[deliverable/linux.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/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 <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) {
		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)();
		}
		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 |= (current->thread.mflags & MF_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 &= ~(ST0_KUP | ST0_IEC);
	regs.cp0_status |= ST0_IEP;
#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;
}
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>
	14	#include <linux/kernel.h>
	15	#include <linux/mm.h>
	16	#include <linux/stddef.h>
	17	#include <linux/unistd.h>
	18	#include <linux/ptrace.h>
	19	#include <linux/slab.h>
	20	#include <linux/mman.h>
	21	#include <linux/personality.h>
	22	#include <linux/sys.h>
	23	#include <linux/user.h>
	24	#include <linux/a.out.h>
	25	#include <linux/init.h>
	26	#include <linux/completion.h>
63077519	27	#include <linux/kallsyms.h>
1da177e4 LT	28
	29	#include <asm/bootinfo.h>
	30	#include <asm/cpu.h>
e50c0a8f	31	#include <asm/dsp.h>
1da177e4 LT	32	#include <asm/fpu.h>
	33	#include <asm/pgtable.h>
	34	#include <asm/system.h>
	35	#include <asm/mipsregs.h>
	36	#include <asm/processor.h>
	37	#include <asm/uaccess.h>
	38	#include <asm/io.h>
	39	#include <asm/elf.h>
	40	#include <asm/isadep.h>
	41	#include <asm/inst.h>
1df0f0ff	42	#include <asm/stacktrace.h>
1da177e4	43
1da177e4 LT	44	/*
	45	* The idle thread. There's no useful work to be done, so just try to conserve
	46	* power and have a low exit latency (ie sit in a loop waiting for somebody to
	47	* say that they'd like to reschedule)
	48	*/
b3f6df9f	49	void __noreturn cpu_idle(void)
1da177e4 LT	50	{
	51	/* endless idle loop with no priority at all */
	52	while (1) {
41c594ab	53	while (!need_resched()) {
c68644d3	54	#ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG
447deafb RB	55	extern void smtc_idle_loop_hook(void);
447deafb RB	56
41c594ab	57	smtc_idle_loop_hook();
c68644d3	58	#endif
1da177e4 LT	59	if (cpu_wait)
1da177e4 LT	60	(*cpu_wait)();
41c594ab	61	}
5bfb5d69	62	preempt_enable_no_resched();
1da177e4	63	schedule();
5bfb5d69	64	preempt_disable();
1da177e4 LT	65	}
	66	}
	67
	68	asmlinkage void ret_from_fork(void);
	69
	70	void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
	71	{
	72	unsigned long status;
	73
	74	/* New thread loses kernel privileges. */
	75	status = regs->cp0_status & ~(ST0_CU0\|ST0_CU1\|KU_MASK);
875d43e7	76	#ifdef CONFIG_64BIT
1da177e4 LT	77	status &= ~ST0_FR;
	78	status \|= (current->thread.mflags & MF_32BIT_REGS) ? 0 : ST0_FR;
	79	#endif
	80	status \|= KU_USER;
	81	regs->cp0_status = status;
	82	clear_used_math();
e04582b7	83	clear_fpu_owner();
e50c0a8f RB	84	if (cpu_has_dsp)
e50c0a8f RB	85	__init_dsp();
1da177e4 LT	86	regs->cp0_epc = pc;
	87	regs->regs[29] = sp;
	88	current_thread_info()->addr_limit = USER_DS;
	89	}
	90
	91	void exit_thread(void)
	92	{
	93	}
	94
	95	void flush_thread(void)
	96	{
	97	}
	98
	99	int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
	100	unsigned long unused, struct task_struct p, struct pt_regs regs)
	101	{
75bb07e7	102	struct thread_info *ti = task_thread_info(p);
1da177e4 LT	103	struct pt_regs *childregs;
1da177e4 LT	104	long childksp;
3c37026d	105	p->set_child_tid = p->clear_child_tid = NULL;
1da177e4	106
75bb07e7	107	childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
1da177e4 LT	108
	109	preempt_disable();
	110
e50c0a8f	111	if (is_fpu_owner())
1da177e4	112	save_fp(p);
e50c0a8f RB	113
	114	if (cpu_has_dsp)
	115	save_dsp(p);
1da177e4 LT	116
	117	preempt_enable();
	118
	119	/* set up new TSS. */
	120	childregs = (struct pt_regs *) childksp - 1;
	121	childregs = regs;
	122	childregs->regs[7] = 0; /* Clear error flag */
	123
	124	#if defined(CONFIG_BINFMT_IRIX)
	125	if (current->personality != PER_LINUX) {
	126	/* Under IRIX things are a little different. */
	127	childregs->regs[3] = 1;
	128	regs->regs[3] = 0;
	129	}
	130	#endif
	131	childregs->regs[2] = 0; /* Child gets zero as return value */
	132	regs->regs[2] = p->pid;
	133
	134	if (childregs->cp0_status & ST0_CU0) {
	135	childregs->regs[28] = (unsigned long) ti;
	136	childregs->regs[29] = childksp;
	137	ti->addr_limit = KERNEL_DS;
	138	} else {
	139	childregs->regs[29] = usp;
	140	ti->addr_limit = USER_DS;
	141	}
	142	p->thread.reg29 = (unsigned long) childregs;
	143	p->thread.reg31 = (unsigned long) ret_from_fork;
	144
	145	/*
	146	* New tasks lose permission to use the fpu. This accelerates context
	147	* switching for most programs since they don't use the fpu.
	148	*/
	149	p->thread.cp0_status = read_c0_status() & ~(ST0_CU2\|ST0_CU1);
	150	childregs->cp0_status &= ~(ST0_CU2\|ST0_CU1);
	151	clear_tsk_thread_flag(p, TIF_USEDFPU);
	152
f088fc84 RB	153	#ifdef CONFIG_MIPS_MT_FPAFF
	154	/*
	155	* FPU affinity support is cleaner if we track the
	156	* user-visible CPU affinity from the very beginning.
	157	* The generic cpus_allowed mask will already have
	158	* been copied from the parent before copy_thread
	159	* is invoked.
	160	*/
	161	p->thread.user_cpus_allowed = p->cpus_allowed;
	162	#endif /* CONFIG_MIPS_MT_FPAFF */
	163
3c37026d RB	164	if (clone_flags & CLONE_SETTLS)
	165	ti->tp_value = regs->regs[7];
	166
1da177e4 LT	167	return 0;
	168	}
	169
	170	/* Fill in the fpu structure for a core dump.. */
	171	int dump_fpu(struct pt_regs regs, elf_fpregset_t r)
	172	{
	173	memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
	174
	175	return 1;
	176	}
	177
d56efda4	178	void elf_dump_regs(elf_greg_t gp, struct pt_regs regs)
1da177e4 LT	179	{
	180	int i;
	181
	182	for (i = 0; i < EF_R0; i++)
	183	gp[i] = 0;
	184	gp[EF_R0] = 0;
	185	for (i = 1; i <= 31; i++)
	186	gp[EF_R0 + i] = regs->regs[i];
	187	gp[EF_R26] = 0;
	188	gp[EF_R27] = 0;
	189	gp[EF_LO] = regs->lo;
	190	gp[EF_HI] = regs->hi;
	191	gp[EF_CP0_EPC] = regs->cp0_epc;
	192	gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
	193	gp[EF_CP0_STATUS] = regs->cp0_status;
	194	gp[EF_CP0_CAUSE] = regs->cp0_cause;
	195	#ifdef EF_UNUSED0
	196	gp[EF_UNUSED0] = 0;
	197	#endif
	198	}
	199
71e0e556 RB	200	int dump_task_regs (struct task_struct tsk, elf_gregset_t regs)
71e0e556 RB	201	{
40bc9c67	202	elf_dump_regs(*regs, task_pt_regs(tsk));
71e0e556 RB	203	return 1;
	204	}
	205
1da177e4 LT	206	int dump_task_fpu (struct task_struct t, elf_fpregset_t fpr)
	207	{
	208	memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
	209
	210	return 1;
	211	}
	212
	213	/*
	214	* Create a kernel thread
	215	*/
b3f6df9f	216	static void __noreturn kernel_thread_helper(void arg, int (fn)(void *))
1da177e4 LT	217	{
	218	do_exit(fn(arg));
	219	}
	220
	221	long kernel_thread(int (fn)(void ), void *arg, unsigned long flags)
	222	{
	223	struct pt_regs regs;
	224
	225	memset(&regs, 0, sizeof(regs));
	226
	227	regs.regs[4] = (unsigned long) arg;
	228	regs.regs[5] = (unsigned long) fn;
	229	regs.cp0_epc = (unsigned long) kernel_thread_helper;
	230	regs.cp0_status = read_c0_status();
	231	#if defined(CONFIG_CPU_R3000) \|\| defined(CONFIG_CPU_TX39XX)
	232	regs.cp0_status &= ~(ST0_KUP \| ST0_IEC);
	233	regs.cp0_status \|= ST0_IEP;
	234	#else
	235	regs.cp0_status \|= ST0_EXL;
	236	#endif
	237
	238	/* Ok, create the new process.. */
	239	return do_fork(flags \| CLONE_VM \| CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
	240	}
	241
b5943182 FBH	242	/*
	243	*
	244	*/
	245	struct mips_frame_info {
	246	void *func;
	247	unsigned long func_size;
	248	int frame_size;
	249	int pc_offset;
	250	};
dc953df1	251
c0efbb6d FBH	252	static inline int is_ra_save_ins(union mips_instruction *ip)
	253	{
	254	/* sw / sd $ra, offset($sp) */
	255	return (ip->i_format.opcode == sw_op \|\| ip->i_format.opcode == sd_op) &&
	256	ip->i_format.rs == 29 &&
	257	ip->i_format.rt == 31;
	258	}
	259
	260	static inline int is_jal_jalr_jr_ins(union mips_instruction *ip)
	261	{
	262	if (ip->j_format.opcode == jal_op)
	263	return 1;
	264	if (ip->r_format.opcode != spec_op)
	265	return 0;
	266	return ip->r_format.func == jalr_op \|\| ip->r_format.func == jr_op;
	267	}
	268
	269	static inline int is_sp_move_ins(union mips_instruction *ip)
	270	{
	271	/* addiu/daddiu sp,sp,-imm */
	272	if (ip->i_format.rs != 29 \|\| ip->i_format.rt != 29)
	273	return 0;
	274	if (ip->i_format.opcode == addiu_op \|\| ip->i_format.opcode == daddiu_op)
	275	return 1;
	276	return 0;
	277	}
	278
f66686f7	279	static int get_frame_info(struct mips_frame_info *info)
1da177e4	280	{
c0efbb6d	281	union mips_instruction *ip = info->func;
29b376ff FBH	282	unsigned max_insns = info->func_size / sizeof(union mips_instruction);
29b376ff FBH	283	unsigned i;
c0efbb6d	284
1da177e4	285	info->pc_offset = -1;
63077519	286	info->frame_size = 0;
1da177e4	287
29b376ff FBH	288	if (!ip)
	289	goto err;
	290
	291	if (max_insns == 0)
	292	max_insns = 128U; /* unknown function size */
	293	max_insns = min(128U, max_insns);
	294
c0efbb6d FBH	295	for (i = 0; i < max_insns; i++, ip++) {
	296
	297	if (is_jal_jalr_jr_ins(ip))
63077519	298	break;
0cceb4aa FBH	299	if (!info->frame_size) {
	300	if (is_sp_move_ins(ip))
	301	info->frame_size = - ip->i_format.simmediate;
	302	continue;
63077519	303	}
0cceb4aa	304	if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
63077519 AN	305	info->pc_offset =
63077519 AN	306	ip->i_format.simmediate / sizeof(long);
0cceb4aa	307	break;
1da177e4 LT	308	}
1da177e4 LT	309	}
f66686f7 AN	310	if (info->frame_size && info->pc_offset >= 0) /* nested */
	311	return 0;
	312	if (info->pc_offset < 0) /* leaf */
	313	return 1;
	314	/* prologue seems boggus... */
29b376ff	315	err:
f66686f7	316	return -1;
1da177e4 LT	317	}
1da177e4 LT	318
b5943182 FBH	319	static struct mips_frame_info schedule_mfi __read_mostly;
b5943182 FBH	320
1da177e4 LT	321	static int __init frame_info_init(void)
1da177e4 LT	322	{
b5943182	323	unsigned long size = 0;
63077519	324	#ifdef CONFIG_KALLSYMS
b5943182	325	unsigned long ofs;
b5943182	326
55b74283	327	kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs);
63077519	328	#endif
b5943182 FBH	329	schedule_mfi.func = schedule;
	330	schedule_mfi.func_size = size;
	331
	332	get_frame_info(&schedule_mfi);
6057a798 FBH	333
	334	/*
	335	* Without schedule() frame info, result given by
	336	* thread_saved_pc() and get_wchan() are not reliable.
	337	*/
b5943182	338	if (schedule_mfi.pc_offset < 0)
6057a798	339	printk("Can't analyze schedule() prologue at %p\n", schedule);
63077519	340
1da177e4 LT	341	return 0;
	342	}
	343
	344	arch_initcall(frame_info_init);
	345
	346	/*
	347	* Return saved PC of a blocked thread.
	348	*/
	349	unsigned long thread_saved_pc(struct task_struct *tsk)
	350	{
	351	struct thread_struct *t = &tsk->thread;
	352
	353	/* New born processes are a special case */
	354	if (t->reg31 == (unsigned long) ret_from_fork)
	355	return t->reg31;
b5943182	356	if (schedule_mfi.pc_offset < 0)
1da177e4	357	return 0;
b5943182	358	return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
1da177e4 LT	359	}
1da177e4 LT	360
1da177e4	361
f66686f7	362	#ifdef CONFIG_KALLSYMS
4d157d5e FBH	363	/* used by show_backtrace() */
4d157d5e FBH	364	unsigned long unwind_stack(struct task_struct task, unsigned long sp,
1924600c	365	unsigned long pc, unsigned long *ra)
f66686f7 AN	366	{
	367	unsigned long stack_page;
	368	struct mips_frame_info info;
f66686f7	369	unsigned long size, ofs;
4d157d5e	370	int leaf;
1924600c AN	371	extern void ret_from_irq(void);
1924600c AN	372	extern void ret_from_exception(void);
f66686f7 AN	373
	374	stack_page = (unsigned long)task_stack_page(task);
	375	if (!stack_page)
	376	return 0;
	377
1924600c AN	378	/*
	379	* If we reached the bottom of interrupt context,
	380	* return saved pc in pt_regs.
	381	*/
	382	if (pc == (unsigned long)ret_from_irq \|\|
	383	pc == (unsigned long)ret_from_exception) {
	384	struct pt_regs *regs;
	385	if (*sp >= stack_page &&
	386	sp + sizeof(regs) <= stack_page + THREAD_SIZE - 32) {
	387	regs = (struct pt_regs )sp;
	388	pc = regs->cp0_epc;
	389	if (__kernel_text_address(pc)) {
	390	*sp = regs->regs[29];
	391	*ra = regs->regs[31];
	392	return pc;
	393	}
	394	}
	395	return 0;
	396	}
55b74283	397	if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
f66686f7	398	return 0;
1fd69098 FBH	399	/*
	400	* Return ra if an exception occured at the first instruction
	401	*/
1924600c AN	402	if (unlikely(ofs == 0)) {
	403	pc = *ra;
	404	*ra = 0;
	405	return pc;
	406	}
f66686f7 AN	407
	408	info.func = (void *)(pc - ofs);
	409	info.func_size = ofs; /* analyze from start to ofs */
4d157d5e FBH	410	leaf = get_frame_info(&info);
4d157d5e FBH	411	if (leaf < 0)
f66686f7	412	return 0;
4d157d5e FBH	413
	414	if (*sp < stack_page \|\|
	415	*sp + info.frame_size > stack_page + THREAD_SIZE - 32)
f66686f7 AN	416	return 0;
f66686f7 AN	417
4d157d5e FBH	418	if (leaf)
	419	/*
	420	* For some extreme cases, get_frame_info() can
	421	* consider wrongly a nested function as a leaf
	422	* one. In that cases avoid to return always the
	423	* same value.
	424	*/
1924600c	425	pc = pc != ra ? ra : 0;
4d157d5e FBH	426	else
	427	pc = ((unsigned long )(sp))[info.pc_offset];
	428
	429	*sp += info.frame_size;
1924600c	430	*ra = 0;
4d157d5e	431	return __kernel_text_address(pc) ? pc : 0;
f66686f7 AN	432	}
f66686f7 AN	433	#endif
b5943182 FBH	434
	435	/*
	436	* get_wchan - a maintenance nightmare^W^Wpain in the ass ...
	437	*/
	438	unsigned long get_wchan(struct task_struct *task)
	439	{
	440	unsigned long pc = 0;
	441	#ifdef CONFIG_KALLSYMS
	442	unsigned long sp;
1924600c	443	unsigned long ra = 0;
b5943182 FBH	444	#endif
	445
	446	if (!task \|\| task == current \|\| task->state == TASK_RUNNING)
	447	goto out;
	448	if (!task_stack_page(task))
	449	goto out;
	450
	451	pc = thread_saved_pc(task);
	452
	453	#ifdef CONFIG_KALLSYMS
	454	sp = task->thread.reg29 + schedule_mfi.frame_size;
	455
	456	while (in_sched_functions(pc))
1924600c	457	pc = unwind_stack(task, &sp, pc, &ra);
b5943182 FBH	458	#endif
	459
	460	out:
	461	return pc;
	462	}