first commit

1 files changed, 946 insertions, 0 deletions

diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
new file mode 100644
index 000000000..8dbf08a59
--- /dev/null
+++ b/arch/arm/kernel/traps.c
@@ -0,0 +1,946 @@
+/*
+ *  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
+ *
+ * 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.
+ *
+ *  '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/module.h>
+#include <linux/kexec.h>
+#include <linux/bug.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+
+#include <linux/atomic.h>
+#include <asm/cacheflush.h>
+#include <asm/exception.h>
+#include <asm/unistd.h>
+#include <asm/traps.h>
+#include <asm/unwind.h>
+#include <asm/tls.h>
+#include <asm/system_misc.h>
+#include <linux/aee.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
+
+static void dump_mem(const char *, const char *, unsigned long, unsigned long);
+
+void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
+{
+#ifdef CONFIG_KALLSYMS
+	printk("[<%08lx>] (%pS) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
+#else
+	printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
+#endif
+
+	if (in_exception_text(where))
+		dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
+}
+
+#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 ||
+	    (sp > (unsigned long)high_memory && high_memory != NULL))
+		return -EFAULT;
+
+	return 0;
+}
+#endif
+
+/*
+ * Dump out the contents of some memory nicely...
+ */
+static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
+		     unsigned long top)
+{
+	unsigned long first;
+	mm_segment_t fs;
+	int i;
+
+	/*
+	 * We need to switch to kernel mode so that we can use __get_user
+	 * to safely read from kernel space.  Note that we now dump the
+	 * code first, just in case the backtrace kills us.
+	 */
+	fs = get_fs();
+	set_fs(KERNEL_DS);
+
+	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_user(val, (unsigned long *)p) == 0)
+					sprintf(str + i * 9, " %08lx", val);
+				else
+					sprintf(str + i * 9, " ????????");
+			}
+		}
+		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
+	}
+
+	set_fs(fs);
+}
+
+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;
+	mm_segment_t fs;
+	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
+	int i;
+
+	/*
+	 * We need to switch to kernel mode so that we can use __get_user
+	 * to safely read from kernel space.  Note that we now dump the
+	 * code first, just in case the backtrace kills us.
+	 */
+	fs = get_fs();
+	set_fs(KERNEL_DS);
+
+	for (i = -4; i < 1 + !!thumb; i++) {
+		unsigned int val, bad;
+
+		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);
+
+	set_fs(fs);
+}
+
+#ifdef CONFIG_ARM_UNWIND
+static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
+{
+	unwind_backtrace(regs, tsk);
+}
+#else
+static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
+{
+	unsigned int fp, mode;
+	int ok = 1;
+
+	printk("Backtrace: ");
+
+	if (!tsk)
+		tsk = current;
+
+	if (regs) {
+		fp = regs->ARM_fp;
+		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) {
+		printk("no frame pointer");
+		ok = 0;
+	} else if (verify_stack(fp)) {
+		printk("invalid frame pointer 0x%08x", fp);
+		ok = 0;
+	} else if (fp < (unsigned long)end_of_stack(tsk))
+		printk("frame pointer underflow");
+	printk("\n");
+
+	if (ok)
+		c_backtrace(fp, mode);
+}
+#endif
+
+void dump_stack(void)
+{
+	dump_backtrace(NULL, NULL);
+}
+
+EXPORT_SYMBOL(dump_stack);
+
+void show_stack(struct task_struct *tsk, unsigned long *sp)
+{
+	dump_backtrace(NULL, tsk);
+	barrier();
+}
+
+#ifdef CONFIG_PREEMPT
+#define S_PREEMPT " PREEMPT"
+#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;
+	unsigned long sp, stack;
+	static int die_counter;
+	int ret;
+
+	printk(KERN_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 ret;
+
+	print_modules();
+	__show_regs(regs);
+	printk(KERN_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()) {
+		sp = regs->ARM_sp;
+		stack = (unsigned long)task_stack_page(tsk);
+		dump_mem(KERN_EMERG, "Stack: ", sp, ALIGN(sp, THREAD_SIZE));
+		if (sp < stack || (sp - stack) > THREAD_SIZE) {
+			printk(KERN_EMERG "Invalid sp[%lx] or stack address[%lx]\n", sp, stack);
+			dump_mem(KERN_EMERG, "Stack(backup) ", stack, THREAD_SIZE + stack);
+		}
+		dump_backtrace(regs, tsk);
+		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);
+	/* not enable irq incase softirq many turn off msdc clock */
+	//raw_local_irq_restore(flags);
+	oops_exit();
+
+	if (in_interrupt())
+		panic("Fatal exception in interrupt");
+	if (panic_on_oops)
+		panic("Fatal exception");
+	if (signr)
+		do_exit(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,
+		struct siginfo *info, unsigned long err, unsigned long trap)
+{
+	if (user_mode(regs)) {
+		current->thread.error_code = err;
+		current->thread.trap_no = trap;
+
+		force_sig_info(info->si_signo, info, current);
+	} 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 (probe_kernel_address((unsigned *)pc, bkpt))
+		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 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;
+}
+
+static DEFINE_PER_CPU(void *, __prev_undefinstr_pc) = 0;
+static DEFINE_PER_CPU(int, __prev_undefinstr_counter) = 0;
+
+asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
+{
+	struct thread_info *thread = current_thread_info();
+	int ret;
+	unsigned int instr;
+	siginfo_t info;
+	void __user *pc;
+	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
+
+	if (!user_mode(regs)) {
+		thread->cpu_excp++;
+		if (thread->cpu_excp == 1) {
+			thread->regs_on_excp = (void *)regs;
+			aee_excp_regs = (void*)regs;
+		}
+		if (thread->cpu_excp >= 2) {
+			aee_stop_nested_panic(regs);
+		}
+	}
+
+	pc = (void __user *)instruction_pointer(regs);
+
+	if (processor_mode(regs) == SVC_MODE) {
+#ifdef CONFIG_THUMB2_KERNEL
+		if (thumb_mode(regs)) {
+			instr = ((u16 *)pc)[0];
+			if (is_wide_instruction(instr)) {
+				instr <<= 16;
+				instr |= ((u16 *)pc)[1];
+			}
+		} else
+#endif
+			instr = *(u32 *) pc;
+	} else if (thumb_mode(regs)) {
+		if (get_user(instr, (u16 __user *)pc))
+			goto die_sig;
+		if (is_wide_instruction(instr)) {
+			unsigned int instr2;
+			if (get_user(instr2, (u16 __user *)pc+1))
+				goto die_sig;
+			instr <<= 16;
+			instr |= instr2;
+		}
+	} else if (get_user(instr, (u32 __user *)pc)) {
+		goto die_sig;
+	}
+
+	ret = call_undef_hook(regs, instr);
+	if (ret == 0) {
+		if (!user_mode(regs)) {
+			thread->cpu_excp--;
+		}	  
+		return;
+	}
+
+die_sig:
+#ifdef CONFIG_DEBUG_USER
+	if (user_debug & UDBG_UNDEFINED) {
+		printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
+			current->comm, task_pid_nr(current), pc);
+		dump_instr(KERN_INFO, regs);
+	}
+#endif
+
+	/* Place the SIGILL ICache Invalidate after the Debugger Undefined-Instruction Solution. */
+	if (((processor_mode(regs) == USR_MODE) || (processor_mode(regs) == SVC_MODE)) && 
+			(instr != insn)) {
+		void **prev_undefinstr_pc = &get_cpu_var(__prev_undefinstr_pc);
+		int *prev_undefinstr_counter = &get_cpu_var(__prev_undefinstr_counter);
+                /* Only do it for User-Space Application. */
+		pr_alert("USR_MODE/SVC_MODE Undefined Instruction Address curr:%p pc=%p:%p, instr: 0x%x\n",
+			(void *)current, (void *)pc, (void *)*prev_undefinstr_pc, 
+			instr);
+		if ((*prev_undefinstr_pc != pc)) {
+			/* If the current process or program counter is changed......renew the counter. */
+			pr_alert("First Time Recovery curr:%p pc=%p:%p\n",
+				(void *)current, (void *)pc, (void *)*prev_undefinstr_pc);
+			*prev_undefinstr_pc = pc;
+			*prev_undefinstr_counter = 0;
+			put_cpu_var(__prev_undefinstr_pc);
+			put_cpu_var(__prev_undefinstr_counter);
+			__cpuc_flush_icache_all();
+			flush_cache_all();
+			if (!user_mode(regs)) {
+				thread->cpu_excp--;
+			}
+			return;
+		}
+		else if(*prev_undefinstr_counter < 1) {
+			pr_alert("2nd Time Recovery curr:%p pc=%p:%p\n",
+				(void *)current, (void *)pc,
+				(void *)*prev_undefinstr_pc);
+			*prev_undefinstr_counter += 1;
+			put_cpu_var(__prev_undefinstr_pc);
+			put_cpu_var(__prev_undefinstr_counter);
+			__cpuc_flush_icache_all();
+			flush_cache_all();
+			if (!user_mode(regs)) {
+				thread->cpu_excp--;
+			}
+			return;
+		}
+		*prev_undefinstr_counter += 1;
+		if(*prev_undefinstr_counter >= 4) {
+			/* 2=first time SigILL,3=2nd time NE-SigILL,4=3rd time CoreDump-SigILL */
+			*prev_undefinstr_pc = 0;
+			*prev_undefinstr_counter = 0;
+		}
+		put_cpu_var(__prev_undefinstr_pc);
+		put_cpu_var(__prev_undefinstr_counter);
+		pr_alert("Go to ARM Notify Die curr:%p pc=%p:%p\n",
+			(void *)current, (void *)pc, (void *)*prev_undefinstr_pc);
+	}
+
+	info.si_signo = SIGILL;
+	info.si_errno = 0;
+	info.si_code  = ILL_ILLOPC;
+	info.si_addr  = pc;
+
+	arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
+}
+
+asmlinkage void do_unexp_fiq (struct pt_regs *regs)
+{
+	printk("Hmm.  Unexpected FIQ received, but trying to continue\n");
+	printk("You may have a hardware problem...\n");
+}
+
+/*
+ * 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();
+
+	printk(KERN_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)
+{
+	struct thread_info *thread = current_thread_info();
+	siginfo_t info;
+
+	if ((current->personality & PER_MASK) != PER_LINUX &&
+	    thread->exec_domain->handler) {
+		thread->exec_domain->handler(n, regs);
+		return regs->ARM_r0;
+	}
+
+#ifdef CONFIG_DEBUG_USER
+	if (user_debug & UDBG_SYSCALL) {
+		printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
+			task_pid_nr(current), current->comm, n);
+		dump_instr(KERN_ERR, regs);
+	}
+#endif
+
+	info.si_signo = SIGILL;
+	info.si_errno = 0;
+	info.si_code  = ILL_ILLTRP;
+	info.si_addr  = (void __user *)instruction_pointer(regs) -
+			 (thumb_mode(regs) ? 2 : 4);
+
+	arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
+
+	return regs->ARM_r0;
+}
+
+static inline int
+do_cache_op(unsigned long start, unsigned long end, int flags)
+{
+	struct mm_struct *mm = current->active_mm;
+	struct vm_area_struct *vma;
+
+	if (end < start || flags)
+		return -EINVAL;
+
+	down_read(&mm->mmap_sem);
+	vma = find_vma(mm, start);
+	if (vma && vma->vm_start < end) {
+		if (start < vma->vm_start)
+			start = vma->vm_start;
+		if (end > vma->vm_end)
+			end = vma->vm_end;
+
+		up_read(&mm->mmap_sem);
+		return flush_cache_user_range(start, end);
+	}
+	up_read(&mm->mmap_sem);
+	return -EINVAL;
+}
+
+/*
+ * 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)
+{
+	struct thread_info *thread = current_thread_info();
+	siginfo_t info;
+
+	if ((no >> 16) != (__ARM_NR_BASE>> 16))
+		return bad_syscall(no, regs);
+
+	switch (no & 0xffff) {
+	case 0: /* branch through 0 */
+		info.si_signo = SIGSEGV;
+		info.si_errno = 0;
+		info.si_code  = SEGV_MAPERR;
+		info.si_addr  = NULL;
+
+		arm_notify_die("branch through zero", regs, &info, 0, 0);
+		return 0;
+
+	case NR(breakpoint): /* SWI BREAK_POINT */
+		regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
+		ptrace_break(current, 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):
+		thread->tp_value = regs->ARM_r0;
+		if (tls_emu)
+			return 0;
+		if (has_tls_reg) {
+			asm ("mcr p15, 0, %0, c13, c0, 3"
+				: : "r" (regs->ARM_r0));
+		} else {
+			/*
+			 * User space must never try to access this directly.
+			 * Expect your app to break eventually if you do so.
+			 * The user helper at 0xffff0fe0 must be used instead.
+			 * (see entry-armv.S for details)
+			 */
+			*((unsigned int *)0xffff0ff0) = regs->ARM_r0;
+		}
+		return 0;
+
+#ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
+	/*
+	 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
+	 * Return zero in r0 if *MEM was changed or non-zero if no exchange
+	 * happened.  Also set the user C flag accordingly.
+	 * If access permissions have to be fixed up then non-zero is
+	 * returned and the operation has to be re-attempted.
+	 *
+	 * *NOTE*: This is a ghost syscall private to the kernel.  Only the
+	 * __kuser_cmpxchg code in entry-armv.S should be aware of its
+	 * existence.  Don't ever use this from user code.
+	 */
+	case NR(cmpxchg):
+	for (;;) {
+		extern void do_DataAbort(unsigned long addr, unsigned int fsr,
+					 struct pt_regs *regs);
+		unsigned long val;
+		unsigned long addr = regs->ARM_r2;
+		struct mm_struct *mm = current->mm;
+		pgd_t *pgd; pmd_t *pmd; pte_t *pte;
+		spinlock_t *ptl;
+
+		regs->ARM_cpsr &= ~PSR_C_BIT;
+		down_read(&mm->mmap_sem);
+		pgd = pgd_offset(mm, addr);
+		if (!pgd_present(*pgd))
+			goto bad_access;
+		pmd = pmd_offset(pgd, addr);
+		if (!pmd_present(*pmd))
+			goto bad_access;
+		pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+		if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
+			pte_unmap_unlock(pte, ptl);
+			goto bad_access;
+		}
+		val = *(unsigned long *)addr;
+		val -= regs->ARM_r0;
+		if (val == 0) {
+			*(unsigned long *)addr = regs->ARM_r1;
+			regs->ARM_cpsr |= PSR_C_BIT;
+		}
+		pte_unmap_unlock(pte, ptl);
+		up_read(&mm->mmap_sem);
+		return val;
+
+		bad_access:
+		up_read(&mm->mmap_sem);
+		/* simulate a write access fault */
+		do_DataAbort(addr, 15 + (1 << 11), regs);
+	}
+#endif
+
+	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) {
+		printk("[%d] %s: arm syscall %d\n",
+		       task_pid_nr(current), current->comm, no);
+		dump_instr("", regs);
+		if (user_mode(regs)) {
+			__show_regs(regs);
+			c_backtrace(regs->ARM_fp, processor_mode(regs));
+		}
+	}
+#endif
+	info.si_signo = SIGILL;
+	info.si_errno = 0;
+	info.si_code  = ILL_ILLTRP;
+	info.si_addr  = (void __user *)instruction_pointer(regs) -
+			 (thumb_mode(regs) ? 2 : 4);
+
+	arm_notify_die("Oops - bad syscall(2)", regs, &info, 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;
+	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
+
+void __bad_xchg(volatile void *ptr, int size)
+{
+	printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
+		__builtin_return_address(0), ptr, size);
+	BUG();
+}
+EXPORT_SYMBOL(__bad_xchg);
+
+/*
+ * 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);
+	siginfo_t info;
+
+#ifdef CONFIG_DEBUG_USER
+	if (user_debug & UDBG_BADABORT) {
+		printk(KERN_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(current->mm, addr);
+	}
+#endif
+
+	info.si_signo = SIGILL;
+	info.si_errno = 0;
+	info.si_code  = ILL_ILLOPC;
+	info.si_addr  = (void __user *)addr;
+
+	arm_notify_die("unknown data abort code", regs, &info, instr, 0);
+}
+
+void __readwrite_bug(const char *fn)
+{
+	printk("%s called, but not implemented\n", fn);
+	BUG();
+}
+EXPORT_SYMBOL(__readwrite_bug);
+
+void __pte_error(const char *file, int line, pte_t pte)
+{
+	printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
+}
+
+void __pmd_error(const char *file, int line, pmd_t pmd)
+{
+	printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
+}
+
+void __pgd_error(const char *file, int line, pgd_t pgd)
+{
+	printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
+}
+
+asmlinkage void __div0(void)
+{
+	printk("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");
+}
+EXPORT_SYMBOL(abort);
+
+void __init trap_init(void)
+{
+	return;
+}
+
+#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 void __init kuser_init(void *vectors)
+{
+}
+#endif
+
+void __init early_trap_init(void *vectors_base)
+{
+	unsigned long vectors = (unsigned long)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.
+	 */
+	memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
+	memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
+
+	kuser_init(vectors_base);
+
+	flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
+	modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
+}