text: /*
   * 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;
  	clear_used_math();
  	clear_fpu_owner();
  	init_dsp();
  	clear_thread_flag(TIF_USEDMSA);
  	clear_thread_flag(TIF_MSA_CTX_LIVE);
  	disable_msa();
  	regs->cp0_epc = pc;
  	regs->regs[29] = sp;
  }
  
  void exit_thread(void)
  {
  }
  
  void flush_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 boggus... */
  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;
  }
  
  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;
  	unsigned long switch_count;
  	struct task_struct *t;
  
  	/* Check the value is valid */
  	if (value & ~known_bits)
  		return -EOPNOTSUPP;
  
  	/* Avoid inadvertently triggering emulation */
  	if ((value & PR_FP_MODE_FR) && raw_cpu_has_fpu &&
  	    !(raw_current_cpu_data.fpu_id & MIPS_FPIR_F64))
  		return -EOPNOTSUPP;
  	if ((value & PR_FP_MODE_FRE) && raw_cpu_has_fpu && !cpu_has_fre)
  		return -EOPNOTSUPP;
  
  	/* FR = 0 not supported in MIPS R6 */
  	if (!(value & PR_FP_MODE_FR) && raw_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 wait until all threads whose
  	 * FP mode is about to change have been context switched. This approach
  	 * allows us to only worry about whether an FP mode switch is in
  	 * progress when FP is first used in a tasks time slice. Pretty much all
  	 * of the mode switch overhead can thus be confined to cases where mode
  	 * switches are actually occuring. That is, to here. However for the
  	 * thread performing the mode switch it may take a while...
  	 */
  	if (num_online_cpus() > 1) {
  		spin_lock_irq(&task->sighand->siglock);
  
  		for_each_thread(task, t) {
  			if (t == current)
  				continue;
  
  			switch_count = t->nvcsw + t->nivcsw;
  
  			do {
  				spin_unlock_irq(&task->sighand->siglock);
  				cond_resched();
  				spin_lock_irq(&task->sighand->siglock);
  			} while ((t->nvcsw + t->nivcsw) == switch_count);
  		}
  
  		spin_unlock_irq(&task->sighand->siglock);
  	}
  
  	/*
  	 * 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;
  }
  