arch/mips/kernel/process.c - kernel/msm-4.9 - Gitiles

 /*
  * 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/abi.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>
 #ifdef CONFIG_MIPS_MT_SMTC
 #include <asm/mipsmtregs.h>
 extern void smtc_idle_loop_hook(void);
 #endif /* CONFIG_MIPS_MT_SMTC */

 /*
  * 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)
  */
 ATTRIB_NORET void cpu_idle(void)
 {
 	/* endless idle loop with no priority at all */
 	while (1) {
 		while (!need_resched()) {
 #ifdef CONFIG_MIPS_MT_SMTC
 			smtc_idle_loop_hook();
 #endif /* CONFIG_MIPS_MT_SMTC */
 			if (cpu_wait)
 				(*cpu_wait)();
 		}
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
 	}
 }

 /*
  * Native o32 and N64 ABI without DSP ASE
  */
 struct mips_abi mips_abi = {
 	.do_signal	= do_signal,
 #ifdef CONFIG_TRAD_SIGNALS
 	.setup_frame	= setup_frame,
 #endif
 	.setup_rt_frame	= setup_rt_frame
 };

 #ifdef CONFIG_MIPS32_O32
 /*
  * o32 compatibility on 64-bit kernels, without DSP ASE
  */
 struct mips_abi mips_abi_32 = {
 	.do_signal	= do_signal32,
 	.setup_frame	= setup_frame_32,
 	.setup_rt_frame	= setup_rt_frame_32
 };
 #endif /* CONFIG_MIPS32_O32 */

 #ifdef CONFIG_MIPS32_N32
 /*
  * N32 on 64-bit kernels, without DSP ASE
  */
 struct mips_abi mips_abi_n32 = {
 	.do_signal	= do_signal,
 	.setup_rt_frame	= setup_rt_frame_n32
 };
 #endif /* CONFIG_MIPS32_N32 */

 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();
 	lose_fpu();
 	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
  */
 ATTRIB_NORET void 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);
 }

 static struct mips_frame_info {
 	void *func;
 	unsigned long func_size;
 	int frame_size;
 	int pc_offset;
 } *schedule_frame, mfinfo[64];
 static int mfinfo_num;

 static int __init get_frame_info(struct mips_frame_info *info)
 {
 	int i;
 	void *func = info->func;
 	union mips_instruction *ip = (union mips_instruction *)func;
 	info->pc_offset = -1;
 	info->frame_size = 0;
 	for (i = 0; i < 128; i++, ip++) {
 		/* if jal, jalr, jr, stop. */
 		if (ip->j_format.opcode == jal_op ||
 		    (ip->r_format.opcode == spec_op &&
 		     (ip->r_format.func == jalr_op ||
 		      ip->r_format.func == jr_op)))
 			break;

 		if (info->func_size && i >= info->func_size / 4)
 			break;
 		if (
 #ifdef CONFIG_32BIT
 		    ip->i_format.opcode == addiu_op &&
 #endif
 #ifdef CONFIG_64BIT
 		    ip->i_format.opcode == daddiu_op &&
 #endif
 		    ip->i_format.rs == 29 &&
 		    ip->i_format.rt == 29) {
 			/* addiu/daddiu sp,sp,-imm */
 			if (info->frame_size)
 				continue;
 			info->frame_size = - ip->i_format.simmediate;
 		}

 		if (
 #ifdef CONFIG_32BIT
 		    ip->i_format.opcode == sw_op &&
 #endif
 #ifdef CONFIG_64BIT
 		    ip->i_format.opcode == sd_op &&
 #endif
 		    ip->i_format.rs == 29 &&
 		    ip->i_format.rt == 31) {
 			/* sw / sd $ra, offset($sp) */
 			if (info->pc_offset != -1)
 				continue;
 			info->pc_offset =
 				ip->i_format.simmediate / sizeof(long);
 		}
 	}
 	if (info->pc_offset == -1 || info->frame_size == 0) {
 		if (func == schedule)
 			printk("Can't analyze prologue code at %p\n", func);
 		info->pc_offset = -1;
 		info->frame_size = 0;
 	}

 	return 0;
 }

 static int __init frame_info_init(void)
 {
 	int i;
 #ifdef CONFIG_KALLSYMS
 	char *modname;
 	char namebuf[KSYM_NAME_LEN + 1];
 	unsigned long start, size, ofs;
 	extern char __sched_text_start[], __sched_text_end[];
 	extern char __lock_text_start[], __lock_text_end[];

 	start = (unsigned long)__sched_text_start;
 	for (i = 0; i < ARRAY_SIZE(mfinfo); i++) {
 		if (start == (unsigned long)schedule)
 			schedule_frame = &mfinfo[i];
 		if (!kallsyms_lookup(start, &size, &ofs, &modname, namebuf))
 			break;
 		mfinfo[i].func = (void *)(start + ofs);
 		mfinfo[i].func_size = size;
 		start += size - ofs;
 		if (start >= (unsigned long)__lock_text_end)
 			break;
 		if (start == (unsigned long)__sched_text_end)
 			start = (unsigned long)__lock_text_start;
 	}
 #else
 	mfinfo[0].func = schedule;
 	schedule_frame = &mfinfo[0];
 #endif
 	for (i = 0; i < ARRAY_SIZE(mfinfo) && mfinfo[i].func; i++)
 		get_frame_info(&mfinfo[i]);

 	mfinfo_num = i;
 	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_frame || schedule_frame->pc_offset < 0)
 		return 0;
 	return ((unsigned long *)t->reg29)[schedule_frame->pc_offset];
 }

 /* get_wchan - a maintenance nightmare^W^Wpain in the ass ...  */
 unsigned long get_wchan(struct task_struct *p)
 {
 	unsigned long stack_page;
 	unsigned long pc;
 #ifdef CONFIG_KALLSYMS
 	unsigned long frame;
 #endif

 	if (!p || p == current || p->state == TASK_RUNNING)
 		return 0;

 	stack_page = (unsigned long)task_stack_page(p);
 	if (!stack_page || !mfinfo_num)
 		return 0;

 	pc = thread_saved_pc(p);
 #ifdef CONFIG_KALLSYMS
 	if (!in_sched_functions(pc))
 		return pc;

 	frame = p->thread.reg29 + schedule_frame->frame_size;
 	do {
 		int i;

 		if (frame < stack_page || frame > stack_page + THREAD_SIZE - 32)
 			return 0;

 		for (i = mfinfo_num - 1; i >= 0; i--) {
 			if (pc >= (unsigned long) mfinfo[i].func)
 				break;
 		}
 		if (i < 0)
 			break;

 		pc = ((unsigned long *)frame)[mfinfo[i].pc_offset];
 		if (!mfinfo[i].frame_size)
 			break;
 		frame += mfinfo[i].frame_size;
 	} while (in_sched_functions(pc));
 #endif

 	return pc;
 }
	/*
	* 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/abi.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>
	#ifdef CONFIG_MIPS_MT_SMTC
	#include <asm/mipsmtregs.h>
	extern void smtc_idle_loop_hook(void);
	#endif /* CONFIG_MIPS_MT_SMTC */

	/*
	* 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)
	*/
	ATTRIB_NORET void cpu_idle(void)
	{
	/* endless idle loop with no priority at all */
	while (1) {
	while (!need_resched()) {
	#ifdef CONFIG_MIPS_MT_SMTC
	smtc_idle_loop_hook();
	#endif /* CONFIG_MIPS_MT_SMTC */
	if (cpu_wait)
	(*cpu_wait)();
	}
	preempt_enable_no_resched();
	schedule();
	preempt_disable();
	}
	}

	/*
	* Native o32 and N64 ABI without DSP ASE
	*/
	struct mips_abi mips_abi = {
	.do_signal = do_signal,
	#ifdef CONFIG_TRAD_SIGNALS
	.setup_frame = setup_frame,
	#endif
	.setup_rt_frame = setup_rt_frame
	};

	#ifdef CONFIG_MIPS32_O32
	/*
	* o32 compatibility on 64-bit kernels, without DSP ASE
	*/
	struct mips_abi mips_abi_32 = {
	.do_signal = do_signal32,
	.setup_frame = setup_frame_32,
	.setup_rt_frame = setup_rt_frame_32
	};
	#endif /* CONFIG_MIPS32_O32 */

	#ifdef CONFIG_MIPS32_N32
	/*
	* N32 on 64-bit kernels, without DSP ASE
	*/
	struct mips_abi mips_abi_n32 = {
	.do_signal = do_signal,
	.setup_rt_frame = setup_rt_frame_n32
	};
	#endif /* CONFIG_MIPS32_N32 */

	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();
	lose_fpu();
	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
	*/
	ATTRIB_NORET void 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);
	}

	static struct mips_frame_info {
	void *func;
	unsigned long func_size;
	int frame_size;
	int pc_offset;
	} *schedule_frame, mfinfo[64];
	static int mfinfo_num;

	static int __init get_frame_info(struct mips_frame_info *info)
	{
	int i;
	void *func = info->func;
	union mips_instruction ip = (union mips_instruction )func;
	info->pc_offset = -1;
	info->frame_size = 0;
	for (i = 0; i < 128; i++, ip++) {
	/* if jal, jalr, jr, stop. */
	if (ip->j_format.opcode == jal_op \|\|
	(ip->r_format.opcode == spec_op &&
	(ip->r_format.func == jalr_op \|\|
	ip->r_format.func == jr_op)))
	break;

	if (info->func_size && i >= info->func_size / 4)
	break;
	if (
	#ifdef CONFIG_32BIT
	ip->i_format.opcode == addiu_op &&
	#endif
	#ifdef CONFIG_64BIT
	ip->i_format.opcode == daddiu_op &&
	#endif
	ip->i_format.rs == 29 &&
	ip->i_format.rt == 29) {
	/* addiu/daddiu sp,sp,-imm */
	if (info->frame_size)
	continue;
	info->frame_size = - ip->i_format.simmediate;
	}

	if (
	#ifdef CONFIG_32BIT
	ip->i_format.opcode == sw_op &&
	#endif
	#ifdef CONFIG_64BIT
	ip->i_format.opcode == sd_op &&
	#endif
	ip->i_format.rs == 29 &&
	ip->i_format.rt == 31) {
	/* sw / sd $ra, offset($sp) */
	if (info->pc_offset != -1)
	continue;
	info->pc_offset =
	ip->i_format.simmediate / sizeof(long);
	}
	}
	if (info->pc_offset == -1 \|\| info->frame_size == 0) {
	if (func == schedule)
	printk("Can't analyze prologue code at %p\n", func);
	info->pc_offset = -1;
	info->frame_size = 0;
	}

	return 0;
	}

	static int __init frame_info_init(void)
	{
	int i;
	#ifdef CONFIG_KALLSYMS
	char *modname;
	char namebuf[KSYM_NAME_LEN + 1];
	unsigned long start, size, ofs;
	extern char __sched_text_start[], __sched_text_end[];
	extern char __lock_text_start[], __lock_text_end[];

	start = (unsigned long)__sched_text_start;
	for (i = 0; i < ARRAY_SIZE(mfinfo); i++) {
	if (start == (unsigned long)schedule)
	schedule_frame = &mfinfo[i];
	if (!kallsyms_lookup(start, &size, &ofs, &modname, namebuf))
	break;
	mfinfo[i].func = (void *)(start + ofs);
	mfinfo[i].func_size = size;
	start += size - ofs;
	if (start >= (unsigned long)__lock_text_end)
	break;
	if (start == (unsigned long)__sched_text_end)
	start = (unsigned long)__lock_text_start;
	}
	#else
	mfinfo[0].func = schedule;
	schedule_frame = &mfinfo[0];
	#endif
	for (i = 0; i < ARRAY_SIZE(mfinfo) && mfinfo[i].func; i++)
	get_frame_info(&mfinfo[i]);

	mfinfo_num = i;
	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_frame \|\| schedule_frame->pc_offset < 0)
	return 0;
	return ((unsigned long *)t->reg29)[schedule_frame->pc_offset];
	}

	/* get_wchan - a maintenance nightmare^W^Wpain in the ass ... */
	unsigned long get_wchan(struct task_struct *p)
	{
	unsigned long stack_page;
	unsigned long pc;
	#ifdef CONFIG_KALLSYMS
	unsigned long frame;
	#endif

	if (!p \|\| p == current \|\| p->state == TASK_RUNNING)
	return 0;

	stack_page = (unsigned long)task_stack_page(p);
	if (!stack_page \|\| !mfinfo_num)
	return 0;

	pc = thread_saved_pc(p);
	#ifdef CONFIG_KALLSYMS
	if (!in_sched_functions(pc))
	return pc;

	frame = p->thread.reg29 + schedule_frame->frame_size;
	do {
	int i;

	if (frame < stack_page \|\| frame > stack_page + THREAD_SIZE - 32)
	return 0;

	for (i = mfinfo_num - 1; i >= 0; i--) {
	if (pc >= (unsigned long) mfinfo[i].func)
	break;
	}
	if (i < 0)
	break;

	pc = ((unsigned long *)frame)[mfinfo[i].pc_offset];
	if (!mfinfo[i].frame_size)
	break;
	frame += mfinfo[i].frame_size;
	} while (in_sched_functions(pc));
	#endif

	return pc;
	}