text: /*
   *  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/export.h>
  #include <linux/sched.h>
  #include <linux/kernel.h>
  #include <linux/mm.h>
  #include <linux/stddef.h>
  #include <linux/unistd.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 <linux/uaccess.h>
  #include <linux/random.h>
  #include <linux/hw_breakpoint.h>
  #include <linux/cpuidle.h>
  #include <linux/console.h>
  
  #include <asm/cacheflush.h>
  #include <asm/processor.h>
  #include <asm/thread_notify.h>
  #include <asm/stacktrace.h>
  #include <asm/mach/time.h>
  
  #ifdef CONFIG_CC_STACKPROTECTOR
  #include <linux/stackprotector.h>
  unsigned long __stack_chk_guard __read_mostly;
  EXPORT_SYMBOL(__stack_chk_guard);
  #endif
  
  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(void);
  
  static volatile int hlt_counter;
  
  #ifdef CONFIG_SMP
  void arch_trigger_all_cpu_backtrace(void)
  {
  	smp_send_all_cpu_backtrace();
  }
  #else
  void arch_trigger_all_cpu_backtrace(void)
  {
  	dump_stack();
  }
  #endif
  
  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);
  
  extern void call_with_stack(void (*fn)(void *), void *arg, void *sp);
  typedef void (*phys_reset_t)(unsigned long);
  
  #ifdef CONFIG_ARM_FLUSH_CONSOLE_ON_RESTART
  void arm_machine_flush_console(void)
  {
  	printk("\n");
  	pr_emerg("Restarting %s\n", linux_banner);
  	if (console_trylock()) {
  		console_unlock();
  		return;
  	}
  
  	mdelay(50);
  
  	local_irq_disable();
  	if (!console_trylock())
  		pr_emerg("arm_restart: Console was locked! Busting\n");
  	else
  		pr_emerg("arm_restart: Console was locked!\n");
  	console_unlock();
  }
  #else
  void arm_machine_flush_console(void)
  {
  }
  #endif
  
  /*
   * A temporary stack to use for CPU reset. This is static so that we
   * don't clobber it with the identity mapping. When running with this
   * stack, any references to the current task *will not work* so you
   * should really do as little as possible before jumping to your reset
   * code.
   */
  static u64 soft_restart_stack[16];
  
  static void __soft_restart(void *addr)
  {
  	phys_reset_t phys_reset;
  
  	/* Take out a flat memory mapping. */
  	setup_mm_for_reboot();
  
  	/* Clean and invalidate caches */
  	flush_cache_all();
  
  	/* Turn off caching */
  	cpu_proc_fin();
  
  	/* Push out any further dirty data, and ensure cache is empty */
  	flush_cache_all();
  
  	/* Switch to the identity mapping. */
  	phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
  	phys_reset((unsigned long)addr);
  
  	/* Should never get here. */
  	BUG();
  }
  
  void soft_restart(unsigned long addr)
  {
  	u64 *stack = soft_restart_stack + ARRAY_SIZE(soft_restart_stack);
  
  	/* Disable interrupts first */
  	local_irq_disable();
  	local_fiq_disable();
  
  	/* Disable the L2 if we're the last man standing. */
  	if (num_online_cpus() == 1)
  		outer_disable();
  
  	/* Change to the new stack and continue with the reset. */
  	call_with_stack(__soft_restart, (void *)addr, (void *)stack);
  
  	/* Should never get here. */
  	BUG();
  }
  
  static void null_restart(char mode, const char *cmd)
  {
  }
  
  /*
   * Function pointers to optional machine specific functions
   */
  void (*pm_power_off)(void);
  EXPORT_SYMBOL(pm_power_off);
  
  void (*arm_pm_restart)(char str, const char *cmd) = null_restart;
  EXPORT_SYMBOL_GPL(arm_pm_restart);
  
  static void do_nothing(void *unused)
  {
  }
  
  /*
   * cpu_idle_wait - Used to ensure that all the CPUs discard old value of
   * pm_idle and update to new pm_idle value. Required while changing pm_idle
   * handler on SMP systems.
   *
   * Caller must have changed pm_idle to the new value before the call. Old
   * pm_idle value will not be used by any CPU after the return of this function.
   */
  void cpu_idle_wait(void)
  {
  	smp_mb();
  	/* kick all the CPUs so that they exit out of pm_idle */
  	smp_call_function(do_nothing, NULL, 1);
  }
  EXPORT_SYMBOL_GPL(cpu_idle_wait);
  
  /*
   * This is our default idle handler.
   */
  
  void (*arm_pm_idle)(void);
  
  static void default_idle(void)
  {
  	if (arm_pm_idle)
  		arm_pm_idle();
  	else
  		cpu_do_idle();
  	local_irq_enable();
  }
  
  void (*pm_idle)(void) = default_idle;
  EXPORT_SYMBOL(pm_idle);
  
  /*
   * The idle thread, has rather strange semantics for calling pm_idle,
   * but this is what x86 does and we need to do the same, so that
   * things like cpuidle get called in the same way.  The only difference
   * is that we always respect 'hlt_counter' to prevent low power idle.
   */
  void cpu_idle(void)
  {
  	local_fiq_enable();
  
  	/* endless idle loop with no priority at all */
  	while (1) {
  		idle_notifier_call_chain(IDLE_START);
  		tick_nohz_idle_enter();
  		rcu_idle_enter();
  		while (!need_resched()) {
  #ifdef CONFIG_HOTPLUG_CPU
  			if (cpu_is_offline(smp_processor_id()))
  				cpu_die();
  #endif
  
  			/*
  			 * We need to disable interrupts here
  			 * to ensure we don't miss a wakeup call.
  			 */
  			local_irq_disable();
  #ifdef CONFIG_PL310_ERRATA_769419
  			wmb();
  #endif
  			if (hlt_counter) {
  				local_irq_enable();
  				cpu_relax();
  			} else if (!need_resched()) {
  				stop_critical_timings();
  				if (cpuidle_idle_call())
  					pm_idle();
  				start_critical_timings();
  				/*
  				 * pm_idle functions must always
  				 * return with IRQs enabled.
  				 */
  				WARN_ON(irqs_disabled());
  			} else
  				local_irq_enable();
  		}
  		rcu_idle_exit();
  		tick_nohz_idle_exit();
  		idle_notifier_call_chain(IDLE_END);
  		schedule_preempt_disabled();
  	}
  }
  
  static char reboot_mode = 'h';
  
  int __init reboot_setup(char *str)
  {
  	reboot_mode = str[0];
  	return 1;
  }
  
  __setup("reboot=", reboot_setup);
  
  void machine_shutdown(void)
  {
  #ifdef CONFIG_SMP
  	/*
  	 * Disable preemption so we're guaranteed to
  	 * run to power off or reboot and prevent
  	 * the possibility of switching to another
  	 * thread that might wind up blocking on
  	 * one of the stopped CPUs.
  	 */
  	preempt_disable();
  
  	smp_send_stop();
  #endif
  }
  
  void machine_halt(void)
  {
  	machine_shutdown();
  	local_irq_disable();
  	while (1);
  }
  
  void machine_power_off(void)
  {
  	machine_shutdown();
  	if (pm_power_off)
  		pm_power_off();
  }
  
  void machine_restart(char *cmd)
  {
  	machine_shutdown();
  
  	/* Flush the console to make sure all the relevant messages make it
  	 * out to the console drivers */
  	arm_machine_flush_console();
  
  	arm_pm_restart(reboot_mode, cmd);
  
  	/* Give a grace period for failure to restart of 1s */
  	mdelay(1000);
  
  	/* Whoops - the platform was unable to reboot. Tell the user! */
  	printk("Reboot failed -- System halted\n");
  	local_irq_disable();
  	while (1);
  }
  
  /*
   * dump a block of kernel memory from around the given address
   */
  static void show_data(unsigned long addr, int nbytes, const char *name)
  {
  	int	i, j;
  	int	nlines;
  	u32	*p;
  
  	/*
  	 * don't attempt to dump non-kernel addresses or
  	 * values that are probably just small negative numbers
  	 */
  	if (addr < PAGE_OFFSET || addr > -256UL)
  		return;
  
  	printk("\n%s: %#lx:\n", name, addr);
  
  	/*
  	 * round address down to a 32 bit boundary
  	 * and always dump a multiple of 32 bytes
  	 */
  	p = (u32 *)(addr & ~(sizeof(u32) - 1));
  	nbytes += (addr & (sizeof(u32) - 1));
  	nlines = (nbytes + 31) / 32;
  
  
  	for (i = 0; i < nlines; i++) {
  		/*
  		 * just display low 16 bits of address to keep
  		 * each line of the dump < 80 characters
  		 */
  		printk("%04lx ", (unsigned long)p & 0xffff);
  		for (j = 0; j < 8; j++) {
  			u32	data;
  			if (probe_kernel_address(p, data)) {
  				printk(" ********");
  			} else {
  				printk(" %08x", data);
  			}
  			++p;
  		}
  		printk("\n");
  	}
  }
  
  static void show_extra_register_data(struct pt_regs *regs, int nbytes)
  {
  	mm_segment_t fs;
  
  	fs = get_fs();
  	set_fs(KERNEL_DS);
  	show_data(regs->ARM_pc - nbytes, nbytes * 2, "PC");
  	show_data(regs->ARM_lr - nbytes, nbytes * 2, "LR");
  	show_data(regs->ARM_sp - nbytes, nbytes * 2, "SP");
  	show_data(regs->ARM_ip - nbytes, nbytes * 2, "IP");
  	show_data(regs->ARM_fp - nbytes, nbytes * 2, "FP");
  	show_data(regs->ARM_r0 - nbytes, nbytes * 2, "R0");
  	show_data(regs->ARM_r1 - nbytes, nbytes * 2, "R1");
  	show_data(regs->ARM_r2 - nbytes, nbytes * 2, "R2");
  	show_data(regs->ARM_r3 - nbytes, nbytes * 2, "R3");
  	show_data(regs->ARM_r4 - nbytes, nbytes * 2, "R4");
  	show_data(regs->ARM_r5 - nbytes, nbytes * 2, "R5");
  	show_data(regs->ARM_r6 - nbytes, nbytes * 2, "R6");
  	show_data(regs->ARM_r7 - nbytes, nbytes * 2, "R7");
  	show_data(regs->ARM_r8 - nbytes, nbytes * 2, "R8");
  	show_data(regs->ARM_r9 - nbytes, nbytes * 2, "R9");
  	show_data(regs->ARM_r10 - nbytes, nbytes * 2, "R10");
  	set_fs(fs);
  }
  
  void __show_regs(struct pt_regs *regs)
  {
  	unsigned long flags;
  	char buf[64];
  
  	printk("CPU: %d    %s  (%s %.*s)\n",
  		raw_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
  
  	show_extra_register_data(regs, 128);
  }
  
  void show_regs(struct pt_regs * regs)
  {
  	printk("\n");
  	printk("Pid: %d, comm: %20s\n", task_pid_nr(current), current->comm);
  	__show_regs(regs);
  	dump_stack();
  }
  
  ATOMIC_NOTIFIER_HEAD(thread_notify_head);
  
  EXPORT_SYMBOL_GPL(thread_notify_head);
  
  /*
   * Free current thread data structures etc..
   */
  void exit_thread(void)
  {
  	thread_notify(THREAD_NOTIFY_EXIT, current_thread_info());
  }
  
  void flush_thread(void)
  {
  	struct thread_info *thread = current_thread_info();
  	struct task_struct *tsk = current;
  
  	flush_ptrace_hw_breakpoint(tsk);
  
  	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)
  {
  }
  
  asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
  
  int
  copy_thread(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;
  
  	clear_ptrace_hw_breakpoint(p);
  
  	if (clone_flags & CLONE_SETTLS)
  		thread->tp_value = regs->ARM_r3;
  
  	thread_notify(THREAD_NOTIFY_COPY, thread);
  
  	return 0;
  }
  
  /*
   * Fill in the task's elfregs structure for a core dump.
   */
  int dump_task_regs(struct task_struct *t, elf_gregset_t *elfregs)
  {
  	elf_core_copy_regs(elfregs, task_pt_regs(t));
  	return 1;
  }
  
  /*
   * 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.  r4 is the thread argument, r5 is the pointer to
   * the thread function, and r6 points to the exit function.
   */
  extern void kernel_thread_helper(void);
  asm(	".pushsection .text\n"
  "	.align\n"
  "	.type	kernel_thread_helper, #function\n"
  "kernel_thread_helper:\n"
  #ifdef CONFIG_TRACE_IRQFLAGS
  "	bl	trace_hardirqs_on\n"
  #endif
  "	msr	cpsr_c, r7\n"
  "	mov	r0, r4\n"
  "	mov	lr, r6\n"
  "	mov	pc, r5\n"
  "	.size	kernel_thread_helper, . - kernel_thread_helper\n"
  "	.popsection");
  
  #ifdef CONFIG_ARM_UNWIND
  extern void kernel_thread_exit(long code);
  asm(	".pushsection .text\n"
  "	.align\n"
  "	.type	kernel_thread_exit, #function\n"
  "kernel_thread_exit:\n"
  "	.fnstart\n"
  "	.cantunwind\n"
  "	bl	do_exit\n"
  "	nop\n"
  "	.fnend\n"
  "	.size	kernel_thread_exit, . - kernel_thread_exit\n"
  "	.popsection");
  #else
  #define kernel_thread_exit	do_exit
  #endif
  
  /*
   * 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_r4 = (unsigned long)arg;
  	regs.ARM_r5 = (unsigned long)fn;
  	regs.ARM_r6 = (unsigned long)kernel_thread_exit;
  	regs.ARM_r7 = SVC_MODE | PSR_ENDSTATE | PSR_ISETSTATE;
  	regs.ARM_pc = (unsigned long)kernel_thread_helper;
  	regs.ARM_cpsr = regs.ARM_r7 | PSR_I_BIT;
  
  	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)
  {
  	struct stackframe frame;
  	int count = 0;
  	if (!p || p == current || p->state == TASK_RUNNING)
  		return 0;
  
  	frame.fp = thread_saved_fp(p);
  	frame.sp = thread_saved_sp(p);
  	frame.lr = 0;			/* recovered from the stack */
  	frame.pc = thread_saved_pc(p);
  	do {
  		int ret = unwind_frame(&frame);
  		if (ret < 0)
  			return 0;
  		if (!in_sched_functions(frame.pc))
  			return frame.pc;
  	} while (count ++ < 16);
  	return 0;
  }
  
  unsigned long arch_randomize_brk(struct mm_struct *mm)
  {
  	unsigned long range_end = mm->brk + 0x02000000;
  	return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
  }
  
  #ifdef CONFIG_MMU
  #ifdef CONFIG_KUSER_HELPERS
  /*
   * The vectors page is always readable from user space for the
   * atomic helpers and the signal restart code. Insert it into the
   * gate_vma so that it is visible through ptrace and /proc/<pid>/mem.
   */
  static struct vm_area_struct gate_vma;
  
  static int __init gate_vma_init(void)
  {
  	gate_vma.vm_start	= 0xffff0000;
  	gate_vma.vm_end		= 0xffff0000 + PAGE_SIZE;
  	gate_vma.vm_page_prot	= PAGE_READONLY_EXEC;
  	gate_vma.vm_flags	= VM_READ | VM_EXEC |
  				  VM_MAYREAD | VM_MAYEXEC;
  	return 0;
  }
  arch_initcall(gate_vma_init);
  
  struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
  {
  	return &gate_vma;
  }
  
  int in_gate_area(struct mm_struct *mm, unsigned long addr)
  {
  	return (addr >= gate_vma.vm_start) && (addr < gate_vma.vm_end);
  }
  
  int in_gate_area_no_mm(unsigned long addr)
  {
  	return in_gate_area(NULL, addr);
  }
  #define is_gate_vma(vma)	((vma) == &gate_vma)
  #else
  #define is_gate_vma(vma)	0
  #endif
  
  const char *arch_vma_name(struct vm_area_struct *vma)
  {
  	return is_gate_vma(vma) ? "[vectors]" : NULL;
  }
  #endif
  