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
  * Copyright (C) 2013  Imagination Technologies Ltd.
  */
 #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/init.h>
 #include <linux/completion.h>
 #include <linux/kallsyms.h>
 #include <linux/random.h>
 #include <linux/prctl.h>

 #include <asm/asm.h>
 #include <asm/bootinfo.h>
 #include <asm/cpu.h>
 #include <asm/dsp.h>
 #include <asm/fpu.h>
 #include <asm/msa.h>
 #include <asm/pgtable.h>
 #include <asm/mipsregs.h>
 #include <asm/processor.h>
 #include <asm/reg.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>
 #include <asm/irq_regs.h>

 #ifdef CONFIG_HOTPLUG_CPU
 void arch_cpu_idle_dead(void)
 {
 	/* What the heck is this check doing ? */
 	if (!cpumask_test_cpu(smp_processor_id(), &cpu_callin_map))
 		play_dead();
 }
 #endif

 asmlinkage void ret_from_fork(void);
 asmlinkage void ret_from_kernel_thread(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);
 	status |= KU_USER;
 	regs->cp0_status = status;
 	lose_fpu(0);
 	clear_thread_flag(TIF_MSA_CTX_LIVE);
 	clear_used_math();
 	init_dsp();
 	regs->cp0_epc = pc;
 	regs->regs[29] = sp;
 }

 void exit_thread(void)
 {
 }

 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
 	/*
 	 * Save any process state which is live in hardware registers to the
 	 * parent context prior to duplication. This prevents the new child
 	 * state becoming stale if the parent is preempted before copy_thread()
 	 * gets a chance to save the parent's live hardware registers to the
 	 * child context.
 	 */
 	preempt_disable();

 	if (is_msa_enabled())
 		save_msa(current);
 	else if (is_fpu_owner())
 		_save_fp(current);

 	save_dsp(current);

 	preempt_enable();

 	*dst = *src;
 	return 0;
 }

 /*
  * Copy architecture-specific thread state
  */
 int copy_thread(unsigned long clone_flags, unsigned long usp,
 	unsigned long kthread_arg, struct task_struct *p)
 {
 	struct thread_info *ti = task_thread_info(p);
 	struct pt_regs *childregs, *regs = current_pt_regs();
 	unsigned long childksp;
 	p->set_child_tid = p->clear_child_tid = NULL;

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

 	/* set up new TSS. */
 	childregs = (struct pt_regs *) childksp - 1;
 	/*  Put the stack after the struct pt_regs.  */
 	childksp = (unsigned long) childregs;
 	p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 	if (unlikely(p->flags & PF_KTHREAD)) {
 		/* kernel thread */
 		unsigned long status = p->thread.cp0_status;
 		memset(childregs, 0, sizeof(struct pt_regs));
 		ti->addr_limit = KERNEL_DS;
 		p->thread.reg16 = usp; /* fn */
 		p->thread.reg17 = kthread_arg;
 		p->thread.reg29 = childksp;
 		p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 		status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
 			 ((status & (ST0_KUC | ST0_IEC)) << 2);
 #else
 		status |= ST0_EXL;
 #endif
 		childregs->cp0_status = status;
 		return 0;
 	}

 	/* user thread */
 	*childregs = *regs;
 	childregs->regs[7] = 0; /* Clear error flag */
 	childregs->regs[2] = 0; /* Child gets zero as return value */
 	if (usp)
 		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.
 	 */
 	childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);

 	clear_tsk_thread_flag(p, TIF_USEDFPU);
 	clear_tsk_thread_flag(p, TIF_USEDMSA);
 	clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);

 #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;
 }

 #ifdef CONFIG_CC_STACKPROTECTOR
 #include <linux/stackprotector.h>
 unsigned long __stack_chk_guard __read_mostly;
 EXPORT_SYMBOL(__stack_chk_guard);
 #endif

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

 #define J_TARGET(pc,target)	\
 		(((unsigned long)(pc) & 0xf0000000) | ((target) << 2))

 static inline int is_ra_save_ins(union mips_instruction *ip)
 {
 #ifdef CONFIG_CPU_MICROMIPS
 	union mips_instruction mmi;

 	/*
 	 * swsp ra,offset
 	 * swm16 reglist,offset(sp)
 	 * swm32 reglist,offset(sp)
 	 * sw32 ra,offset(sp)
 	 * jradiussp - NOT SUPPORTED
 	 *
 	 * microMIPS is way more fun...
 	 */
 	if (mm_insn_16bit(ip->halfword[0])) {
 		mmi.word = (ip->halfword[0] << 16);
 		return (mmi.mm16_r5_format.opcode == mm_swsp16_op &&
 			mmi.mm16_r5_format.rt == 31) ||
 		       (mmi.mm16_m_format.opcode == mm_pool16c_op &&
 			mmi.mm16_m_format.func == mm_swm16_op);
 	}
 	else {
 		mmi.halfword[0] = ip->halfword[1];
 		mmi.halfword[1] = ip->halfword[0];
 		return (mmi.mm_m_format.opcode == mm_pool32b_op &&
 			mmi.mm_m_format.rd > 9 &&
 			mmi.mm_m_format.base == 29 &&
 			mmi.mm_m_format.func == mm_swm32_func) ||
 		       (mmi.i_format.opcode == mm_sw32_op &&
 			mmi.i_format.rs == 29 &&
 			mmi.i_format.rt == 31);
 	}
 #else
 	/* 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;
 #endif
 }

 static inline int is_jump_ins(union mips_instruction *ip)
 {
 #ifdef CONFIG_CPU_MICROMIPS
 	/*
 	 * jr16,jrc,jalr16,jalr16
 	 * jal
 	 * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
 	 * jraddiusp - NOT SUPPORTED
 	 *
 	 * microMIPS is kind of more fun...
 	 */
 	union mips_instruction mmi;

 	mmi.word = (ip->halfword[0] << 16);

 	if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
 	    (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
 	    ip->j_format.opcode == mm_jal32_op)
 		return 1;
 	if (ip->r_format.opcode != mm_pool32a_op ||
 			ip->r_format.func != mm_pool32axf_op)
 		return 0;
 	return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
 #else
 	if (ip->j_format.opcode == j_op)
 		return 1;
 	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;
 #endif
 }

 static inline int is_sp_move_ins(union mips_instruction *ip)
 {
 #ifdef CONFIG_CPU_MICROMIPS
 	/*
 	 * addiusp -imm
 	 * addius5 sp,-imm
 	 * addiu32 sp,sp,-imm
 	 * jradiussp - NOT SUPPORTED
 	 *
 	 * microMIPS is not more fun...
 	 */
 	if (mm_insn_16bit(ip->halfword[0])) {
 		union mips_instruction mmi;

 		mmi.word = (ip->halfword[0] << 16);
 		return (mmi.mm16_r3_format.opcode == mm_pool16d_op &&
 			mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
 		       (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
 			mmi.mm16_r5_format.rt == 29);
 	}
 	return ip->mm_i_format.opcode == mm_addiu32_op &&
 	       ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;
 #else
 	/* 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;
 #endif
 	return 0;
 }

 static int get_frame_info(struct mips_frame_info *info)
 {
 #ifdef CONFIG_CPU_MICROMIPS
 	union mips_instruction *ip = (void *) (((char *) info->func) - 1);
 #else
 	union mips_instruction *ip = info->func;
 #endif
 	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_jump_ins(ip))
 			break;
 		if (!info->frame_size) {
 			if (is_sp_move_ins(ip))
 			{
 #ifdef CONFIG_CPU_MICROMIPS
 				if (mm_insn_16bit(ip->halfword[0]))
 				{
 					unsigned short tmp;

 					if (ip->halfword[0] & mm_addiusp_func)
 					{
 						tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
 						info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
 					} else {
 						tmp = (ip->halfword[0] >> 1);
 						info->frame_size = -(signed short)(tmp & 0xf);
 					}
 					ip = (void *) &ip->halfword[1];
 					ip--;
 				} else
 #endif
 				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 bogus... */
 err:
 	return -1;
 }

 static struct mips_frame_info schedule_mfi __read_mostly;

 #ifdef CONFIG_KALLSYMS
 static unsigned long get___schedule_addr(void)
 {
 	return kallsyms_lookup_name("__schedule");
 }
 #else
 static unsigned long get___schedule_addr(void)
 {
 	union mips_instruction *ip = (void *)schedule;
 	int max_insns = 8;
 	int i;

 	for (i = 0; i < max_insns; i++, ip++) {
 		if (ip->j_format.opcode == j_op)
 			return J_TARGET(ip, ip->j_format.target);
 	}
 	return 0;
 }
 #endif

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

 	addr = get___schedule_addr();
 	if (!addr)
 		addr = (unsigned long)schedule;

 #ifdef CONFIG_KALLSYMS
 	kallsyms_lookup_size_offset(addr, &size, &ofs);
 #endif
 	schedule_mfi.func = (void *)addr;
 	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 (!user_mode(regs) && __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;
 }

 static void arch_dump_stack(void *info)
 {
 	struct pt_regs *regs;

 	regs = get_irq_regs();

 	if (regs)
 		show_regs(regs);

 	dump_stack();
 }

 void arch_trigger_all_cpu_backtrace(bool include_self)
 {
 	smp_call_function(arch_dump_stack, NULL, 1);
 }

 int mips_get_process_fp_mode(struct task_struct *task)
 {
 	int value = 0;

 	if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
 		value |= PR_FP_MODE_FR;
 	if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
 		value |= PR_FP_MODE_FRE;

 	return value;
 }

 static void prepare_for_fp_mode_switch(void *info)
 {
 	struct mm_struct *mm = info;

 	if (current->mm == mm)
 		lose_fpu(1);
 }

 int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
 {
 	const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
 	struct task_struct *t;
 	int max_users;

 	/* Check the value is valid */
 	if (value & ~known_bits)
 		return -EOPNOTSUPP;

 	/* Avoid inadvertently triggering emulation */
 	if ((value & PR_FP_MODE_FR) && cpu_has_fpu &&
 	    !(current_cpu_data.fpu_id & MIPS_FPIR_F64))
 		return -EOPNOTSUPP;
 	if ((value & PR_FP_MODE_FRE) && cpu_has_fpu && !cpu_has_fre)
 		return -EOPNOTSUPP;

 	/* FR = 0 not supported in MIPS R6 */
 	if (!(value & PR_FP_MODE_FR) && cpu_has_fpu && cpu_has_mips_r6)
 		return -EOPNOTSUPP;

 	/* Proceed with the mode switch */
 	preempt_disable();

 	/* Save FP & vector context, then disable FPU & MSA */
 	if (task->signal == current->signal)
 		lose_fpu(1);

 	/* Prevent any threads from obtaining live FP context */
 	atomic_set(&task->mm->context.fp_mode_switching, 1);
 	smp_mb__after_atomic();

 	/*
 	 * If there are multiple online CPUs then force any which are running
 	 * threads in this process to lose their FPU context, which they can't
 	 * regain until fp_mode_switching is cleared later.
 	 */
 	if (num_online_cpus() > 1) {
 		/* No need to send an IPI for the local CPU */
 		max_users = (task->mm == current->mm) ? 1 : 0;

 		if (atomic_read(&current->mm->mm_users) > max_users)
 			smp_call_function(prepare_for_fp_mode_switch,
 					  (void *)current->mm, 1);
 	}

 	/*
 	 * There are now no threads of the process with live FP context, so it
 	 * is safe to proceed with the FP mode switch.
 	 */
 	for_each_thread(task, t) {
 		/* Update desired FP register width */
 		if (value & PR_FP_MODE_FR) {
 			clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 		} else {
 			set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 			clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
 		}

 		/* Update desired FP single layout */
 		if (value & PR_FP_MODE_FRE)
 			set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 		else
 			clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 	}

 	/* Allow threads to use FP again */
 	atomic_set(&task->mm->context.fp_mode_switching, 0);
 	preempt_enable();

 	return 0;
 }
	/*
	* 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
	* Copyright (C) 2013 Imagination Technologies Ltd.
	*/
	#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/init.h>
	#include <linux/completion.h>
	#include <linux/kallsyms.h>
	#include <linux/random.h>
	#include <linux/prctl.h>

	#include <asm/asm.h>
	#include <asm/bootinfo.h>
	#include <asm/cpu.h>
	#include <asm/dsp.h>
	#include <asm/fpu.h>
	#include <asm/msa.h>
	#include <asm/pgtable.h>
	#include <asm/mipsregs.h>
	#include <asm/processor.h>
	#include <asm/reg.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>
	#include <asm/irq_regs.h>

	#ifdef CONFIG_HOTPLUG_CPU
	void arch_cpu_idle_dead(void)
	{
	/* What the heck is this check doing ? */
	if (!cpumask_test_cpu(smp_processor_id(), &cpu_callin_map))
	play_dead();
	}
	#endif

	asmlinkage void ret_from_fork(void);
	asmlinkage void ret_from_kernel_thread(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);
	status \|= KU_USER;
	regs->cp0_status = status;
	lose_fpu(0);
	clear_thread_flag(TIF_MSA_CTX_LIVE);
	clear_used_math();
	init_dsp();
	regs->cp0_epc = pc;
	regs->regs[29] = sp;
	}

	void exit_thread(void)
	{
	}

	int arch_dup_task_struct(struct task_struct dst, struct task_struct src)
	{
	/*
	* Save any process state which is live in hardware registers to the
	* parent context prior to duplication. This prevents the new child
	* state becoming stale if the parent is preempted before copy_thread()
	* gets a chance to save the parent's live hardware registers to the
	* child context.
	*/
	preempt_disable();

	if (is_msa_enabled())
	save_msa(current);
	else if (is_fpu_owner())
	_save_fp(current);

	save_dsp(current);

	preempt_enable();

	dst = src;
	return 0;
	}

	/*
	* Copy architecture-specific thread state
	*/
	int copy_thread(unsigned long clone_flags, unsigned long usp,
	unsigned long kthread_arg, struct task_struct *p)
	{
	struct thread_info *ti = task_thread_info(p);
	struct pt_regs childregs, regs = current_pt_regs();
	unsigned long childksp;
	p->set_child_tid = p->clear_child_tid = NULL;

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

	/* set up new TSS. */
	childregs = (struct pt_regs *) childksp - 1;
	/* Put the stack after the struct pt_regs. */
	childksp = (unsigned long) childregs;
	p->thread.cp0_status = read_c0_status() & ~(ST0_CU2\|ST0_CU1);
	if (unlikely(p->flags & PF_KTHREAD)) {
	/* kernel thread */
	unsigned long status = p->thread.cp0_status;
	memset(childregs, 0, sizeof(struct pt_regs));
	ti->addr_limit = KERNEL_DS;
	p->thread.reg16 = usp; /* fn */
	p->thread.reg17 = kthread_arg;
	p->thread.reg29 = childksp;
	p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
	#if defined(CONFIG_CPU_R3000) \|\| defined(CONFIG_CPU_TX39XX)
	status = (status & ~(ST0_KUP \| ST0_IEP \| ST0_IEC)) \|
	((status & (ST0_KUC \| ST0_IEC)) << 2);
	#else
	status \|= ST0_EXL;
	#endif
	childregs->cp0_status = status;
	return 0;
	}

	/* user thread */
	childregs = regs;
	childregs->regs[7] = 0; /* Clear error flag */
	childregs->regs[2] = 0; /* Child gets zero as return value */
	if (usp)
	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.
	*/
	childregs->cp0_status &= ~(ST0_CU2\|ST0_CU1);

	clear_tsk_thread_flag(p, TIF_USEDFPU);
	clear_tsk_thread_flag(p, TIF_USEDMSA);
	clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);

	#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;
	}

	#ifdef CONFIG_CC_STACKPROTECTOR
	#include <linux/stackprotector.h>
	unsigned long __stack_chk_guard __read_mostly;
	EXPORT_SYMBOL(__stack_chk_guard);
	#endif

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

	#define J_TARGET(pc,target) \
	(((unsigned long)(pc) & 0xf0000000) \| ((target) << 2))

	static inline int is_ra_save_ins(union mips_instruction *ip)
	{
	#ifdef CONFIG_CPU_MICROMIPS
	union mips_instruction mmi;

	/*
	* swsp ra,offset
	* swm16 reglist,offset(sp)
	* swm32 reglist,offset(sp)
	* sw32 ra,offset(sp)
	* jradiussp - NOT SUPPORTED
	*
	* microMIPS is way more fun...
	*/
	if (mm_insn_16bit(ip->halfword[0])) {
	mmi.word = (ip->halfword[0] << 16);
	return (mmi.mm16_r5_format.opcode == mm_swsp16_op &&
	mmi.mm16_r5_format.rt == 31) \|\|
	(mmi.mm16_m_format.opcode == mm_pool16c_op &&
	mmi.mm16_m_format.func == mm_swm16_op);
	}
	else {
	mmi.halfword[0] = ip->halfword[1];
	mmi.halfword[1] = ip->halfword[0];
	return (mmi.mm_m_format.opcode == mm_pool32b_op &&
	mmi.mm_m_format.rd > 9 &&
	mmi.mm_m_format.base == 29 &&
	mmi.mm_m_format.func == mm_swm32_func) \|\|
	(mmi.i_format.opcode == mm_sw32_op &&
	mmi.i_format.rs == 29 &&
	mmi.i_format.rt == 31);
	}
	#else
	/* 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;
	#endif
	}

	static inline int is_jump_ins(union mips_instruction *ip)
	{
	#ifdef CONFIG_CPU_MICROMIPS
	/*
	* jr16,jrc,jalr16,jalr16
	* jal
	* jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
	* jraddiusp - NOT SUPPORTED
	*
	* microMIPS is kind of more fun...
	*/
	union mips_instruction mmi;

	mmi.word = (ip->halfword[0] << 16);

	if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
	(mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) \|\|
	ip->j_format.opcode == mm_jal32_op)
	return 1;
	if (ip->r_format.opcode != mm_pool32a_op \|\|
	ip->r_format.func != mm_pool32axf_op)
	return 0;
	return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
	#else
	if (ip->j_format.opcode == j_op)
	return 1;
	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;
	#endif
	}

	static inline int is_sp_move_ins(union mips_instruction *ip)
	{
	#ifdef CONFIG_CPU_MICROMIPS
	/*
	* addiusp -imm
	* addius5 sp,-imm
	* addiu32 sp,sp,-imm
	* jradiussp - NOT SUPPORTED
	*
	* microMIPS is not more fun...
	*/
	if (mm_insn_16bit(ip->halfword[0])) {
	union mips_instruction mmi;

	mmi.word = (ip->halfword[0] << 16);
	return (mmi.mm16_r3_format.opcode == mm_pool16d_op &&
	mmi.mm16_r3_format.simmediate && mm_addiusp_func) \|\|
	(mmi.mm16_r5_format.opcode == mm_pool16d_op &&
	mmi.mm16_r5_format.rt == 29);
	}
	return ip->mm_i_format.opcode == mm_addiu32_op &&
	ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;
	#else
	/* 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;
	#endif
	return 0;
	}

	static int get_frame_info(struct mips_frame_info *info)
	{
	#ifdef CONFIG_CPU_MICROMIPS
	union mips_instruction ip = (void ) (((char *) info->func) - 1);
	#else
	union mips_instruction *ip = info->func;
	#endif
	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_jump_ins(ip))
	break;
	if (!info->frame_size) {
	if (is_sp_move_ins(ip))
	{
	#ifdef CONFIG_CPU_MICROMIPS
	if (mm_insn_16bit(ip->halfword[0]))
	{
	unsigned short tmp;

	if (ip->halfword[0] & mm_addiusp_func)
	{
	tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
	info->frame_size = -(signed short)(tmp \| ((tmp & 0x100) ? 0xfe00 : 0));
	} else {
	tmp = (ip->halfword[0] >> 1);
	info->frame_size = -(signed short)(tmp & 0xf);
	}
	ip = (void *) &ip->halfword[1];
	ip--;
	} else
	#endif
	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 bogus... */
	err:
	return -1;
	}

	static struct mips_frame_info schedule_mfi __read_mostly;

	#ifdef CONFIG_KALLSYMS
	static unsigned long get___schedule_addr(void)
	{
	return kallsyms_lookup_name("__schedule");
	}
	#else
	static unsigned long get___schedule_addr(void)
	{
	union mips_instruction ip = (void )schedule;
	int max_insns = 8;
	int i;

	for (i = 0; i < max_insns; i++, ip++) {
	if (ip->j_format.opcode == j_op)
	return J_TARGET(ip, ip->j_format.target);
	}
	return 0;
	}
	#endif

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

	addr = get___schedule_addr();
	if (!addr)
	addr = (unsigned long)schedule;

	#ifdef CONFIG_KALLSYMS
	kallsyms_lookup_size_offset(addr, &size, &ofs);
	#endif
	schedule_mfi.func = (void *)addr;
	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 (!user_mode(regs) && __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;
	}

	static void arch_dump_stack(void *info)
	{
	struct pt_regs *regs;

	regs = get_irq_regs();

	if (regs)
	show_regs(regs);

	dump_stack();
	}

	void arch_trigger_all_cpu_backtrace(bool include_self)
	{
	smp_call_function(arch_dump_stack, NULL, 1);
	}

	int mips_get_process_fp_mode(struct task_struct *task)
	{
	int value = 0;

	if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
	value \|= PR_FP_MODE_FR;
	if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
	value \|= PR_FP_MODE_FRE;

	return value;
	}

	static void prepare_for_fp_mode_switch(void *info)
	{
	struct mm_struct *mm = info;

	if (current->mm == mm)
	lose_fpu(1);
	}

	int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
	{
	const unsigned int known_bits = PR_FP_MODE_FR \| PR_FP_MODE_FRE;
	struct task_struct *t;
	int max_users;

	/* Check the value is valid */
	if (value & ~known_bits)
	return -EOPNOTSUPP;

	/* Avoid inadvertently triggering emulation */
	if ((value & PR_FP_MODE_FR) && cpu_has_fpu &&
	!(current_cpu_data.fpu_id & MIPS_FPIR_F64))
	return -EOPNOTSUPP;
	if ((value & PR_FP_MODE_FRE) && cpu_has_fpu && !cpu_has_fre)
	return -EOPNOTSUPP;

	/* FR = 0 not supported in MIPS R6 */
	if (!(value & PR_FP_MODE_FR) && cpu_has_fpu && cpu_has_mips_r6)
	return -EOPNOTSUPP;

	/* Proceed with the mode switch */
	preempt_disable();

	/* Save FP & vector context, then disable FPU & MSA */
	if (task->signal == current->signal)
	lose_fpu(1);

	/* Prevent any threads from obtaining live FP context */
	atomic_set(&task->mm->context.fp_mode_switching, 1);
	smp_mb__after_atomic();

	/*
	* If there are multiple online CPUs then force any which are running
	* threads in this process to lose their FPU context, which they can't
	* regain until fp_mode_switching is cleared later.
	*/
	if (num_online_cpus() > 1) {
	/* No need to send an IPI for the local CPU */
	max_users = (task->mm == current->mm) ? 1 : 0;

	if (atomic_read(&current->mm->mm_users) > max_users)
	smp_call_function(prepare_for_fp_mode_switch,
	(void *)current->mm, 1);
	}

	/*
	* There are now no threads of the process with live FP context, so it
	* is safe to proceed with the FP mode switch.
	*/
	for_each_thread(task, t) {
	/* Update desired FP register width */
	if (value & PR_FP_MODE_FR) {
	clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
	} else {
	set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
	clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
	}

	/* Update desired FP single layout */
	if (value & PR_FP_MODE_FRE)
	set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
	else
	clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
	}

	/* Allow threads to use FP again */
	atomic_set(&task->mm->context.fp_mode_switching, 0);
	preempt_enable();

	return 0;
	}