[linux-2.6-block.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/slab.h>
#include <linux/mman.h>
#include <linux/personality.h>
#include <linux/sys.h>
#include <linux/user.h>
#include <linux/a.out.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)
{
	/* endless idle loop with no priority at all */
	while (1) {
		tick_nohz_stop_sched_tick();
		while (!need_resched()) {
#ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG
			extern void smtc_idle_loop_hook(void);

			smtc_idle_loop_hook();
#endif
			if (cpu_wait)
				(*cpu_wait)();
		}
		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|KU_MASK);
#ifdef CONFIG_64BIT
	status &= ~ST0_FR;
	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(int nr, 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;
	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;
	*childregs = *regs;
	childregs->regs[7] = 0;	/* Clear error flag */

#if defined(CONFIG_BINFMT_IRIX)
	if (current->personality != PER_LINUX) {
		/* Under IRIX things are a little different. */
		childregs->regs[3] = 1;
		regs->regs[3] = 0;
	}
#endif
	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);
	clear_tsk_thread_flag(p, TIF_USEDFPU);

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