text: /*
   * Based on arch/arm/kernel/process.c
   *
   * Original Copyright (C) 1995  Linus Torvalds
   * Copyright (C) 1996-2000 Russell King - Converted to ARM.
   * Copyright (C) 2012 ARM Ltd.
   *
   * 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.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  #include <stdarg.h>
  
  #include <linux/compat.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/personality.h>
  #include <linux/notifier.h>
  
  #include <asm/compat.h>
  #include <asm/cacheflush.h>
  #include <asm/fpsimd.h>
  #include <asm/mmu_context.h>
  #include <asm/processor.h>
  #include <asm/stacktrace.h>
  
  #ifdef CONFIG_CC_STACKPROTECTOR
  #include <linux/stackprotector.h>
  unsigned long __stack_chk_guard __read_mostly;
  EXPORT_SYMBOL(__stack_chk_guard);
  #endif
  
  void soft_restart(unsigned long addr)
  {
  	setup_mm_for_reboot();
  	cpu_soft_restart(virt_to_phys(cpu_reset), addr);
  	/* Should never get here */
  	BUG();
  }
  
  /*
   * Function pointers to optional machine specific functions
   */
  void (*pm_power_off)(void);
  EXPORT_SYMBOL_GPL(pm_power_off);
  
  void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
  
  /*
   * This is our default idle handler.
   */
  void arch_cpu_idle(void)
  {
  	/*
  	 * This should do all the clock switching and wait for interrupt
  	 * tricks
  	 */
  	cpu_do_idle();
  	local_irq_enable();
  }
  
  #ifdef CONFIG_HOTPLUG_CPU
  void arch_cpu_idle_dead(void)
  {
         cpu_die();
  }
  #endif
  
  /*
   * Called by kexec, immediately prior to machine_kexec().
   *
   * This must completely disable all secondary CPUs; simply causing those CPUs
   * to execute e.g. a RAM-based pin loop is not sufficient. This allows the
   * kexec'd kernel to use any and all RAM as it sees fit, without having to
   * avoid any code or data used by any SW CPU pin loop. The CPU hotplug
   * functionality embodied in disable_nonboot_cpus() to achieve this.
   */
  void machine_shutdown(void)
  {
  	disable_nonboot_cpus();
  }
  
  /*
   * Halting simply requires that the secondary CPUs stop performing any
   * activity (executing tasks, handling interrupts). smp_send_stop()
   * achieves this.
   */
  void machine_halt(void)
  {
  	local_irq_disable();
  	smp_send_stop();
  	while (1);
  }
  
  /*
   * Power-off simply requires that the secondary CPUs stop performing any
   * activity (executing tasks, handling interrupts). smp_send_stop()
   * achieves this. When the system power is turned off, it will take all CPUs
   * with it.
   */
  void machine_power_off(void)
  {
  	local_irq_disable();
  	smp_send_stop();
  	pr_emerg("machine_power_off, pm_power_off(%p)\n", pm_power_off);
  	dump_stack();
  	if (pm_power_off)
  		pm_power_off();
  }
  
  /*
   * Restart requires that the secondary CPUs stop performing any activity
   * while the primary CPU resets the system. Systems with a single CPU can
   * use soft_restart() as their machine descriptor's .restart hook, since that
   * will cause the only available CPU to reset. Systems with multiple CPUs must
   * provide a HW restart implementation, to ensure that all CPUs reset at once.
   * This is required so that any code running after reset on the primary CPU
   * doesn't have to co-ordinate with other CPUs to ensure they aren't still
   * executing pre-reset code, and using RAM that the primary CPU's code wishes
   * to use. Implementing such co-ordination would be essentially impossible.
   */
  void machine_restart(char *cmd)
  {
  	/* Disable interrupts first */
  	local_irq_disable();
  	smp_send_stop();
  
  	/* Now call the architecture specific reboot code. */
  	pr_emerg("machine_restart, arm_pm_restart(%p)\n", arm_pm_restart);
  	if (arm_pm_restart)
  		arm_pm_restart(reboot_mode, cmd);
  	else
  		do_kernel_restart(cmd);
  
  	/*
  	 * Whoops - the architecture was unable to reboot.
  	 */
  	printk("Reboot failed -- System halted\n");
  	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;
  	unsigned int i;
  
  	fs = get_fs();
  	set_fs(KERNEL_DS);
  	show_data(regs->pc - nbytes, nbytes * 2, "PC");
  	show_data(regs->regs[30] - nbytes, nbytes * 2, "LR");
  	show_data(regs->sp - nbytes, nbytes * 2, "SP");
  	for (i = 0; i < 30; i++) {
  		char name[4];
  		snprintf(name, sizeof(name), "X%u", i);
  		show_data(regs->regs[i] - nbytes, nbytes * 2, name);
  	}
  	set_fs(fs);
  }
  
  void __show_regs(struct pt_regs *regs)
  {
  	int i, top_reg;
  	u64 lr, sp;
  
  	if (compat_user_mode(regs)) {
  		lr = regs->compat_lr;
  		sp = regs->compat_sp;
  		top_reg = 12;
  	} else {
  		lr = regs->regs[30];
  		sp = regs->sp;
  		top_reg = 29;
  	}
  
  	show_regs_print_info(KERN_DEFAULT);
  	print_symbol("PC is at %s\n", instruction_pointer(regs));
  	print_symbol("LR is at %s\n", lr);
  	printk("pc : [<%016llx>] lr : [<%016llx>] pstate: %08llx\n",
  	       regs->pc, lr, regs->pstate);
  	printk("sp : %016llx\n", sp);
  	for (i = top_reg; i >= 0; i--) {
  		printk("x%-2d: %016llx ", i, regs->regs[i]);
  		if (i % 2 == 0)
  			printk("\n");
  	}
  	if (!user_mode(regs))
  		show_extra_register_data(regs, 128);
  	printk("\n");
  }
  
  void show_regs(struct pt_regs * regs)
  {
  	printk("\n");
  	__show_regs(regs);
  }
  
  /*
   * Free current thread data structures etc..
   */
  void exit_thread(void)
  {
  }
  
  static void tls_thread_flush(void)
  {
  	asm ("msr tpidr_el0, xzr");
  
  	if (is_compat_task()) {
  		current->thread.tp_value = 0;
  
  		/*
  		 * We need to ensure ordering between the shadow state and the
  		 * hardware state, so that we don't corrupt the hardware state
  		 * with a stale shadow state during context switch.
  		 */
  		barrier();
  		asm ("msr tpidrro_el0, xzr");
  	}
  }
  
  void flush_thread(void)
  {
  	fpsimd_flush_thread();
  	tls_thread_flush();
  	flush_ptrace_hw_breakpoint(current);
  }
  
  void release_thread(struct task_struct *dead_task)
  {
  }
  
  int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  {
  	fpsimd_preserve_current_state();
  	*dst = *src;
  	return 0;
  }
  
  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 *childregs = task_pt_regs(p);
  	unsigned long tls = p->thread.tp_value;
  
  	memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));
  
  	if (likely(!(p->flags & PF_KTHREAD))) {
  		*childregs = *current_pt_regs();
  		childregs->regs[0] = 0;
  		if (is_compat_thread(task_thread_info(p))) {
  			if (stack_start)
  				childregs->compat_sp = stack_start;
  		} else {
  			/*
  			 * Read the current TLS pointer from tpidr_el0 as it may be
  			 * out-of-sync with the saved value.
  			 */
  			asm("mrs %0, tpidr_el0" : "=r" (tls));
  			if (stack_start) {
  				/* 16-byte aligned stack mandatory on AArch64 */
  				if (stack_start & 15)
  					return -EINVAL;
  				childregs->sp = stack_start;
  			}
  		}
  		/*
  		 * If a TLS pointer was passed to clone (4th argument), use it
  		 * for the new thread.
  		 */
  		if (clone_flags & CLONE_SETTLS)
  			tls = childregs->regs[3];
  	} else {
  		memset(childregs, 0, sizeof(struct pt_regs));
  		childregs->pstate = PSR_MODE_EL1h;
  		p->thread.cpu_context.x19 = stack_start;
  		p->thread.cpu_context.x20 = stk_sz;
  	}
  	p->thread.cpu_context.pc = (unsigned long)ret_from_fork;
  	p->thread.cpu_context.sp = (unsigned long)childregs;
  	p->thread.tp_value = tls;
  
  	ptrace_hw_copy_thread(p);
  
  	return 0;
  }
  
  static void tls_thread_switch(struct task_struct *next)
  {
  	unsigned long tpidr, tpidrro;
  
  	if (!is_compat_task()) {
  		asm("mrs %0, tpidr_el0" : "=r" (tpidr));
  		current->thread.tp_value = tpidr;
  	}
  
  	if (is_compat_thread(task_thread_info(next))) {
  		tpidr = 0;
  		tpidrro = next->thread.tp_value;
  	} else {
  		tpidr = next->thread.tp_value;
  		tpidrro = 0;
  	}
  
  	asm(
  	"	msr	tpidr_el0, %0\n"
  	"	msr	tpidrro_el0, %1"
  	: : "r" (tpidr), "r" (tpidrro));
  }
  
  /*
   * Thread switching.
   */
  struct task_struct *__switch_to(struct task_struct *prev,
  				struct task_struct *next)
  {
  	struct task_struct *last;
  
  	fpsimd_thread_switch(next);
  	tls_thread_switch(next);
  	hw_breakpoint_thread_switch(next);
  	contextidr_thread_switch(next);
  
  	/*
  	 * Complete any pending TLB or cache maintenance on this CPU in case
  	 * the thread migrates to a different CPU.
  	 */
  	dsb(ish);
  
  	/* the actual thread switch */
  	last = cpu_switch_to(prev, next);
  
  	return last;
  }
  
  unsigned long get_wchan(struct task_struct *p)
  {
  	struct stackframe frame;
  	unsigned long stack_page;
  	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.pc = thread_saved_pc(p);
  	stack_page = (unsigned long)task_stack_page(p);
  	do {
  		if (frame.sp < stack_page ||
  		    frame.sp >= stack_page + THREAD_SIZE ||
  		    unwind_frame(&frame))
  			return 0;
  		if (!in_sched_functions(frame.pc))
  			return frame.pc;
  	} while (count ++ < 16);
  	return 0;
  }
  
  unsigned long arch_align_stack(unsigned long sp)
  {
  	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
  		sp -= get_random_int() & ~PAGE_MASK;
  	return sp & ~0xf;
  }
  
  static unsigned long randomize_base(unsigned long base)
  {
  	unsigned long range_end = base + (STACK_RND_MASK << PAGE_SHIFT) + 1;
  	return randomize_range(base, range_end, 0) ? : base;
  }
  
  unsigned long arch_randomize_brk(struct mm_struct *mm)
  {
  	return randomize_base(mm->brk);
  }
  