[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/sched.h>
#include <linux/tick.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/export.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_idle_enter();
		rcu_idle_enter();
		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) {
				/* Don't trace irqs off for idle */
				stop_critical_timings();
				(*cpu_wait)();
				start_critical_timings();
			}
		}
#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
		rcu_idle_exit();
		tick_nohz_idle_exit();
		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;
}

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 */

	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
/* generic stack unwinding function */
unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
					      unsigned long *sp,
					      unsigned long pc,
					      unsigned long *ra)
{
	struct mips_frame_info info;
	unsigned long size, ofs;
	int leaf;
	extern void ret_from_irq(void);
	extern void ret_from_exception(void);

	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 occurred 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;
}
EXPORT_SYMBOL(unwind_stack_by_address);

/* 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 = (unsigned long)task_stack_page(task);
	return unwind_stack_by_address(stack_page, sp, pc, ra);
}
#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	11	#include <linux/errno.h>
1da177e4	12	#include <linux/sched.h>
7bcf7717	13	#include <linux/tick.h>
1da177e4 LT	14	#include <linux/kernel.h>
	15	#include <linux/mm.h>
	16	#include <linux/stddef.h>
	17	#include <linux/unistd.h>
cae39d13	18	#include <linux/export.h>
1da177e4	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) {
1268fbc7 FW	59	tick_nohz_idle_enter();
1268fbc7 FW	60	rcu_idle_enter();
1b2bc75c	61	while (!need_resched() && cpu_online(cpu)) {
9cc12363	62	#ifdef CONFIG_MIPS_MT_SMTC
447deafb RB	63	extern void smtc_idle_loop_hook(void);
447deafb RB	64
41c594ab	65	smtc_idle_loop_hook();
c68644d3	66	#endif
7a7ac952 WZ	67
	68	if (cpu_wait) {
	69	/* Don't trace irqs off for idle */
	70	stop_critical_timings();
1da177e4	71	(*cpu_wait)();
7a7ac952 WZ	72	start_critical_timings();
7a7ac952 WZ	73	}
41c594ab	74	}
1b2bc75c RB	75	#ifdef CONFIG_HOTPLUG_CPU
	76	if (!cpu_online(cpu) && !cpu_isset(cpu, cpu_callin_map) &&
	77	(system_state == SYSTEM_RUNNING \|\|
	78	system_state == SYSTEM_BOOTING))
	79	play_dead();
	80	#endif
1268fbc7 FW	81	rcu_idle_exit();
1268fbc7 FW	82	tick_nohz_idle_exit();
5bfb5d69	83	preempt_enable_no_resched();
1da177e4	84	schedule();
5bfb5d69	85	preempt_disable();
1da177e4 LT	86	}
	87	}
	88
	89	asmlinkage void ret_from_fork(void);
	90
	91	void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
	92	{
	93	unsigned long status;
	94
	95	/* New thread loses kernel privileges. */
bbaf238b	96	status = regs->cp0_status & ~(ST0_CU0\|ST0_CU1\|ST0_FR\|KU_MASK);
875d43e7	97	#ifdef CONFIG_64BIT
293c5bd1	98	status \|= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR;
1da177e4 LT	99	#endif
	100	status \|= KU_USER;
	101	regs->cp0_status = status;
	102	clear_used_math();
e04582b7	103	clear_fpu_owner();
e50c0a8f RB	104	if (cpu_has_dsp)
e50c0a8f RB	105	__init_dsp();
1da177e4 LT	106	regs->cp0_epc = pc;
1da177e4 LT	107	regs->regs[29] = sp;
1da177e4 LT	108	}
	109
	110	void exit_thread(void)
	111	{
	112	}
	113
	114	void flush_thread(void)
	115	{
	116	}
	117
6f2c55b8	118	int copy_thread(unsigned long clone_flags, unsigned long usp,
1da177e4 LT	119	unsigned long unused, struct task_struct p, struct pt_regs regs)
1da177e4 LT	120	{
75bb07e7	121	struct thread_info *ti = task_thread_info(p);
1da177e4	122	struct pt_regs *childregs;
484889fc	123	unsigned long childksp;
3c37026d	124	p->set_child_tid = p->clear_child_tid = NULL;
1da177e4	125
75bb07e7	126	childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
1da177e4 LT	127
	128	preempt_disable();
	129
e50c0a8f	130	if (is_fpu_owner())
1da177e4	131	save_fp(p);
e50c0a8f RB	132
	133	if (cpu_has_dsp)
	134	save_dsp(p);
1da177e4 LT	135
	136	preempt_enable();
	137
	138	/* set up new TSS. */
	139	childregs = (struct pt_regs *) childksp - 1;
484889fc DD	140	/* Put the stack after the struct pt_regs. */
484889fc DD	141	childksp = (unsigned long) childregs;
1da177e4 LT	142	childregs = regs;
	143	childregs->regs[7] = 0; /* Clear error flag */
	144
1da177e4	145	childregs->regs[2] = 0; /* Child gets zero as return value */
1da177e4 LT	146
	147	if (childregs->cp0_status & ST0_CU0) {
	148	childregs->regs[28] = (unsigned long) ti;
	149	childregs->regs[29] = childksp;
	150	ti->addr_limit = KERNEL_DS;
	151	} else {
	152	childregs->regs[29] = usp;
	153	ti->addr_limit = USER_DS;
	154	}
	155	p->thread.reg29 = (unsigned long) childregs;
	156	p->thread.reg31 = (unsigned long) ret_from_fork;
	157
	158	/*
	159	* New tasks lose permission to use the fpu. This accelerates context
	160	* switching for most programs since they don't use the fpu.
	161	*/
	162	p->thread.cp0_status = read_c0_status() & ~(ST0_CU2\|ST0_CU1);
	163	childregs->cp0_status &= ~(ST0_CU2\|ST0_CU1);
1da177e4	164
9cc12363	165	#ifdef CONFIG_MIPS_MT_SMTC
f088fc84	166	/*
9cc12363 KK	167	* SMTC restores TCStatus after Status, and the CU bits
9cc12363 KK	168	* are aliased there.
f088fc84	169	*/
9cc12363 KK	170	childregs->cp0_tcstatus &= ~(ST0_CU2\|ST0_CU1);
9cc12363 KK	171	#endif
1da177e4 LT	172	clear_tsk_thread_flag(p, TIF_USEDFPU);
1da177e4 LT	173
f088fc84	174	#ifdef CONFIG_MIPS_MT_FPAFF
6657fe0a	175	clear_tsk_thread_flag(p, TIF_FPUBOUND);
f088fc84 RB	176	#endif /* CONFIG_MIPS_MT_FPAFF */
f088fc84 RB	177
3c37026d RB	178	if (clone_flags & CLONE_SETTLS)
	179	ti->tp_value = regs->regs[7];
	180
1da177e4 LT	181	return 0;
	182	}
	183
	184	/* Fill in the fpu structure for a core dump.. */
	185	int dump_fpu(struct pt_regs regs, elf_fpregset_t r)
	186	{
	187	memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
	188
	189	return 1;
	190	}
	191
d56efda4	192	void elf_dump_regs(elf_greg_t gp, struct pt_regs regs)
1da177e4 LT	193	{
	194	int i;
	195
	196	for (i = 0; i < EF_R0; i++)
	197	gp[i] = 0;
	198	gp[EF_R0] = 0;
	199	for (i = 1; i <= 31; i++)
	200	gp[EF_R0 + i] = regs->regs[i];
	201	gp[EF_R26] = 0;
	202	gp[EF_R27] = 0;
	203	gp[EF_LO] = regs->lo;
	204	gp[EF_HI] = regs->hi;
	205	gp[EF_CP0_EPC] = regs->cp0_epc;
	206	gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
	207	gp[EF_CP0_STATUS] = regs->cp0_status;
	208	gp[EF_CP0_CAUSE] = regs->cp0_cause;
	209	#ifdef EF_UNUSED0
	210	gp[EF_UNUSED0] = 0;
	211	#endif
	212	}
	213
49a89efb	214	int dump_task_regs(struct task_struct tsk, elf_gregset_t regs)
71e0e556	215	{
40bc9c67	216	elf_dump_regs(*regs, task_pt_regs(tsk));
71e0e556 RB	217	return 1;
	218	}
	219
49a89efb	220	int dump_task_fpu(struct task_struct t, elf_fpregset_t fpr)
1da177e4 LT	221	{
	222	memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
	223
	224	return 1;
	225	}
	226
	227	/*
	228	* Create a kernel thread
	229	*/
b3f6df9f	230	static void __noreturn kernel_thread_helper(void arg, int (fn)(void *))
1da177e4 LT	231	{
	232	do_exit(fn(arg));
	233	}
	234
	235	long kernel_thread(int (fn)(void ), void *arg, unsigned long flags)
	236	{
	237	struct pt_regs regs;
	238
	239	memset(&regs, 0, sizeof(regs));
	240
	241	regs.regs[4] = (unsigned long) arg;
	242	regs.regs[5] = (unsigned long) fn;
	243	regs.cp0_epc = (unsigned long) kernel_thread_helper;
	244	regs.cp0_status = read_c0_status();
	245	#if defined(CONFIG_CPU_R3000) \|\| defined(CONFIG_CPU_TX39XX)
e5d77754 MR	246	regs.cp0_status = (regs.cp0_status & ~(ST0_KUP \| ST0_IEP \| ST0_IEC)) \|
e5d77754 MR	247	((regs.cp0_status & (ST0_KUC \| ST0_IEC)) << 2);
1da177e4 LT	248	#else
	249	regs.cp0_status \|= ST0_EXL;
	250	#endif
	251
	252	/* Ok, create the new process.. */
	253	return do_fork(flags \| CLONE_VM \| CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
	254	}
	255
b5943182 FBH	256	/*
	257	*
	258	*/
	259	struct mips_frame_info {
	260	void *func;
	261	unsigned long func_size;
	262	int frame_size;
	263	int pc_offset;
	264	};
dc953df1	265
c0efbb6d FBH	266	static inline int is_ra_save_ins(union mips_instruction *ip)
	267	{
	268	/* sw / sd $ra, offset($sp) */
	269	return (ip->i_format.opcode == sw_op \|\| ip->i_format.opcode == sd_op) &&
	270	ip->i_format.rs == 29 &&
	271	ip->i_format.rt == 31;
	272	}
	273
	274	static inline int is_jal_jalr_jr_ins(union mips_instruction *ip)
	275	{
	276	if (ip->j_format.opcode == jal_op)
	277	return 1;
	278	if (ip->r_format.opcode != spec_op)
	279	return 0;
	280	return ip->r_format.func == jalr_op \|\| ip->r_format.func == jr_op;
	281	}
	282
	283	static inline int is_sp_move_ins(union mips_instruction *ip)
	284	{
	285	/* addiu/daddiu sp,sp,-imm */
	286	if (ip->i_format.rs != 29 \|\| ip->i_format.rt != 29)
	287	return 0;
	288	if (ip->i_format.opcode == addiu_op \|\| ip->i_format.opcode == daddiu_op)
	289	return 1;
	290	return 0;
	291	}
	292
f66686f7	293	static int get_frame_info(struct mips_frame_info *info)
1da177e4	294	{
c0efbb6d	295	union mips_instruction *ip = info->func;
29b376ff FBH	296	unsigned max_insns = info->func_size / sizeof(union mips_instruction);
29b376ff FBH	297	unsigned i;
c0efbb6d	298
1da177e4	299	info->pc_offset = -1;
63077519	300	info->frame_size = 0;
1da177e4	301
29b376ff FBH	302	if (!ip)
	303	goto err;
	304
	305	if (max_insns == 0)
	306	max_insns = 128U; /* unknown function size */
	307	max_insns = min(128U, max_insns);
	308
c0efbb6d FBH	309	for (i = 0; i < max_insns; i++, ip++) {
	310
	311	if (is_jal_jalr_jr_ins(ip))
63077519	312	break;
0cceb4aa FBH	313	if (!info->frame_size) {
	314	if (is_sp_move_ins(ip))
	315	info->frame_size = - ip->i_format.simmediate;
	316	continue;
63077519	317	}
0cceb4aa	318	if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
63077519 AN	319	info->pc_offset =
63077519 AN	320	ip->i_format.simmediate / sizeof(long);
0cceb4aa	321	break;
1da177e4 LT	322	}
1da177e4 LT	323	}
f66686f7 AN	324	if (info->frame_size && info->pc_offset >= 0) /* nested */
	325	return 0;
	326	if (info->pc_offset < 0) /* leaf */
	327	return 1;
	328	/* prologue seems boggus... */
29b376ff	329	err:
f66686f7	330	return -1;
1da177e4 LT	331	}
1da177e4 LT	332
b5943182 FBH	333	static struct mips_frame_info schedule_mfi __read_mostly;
b5943182 FBH	334
1da177e4 LT	335	static int __init frame_info_init(void)
1da177e4 LT	336	{
b5943182	337	unsigned long size = 0;
63077519	338	#ifdef CONFIG_KALLSYMS
b5943182	339	unsigned long ofs;
b5943182	340
55b74283	341	kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs);
63077519	342	#endif
b5943182 FBH	343	schedule_mfi.func = schedule;
	344	schedule_mfi.func_size = size;
	345
	346	get_frame_info(&schedule_mfi);
6057a798 FBH	347
	348	/*
	349	* Without schedule() frame info, result given by
	350	* thread_saved_pc() and get_wchan() are not reliable.
	351	*/
b5943182	352	if (schedule_mfi.pc_offset < 0)
6057a798	353	printk("Can't analyze schedule() prologue at %p\n", schedule);
63077519	354
1da177e4 LT	355	return 0;
	356	}
	357
	358	arch_initcall(frame_info_init);
	359
	360	/*
	361	* Return saved PC of a blocked thread.
	362	*/
	363	unsigned long thread_saved_pc(struct task_struct *tsk)
	364	{
	365	struct thread_struct *t = &tsk->thread;
	366
	367	/* New born processes are a special case */
	368	if (t->reg31 == (unsigned long) ret_from_fork)
	369	return t->reg31;
b5943182	370	if (schedule_mfi.pc_offset < 0)
1da177e4	371	return 0;
b5943182	372	return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
1da177e4 LT	373	}
1da177e4 LT	374
1da177e4	375
f66686f7	376	#ifdef CONFIG_KALLSYMS
94ea09c6 DK	377	/* generic stack unwinding function */
	378	unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
	379	unsigned long *sp,
	380	unsigned long pc,
	381	unsigned long *ra)
f66686f7	382	{
f66686f7	383	struct mips_frame_info info;
f66686f7	384	unsigned long size, ofs;
4d157d5e	385	int leaf;
1924600c AN	386	extern void ret_from_irq(void);
1924600c AN	387	extern void ret_from_exception(void);
f66686f7	388
f66686f7 AN	389	if (!stack_page)
	390	return 0;
	391
1924600c AN	392	/*
	393	* If we reached the bottom of interrupt context,
	394	* return saved pc in pt_regs.
	395	*/
	396	if (pc == (unsigned long)ret_from_irq \|\|
	397	pc == (unsigned long)ret_from_exception) {
	398	struct pt_regs *regs;
	399	if (*sp >= stack_page &&
	400	sp + sizeof(regs) <= stack_page + THREAD_SIZE - 32) {
	401	regs = (struct pt_regs )sp;
	402	pc = regs->cp0_epc;
	403	if (__kernel_text_address(pc)) {
	404	*sp = regs->regs[29];
	405	*ra = regs->regs[31];
	406	return pc;
	407	}
	408	}
	409	return 0;
	410	}
55b74283	411	if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
f66686f7	412	return 0;
1fd69098	413	/*
25985edc	414	* Return ra if an exception occurred at the first instruction
1fd69098	415	*/
1924600c AN	416	if (unlikely(ofs == 0)) {
	417	pc = *ra;
	418	*ra = 0;
	419	return pc;
	420	}
f66686f7 AN	421
	422	info.func = (void *)(pc - ofs);
	423	info.func_size = ofs; /* analyze from start to ofs */
4d157d5e FBH	424	leaf = get_frame_info(&info);
4d157d5e FBH	425	if (leaf < 0)
f66686f7	426	return 0;
4d157d5e FBH	427
	428	if (*sp < stack_page \|\|
	429	*sp + info.frame_size > stack_page + THREAD_SIZE - 32)
f66686f7 AN	430	return 0;
f66686f7 AN	431
4d157d5e FBH	432	if (leaf)
	433	/*
	434	* For some extreme cases, get_frame_info() can
	435	* consider wrongly a nested function as a leaf
	436	* one. In that cases avoid to return always the
	437	* same value.
	438	*/
1924600c	439	pc = pc != ra ? ra : 0;
4d157d5e FBH	440	else
	441	pc = ((unsigned long )(sp))[info.pc_offset];
	442
	443	*sp += info.frame_size;
1924600c	444	*ra = 0;
4d157d5e	445	return __kernel_text_address(pc) ? pc : 0;
f66686f7	446	}
94ea09c6 DK	447	EXPORT_SYMBOL(unwind_stack_by_address);
	448
	449	/* used by show_backtrace() */
	450	unsigned long unwind_stack(struct task_struct task, unsigned long sp,
	451	unsigned long pc, unsigned long *ra)
	452	{
	453	unsigned long stack_page = (unsigned long)task_stack_page(task);
	454	return unwind_stack_by_address(stack_page, sp, pc, ra);
	455	}
f66686f7	456	#endif
b5943182 FBH	457
	458	/*
	459	* get_wchan - a maintenance nightmare^W^Wpain in the ass ...
	460	*/
	461	unsigned long get_wchan(struct task_struct *task)
	462	{
	463	unsigned long pc = 0;
	464	#ifdef CONFIG_KALLSYMS
	465	unsigned long sp;
1924600c	466	unsigned long ra = 0;
b5943182 FBH	467	#endif
	468
	469	if (!task \|\| task == current \|\| task->state == TASK_RUNNING)
	470	goto out;
	471	if (!task_stack_page(task))
	472	goto out;
	473
	474	pc = thread_saved_pc(task);
	475
	476	#ifdef CONFIG_KALLSYMS
	477	sp = task->thread.reg29 + schedule_mfi.frame_size;
	478
	479	while (in_sched_functions(pc))
1924600c	480	pc = unwind_stack(task, &sp, pc, &ra);
b5943182 FBH	481	#endif
	482
	483	out:
	484	return pc;
	485	}
94109102 FBH	486
	487	/*
	488	* Don't forget that the stack pointer must be aligned on a 8 bytes
	489	* boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
	490	*/
	491	unsigned long arch_align_stack(unsigned long sp)
	492	{
	493	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
	494	sp -= get_random_int() & ~PAGE_MASK;
	495
	496	return sp & ALMASK;
	497	}