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process.c

/*
 *  linux/arch/arm/kernel/process.c
 *
 *  Copyright (C) 1996-2000 Russell King - Converted to ARM.
 *  Original Copyright (C) 1995  Linus Torvalds
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <stdarg.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/slab.h>
#include <linux/user.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/interrupt.h>
#include <linux/kallsyms.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/elfcore.h>
#include <linux/pm.h>
#include <linux/tick.h>
#include <linux/utsname.h>

#include <asm/leds.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/thread_notify.h>
#include <asm/uaccess.h>
#include <asm/mach/time.h>

static const char *processor_modes[] = {
  "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
  "UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
  "USER_32", "FIQ_32" , "IRQ_32" , "SVC_32" , "UK4_32" , "UK5_32" , "UK6_32" , "ABT_32" ,
  "UK8_32" , "UK9_32" , "UK10_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
};

static const char *isa_modes[] = {
  "ARM" , "Thumb" , "Jazelle", "ThumbEE"
};

extern void setup_mm_for_reboot(char mode);

static volatile int hlt_counter;

#include <mach/system.h>

void disable_hlt(void)
{
      hlt_counter++;
}

EXPORT_SYMBOL(disable_hlt);

void enable_hlt(void)
{
      hlt_counter--;
}

EXPORT_SYMBOL(enable_hlt);

static int __init nohlt_setup(char *__unused)
{
      hlt_counter = 1;
      return 1;
}

static int __init hlt_setup(char *__unused)
{
      hlt_counter = 0;
      return 1;
}

__setup("nohlt", nohlt_setup);
__setup("hlt", hlt_setup);

void arm_machine_restart(char mode)
{
      /*
       * Clean and disable cache, and turn off interrupts
       */
      cpu_proc_fin();

      /*
       * Tell the mm system that we are going to reboot -
       * we may need it to insert some 1:1 mappings so that
       * soft boot works.
       */
      setup_mm_for_reboot(mode);

      /*
       * Now call the architecture specific reboot code.
       */
      arch_reset(mode);

      /*
       * Whoops - the architecture was unable to reboot.
       * Tell the user!
       */
      mdelay(1000);
      printk("Reboot failed -- System halted\n");
      while (1);
}

/*
 * Function pointers to optional machine specific functions
 */
void (*pm_idle)(void);
EXPORT_SYMBOL(pm_idle);

void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);

void (*arm_pm_restart)(char str) = arm_machine_restart;
EXPORT_SYMBOL_GPL(arm_pm_restart);


/*
 * This is our default idle handler.  We need to disable
 * interrupts here to ensure we don't miss a wakeup call.
 */
static void default_idle(void)
{
      if (hlt_counter)
            cpu_relax();
      else {
            local_irq_disable();
            if (!need_resched())
                  arch_idle();
            local_irq_enable();
      }
}

/*
 * The idle thread.  We try to conserve power, while trying to keep
 * overall latency low.  The architecture specific idle is passed
 * a value to indicate the level of "idleness" of the system.
 */
void cpu_idle(void)
{
      local_fiq_enable();

      /* endless idle loop with no priority at all */
      while (1) {
            void (*idle)(void) = pm_idle;

#ifdef CONFIG_HOTPLUG_CPU
            if (cpu_is_offline(smp_processor_id())) {
                  leds_event(led_idle_start);
                  cpu_die();
            }
#endif

            if (!idle)
                  idle = default_idle;
            leds_event(led_idle_start);
            tick_nohz_stop_sched_tick(1);
            while (!need_resched())
                  idle();
            leds_event(led_idle_end);
            tick_nohz_restart_sched_tick();
            preempt_enable_no_resched();
            schedule();
            preempt_disable();
      }
}

static char reboot_mode = 'h';

int __init reboot_setup(char *str)
{
      reboot_mode = str[0];
      return 1;
}

__setup("reboot=", reboot_setup);

void machine_halt(void)
{
}


void machine_power_off(void)
{
      if (pm_power_off)
            pm_power_off();
}

void machine_restart(char * __unused)
{
      arm_pm_restart(reboot_mode);
}

void __show_regs(struct pt_regs *regs)
{
      unsigned long flags;
      char buf[64];

      printk("CPU: %d    %s  (%s %.*s)\n",
            smp_processor_id(), print_tainted(), init_utsname()->release,
            (int)strcspn(init_utsname()->version, " "),
            init_utsname()->version);
      print_symbol("PC is at %s\n", instruction_pointer(regs));
      print_symbol("LR is at %s\n", regs->ARM_lr);
      printk("pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n"
             "sp : %08lx  ip : %08lx  fp : %08lx\n",
            regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr,
            regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
      printk("r10: %08lx  r9 : %08lx  r8 : %08lx\n",
            regs->ARM_r10, regs->ARM_r9,
            regs->ARM_r8);
      printk("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
            regs->ARM_r7, regs->ARM_r6,
            regs->ARM_r5, regs->ARM_r4);
      printk("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
            regs->ARM_r3, regs->ARM_r2,
            regs->ARM_r1, regs->ARM_r0);

      flags = regs->ARM_cpsr;
      buf[0] = flags & PSR_N_BIT ? 'N' : 'n';
      buf[1] = flags & PSR_Z_BIT ? 'Z' : 'z';
      buf[2] = flags & PSR_C_BIT ? 'C' : 'c';
      buf[3] = flags & PSR_V_BIT ? 'V' : 'v';
      buf[4] = '\0';

      printk("Flags: %s  IRQs o%s  FIQs o%s  Mode %s  ISA %s  Segment %s\n",
            buf, interrupts_enabled(regs) ? "n" : "ff",
            fast_interrupts_enabled(regs) ? "n" : "ff",
            processor_modes[processor_mode(regs)],
            isa_modes[isa_mode(regs)],
            get_fs() == get_ds() ? "kernel" : "user");
#ifdef CONFIG_CPU_CP15
      {
            unsigned int ctrl;

            buf[0] = '\0';
#ifdef CONFIG_CPU_CP15_MMU
            {
                  unsigned int transbase, dac;
                  asm("mrc p15, 0, %0, c2, c0\n\t"
                      "mrc p15, 0, %1, c3, c0\n"
                      : "=r" (transbase), "=r" (dac));
                  snprintf(buf, sizeof(buf), "  Table: %08x  DAC: %08x",
                        transbase, dac);
            }
#endif
            asm("mrc p15, 0, %0, c1, c0\n" : "=r" (ctrl));

            printk("Control: %08x%s\n", ctrl, buf);
      }
#endif
}

void show_regs(struct pt_regs * regs)
{
      printk("\n");
      printk("Pid: %d, comm: %20s\n", task_pid_nr(current), current->comm);
      __show_regs(regs);
      __backtrace();
}

void show_fpregs(struct user_fp *regs)
{
      int i;

      for (i = 0; i < 8; i++) {
            unsigned long *p;
            char type;

            p = (unsigned long *)(regs->fpregs + i);

            switch (regs->ftype[i]) {
                  case 1: type = 'f'; break;
                  case 2: type = 'd'; break;
                  case 3: type = 'e'; break;
                  default: type = '?'; break;
            }
            if (regs->init_flag)
                  type = '?';

            printk("  f%d(%c): %08lx %08lx %08lx%c",
                  i, type, p[0], p[1], p[2], i & 1 ? '\n' : ' ');
      }
                  

      printk("FPSR: %08lx FPCR: %08lx\n",
            (unsigned long)regs->fpsr,
            (unsigned long)regs->fpcr);
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
}

ATOMIC_NOTIFIER_HEAD(thread_notify_head);

EXPORT_SYMBOL_GPL(thread_notify_head);

void flush_thread(void)
{
      struct thread_info *thread = current_thread_info();
      struct task_struct *tsk = current;

      memset(thread->used_cp, 0, sizeof(thread->used_cp));
      memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
      memset(&thread->fpstate, 0, sizeof(union fp_state));

      thread_notify(THREAD_NOTIFY_FLUSH, thread);
}

void release_thread(struct task_struct *dead_task)
{
      struct thread_info *thread = task_thread_info(dead_task);

      thread_notify(THREAD_NOTIFY_RELEASE, thread);
}

asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");

int
copy_thread(int nr, unsigned long clone_flags, unsigned long stack_start,
          unsigned long stk_sz, struct task_struct *p, struct pt_regs *regs)
{
      struct thread_info *thread = task_thread_info(p);
      struct pt_regs *childregs = task_pt_regs(p);

      *childregs = *regs;
      childregs->ARM_r0 = 0;
      childregs->ARM_sp = stack_start;

      memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
      thread->cpu_context.sp = (unsigned long)childregs;
      thread->cpu_context.pc = (unsigned long)ret_from_fork;

      if (clone_flags & CLONE_SETTLS)
            thread->tp_value = regs->ARM_r3;

      return 0;
}

/*
 * fill in the fpe structure for a core dump...
 */
int dump_fpu (struct pt_regs *regs, struct user_fp *fp)
{
      struct thread_info *thread = current_thread_info();
      int used_math = thread->used_cp[1] | thread->used_cp[2];

      if (used_math)
            memcpy(fp, &thread->fpstate.soft, sizeof (*fp));

      return used_math != 0;
}
EXPORT_SYMBOL(dump_fpu);

/*
 * Shuffle the argument into the correct register before calling the
 * thread function.  r1 is the thread argument, r2 is the pointer to
 * the thread function, and r3 points to the exit function.
 */
extern void kernel_thread_helper(void);
asm(  ".section .text\n"
"     .align\n"
"     .type kernel_thread_helper, #function\n"
"kernel_thread_helper:\n"
"     mov   r0, r1\n"
"     mov   lr, r3\n"
"     mov   pc, r2\n"
"     .size kernel_thread_helper, . - kernel_thread_helper\n"
"     .previous");

/*
 * Create a kernel thread.
 */
pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
      struct pt_regs regs;

      memset(&regs, 0, sizeof(regs));

      regs.ARM_r1 = (unsigned long)arg;
      regs.ARM_r2 = (unsigned long)fn;
      regs.ARM_r3 = (unsigned long)do_exit;
      regs.ARM_pc = (unsigned long)kernel_thread_helper;
      regs.ARM_cpsr = SVC_MODE;

      return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
}
EXPORT_SYMBOL(kernel_thread);

unsigned long get_wchan(struct task_struct *p)
{
      unsigned long fp, lr;
      unsigned long stack_start, stack_end;
      int count = 0;
      if (!p || p == current || p->state == TASK_RUNNING)
            return 0;

      stack_start = (unsigned long)end_of_stack(p);
      stack_end = (unsigned long)task_stack_page(p) + THREAD_SIZE;

      fp = thread_saved_fp(p);
      do {
            if (fp < stack_start || fp > stack_end)
                  return 0;
            lr = pc_pointer (((unsigned long *)fp)[-1]);
            if (!in_sched_functions(lr))
                  return lr;
            fp = *(unsigned long *) (fp - 12);
      } while (count ++ < 16);
      return 0;
}

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