text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   *  linux/arch/arm/kernel/process.c
   *
   *  Copyright (C) 1996-2000 Russell King - Converted to ARM.
   *  Original Copyright (C) 1995  Linus Torvalds
   */
  #include <linux/export.h>
  #include <linux/sched.h>
  #include <linux/sched/debug.h>
  #include <linux/sched/task.h>
  #include <linux/sched/task_stack.h>
  #include <linux/kernel.h>
  #include <linux/mm.h>
  #include <linux/stddef.h>
  #include <linux/unistd.h>
  #include <linux/user.h>
  #include <linux/interrupt.h>
  #include <linux/init.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/leds.h>
  
  #include <asm/processor.h>
  #include <asm/thread_notify.h>
  #include <asm/stacktrace.h>
  #include <asm/system_misc.h>
  #include <asm/mach/time.h>
  #include <asm/tls.h>
  #include <asm/vdso.h>
  
  #include "signal.h"
  
  #if defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP)
  DEFINE_PER_CPU(struct task_struct *, __entry_task);
  #endif
  
  #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
  #include <linux/stackprotector.h>
  unsigned long __stack_chk_guard __read_mostly;
  EXPORT_SYMBOL(__stack_chk_guard);
  #endif
  
  #ifndef CONFIG_CURRENT_POINTER_IN_TPIDRURO
  asmlinkage struct task_struct *__current;
  EXPORT_SYMBOL(__current);
  #endif
  
  static const char *processor_modes[] __maybe_unused = {
    "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" , "MON_32" , "ABT_32" ,
    "UK8_32" , "UK9_32" , "HYP_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
  };
  
  static const char *isa_modes[] __maybe_unused = {
    "ARM" , "Thumb" , "Jazelle", "ThumbEE"
  };
  
  /*
   * This is our default idle handler.
   */
  
  void (*arm_pm_idle)(void);
  
  /*
   * Called from the core idle loop.
   */
  
  void arch_cpu_idle(void)
  {
  	if (arm_pm_idle)
  		arm_pm_idle();
  	else
  		cpu_do_idle();
  	raw_local_irq_enable();
  }
  
  void arch_cpu_idle_prepare(void)
  {
  	local_fiq_enable();
  }
  
  void arch_cpu_idle_enter(void)
  {
  	ledtrig_cpu(CPU_LED_IDLE_START);
  #ifdef CONFIG_PL310_ERRATA_769419
  	wmb();
  #endif
  }
  
  void arch_cpu_idle_exit(void)
  {
  	ledtrig_cpu(CPU_LED_IDLE_END);
  }
  
  void __show_regs_alloc_free(struct pt_regs *regs)
  {
  	int i;
  
  	/* check for r0 - r12 only */
  	for (i = 0; i < 13; i++) {
  		pr_alert("Register r%d information:", i);
  		mem_dump_obj((void *)regs->uregs[i]);
  	}
  }
  
  void __show_regs(struct pt_regs *regs)
  {
  	unsigned long flags;
  	char buf[64];
  #ifndef CONFIG_CPU_V7M
  	unsigned int domain;
  #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  	/*
  	 * Get the domain register for the parent context. In user
  	 * mode, we don't save the DACR, so lets use what it should
  	 * be. For other modes, we place it after the pt_regs struct.
  	 */
  	if (user_mode(regs)) {
  		domain = DACR_UACCESS_ENABLE;
  	} else {
  		domain = to_svc_pt_regs(regs)->dacr;
  	}
  #else
  	domain = get_domain();
  #endif
  #endif
  
  	show_regs_print_info(KERN_DEFAULT);
  
  	printk("PC is at %pS\n", (void *)instruction_pointer(regs));
  	printk("LR is at %pS\n", (void *)regs->ARM_lr);
  	printk("pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n",
  	       regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr);
  	printk("sp : %08lx  ip : %08lx  fp : %08lx\n",
  	       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';
  
  #ifndef CONFIG_CPU_V7M
  	{
  		const char *segment;
  
  		if ((domain & domain_mask(DOMAIN_USER)) ==
  		    domain_val(DOMAIN_USER, DOMAIN_NOACCESS))
  			segment = "none";
  		else
  			segment = "user";
  
  		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)], segment);
  	}
  #else
  	printk("xPSR: %08lx\n", regs->ARM_cpsr);
  #endif
  
  #ifdef CONFIG_CPU_CP15
  	{
  		unsigned int ctrl;
  
  		buf[0] = '\0';
  #ifdef CONFIG_CPU_CP15_MMU
  		{
  			unsigned int transbase;
  			asm("mrc p15, 0, %0, c2, c0\n\t"
  			    : "=r" (transbase));
  			snprintf(buf, sizeof(buf), "  Table: %08x  DAC: %08x",
  				transbase, domain);
  		}
  #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)
  {
  	__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(struct task_struct *tsk)
  {
  	thread_notify(THREAD_NOTIFY_EXIT, task_thread_info(tsk));
  }
  
  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));
  
  	flush_tls();
  
  	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, unsigned long tls)
  {
  	struct thread_info *thread = task_thread_info(p);
  	struct pt_regs *childregs = task_pt_regs(p);
  
  	memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
  
  #ifdef CONFIG_CPU_USE_DOMAINS
  	/*
  	 * Copy the initial value of the domain access control register
  	 * from the current thread: thread->addr_limit will have been
  	 * copied from the current thread via setup_thread_stack() in
  	 * kernel/fork.c
  	 */
  	thread->cpu_domain = get_domain();
  #endif
  
  	if (likely(!(p->flags & (PF_KTHREAD | PF_IO_WORKER)))) {
  		*childregs = *current_pt_regs();
  		childregs->ARM_r0 = 0;
  		if (stack_start)
  			childregs->ARM_sp = stack_start;
  	} else {
  		memset(childregs, 0, sizeof(struct pt_regs));
  		thread->cpu_context.r4 = stk_sz;
  		thread->cpu_context.r5 = stack_start;
  		childregs->ARM_cpsr = SVC_MODE;
  	}
  	thread->cpu_context.pc = (unsigned long)ret_from_fork;
  	thread->cpu_context.sp = (unsigned long)childregs;
  
  	clear_ptrace_hw_breakpoint(p);
  
  	if (clone_flags & CLONE_SETTLS)
  		thread->tp_value[0] = tls;
  	thread->tp_value[1] = get_tpuser();
  
  	thread_notify(THREAD_NOTIFY_COPY, thread);
  
  	return 0;
  }
  
  unsigned long __get_wchan(struct task_struct *p)
  {
  	struct stackframe frame;
  	unsigned long stack_page;
  	int count = 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);
  	stack_page = (unsigned long)task_stack_page(p);
  	do {
  		if (frame.sp < stack_page ||
  		    frame.sp >= stack_page + THREAD_SIZE ||
  		    unwind_frame(&frame) < 0)
  			return 0;
  		if (!in_sched_functions(frame.pc))
  			return frame.pc;
  	} while (count ++ < 16);
  	return 0;
  }
  
  #ifdef CONFIG_MMU
  #ifdef CONFIG_KUSER_HELPERS
  /*
   * The vectors page is always readable from user space for the
   * atomic helpers. 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)
  {
  	vma_init(&gate_vma, NULL);
  	gate_vma.vm_page_prot = PAGE_READONLY_EXEC;
  	gate_vma.vm_start = 0xffff0000;
  	gate_vma.vm_end	= 0xffff0000 + PAGE_SIZE;
  	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;
  }
  
  /* If possible, provide a placement hint at a random offset from the
   * stack for the sigpage and vdso pages.
   */
  static unsigned long sigpage_addr(const struct mm_struct *mm,
  				  unsigned int npages)
  {
  	unsigned long offset;
  	unsigned long first;
  	unsigned long last;
  	unsigned long addr;
  	unsigned int slots;
  
  	first = PAGE_ALIGN(mm->start_stack);
  
  	last = TASK_SIZE - (npages << PAGE_SHIFT);
  
  	/* No room after stack? */
  	if (first > last)
  		return 0;
  
  	/* Just enough room? */
  	if (first == last)
  		return first;
  
  	slots = ((last - first) >> PAGE_SHIFT) + 1;
  
  	offset = get_random_int() % slots;
  
  	addr = first + (offset << PAGE_SHIFT);
  
  	return addr;
  }
  
  static struct page *signal_page;
  extern struct page *get_signal_page(void);
  
  static int sigpage_mremap(const struct vm_special_mapping *sm,
  		struct vm_area_struct *new_vma)
  {
  	current->mm->context.sigpage = new_vma->vm_start;
  	return 0;
  }
  
  static const struct vm_special_mapping sigpage_mapping = {
  	.name = "[sigpage]",
  	.pages = &signal_page,
  	.mremap = sigpage_mremap,
  };
  
  int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
  {
  	struct mm_struct *mm = current->mm;
  	struct vm_area_struct *vma;
  	unsigned long npages;
  	unsigned long addr;
  	unsigned long hint;
  	int ret = 0;
  
  	if (!signal_page)
  		signal_page = get_signal_page();
  	if (!signal_page)
  		return -ENOMEM;
  
  	npages = 1; /* for sigpage */
  	npages += vdso_total_pages;
  
  	if (mmap_write_lock_killable(mm))
  		return -EINTR;
  	hint = sigpage_addr(mm, npages);
  	addr = get_unmapped_area(NULL, hint, npages << PAGE_SHIFT, 0, 0);
  	if (IS_ERR_VALUE(addr)) {
  		ret = addr;
  		goto up_fail;
  	}
  
  	vma = _install_special_mapping(mm, addr, PAGE_SIZE,
  		VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
  		&sigpage_mapping);
  
  	if (IS_ERR(vma)) {
  		ret = PTR_ERR(vma);
  		goto up_fail;
  	}
  
  	mm->context.sigpage = addr;
  
  	/* Unlike the sigpage, failure to install the vdso is unlikely
  	 * to be fatal to the process, so no error check needed
  	 * here.
  	 */
  	arm_install_vdso(mm, addr + PAGE_SIZE);
  
   up_fail:
  	mmap_write_unlock(mm);
  	return ret;
  }
  #endif
  