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process.c

/*
 * Copyright (C) 2004-2006 Atmel Corporation
 *
 * 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 <linux/sched.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/fs.h>
#include <linux/ptrace.h>
#include <linux/reboot.h>
#include <linux/tick.h>
#include <linux/uaccess.h>
#include <linux/unistd.h>

#include <asm/sysreg.h>
#include <asm/ocd.h>

#include <mach/pm.h>

void (*pm_power_off)(void) = NULL;
EXPORT_SYMBOL(pm_power_off);

/*
 * This file handles the architecture-dependent parts of process handling..
 */

void cpu_idle(void)
{
      /* endless idle loop with no priority at all */
      while (1) {
            tick_nohz_stop_sched_tick(1);
            while (!need_resched())
                  cpu_idle_sleep();
            tick_nohz_restart_sched_tick();
            preempt_enable_no_resched();
            schedule();
            preempt_disable();
      }
}

void machine_halt(void)
{
      /*
       * Enter Stop mode. The 32 kHz oscillator will keep running so
       * the RTC will keep the time properly and the system will
       * boot quickly.
       */
      asm volatile("sleep 3\n\t"
                 "sub pc, -2");
}

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

void machine_restart(char *cmd)
{
      ocd_write(DC, (1 << OCD_DC_DBE_BIT));
      ocd_write(DC, (1 << OCD_DC_RES_BIT));
      while (1) ;
}

/*
 * PC is actually discarded when returning from a system call -- the
 * return address must be stored in LR. This function will make sure
 * LR points to do_exit before starting the thread.
 *
 * Also, when returning from fork(), r12 is 0, so we must copy the
 * argument as well.
 *
 *  r0 : The argument to the main thread function
 *  r1 : The address of do_exit
 *  r2 : The address of the main thread function
 */
asmlinkage extern void kernel_thread_helper(void);
__asm__("   .type kernel_thread_helper, @function\n"
      "kernel_thread_helper:\n"
      "     mov   r12, r0\n"
      "     mov   lr, r2\n"
      "     mov   pc, r1\n"
      "     .size kernel_thread_helper, . - kernel_thread_helper");

int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
      struct pt_regs regs;

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

      regs.r0 = (unsigned long)arg;
      regs.r1 = (unsigned long)fn;
      regs.r2 = (unsigned long)do_exit;
      regs.lr = (unsigned long)kernel_thread_helper;
      regs.pc = (unsigned long)kernel_thread_helper;
      regs.sr = MODE_SUPERVISOR;

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

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

void flush_thread(void)
{
      /* nothing to do */
}

void release_thread(struct task_struct *dead_task)
{
      /* do nothing */
}

static void dump_mem(const char *str, const char *log_lvl,
                 unsigned long bottom, unsigned long top)
{
      unsigned long p;
      int i;

      printk("%s%s(0x%08lx to 0x%08lx)\n", log_lvl, str, bottom, top);

      for (p = bottom & ~31; p < top; ) {
            printk("%s%04lx: ", log_lvl, p & 0xffff);

            for (i = 0; i < 8; i++, p += 4) {
                  unsigned int val;

                  if (p < bottom || p >= top)
                        printk("         ");
                  else {
                        if (__get_user(val, (unsigned int __user *)p)) {
                              printk("\n");
                              goto out;
                        }
                        printk("%08x ", val);
                  }
            }
            printk("\n");
      }

out:
      return;
}

static inline int valid_stack_ptr(struct thread_info *tinfo, unsigned long p)
{
      return (p > (unsigned long)tinfo)
            && (p < (unsigned long)tinfo + THREAD_SIZE - 3);
}

#ifdef CONFIG_FRAME_POINTER
static void show_trace_log_lvl(struct task_struct *tsk, unsigned long *sp,
                         struct pt_regs *regs, const char *log_lvl)
{
      unsigned long lr, fp;
      struct thread_info *tinfo;

      if (regs)
            fp = regs->r7;
      else if (tsk == current)
            asm("mov %0, r7" : "=r"(fp));
      else
            fp = tsk->thread.cpu_context.r7;

      /*
       * Walk the stack as long as the frame pointer (a) is within
       * the kernel stack of the task, and (b) it doesn't move
       * downwards.
       */
      tinfo = task_thread_info(tsk);
      printk("%sCall trace:\n", log_lvl);
      while (valid_stack_ptr(tinfo, fp)) {
            unsigned long new_fp;

            lr = *(unsigned long *)fp;
#ifdef CONFIG_KALLSYMS
            printk("%s [<%08lx>] ", log_lvl, lr);
#else
            printk(" [<%08lx>] ", lr);
#endif
            print_symbol("%s\n", lr);

            new_fp = *(unsigned long *)(fp + 4);
            if (new_fp <= fp)
                  break;
            fp = new_fp;
      }
      printk("\n");
}
#else
static void show_trace_log_lvl(struct task_struct *tsk, unsigned long *sp,
                         struct pt_regs *regs, const char *log_lvl)
{
      unsigned long addr;

      printk("%sCall trace:\n", log_lvl);

      while (!kstack_end(sp)) {
            addr = *sp++;
            if (kernel_text_address(addr)) {
#ifdef CONFIG_KALLSYMS
                  printk("%s [<%08lx>] ", log_lvl, addr);
#else
                  printk(" [<%08lx>] ", addr);
#endif
                  print_symbol("%s\n", addr);
            }
      }
      printk("\n");
}
#endif

void show_stack_log_lvl(struct task_struct *tsk, unsigned long sp,
                  struct pt_regs *regs, const char *log_lvl)
{
      struct thread_info *tinfo;

      if (sp == 0) {
            if (tsk)
                  sp = tsk->thread.cpu_context.ksp;
            else
                  sp = (unsigned long)&tinfo;
      }
      if (!tsk)
            tsk = current;

      tinfo = task_thread_info(tsk);

      if (valid_stack_ptr(tinfo, sp)) {
            dump_mem("Stack: ", log_lvl, sp,
                   THREAD_SIZE + (unsigned long)tinfo);
            show_trace_log_lvl(tsk, (unsigned long *)sp, regs, log_lvl);
      }
}

void show_stack(struct task_struct *tsk, unsigned long *stack)
{
      show_stack_log_lvl(tsk, (unsigned long)stack, NULL, "");
}

void dump_stack(void)
{
      unsigned long stack;

      show_trace_log_lvl(current, &stack, NULL, "");
}
EXPORT_SYMBOL(dump_stack);

static const char *cpu_modes[] = {
      "Application", "Supervisor", "Interrupt level 0", "Interrupt level 1",
      "Interrupt level 2", "Interrupt level 3", "Exception", "NMI"
};

void show_regs_log_lvl(struct pt_regs *regs, const char *log_lvl)
{
      unsigned long sp = regs->sp;
      unsigned long lr = regs->lr;
      unsigned long mode = (regs->sr & MODE_MASK) >> MODE_SHIFT;

      if (!user_mode(regs)) {
            sp = (unsigned long)regs + FRAME_SIZE_FULL;

            printk("%s", log_lvl);
            print_symbol("PC is at %s\n", instruction_pointer(regs));
            printk("%s", log_lvl);
            print_symbol("LR is at %s\n", lr);
      }

      printk("%spc : [<%08lx>]    lr : [<%08lx>]    %s\n"
             "%ssp : %08lx  r12: %08lx  r11: %08lx\n",
             log_lvl, instruction_pointer(regs), lr, print_tainted(),
             log_lvl, sp, regs->r12, regs->r11);
      printk("%sr10: %08lx  r9 : %08lx  r8 : %08lx\n",
             log_lvl, regs->r10, regs->r9, regs->r8);
      printk("%sr7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
             log_lvl, regs->r7, regs->r6, regs->r5, regs->r4);
      printk("%sr3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
             log_lvl, regs->r3, regs->r2, regs->r1, regs->r0);
      printk("%sFlags: %c%c%c%c%c\n", log_lvl,
             regs->sr & SR_Q ? 'Q' : 'q',
             regs->sr & SR_V ? 'V' : 'v',
             regs->sr & SR_N ? 'N' : 'n',
             regs->sr & SR_Z ? 'Z' : 'z',
             regs->sr & SR_C ? 'C' : 'c');
      printk("%sMode bits: %c%c%c%c%c%c%c%c%c%c\n", log_lvl,
             regs->sr & SR_H ? 'H' : 'h',
             regs->sr & SR_J ? 'J' : 'j',
             regs->sr & SR_DM ? 'M' : 'm',
             regs->sr & SR_D ? 'D' : 'd',
             regs->sr & SR_EM ? 'E' : 'e',
             regs->sr & SR_I3M ? '3' : '.',
             regs->sr & SR_I2M ? '2' : '.',
             regs->sr & SR_I1M ? '1' : '.',
             regs->sr & SR_I0M ? '0' : '.',
             regs->sr & SR_GM ? 'G' : 'g');
      printk("%sCPU Mode: %s\n", log_lvl, cpu_modes[mode]);
      printk("%sProcess: %s [%d] (task: %p thread: %p)\n",
             log_lvl, current->comm, current->pid, current,
             task_thread_info(current));
}

void show_regs(struct pt_regs *regs)
{
      unsigned long sp = regs->sp;

      if (!user_mode(regs))
            sp = (unsigned long)regs + FRAME_SIZE_FULL;

      show_regs_log_lvl(regs, "");
      show_trace_log_lvl(current, (unsigned long *)sp, regs, "");
}
EXPORT_SYMBOL(show_regs);

/* Fill in the fpu structure for a core dump. This is easy -- we don't have any */
int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
{
      /* Not valid */
      return 0;
}

asmlinkage void ret_from_fork(void);

int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
            unsigned long unused,
            struct task_struct *p, struct pt_regs *regs)
{
      struct pt_regs *childregs;

      childregs = ((struct pt_regs *)(THREAD_SIZE + (unsigned long)task_stack_page(p))) - 1;
      *childregs = *regs;

      if (user_mode(regs))
            childregs->sp = usp;
      else
            childregs->sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;

      childregs->r12 = 0; /* Set return value for child */

      p->thread.cpu_context.sr = MODE_SUPERVISOR | SR_GM;
      p->thread.cpu_context.ksp = (unsigned long)childregs;
      p->thread.cpu_context.pc = (unsigned long)ret_from_fork;

      clear_tsk_thread_flag(p, TIF_DEBUG);
      if ((clone_flags & CLONE_PTRACE) && test_thread_flag(TIF_DEBUG))
            ocd_enable(p);

      return 0;
}

/* r12-r8 are dummy parameters to force the compiler to use the stack */
asmlinkage int sys_fork(struct pt_regs *regs)
{
      return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
}

asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
                   unsigned long parent_tidptr,
                   unsigned long child_tidptr, struct pt_regs *regs)
{
      if (!newsp)
            newsp = regs->sp;
      return do_fork(clone_flags, newsp, regs, 0,
                   (int __user *)parent_tidptr,
                   (int __user *)child_tidptr);
}

asmlinkage int sys_vfork(struct pt_regs *regs)
{
      return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, regs,
                   0, NULL, NULL);
}

asmlinkage int sys_execve(char __user *ufilename, char __user *__user *uargv,
                    char __user *__user *uenvp, struct pt_regs *regs)
{
      int error;
      char *filename;

      filename = getname(ufilename);
      error = PTR_ERR(filename);
      if (IS_ERR(filename))
            goto out;

      error = do_execve(filename, uargv, uenvp, regs);
      if (error == 0)
            current->ptrace &= ~PT_DTRACE;
      putname(filename);

out:
      return error;
}


/*
 * This function is supposed to answer the question "who called
 * schedule()?"
 */
unsigned long get_wchan(struct task_struct *p)
{
      unsigned long pc;
      unsigned long stack_page;

      if (!p || p == current || p->state == TASK_RUNNING)
            return 0;

      stack_page = (unsigned long)task_stack_page(p);
      BUG_ON(!stack_page);

      /*
       * The stored value of PC is either the address right after
       * the call to __switch_to() or ret_from_fork.
       */
      pc = thread_saved_pc(p);
      if (in_sched_functions(pc)) {
#ifdef CONFIG_FRAME_POINTER
            unsigned long fp = p->thread.cpu_context.r7;
            BUG_ON(fp < stack_page || fp > (THREAD_SIZE + stack_page));
            pc = *(unsigned long *)fp;
#else
            /*
             * We depend on the frame size of schedule here, which
             * is actually quite ugly. It might be possible to
             * determine the frame size automatically at build
             * time by doing this:
             *   - compile sched.c
             *   - disassemble the resulting sched.o
             *   - look for 'sub sp,??' shortly after '<schedule>:'
             */
            unsigned long sp = p->thread.cpu_context.ksp + 16;
            BUG_ON(sp < stack_page || sp > (THREAD_SIZE + stack_page));
            pc = *(unsigned long *)sp;
#endif
      }

      return pc;
}

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