Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 963 insertions, 0 deletions

diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
new file mode 100644
index 000000000..20b2db6dc
--- /dev/null
+++ b/arch/arm/kernel/traps.c
@@ -0,0 +1,963 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/arch/arm/kernel/traps.c
+ *
+ *  Copyright (C) 1995-2009 Russell King
+ *  Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
+ *
+ *  'traps.c' handles hardware exceptions after we have saved some state in
+ *  'linux/arch/arm/lib/traps.S'.  Mostly a debugging aid, but will probably
+ *  kill the offending process.
+ */
+#include <linux/signal.h>
+#include <linux/personality.h>
+#include <linux/kallsyms.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <linux/hardirq.h>
+#include <linux/kdebug.h>
+#include <linux/kprobes.h>
+#include <linux/module.h>
+#include <linux/kexec.h>
+#include <linux/bug.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
+#include <linux/irq.h>
+
+#include <linux/atomic.h>
+#include <asm/cacheflush.h>
+#include <asm/exception.h>
+#include <asm/spectre.h>
+#include <asm/unistd.h>
+#include <asm/traps.h>
+#include <asm/ptrace.h>
+#include <asm/unwind.h>
+#include <asm/tls.h>
+#include <asm/stacktrace.h>
+#include <asm/system_misc.h>
+#include <asm/opcodes.h>
+
+
+static const char *handler[]= {
+	"prefetch abort",
+	"data abort",
+	"address exception",
+	"interrupt",
+	"undefined instruction",
+};
+
+void *vectors_page;
+
+#ifdef CONFIG_DEBUG_USER
+unsigned int user_debug;
+
+static int __init user_debug_setup(char *str)
+{
+	get_option(&str, &user_debug);
+	return 1;
+}
+__setup("user_debug=", user_debug_setup);
+#endif
+
+void dump_backtrace_entry(unsigned long where, unsigned long from,
+			  unsigned long frame, const char *loglvl)
+{
+	unsigned long end = frame + 4 + sizeof(struct pt_regs);
+
+	if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER) &&
+	    IS_ENABLED(CONFIG_CC_IS_GCC) &&
+	    end > ALIGN(frame, THREAD_SIZE)) {
+		/*
+		 * If we are walking past the end of the stack, it may be due
+		 * to the fact that we are on an IRQ or overflow stack. In this
+		 * case, we can load the address of the other stack from the
+		 * frame record.
+		 */
+		frame = ((unsigned long *)frame)[-2] - 4;
+		end = frame + 4 + sizeof(struct pt_regs);
+	}
+
+#ifndef CONFIG_KALLSYMS
+	printk("%sFunction entered at [<%08lx>] from [<%08lx>]\n",
+		loglvl, where, from);
+#elif defined CONFIG_BACKTRACE_VERBOSE
+	printk("%s[<%08lx>] (%ps) from [<%08lx>] (%pS)\n",
+		loglvl, where, (void *)where, from, (void *)from);
+#else
+	printk("%s %ps from %pS\n", loglvl, (void *)where, (void *)from);
+#endif
+
+	if (in_entry_text(from) && end <= ALIGN(frame, THREAD_SIZE))
+		dump_mem(loglvl, "Exception stack", frame + 4, end);
+}
+
+void dump_backtrace_stm(u32 *stack, u32 instruction, const char *loglvl)
+{
+	char str[80], *p;
+	unsigned int x;
+	int reg;
+
+	for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
+		if (instruction & BIT(reg)) {
+			p += sprintf(p, " r%d:%08x", reg, *stack--);
+			if (++x == 6) {
+				x = 0;
+				p = str;
+				printk("%s%s\n", loglvl, str);
+			}
+		}
+	}
+	if (p != str)
+		printk("%s%s\n", loglvl, str);
+}
+
+#ifndef CONFIG_ARM_UNWIND
+/*
+ * Stack pointers should always be within the kernels view of
+ * physical memory.  If it is not there, then we can't dump
+ * out any information relating to the stack.
+ */
+static int verify_stack(unsigned long sp)
+{
+	if (sp < PAGE_OFFSET ||
+	    (!IS_ENABLED(CONFIG_VMAP_STACK) &&
+	     sp > (unsigned long)high_memory && high_memory != NULL))
+		return -EFAULT;
+
+	return 0;
+}
+#endif
+
+/*
+ * Dump out the contents of some memory nicely...
+ */
+void dump_mem(const char *lvl, const char *str, unsigned long bottom,
+	      unsigned long top)
+{
+	unsigned long first;
+	int i;
+
+	printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
+
+	for (first = bottom & ~31; first < top; first += 32) {
+		unsigned long p;
+		char str[sizeof(" 12345678") * 8 + 1];
+
+		memset(str, ' ', sizeof(str));
+		str[sizeof(str) - 1] = '\0';
+
+		for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
+			if (p >= bottom && p < top) {
+				unsigned long val;
+				if (!get_kernel_nofault(val, (unsigned long *)p))
+					sprintf(str + i * 9, " %08lx", val);
+				else
+					sprintf(str + i * 9, " ????????");
+			}
+		}
+		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
+	}
+}
+
+static void dump_instr(const char *lvl, struct pt_regs *regs)
+{
+	unsigned long addr = instruction_pointer(regs);
+	const int thumb = thumb_mode(regs);
+	const int width = thumb ? 4 : 8;
+	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
+	int i;
+
+	/*
+	 * Note that we now dump the code first, just in case the backtrace
+	 * kills us.
+	 */
+
+	for (i = -4; i < 1 + !!thumb; i++) {
+		unsigned int val, bad;
+
+		if (!user_mode(regs)) {
+			if (thumb) {
+				u16 val16;
+				bad = get_kernel_nofault(val16, &((u16 *)addr)[i]);
+				val = val16;
+			} else {
+				bad = get_kernel_nofault(val, &((u32 *)addr)[i]);
+			}
+		} else {
+			if (thumb)
+				bad = get_user(val, &((u16 *)addr)[i]);
+			else
+				bad = get_user(val, &((u32 *)addr)[i]);
+		}
+
+		if (!bad)
+			p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
+					width, val);
+		else {
+			p += sprintf(p, "bad PC value");
+			break;
+		}
+	}
+	printk("%sCode: %s\n", lvl, str);
+}
+
+#ifdef CONFIG_ARM_UNWIND
+void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
+		    const char *loglvl)
+{
+	unwind_backtrace(regs, tsk, loglvl);
+}
+#else
+void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
+		    const char *loglvl)
+{
+	unsigned int fp, mode;
+	int ok = 1;
+
+	printk("%sBacktrace: ", loglvl);
+
+	if (!tsk)
+		tsk = current;
+
+	if (regs) {
+		fp = frame_pointer(regs);
+		mode = processor_mode(regs);
+	} else if (tsk != current) {
+		fp = thread_saved_fp(tsk);
+		mode = 0x10;
+	} else {
+		asm("mov %0, fp" : "=r" (fp) : : "cc");
+		mode = 0x10;
+	}
+
+	if (!fp) {
+		pr_cont("no frame pointer");
+		ok = 0;
+	} else if (verify_stack(fp)) {
+		pr_cont("invalid frame pointer 0x%08x", fp);
+		ok = 0;
+	} else if (fp < (unsigned long)end_of_stack(tsk))
+		pr_cont("frame pointer underflow");
+	pr_cont("\n");
+
+	if (ok)
+		c_backtrace(fp, mode, loglvl);
+}
+#endif
+
+void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
+{
+	dump_backtrace(NULL, tsk, loglvl);
+	barrier();
+}
+
+#ifdef CONFIG_PREEMPT
+#define S_PREEMPT " PREEMPT"
+#elif defined(CONFIG_PREEMPT_RT)
+#define S_PREEMPT " PREEMPT_RT"
+#else
+#define S_PREEMPT ""
+#endif
+#ifdef CONFIG_SMP
+#define S_SMP " SMP"
+#else
+#define S_SMP ""
+#endif
+#ifdef CONFIG_THUMB2_KERNEL
+#define S_ISA " THUMB2"
+#else
+#define S_ISA " ARM"
+#endif
+
+static int __die(const char *str, int err, struct pt_regs *regs)
+{
+	struct task_struct *tsk = current;
+	static int die_counter;
+	int ret;
+
+	pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
+	         str, err, ++die_counter);
+
+	/* trap and error numbers are mostly meaningless on ARM */
+	ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
+	if (ret == NOTIFY_STOP)
+		return 1;
+
+	print_modules();
+	__show_regs(regs);
+	__show_regs_alloc_free(regs);
+	pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
+		 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
+
+	if (!user_mode(regs) || in_interrupt()) {
+		dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
+			 ALIGN(regs->ARM_sp - THREAD_SIZE, THREAD_ALIGN)
+			 + THREAD_SIZE);
+		dump_backtrace(regs, tsk, KERN_EMERG);
+		dump_instr(KERN_EMERG, regs);
+	}
+
+	return 0;
+}
+
+static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
+static int die_owner = -1;
+static unsigned int die_nest_count;
+
+static unsigned long oops_begin(void)
+{
+	int cpu;
+	unsigned long flags;
+
+	oops_enter();
+
+	/* racy, but better than risking deadlock. */
+	raw_local_irq_save(flags);
+	cpu = smp_processor_id();
+	if (!arch_spin_trylock(&die_lock)) {
+		if (cpu == die_owner)
+			/* nested oops. should stop eventually */;
+		else
+			arch_spin_lock(&die_lock);
+	}
+	die_nest_count++;
+	die_owner = cpu;
+	console_verbose();
+	bust_spinlocks(1);
+	return flags;
+}
+
+static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
+{
+	if (regs && kexec_should_crash(current))
+		crash_kexec(regs);
+
+	bust_spinlocks(0);
+	die_owner = -1;
+	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
+	die_nest_count--;
+	if (!die_nest_count)
+		/* Nest count reaches zero, release the lock. */
+		arch_spin_unlock(&die_lock);
+	raw_local_irq_restore(flags);
+	oops_exit();
+
+	if (in_interrupt())
+		panic("Fatal exception in interrupt");
+	if (panic_on_oops)
+		panic("Fatal exception");
+	if (signr)
+		make_task_dead(signr);
+}
+
+/*
+ * This function is protected against re-entrancy.
+ */
+void die(const char *str, struct pt_regs *regs, int err)
+{
+	enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
+	unsigned long flags = oops_begin();
+	int sig = SIGSEGV;
+
+	if (!user_mode(regs))
+		bug_type = report_bug(regs->ARM_pc, regs);
+	if (bug_type != BUG_TRAP_TYPE_NONE)
+		str = "Oops - BUG";
+
+	if (__die(str, err, regs))
+		sig = 0;
+
+	oops_end(flags, regs, sig);
+}
+
+void arm_notify_die(const char *str, struct pt_regs *regs,
+		int signo, int si_code, void __user *addr,
+		unsigned long err, unsigned long trap)
+{
+	if (user_mode(regs)) {
+		current->thread.error_code = err;
+		current->thread.trap_no = trap;
+
+		force_sig_fault(signo, si_code, addr);
+	} else {
+		die(str, regs, err);
+	}
+}
+
+#ifdef CONFIG_GENERIC_BUG
+
+int is_valid_bugaddr(unsigned long pc)
+{
+#ifdef CONFIG_THUMB2_KERNEL
+	u16 bkpt;
+	u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
+#else
+	u32 bkpt;
+	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
+#endif
+
+	if (get_kernel_nofault(bkpt, (void *)pc))
+		return 0;
+
+	return bkpt == insn;
+}
+
+#endif
+
+static LIST_HEAD(undef_hook);
+static DEFINE_RAW_SPINLOCK(undef_lock);
+
+void register_undef_hook(struct undef_hook *hook)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&undef_lock, flags);
+	list_add(&hook->node, &undef_hook);
+	raw_spin_unlock_irqrestore(&undef_lock, flags);
+}
+
+void unregister_undef_hook(struct undef_hook *hook)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&undef_lock, flags);
+	list_del(&hook->node);
+	raw_spin_unlock_irqrestore(&undef_lock, flags);
+}
+
+static nokprobe_inline
+int call_undef_hook(struct pt_regs *regs, unsigned int instr)
+{
+	struct undef_hook *hook;
+	unsigned long flags;
+	int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
+
+	raw_spin_lock_irqsave(&undef_lock, flags);
+	list_for_each_entry(hook, &undef_hook, node)
+		if ((instr & hook->instr_mask) == hook->instr_val &&
+		    (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
+			fn = hook->fn;
+	raw_spin_unlock_irqrestore(&undef_lock, flags);
+
+	return fn ? fn(regs, instr) : 1;
+}
+
+asmlinkage void do_undefinstr(struct pt_regs *regs)
+{
+	unsigned int instr;
+	void __user *pc;
+
+	pc = (void __user *)instruction_pointer(regs);
+
+	if (processor_mode(regs) == SVC_MODE) {
+#ifdef CONFIG_THUMB2_KERNEL
+		if (thumb_mode(regs)) {
+			instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
+			if (is_wide_instruction(instr)) {
+				u16 inst2;
+				inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
+				instr = __opcode_thumb32_compose(instr, inst2);
+			}
+		} else
+#endif
+			instr = __mem_to_opcode_arm(*(u32 *) pc);
+	} else if (thumb_mode(regs)) {
+		if (get_user(instr, (u16 __user *)pc))
+			goto die_sig;
+		instr = __mem_to_opcode_thumb16(instr);
+		if (is_wide_instruction(instr)) {
+			unsigned int instr2;
+			if (get_user(instr2, (u16 __user *)pc+1))
+				goto die_sig;
+			instr2 = __mem_to_opcode_thumb16(instr2);
+			instr = __opcode_thumb32_compose(instr, instr2);
+		}
+	} else {
+		if (get_user(instr, (u32 __user *)pc))
+			goto die_sig;
+		instr = __mem_to_opcode_arm(instr);
+	}
+
+	if (call_undef_hook(regs, instr) == 0)
+		return;
+
+die_sig:
+#ifdef CONFIG_DEBUG_USER
+	if (user_debug & UDBG_UNDEFINED) {
+		pr_info("%s (%d): undefined instruction: pc=%px\n",
+			current->comm, task_pid_nr(current), pc);
+		__show_regs(regs);
+		dump_instr(KERN_INFO, regs);
+	}
+#endif
+	arm_notify_die("Oops - undefined instruction", regs,
+		       SIGILL, ILL_ILLOPC, pc, 0, 6);
+}
+NOKPROBE_SYMBOL(do_undefinstr)
+
+/*
+ * Handle FIQ similarly to NMI on x86 systems.
+ *
+ * The runtime environment for NMIs is extremely restrictive
+ * (NMIs can pre-empt critical sections meaning almost all locking is
+ * forbidden) meaning this default FIQ handling must only be used in
+ * circumstances where non-maskability improves robustness, such as
+ * watchdog or debug logic.
+ *
+ * This handler is not appropriate for general purpose use in drivers
+ * platform code and can be overrideen using set_fiq_handler.
+ */
+asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
+{
+	struct pt_regs *old_regs = set_irq_regs(regs);
+
+	nmi_enter();
+
+	/* nop. FIQ handlers for special arch/arm features can be added here. */
+
+	nmi_exit();
+
+	set_irq_regs(old_regs);
+}
+
+/*
+ * bad_mode handles the impossible case in the vectors.  If you see one of
+ * these, then it's extremely serious, and could mean you have buggy hardware.
+ * It never returns, and never tries to sync.  We hope that we can at least
+ * dump out some state information...
+ */
+asmlinkage void bad_mode(struct pt_regs *regs, int reason)
+{
+	console_verbose();
+
+	pr_crit("Bad mode in %s handler detected\n", handler[reason]);
+
+	die("Oops - bad mode", regs, 0);
+	local_irq_disable();
+	panic("bad mode");
+}
+
+static int bad_syscall(int n, struct pt_regs *regs)
+{
+	if ((current->personality & PER_MASK) != PER_LINUX) {
+		send_sig(SIGSEGV, current, 1);
+		return regs->ARM_r0;
+	}
+
+#ifdef CONFIG_DEBUG_USER
+	if (user_debug & UDBG_SYSCALL) {
+		pr_err("[%d] %s: obsolete system call %08x.\n",
+			task_pid_nr(current), current->comm, n);
+		dump_instr(KERN_ERR, regs);
+	}
+#endif
+
+	arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
+		       (void __user *)instruction_pointer(regs) -
+			 (thumb_mode(regs) ? 2 : 4),
+		       n, 0);
+
+	return regs->ARM_r0;
+}
+
+static inline int
+__do_cache_op(unsigned long start, unsigned long end)
+{
+	int ret;
+
+	do {
+		unsigned long chunk = min(PAGE_SIZE, end - start);
+
+		if (fatal_signal_pending(current))
+			return 0;
+
+		ret = flush_icache_user_range(start, start + chunk);
+		if (ret)
+			return ret;
+
+		cond_resched();
+		start += chunk;
+	} while (start < end);
+
+	return 0;
+}
+
+static inline int
+do_cache_op(unsigned long start, unsigned long end, int flags)
+{
+	if (end < start || flags)
+		return -EINVAL;
+
+	if (!access_ok((void __user *)start, end - start))
+		return -EFAULT;
+
+	return __do_cache_op(start, end);
+}
+
+/*
+ * Handle all unrecognised system calls.
+ *  0x9f0000 - 0x9fffff are some more esoteric system calls
+ */
+#define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
+asmlinkage int arm_syscall(int no, struct pt_regs *regs)
+{
+	if ((no >> 16) != (__ARM_NR_BASE>> 16))
+		return bad_syscall(no, regs);
+
+	switch (no & 0xffff) {
+	case 0: /* branch through 0 */
+		arm_notify_die("branch through zero", regs,
+			       SIGSEGV, SEGV_MAPERR, NULL, 0, 0);
+		return 0;
+
+	case NR(breakpoint): /* SWI BREAK_POINT */
+		regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
+		ptrace_break(regs);
+		return regs->ARM_r0;
+
+	/*
+	 * Flush a region from virtual address 'r0' to virtual address 'r1'
+	 * _exclusive_.  There is no alignment requirement on either address;
+	 * user space does not need to know the hardware cache layout.
+	 *
+	 * r2 contains flags.  It should ALWAYS be passed as ZERO until it
+	 * is defined to be something else.  For now we ignore it, but may
+	 * the fires of hell burn in your belly if you break this rule. ;)
+	 *
+	 * (at a later date, we may want to allow this call to not flush
+	 * various aspects of the cache.  Passing '0' will guarantee that
+	 * everything necessary gets flushed to maintain consistency in
+	 * the specified region).
+	 */
+	case NR(cacheflush):
+		return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
+
+	case NR(usr26):
+		if (!(elf_hwcap & HWCAP_26BIT))
+			break;
+		regs->ARM_cpsr &= ~MODE32_BIT;
+		return regs->ARM_r0;
+
+	case NR(usr32):
+		if (!(elf_hwcap & HWCAP_26BIT))
+			break;
+		regs->ARM_cpsr |= MODE32_BIT;
+		return regs->ARM_r0;
+
+	case NR(set_tls):
+		set_tls(regs->ARM_r0);
+		return 0;
+
+	case NR(get_tls):
+		return current_thread_info()->tp_value[0];
+
+	default:
+		/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
+		   if not implemented, rather than raising SIGILL.  This
+		   way the calling program can gracefully determine whether
+		   a feature is supported.  */
+		if ((no & 0xffff) <= 0x7ff)
+			return -ENOSYS;
+		break;
+	}
+#ifdef CONFIG_DEBUG_USER
+	/*
+	 * experience shows that these seem to indicate that
+	 * something catastrophic has happened
+	 */
+	if (user_debug & UDBG_SYSCALL) {
+		pr_err("[%d] %s: arm syscall %d\n",
+		       task_pid_nr(current), current->comm, no);
+		dump_instr(KERN_ERR, regs);
+		if (user_mode(regs)) {
+			__show_regs(regs);
+			c_backtrace(frame_pointer(regs), processor_mode(regs), KERN_ERR);
+		}
+	}
+#endif
+	arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
+		       (void __user *)instruction_pointer(regs) -
+			 (thumb_mode(regs) ? 2 : 4),
+		       no, 0);
+	return 0;
+}
+
+#ifdef CONFIG_TLS_REG_EMUL
+
+/*
+ * We might be running on an ARMv6+ processor which should have the TLS
+ * register but for some reason we can't use it, or maybe an SMP system
+ * using a pre-ARMv6 processor (there are apparently a few prototypes like
+ * that in existence) and therefore access to that register must be
+ * emulated.
+ */
+
+static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
+{
+	int reg = (instr >> 12) & 15;
+	if (reg == 15)
+		return 1;
+	regs->uregs[reg] = current_thread_info()->tp_value[0];
+	regs->ARM_pc += 4;
+	return 0;
+}
+
+static struct undef_hook arm_mrc_hook = {
+	.instr_mask	= 0x0fff0fff,
+	.instr_val	= 0x0e1d0f70,
+	.cpsr_mask	= PSR_T_BIT,
+	.cpsr_val	= 0,
+	.fn		= get_tp_trap,
+};
+
+static int __init arm_mrc_hook_init(void)
+{
+	register_undef_hook(&arm_mrc_hook);
+	return 0;
+}
+
+late_initcall(arm_mrc_hook_init);
+
+#endif
+
+/*
+ * A data abort trap was taken, but we did not handle the instruction.
+ * Try to abort the user program, or panic if it was the kernel.
+ */
+asmlinkage void
+baddataabort(int code, unsigned long instr, struct pt_regs *regs)
+{
+	unsigned long addr = instruction_pointer(regs);
+
+#ifdef CONFIG_DEBUG_USER
+	if (user_debug & UDBG_BADABORT) {
+		pr_err("8<--- cut here ---\n");
+		pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
+		       task_pid_nr(current), current->comm, code, instr);
+		dump_instr(KERN_ERR, regs);
+		show_pte(KERN_ERR, current->mm, addr);
+	}
+#endif
+
+	arm_notify_die("unknown data abort code", regs,
+		       SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0);
+}
+
+void __readwrite_bug(const char *fn)
+{
+	pr_err("%s called, but not implemented\n", fn);
+	BUG();
+}
+EXPORT_SYMBOL(__readwrite_bug);
+
+void __pte_error(const char *file, int line, pte_t pte)
+{
+	pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
+}
+
+void __pmd_error(const char *file, int line, pmd_t pmd)
+{
+	pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
+}
+
+void __pgd_error(const char *file, int line, pgd_t pgd)
+{
+	pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
+}
+
+asmlinkage void __div0(void)
+{
+	pr_err("Division by zero in kernel.\n");
+	dump_stack();
+}
+EXPORT_SYMBOL(__div0);
+
+void abort(void)
+{
+	BUG();
+
+	/* if that doesn't kill us, halt */
+	panic("Oops failed to kill thread");
+}
+
+#ifdef CONFIG_KUSER_HELPERS
+static void __init kuser_init(void *vectors)
+{
+	extern char __kuser_helper_start[], __kuser_helper_end[];
+	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
+
+	memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
+
+	/*
+	 * vectors + 0xfe0 = __kuser_get_tls
+	 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
+	 */
+	if (tls_emu || has_tls_reg)
+		memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
+}
+#else
+static inline void __init kuser_init(void *vectors)
+{
+}
+#endif
+
+#ifndef CONFIG_CPU_V7M
+static void copy_from_lma(void *vma, void *lma_start, void *lma_end)
+{
+	memcpy(vma, lma_start, lma_end - lma_start);
+}
+
+static void flush_vectors(void *vma, size_t offset, size_t size)
+{
+	unsigned long start = (unsigned long)vma + offset;
+	unsigned long end = start + size;
+
+	flush_icache_range(start, end);
+}
+
+#ifdef CONFIG_HARDEN_BRANCH_HISTORY
+int spectre_bhb_update_vectors(unsigned int method)
+{
+	extern char __vectors_bhb_bpiall_start[], __vectors_bhb_bpiall_end[];
+	extern char __vectors_bhb_loop8_start[], __vectors_bhb_loop8_end[];
+	void *vec_start, *vec_end;
+
+	if (system_state >= SYSTEM_FREEING_INITMEM) {
+		pr_err("CPU%u: Spectre BHB workaround too late - system vulnerable\n",
+		       smp_processor_id());
+		return SPECTRE_VULNERABLE;
+	}
+
+	switch (method) {
+	case SPECTRE_V2_METHOD_LOOP8:
+		vec_start = __vectors_bhb_loop8_start;
+		vec_end = __vectors_bhb_loop8_end;
+		break;
+
+	case SPECTRE_V2_METHOD_BPIALL:
+		vec_start = __vectors_bhb_bpiall_start;
+		vec_end = __vectors_bhb_bpiall_end;
+		break;
+
+	default:
+		pr_err("CPU%u: unknown Spectre BHB state %d\n",
+		       smp_processor_id(), method);
+		return SPECTRE_VULNERABLE;
+	}
+
+	copy_from_lma(vectors_page, vec_start, vec_end);
+	flush_vectors(vectors_page, 0, vec_end - vec_start);
+
+	return SPECTRE_MITIGATED;
+}
+#endif
+
+void __init early_trap_init(void *vectors_base)
+{
+	extern char __stubs_start[], __stubs_end[];
+	extern char __vectors_start[], __vectors_end[];
+	unsigned i;
+
+	vectors_page = vectors_base;
+
+	/*
+	 * Poison the vectors page with an undefined instruction.  This
+	 * instruction is chosen to be undefined for both ARM and Thumb
+	 * ISAs.  The Thumb version is an undefined instruction with a
+	 * branch back to the undefined instruction.
+	 */
+	for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
+		((u32 *)vectors_base)[i] = 0xe7fddef1;
+
+	/*
+	 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
+	 * into the vector page, mapped at 0xffff0000, and ensure these
+	 * are visible to the instruction stream.
+	 */
+	copy_from_lma(vectors_base, __vectors_start, __vectors_end);
+	copy_from_lma(vectors_base + 0x1000, __stubs_start, __stubs_end);
+
+	kuser_init(vectors_base);
+
+	flush_vectors(vectors_base, 0, PAGE_SIZE * 2);
+}
+#else /* ifndef CONFIG_CPU_V7M */
+void __init early_trap_init(void *vectors_base)
+{
+	/*
+	 * on V7-M there is no need to copy the vector table to a dedicated
+	 * memory area. The address is configurable and so a table in the kernel
+	 * image can be used.
+	 */
+}
+#endif
+
+#ifdef CONFIG_VMAP_STACK
+
+DECLARE_PER_CPU(u8 *, irq_stack_ptr);
+
+asmlinkage DEFINE_PER_CPU(u8 *, overflow_stack_ptr);
+
+static int __init allocate_overflow_stacks(void)
+{
+	u8 *stack;
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		stack = (u8 *)__get_free_page(GFP_KERNEL);
+		if (WARN_ON(!stack))
+			return -ENOMEM;
+		per_cpu(overflow_stack_ptr, cpu) = &stack[OVERFLOW_STACK_SIZE];
+	}
+	return 0;
+}
+early_initcall(allocate_overflow_stacks);
+
+asmlinkage void handle_bad_stack(struct pt_regs *regs)
+{
+	unsigned long tsk_stk = (unsigned long)current->stack;
+#ifdef CONFIG_IRQSTACKS
+	unsigned long irq_stk = (unsigned long)raw_cpu_read(irq_stack_ptr);
+#endif
+	unsigned long ovf_stk = (unsigned long)raw_cpu_read(overflow_stack_ptr);
+
+	console_verbose();
+	pr_emerg("Insufficient stack space to handle exception!");
+
+	pr_emerg("Task stack:     [0x%08lx..0x%08lx]\n",
+		 tsk_stk, tsk_stk + THREAD_SIZE);
+#ifdef CONFIG_IRQSTACKS
+	pr_emerg("IRQ stack:      [0x%08lx..0x%08lx]\n",
+		 irq_stk - THREAD_SIZE, irq_stk);
+#endif
+	pr_emerg("Overflow stack: [0x%08lx..0x%08lx]\n",
+		 ovf_stk - OVERFLOW_STACK_SIZE, ovf_stk);
+
+	die("kernel stack overflow", regs, 0);
+}
+
+#ifndef CONFIG_ARM_LPAE
+/*
+ * Normally, we rely on the logic in do_translation_fault() to update stale PMD
+ * entries covering the vmalloc space in a task's page tables when it first
+ * accesses the region in question. Unfortunately, this is not sufficient when
+ * the task stack resides in the vmalloc region, as do_translation_fault() is a
+ * C function that needs a stack to run.
+ *
+ * So we need to ensure that these PMD entries are up to date *before* the MM
+ * switch. As we already have some logic in the MM switch path that takes care
+ * of this, let's trigger it by bumping the counter every time the core vmalloc
+ * code modifies a PMD entry in the vmalloc region. Use release semantics on
+ * the store so that other CPUs observing the counter's new value are
+ * guaranteed to see the updated page table entries as well.
+ */
+void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
+{
+	if (start < VMALLOC_END && end > VMALLOC_START)
+		atomic_inc_return_release(&init_mm.context.vmalloc_seq);
+}
+#endif
+#endif