linux/arch/cris/kernel/process.c
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   1/*
   2 *  linux/arch/cris/kernel/process.c
   3 *
   4 *  Copyright (C) 1995  Linus Torvalds
   5 *  Copyright (C) 2000-2002  Axis Communications AB
   6 *
   7 *  Authors:   Bjorn Wesen (bjornw@axis.com)
   8 *
   9 */
  10
  11/*
  12 * This file handles the architecture-dependent parts of process handling..
  13 */
  14
  15#include <asm/atomic.h>
  16#include <asm/pgtable.h>
  17#include <asm/uaccess.h>
  18#include <asm/irq.h>
  19#include <asm/system.h>
  20#include <linux/module.h>
  21#include <linux/spinlock.h>
  22#include <linux/fs_struct.h>
  23#include <linux/init_task.h>
  24#include <linux/sched.h>
  25#include <linux/fs.h>
  26#include <linux/user.h>
  27#include <linux/elfcore.h>
  28#include <linux/mqueue.h>
  29#include <linux/reboot.h>
  30
  31//#define DEBUG
  32
  33/*
  34 * Initial task structure. Make this a per-architecture thing,
  35 * because different architectures tend to have different
  36 * alignment requirements and potentially different initial
  37 * setup.
  38 */
  39
  40static struct fs_struct init_fs = INIT_FS;
  41static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
  42static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
  43struct mm_struct init_mm = INIT_MM(init_mm);
  44
  45EXPORT_SYMBOL(init_mm);
  46
  47/*
  48 * Initial thread structure.
  49 *
  50 * We need to make sure that this is 8192-byte aligned due to the
  51 * way process stacks are handled. This is done by having a special
  52 * "init_task" linker map entry..
  53 */
  54union thread_union init_thread_union 
  55        __attribute__((__section__(".data.init_task"))) =
  56                { INIT_THREAD_INFO(init_task) };
  57
  58/*
  59 * Initial task structure.
  60 *
  61 * All other task structs will be allocated on slabs in fork.c
  62 */
  63struct task_struct init_task = INIT_TASK(init_task);
  64
  65EXPORT_SYMBOL(init_task);
  66
  67/*
  68 * The hlt_counter, disable_hlt and enable_hlt is just here as a hook if
  69 * there would ever be a halt sequence (for power save when idle) with
  70 * some largish delay when halting or resuming *and* a driver that can't
  71 * afford that delay.  The hlt_counter would then be checked before
  72 * executing the halt sequence, and the driver marks the unhaltable
  73 * region by enable_hlt/disable_hlt.
  74 */
  75
  76int cris_hlt_counter=0;
  77
  78void disable_hlt(void)
  79{
  80        cris_hlt_counter++;
  81}
  82
  83EXPORT_SYMBOL(disable_hlt);
  84
  85void enable_hlt(void)
  86{
  87        cris_hlt_counter--;
  88}
  89
  90EXPORT_SYMBOL(enable_hlt);
  91 
  92/*
  93 * The following aren't currently used.
  94 */
  95void (*pm_idle)(void);
  96
  97extern void default_idle(void);
  98
  99void (*pm_power_off)(void);
 100EXPORT_SYMBOL(pm_power_off);
 101
 102/*
 103 * The idle thread. There's no useful work to be
 104 * done, so just try to conserve power and have a
 105 * low exit latency (ie sit in a loop waiting for
 106 * somebody to say that they'd like to reschedule)
 107 */
 108
 109void cpu_idle (void)
 110{
 111        /* endless idle loop with no priority at all */
 112        while (1) {
 113                while (!need_resched()) {
 114                        void (*idle)(void);
 115                        /*
 116                         * Mark this as an RCU critical section so that
 117                         * synchronize_kernel() in the unload path waits
 118                         * for our completion.
 119                         */
 120                        idle = pm_idle;
 121                        if (!idle)
 122                                idle = default_idle;
 123                        idle();
 124                }
 125                preempt_enable_no_resched();
 126                schedule();
 127                preempt_disable();
 128        }
 129}
 130
 131void hard_reset_now (void);
 132
 133void machine_restart(char *cmd)
 134{
 135        hard_reset_now();
 136}
 137
 138/*
 139 * Similar to machine_power_off, but don't shut off power.  Add code
 140 * here to freeze the system for e.g. post-mortem debug purpose when
 141 * possible.  This halt has nothing to do with the idle halt.
 142 */
 143
 144void machine_halt(void)
 145{
 146}
 147
 148/* If or when software power-off is implemented, add code here.  */
 149
 150void machine_power_off(void)
 151{
 152}
 153
 154/*
 155 * When a process does an "exec", machine state like FPU and debug
 156 * registers need to be reset.  This is a hook function for that.
 157 * Currently we don't have any such state to reset, so this is empty.
 158 */
 159
 160void flush_thread(void)
 161{
 162}
 163
 164/* Fill in the fpu structure for a core dump. */
 165int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 166{
 167        return 0;
 168}
 169