arch/mn10300/kernel/process.c

   1 /* MN10300  Process handling code
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11 #include <linux/module.h>
  12 #include <linux/errno.h>
  13 #include <linux/sched.h>
  14 #include <linux/kernel.h>
  15 #include <linux/mm.h>
  16 #include <linux/smp.h>
  17 #include <linux/stddef.h>
  18 #include <linux/unistd.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/user.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/delay.h>
  23 #include <linux/reboot.h>
  24 #include <linux/percpu.h>
  25 #include <linux/err.h>
  26 #include <linux/fs.h>
  27 #include <linux/slab.h>
  28 #include <linux/rcupdate.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/pgtable.h>
  31 #include <asm/io.h>
  32 #include <asm/processor.h>
  33 #include <asm/mmu_context.h>
  34 #include <asm/fpu.h>
  35 #include <asm/reset-regs.h>
  36 #include <asm/gdb-stub.h>
  37 #include "internal.h"
  38
  39 /*
  40  * power management idle function, if any..
  41  */
  42 void (*pm_idle)(void);
  43 EXPORT_SYMBOL(pm_idle);
  44
  45 /*
  46  * return saved PC of a blocked thread.
  47  */
  48 unsigned long thread_saved_pc(struct task_struct *tsk)
  49 {
  50         return ((unsigned long *) tsk->thread.sp)[3];
  51 }
  52
  53 /*
  54  * power off function, if any
  55  */
  56 void (*pm_power_off)(void);
  57 EXPORT_SYMBOL(pm_power_off);
  58
  59 #if !defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
  60 /*
  61  * we use this if we don't have any better idle routine
  62  */
  63 static void default_idle(void)
  64 {
  65         local_irq_disable();
  66         if (!need_resched())
  67                 safe_halt();
  68         else
  69                 local_irq_enable();
  70 }
  71
  72 #else /* !CONFIG_SMP || CONFIG_HOTPLUG_CPU  */
  73 /*
  74  * On SMP it's slightly faster (but much more power-consuming!)
  75  * to poll the ->work.need_resched flag instead of waiting for the
  76  * cross-CPU IPI to arrive. Use this option with caution.
  77  */
  78 static inline void poll_idle(void)
  79 {
  80         int oldval;
  81
  82         local_irq_enable();
  83
  84         /*
  85          * Deal with another CPU just having chosen a thread to
  86          * run here:
  87          */
  88         oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
  89
  90         if (!oldval) {
  91                 set_thread_flag(TIF_POLLING_NRFLAG);
  92                 while (!need_resched())
  93                         cpu_relax();
  94                 clear_thread_flag(TIF_POLLING_NRFLAG);
  95         } else {
  96                 set_need_resched();
  97         }
  98 }
  99 #endif /* !CONFIG_SMP || CONFIG_HOTPLUG_CPU */
 100
 101 /*
 102  * the idle thread
 103  * - there's no useful work to be done, so just try to conserve power and have
 104  *   a low exit latency (ie sit in a loop waiting for somebody to say that
 105  *   they'd like to reschedule)
 106  */
 107 void cpu_idle(void)
 108 {
 109         /* endless idle loop with no priority at all */
 110         for (;;) {
 111                 rcu_idle_enter();
 112                 while (!need_resched()) {
 113                         void (*idle)(void);
 114
 115                         smp_rmb();
 116                         idle = pm_idle;
 117                         if (!idle) {
 118 #if defined(CONFIG_SMP) && !defined(CONFIG_HOTPLUG_CPU)
 119                                 idle = poll_idle;
 120 #else  /* CONFIG_SMP && !CONFIG_HOTPLUG_CPU */
 121                                 idle = default_idle;
 122 #endif /* CONFIG_SMP && !CONFIG_HOTPLUG_CPU */
 123                         }
 124                         idle();
 125                 }
 126                 rcu_idle_exit();
 127
 128                 schedule_preempt_disabled();
 129         }
 130 }
 131
 132 void release_segments(struct mm_struct *mm)
 133 {
 134 }
 135
 136 void machine_restart(char *cmd)
 137 {
 138 #ifdef CONFIG_KERNEL_DEBUGGER
 139         gdbstub_exit(0);
 140 #endif
 141
 142 #ifdef mn10300_unit_hard_reset
 143         mn10300_unit_hard_reset();
 144 #else
 145         mn10300_proc_hard_reset();
 146 #endif
 147 }
 148
 149 void machine_halt(void)
 150 {
 151 #ifdef CONFIG_KERNEL_DEBUGGER
 152         gdbstub_exit(0);
 153 #endif
 154 }
 155
 156 void machine_power_off(void)
 157 {
 158 #ifdef CONFIG_KERNEL_DEBUGGER
 159         gdbstub_exit(0);
 160 #endif
 161 }
 162
 163 void show_regs(struct pt_regs *regs)
 164 {
 165 }
 166
 167 /*
 168  * free current thread data structures etc..
 169  */
 170 void exit_thread(void)
 171 {
 172         exit_fpu();
 173 }
 174
 175 void flush_thread(void)
 176 {
 177         flush_fpu();
 178 }
 179
 180 void release_thread(struct task_struct *dead_task)
 181 {
 182 }
 183
 184 /*
 185  * we do not have to muck with descriptors here, that is
 186  * done in switch_mm() as needed.
 187  */
 188 void copy_segments(struct task_struct *p, struct mm_struct *new_mm)
 189 {
 190 }
 191
 192 /*
 193  * this gets called so that we can store lazy state into memory and copy the
 194  * current task into the new thread.
 195  */
 196 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 197 {
 198         unlazy_fpu(src);
 199         *dst = *src;
 200         return 0;
 201 }
 202
 203 /*
 204  * set up the kernel stack for a new thread and copy arch-specific thread
 205  * control information
 206  */
 207 int copy_thread(unsigned long clone_flags,
 208                 unsigned long c_usp, unsigned long ustk_size,
 209                 struct task_struct *p)
 210 {
 211         struct thread_info *ti = task_thread_info(p);
 212         struct pt_regs *c_regs;
 213         unsigned long c_ksp;
 214
 215         c_ksp = (unsigned long) task_stack_page(p) + THREAD_SIZE;
 216
 217         /* allocate the userspace exception frame and set it up */
 218         c_ksp -= sizeof(struct pt_regs);
 219         c_regs = (struct pt_regs *) c_ksp;
 220         c_ksp -= 12; /* allocate function call ABI slack */
 221
 222         /* set up things up so the scheduler can start the new task */
 223         p->thread.uregs = c_regs;
 224         ti->frame       = c_regs;
 225         p->thread.a3    = (unsigned long) c_regs;
 226         p->thread.sp    = c_ksp;
 227         p->thread.wchan = p->thread.pc;
 228         p->thread.usp   = c_usp;
 229
 230         if (unlikely(p->flags & PF_KTHREAD)) {
 231                 memset(c_regs, 0, sizeof(struct pt_regs));
 232                 c_regs->a0 = c_usp; /* function */
 233                 c_regs->d0 = ustk_size; /* argument */
 234                 local_save_flags(c_regs->epsw);
 235                 c_regs->epsw |= EPSW_IE | EPSW_IM_7;
 236                 p->thread.pc    = (unsigned long) ret_from_kernel_thread;
 237                 return 0;
 238         }
 239         *c_regs = *current_pt_regs();
 240         if (c_usp)
 241                 c_regs->sp = c_usp;
 242         c_regs->epsw &= ~EPSW_FE; /* my FPU */
 243
 244         /* the new TLS pointer is passed in as arg #5 to sys_clone() */
 245         if (clone_flags & CLONE_SETTLS)
 246                 c_regs->e2 = current_frame()->d3;
 247
 248         p->thread.pc    = (unsigned long) ret_from_fork;
 249
 250         return 0;
 251 }
 252
 253 unsigned long get_wchan(struct task_struct *p)
 254 {
 255         return p->thread.wchan;
 256 }