state == TASK_RUNNING)
		goto out;
	if (!task_stack_page(task))
		goto out;

	pc = thread_saved_pc(task);

#ifdef CONFIG_KALLSYMS
	sp = task->thread.reg29 + schedule_mfi.frame_size;

	while (in_sched_functions(pc))
		pc = unwind_stack(task, &sp, pc, &ra);
#endif

out:
	return pc;
}

/*
 * Don't forget that the stack pointer must be aligned on a 8 bytes
 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 */
unsigned long arch_align_stack(unsigned long sp)
{
	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
		sp -= get_random_int() & ~PAGE_MASK;

	return sp & ALMASK;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* This file is subject to the terms and conditions of the GNU General Public
	3	* License. See the file "COPYING" in the main directory of this archive
	4	* for more details.
	5	*
	6	* Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others.
40ac5d47	7	* Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org)
1da177e4 LT	8	* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
	9	* Copyright (C) 2004 Thiemo Seufer
	10	*/
1da177e4 LT	11	#include <linux/errno.h>
	12	#include <linux/module.h>
	13	#include <linux/sched.h>
7bcf7717	14	#include <linux/tick.h>
1da177e4 LT	15	#include <linux/kernel.h>
	16	#include <linux/mm.h>
	17	#include <linux/stddef.h>
	18	#include <linux/unistd.h>
	19	#include <linux/ptrace.h>
1da177e4 LT	20	#include <linux/mman.h>
	21	#include <linux/personality.h>
	22	#include <linux/sys.h>
	23	#include <linux/user.h>
1da177e4 LT	24	#include <linux/init.h>
1da177e4 LT	25	#include <linux/completion.h>
63077519	26	#include <linux/kallsyms.h>
94109102	27	#include <linux/random.h>
1da177e4	28
94109102	29	#include <asm/asm.h>
1da177e4 LT	30	#include <asm/bootinfo.h>
1da177e4 LT	31	#include <asm/cpu.h>
e50c0a8f	32	#include <asm/dsp.h>
1da177e4 LT	33	#include <asm/fpu.h>
	34	#include <asm/pgtable.h>
	35	#include <asm/system.h>
	36	#include <asm/mipsregs.h>
	37	#include <asm/processor.h>
	38	#include <asm/uaccess.h>
	39	#include <asm/io.h>
	40	#include <asm/elf.h>
	41	#include <asm/isadep.h>
	42	#include <asm/inst.h>
1df0f0ff	43	#include <asm/stacktrace.h>
1da177e4	44
1da177e4 LT	45	/*
	46	* The idle thread. There's no useful work to be done, so just try to conserve
	47	* power and have a low exit latency (ie sit in a loop waiting for somebody to
	48	* say that they'd like to reschedule)
	49	*/
b3f6df9f	50	void __noreturn cpu_idle(void)
1da177e4	51	{
1b2bc75c RB	52	int cpu;
	53
	54	/* CPU is going idle. */
	55	cpu = smp_processor_id();
	56
1da177e4 LT	57	/* endless idle loop with no priority at all */
1da177e4 LT	58	while (1) {
b8f8c3cf	59	tick_nohz_stop_sched_tick(1);
1b2bc75c	60	while (!need_resched() && cpu_online(cpu)) {
9cc12363	61	#ifdef CONFIG_MIPS_MT_SMTC
447deafb RB	62	extern void smtc_idle_loop_hook(void);
447deafb RB	63
41c594ab	64	smtc_idle_loop_hook();
c68644d3	65	#endif
1da177e4 LT	66	if (cpu_wait)
1da177e4 LT	67	(*cpu_wait)();
41c594ab	68	}
1b2bc75c RB	69	#ifdef CONFIG_HOTPLUG_CPU
	70	if (!cpu_online(cpu) && !cpu_isset(cpu, cpu_callin_map) &&
	71	(system_state == SYSTEM_RUNNING \|\|
	72	system_state == SYSTEM_BOOTING))
	73	play_dead();
	74	#endif
7bcf7717	75	tick_nohz_restart_sched_tick();
5bfb5d69	76	preempt_enable_no_resched();
1da177e4	77	schedule();
5bfb5d69	78	preempt_disable();
1da177e4 LT	79	}
	80	}
	81
	82	asmlinkage void ret_from_fork(void);
	83
	84	void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
	85	{
	86	unsigned long status;
	87
	88	/* New thread loses kernel privileges. */
bbaf238b	89	status = regs->cp0_status & ~(ST0_CU0\|ST0_CU1\|ST0_FR\|KU_MASK);
875d43e7	90	#ifdef CONFIG_64BIT
293c5bd1	91	status \|= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR;
1da177e4 LT	92	#endif
	93	status \|= KU_USER;
	94	regs->cp0_status = status;
	95	clear_used_math();
e04582b7	96	clear_fpu_owner();
e50c0a8f RB	97	if (cpu_has_dsp)
e50c0a8f RB	98	__init_dsp();
1da177e4 LT	99	regs->cp0_epc = pc;
	100	regs->regs[29] = sp;
	101	current_thread_info()->addr_limit = USER_DS;
	102	}
	103
	104	void exit_thread(void)
	105	{
	106	}
	107
	108	void flush_thread(void)
	109	{
	110	}
	111
6f2c55b8	112	int copy_thread(unsigned long clone_flags, unsigned long usp,
1da177e4 LT	113	unsigned long unused, struct task_struct p, struct pt_regs regs)
1da177e4 LT	114	{
75bb07e7	115	struct thread_info *ti = task_thread_info(p);
1da177e4	116	struct pt_regs *childregs;
484889fc	117	unsigned long childksp;
3c37026d	118	p->set_child_tid = p->clear_child_tid = NULL;
1da177e4	119
75bb07e7	120	childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
1da177e4 LT	121
	122	preempt_disable();
	123
e50c0a8f	124	if (is_fpu_owner())
1da177e4	125	save_fp(p);
e50c0a8f RB	126
	127	if (cpu_has_dsp)
	128	save_dsp(p);
1da177e4 LT	129
	130	preempt_enable();
	131
	132	/* set up new TSS. */
	133	childregs = (struct pt_regs *) childksp - 1;
484889fc DD	134	/* Put the stack after the struct pt_regs. */
484889fc DD	135	childksp = (unsigned long) childregs;
1da177e4 LT	136	childregs = regs;
	137	childregs->regs[7] = 0; /* Clear error flag */
	138
1da177e4 LT	139	childregs->regs[2] = 0; /* Child gets zero as return value */
	140	regs->regs[2] = p->pid;
	141
	142	if (childregs->cp0_status & ST0_CU0) {
	143	childregs->regs[28] = (unsigned long) ti;
	144	childregs->regs[29] = childksp;
	145	ti->addr_limit = KERNEL_DS;
	146	} else {
	147	childregs->regs[29] = usp;
	148	ti->addr_limit = USER_DS;
	149	}
	150	p->thread.reg29 = (unsigned long) childregs;
	151	p->thread.reg31 = (unsigned long) ret_from_fork;
	152
	153	/*
	154	* New tasks lose permission to use the fpu. This accelerates context
	155	* switching for most programs since they don't use the fpu.
	156	*/
	157	p->thread.cp0_status = read_c0_status() & ~(ST0_CU2\|ST0_CU1);
	158	childregs->cp0_status &= ~(ST0_CU2\|ST0_CU1);
1da177e4	159
9cc12363	160	#ifdef CONFIG_MIPS_MT_SMTC
f088fc84	161	/*
9cc12363 KK	162	* SMTC restores TCStatus after Status, and the CU bits
9cc12363 KK	163	* are aliased there.
f088fc84	164	*/
9cc12363 KK	165	childregs->cp0_tcstatus &= ~(ST0_CU2\|ST0_CU1);
9cc12363 KK	166	#endif
1da177e4 LT	167	clear_tsk_thread_flag(p, TIF_USEDFPU);
1da177e4 LT	168
f088fc84	169	#ifdef CONFIG_MIPS_MT_FPAFF
6657fe0a	170	clear_tsk_thread_flag(p, TIF_FPUBOUND);
f088fc84 RB	171	#endif /* CONFIG_MIPS_MT_FPAFF */
f088fc84 RB	172
3c37026d RB	173	if (clone_flags & CLONE_SETTLS)
	174	ti->tp_value = regs->regs[7];
	175
1da177e4 LT	176	return 0;
	177	}
	178
	179	/* Fill in the fpu structure for a core dump.. */
	180	int dump_fpu(struct pt_regs regs, elf_fpregset_t r)
	181	{
	182	memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
	183
	184	return 1;
	185	}
	186
d56efda4	187	void elf_dump_regs(elf_greg_t gp, struct pt_regs regs)
1da177e4 LT	188	{
	189	int i;
	190
	191	for (i = 0; i < EF_R0; i++)
	192	gp[i] = 0;
	193	gp[EF_R0] = 0;
	194	for (i = 1; i <= 31; i++)
	195	gp[EF_R0 + i] = regs->regs[i];
	196	gp[EF_R26] = 0;
	197	gp[EF_R27] = 0;
	198	gp[EF_LO] = regs->lo;
	199	gp[EF_HI] = regs->hi;
	200	gp[EF_CP0_EPC] = regs->cp0_epc;
	201	gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
	202	gp[EF_CP0_STATUS] = regs->cp0_status;
	203	gp[EF_CP0_CAUSE] = regs->cp0_cause;
	204	#ifdef EF_UNUSED0
	205	gp[EF_UNUSED0] = 0;
	206	#endif
	207	}
	208
49a89efb	209	int dump_task_regs(struct task_struct tsk, elf_gregset_t regs)
71e0e556	210	{
40bc9c67	211	elf_dump_regs(*regs, task_pt_regs(tsk));
71e0e556 RB	212	return 1;
	213	}
	214
49a89efb	215	int dump_task_fpu(struct task_struct t, elf_fpregset_t fpr)
1da177e4 LT	216	{
	217	memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
	218
	219	return 1;
	220	}
	221
	222	/*
	223	* Create a kernel thread
	224	*/
b3f6df9f	225	static void __noreturn kernel_thread_helper(void arg, int (fn)(void *))
1da177e4 LT	226	{
	227	do_exit(fn(arg));
	228	}
	229
	230	long kernel_thread(int (fn)(void ), void *arg, unsigned long flags)
	231	{
	232	struct pt_regs regs;
	233
	234	memset(&regs, 0, sizeof(regs));
	235
	236	regs.regs[4] = (unsigned long) arg;
	237	regs.regs[5] = (unsigned long) fn;
	238	regs.cp0_epc = (unsigned long) kernel_thread_helper;
	239	regs.cp0_status = read_c0_status();
	240	#if defined(CONFIG_CPU_R3000) \|\| defined(CONFIG_CPU_TX39XX)
e5d77754 MR	241	regs.cp0_status = (regs.cp0_status & ~(ST0_KUP \| ST0_IEP \| ST0_IEC)) \|
e5d77754 MR	242	((regs.cp0_status & (ST0_KUC \| ST0_IEC)) << 2);
1da177e4 LT	243	#else
	244	regs.cp0_status \|= ST0_EXL;
	245	#endif
	246
	247	/* Ok, create the new process.. */
	248	return do_fork(flags \| CLONE_VM \| CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
	249	}
	250
b5943182 FBH	251	/*
	252	*
	253	*/
	254	struct mips_frame_info {
	255	void *func;
	256	unsigned long func_size;
	257	int frame_size;
	258	int pc_offset;
	259	};
dc953df1	260
c0efbb6d FBH	261	static inline int is_ra_save_ins(union mips_instruction *ip)
	262	{
	263	/* sw / sd $ra, offset($sp) */
	264	return (ip->i_format.opcode == sw_op \|\| ip->i_format.opcode == sd_op) &&
	265	ip->i_format.rs == 29 &&
	266	ip->i_format.rt == 31;
	267	}
	268
	269	static inline int is_jal_jalr_jr_ins(union mips_instruction *ip)
	270	{
	271	if (ip->j_format.opcode == jal_op)
	272	return 1;
	273	if (ip->r_format.opcode != spec_op)
	274	return 0;
	275	return ip->r_format.func == jalr_op \|\| ip->r_format.func == jr_op;
	276	}
	277
	278	static inline int is_sp_move_ins(union mips_instruction *ip)
	279	{
	280	/* addiu/daddiu sp,sp,-imm */
	281	if (ip->i_format.rs != 29 \|\| ip->i_format.rt != 29)
	282	return 0;
	283	if (ip->i_format.opcode == addiu_op \|\| ip->i_format.opcode == daddiu_op)
	284	return 1;
	285	return 0;
	286	}
	287
f66686f7	288	static int get_frame_info(struct mips_frame_info *info)
1da177e4	289	{
c0efbb6d	290	union mips_instruction *ip = info->func;
29b376ff FBH	291	unsigned max_insns = info->func_size / sizeof(union mips_instruction);
29b376ff FBH	292	unsigned i;
c0efbb6d	293
1da177e4	294	info->pc_offset = -1;
63077519	295	info->frame_size = 0;
1da177e4	296
29b376ff FBH	297	if (!ip)
	298	goto err;
	299
	300	if (max_insns == 0)
	301	max_insns = 128U; /* unknown function size */
	302	max_insns = min(128U, max_insns);
	303
c0efbb6d FBH	304	for (i = 0; i < max_insns; i++, ip++) {
	305
	306	if (is_jal_jalr_jr_ins(ip))
63077519	307	break;
0cceb4aa FBH	308	if (!info->frame_size) {
	309	if (is_sp_move_ins(ip))
	310	info->frame_size = - ip->i_format.simmediate;
	311	continue;
63077519	312	}
0cceb4aa	313	if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
63077519 AN	314	info->pc_offset =
63077519 AN	315	ip->i_format.simmediate / sizeof(long);
0cceb4aa	316	break;
1da177e4 LT	317	}
1da177e4 LT	318	}
f66686f7 AN	319	if (info->frame_size && info->pc_offset >= 0) /* nested */
	320	return 0;
	321	if (info->pc_offset < 0) /* leaf */
	322	return 1;
	323	/* prologue seems boggus... */
29b376ff	324	err:
f66686f7	325	return -1;
1da177e4 LT	326	}
1da177e4 LT	327
b5943182 FBH	328	static struct mips_frame_info schedule_mfi __read_mostly;
b5943182 FBH	329
1da177e4 LT	330	static int __init frame_info_init(void)
1da177e4 LT	331	{
b5943182	332	unsigned long size = 0;
63077519	333	#ifdef CONFIG_KALLSYMS
b5943182	334	unsigned long ofs;
b5943182	335
55b74283	336	kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs);
63077519	337	#endif
b5943182 FBH	338	schedule_mfi.func = schedule;
	339	schedule_mfi.func_size = size;
	340
	341	get_frame_info(&schedule_mfi);
6057a798 FBH	342
	343	/*
	344	* Without schedule() frame info, result given by
	345	* thread_saved_pc() and get_wchan() are not reliable.
	346	*/
b5943182	347	if (schedule_mfi.pc_offset < 0)
6057a798	348	printk("Can't analyze schedule() prologue at %p\n", schedule);
63077519	349
1da177e4 LT	350	return 0;
	351	}
	352
	353	arch_initcall(frame_info_init);
	354
	355	/*
	356	* Return saved PC of a blocked thread.
	357	*/
	358	unsigned long thread_saved_pc(struct task_struct *tsk)
	359	{
	360	struct thread_struct *t = &tsk->thread;
	361
	362	/* New born processes are a special case */
	363	if (t->reg31 == (unsigned long) ret_from_fork)
	364	return t->reg31;
b5943182	365	if (schedule_mfi.pc_offset < 0)
1da177e4	366	return 0;
b5943182	367	return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
1da177e4 LT	368	}
1da177e4 LT	369
1da177e4	370
f66686f7	371	#ifdef CONFIG_KALLSYMS
4d157d5e FBH	372	/* used by show_backtrace() */
4d157d5e FBH	373	unsigned long unwind_stack(struct task_struct task, unsigned long sp,
1924600c	374	unsigned long pc, unsigned long *ra)
f66686f7 AN	375	{
	376	unsigned long stack_page;
	377	struct mips_frame_info info;
f66686f7	378	unsigned long size, ofs;
4d157d5e	379	int leaf;
1924600c AN	380	extern void ret_from_irq(void);
1924600c AN	381	extern void ret_from_exception(void);
f66686f7 AN	382
	383	stack_page = (unsigned long)task_stack_page(task);
	384	if (!stack_page)
	385	return 0;
	386
1924600c AN	387	/*
	388	* If we reached the bottom of interrupt context,
	389	* return saved pc in pt_regs.
	390	*/
	391	if (pc == (unsigned long)ret_from_irq \|\|
	392	pc == (unsigned long)ret_from_exception) {
	393	struct pt_regs *regs;
	394	if (*sp >= stack_page &&
	395	sp + sizeof(regs) <= stack_page + THREAD_SIZE - 32) {
	396	regs = (struct pt_regs )sp;
	397	pc = regs->cp0_epc;
	398	if (__kernel_text_address(pc)) {
	399	*sp = regs->regs[29];
	400	*ra = regs->regs[31];
	401	return pc;
	402	}
	403	}
	404	return 0;
	405	}
55b74283	406	if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
f66686f7	407	return 0;
1fd69098 FBH	408	/*
	409	* Return ra if an exception occured at the first instruction
	410	*/
1924600c AN	411	if (unlikely(ofs == 0)) {
	412	pc = *ra;
	413	*ra = 0;
	414	return pc;
	415	}
f66686f7 AN	416
	417	info.func = (void *)(pc - ofs);
	418	info.func_size = ofs; /* analyze from start to ofs */
4d157d5e FBH	419	leaf = get_frame_info(&info);
4d157d5e FBH	420	if (leaf < 0)
f66686f7	421	return 0;
4d157d5e FBH	422
	423	if (*sp < stack_page \|\|
	424	*sp + info.frame_size > stack_page + THREAD_SIZE - 32)
f66686f7 AN	425	return 0;
f66686f7 AN	426
4d157d5e FBH	427	if (leaf)
	428	/*
	429	* For some extreme cases, get_frame_info() can
	430	* consider wrongly a nested function as a leaf
	431	* one. In that cases avoid to return always the
	432	* same value.
	433	*/
1924600c	434	pc = pc != ra ? ra : 0;
4d157d5e FBH	435	else
	436	pc = ((unsigned long )(sp))[info.pc_offset];
	437
	438	*sp += info.frame_size;
1924600c	439	*ra = 0;
4d157d5e	440	return __kernel_text_address(pc) ? pc : 0;
f66686f7 AN	441	}
f66686f7 AN	442	#endif
b5943182 FBH	443
	444	/*
	445	* get_wchan - a maintenance nightmare^W^Wpain in the ass ...
	446	*/
	447	unsigned long get_wchan(struct task_struct *task)
	448	{
	449	unsigned long pc = 0;
	450	#ifdef CONFIG_KALLSYMS
	451	unsigned long sp;
1924600c	452	unsigned long ra = 0;
b5943182 FBH	453	#endif
	454
	455	if (!task \|\| task == current \|\| task->state == TASK_RUNNING)
	456	goto out;
	457	if (!task_stack_page(task))
	458	goto out;
	459
	460	pc = thread_saved_pc(task);
	461
	462	#ifdef CONFIG_KALLSYMS
	463	sp = task->thread.reg29 + schedule_mfi.frame_size;
	464
	465	while (in_sched_functions(pc))
1924600c	466	pc = unwind_stack(task, &sp, pc, &ra);
b5943182 FBH	467	#endif
	468
	469	out:
	470	return pc;
	471	}
94109102 FBH	472
	473	/*
	474	* Don't forget that the stack pointer must be aligned on a 8 bytes
	475	* boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
	476	*/
	477	unsigned long arch_align_stack(unsigned long sp)
	478	{
	479	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
	480	sp -= get_random_int() & ~PAGE_MASK;
	481
	482	return sp & ALMASK;
	483	}