traps_32.c 30.8 KB
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/*
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Pentium III FXSR, SSE support
 *	Gareth Hughes <gareth@valinux.com>, May 2000
 */

/*
 * 'Traps.c' handles hardware traps and faults after we have saved some
 * state in 'asm.s'.
 */
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#include <linux/interrupt.h>
#include <linux/kallsyms.h>
#include <linux/spinlock.h>
#include <linux/highmem.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/utsname.h>
#include <linux/kdebug.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
#include <linux/ptrace.h>
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#include <linux/string.h>
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#include <linux/unwind.h>
#include <linux/delay.h>
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#include <linux/errno.h>
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#include <linux/kexec.h>
#include <linux/sched.h>
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#include <linux/timer.h>
#include <linux/init.h>
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#include <linux/bug.h>
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#include <linux/nmi.h>
#include <linux/mm.h>
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#ifdef CONFIG_EISA
#include <linux/ioport.h>
#include <linux/eisa.h>
#endif

#ifdef CONFIG_MCA
#include <linux/mca.h>
#endif

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#if defined(CONFIG_EDAC)
#include <linux/edac.h>
#endif

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#include <asm/arch_hooks.h>
#include <asm/stacktrace.h>
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#include <asm/processor.h>
#include <asm/debugreg.h>
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#include <asm/atomic.h>
#include <asm/system.h>
#include <asm/unwind.h>
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#include <asm/desc.h>
#include <asm/i387.h>
#include <asm/nmi.h>
#include <asm/smp.h>
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#include <asm/io.h>
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#include "mach_traps.h"

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int panic_on_unrecovered_nmi;

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DECLARE_BITMAP(used_vectors, NR_VECTORS);
EXPORT_SYMBOL_GPL(used_vectors);

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asmlinkage int system_call(void);

/* Do we ignore FPU interrupts ? */
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char ignore_fpu_irq;
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/*
 * The IDT has to be page-aligned to simplify the Pentium
 * F0 0F bug workaround.. We have a special link segment
 * for this.
 */
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gate_desc idt_table[256]
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	__attribute__((__section__(".data.idt"))) = { { { { 0, 0 } } }, };
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asmlinkage void divide_error(void);
asmlinkage void debug(void);
asmlinkage void nmi(void);
asmlinkage void int3(void);
asmlinkage void overflow(void);
asmlinkage void bounds(void);
asmlinkage void invalid_op(void);
asmlinkage void device_not_available(void);
asmlinkage void coprocessor_segment_overrun(void);
asmlinkage void invalid_TSS(void);
asmlinkage void segment_not_present(void);
asmlinkage void stack_segment(void);
asmlinkage void general_protection(void);
asmlinkage void page_fault(void);
asmlinkage void coprocessor_error(void);
asmlinkage void simd_coprocessor_error(void);
asmlinkage void alignment_check(void);
asmlinkage void spurious_interrupt_bug(void);
asmlinkage void machine_check(void);

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int kstack_depth_to_print = 24;
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static unsigned int code_bytes = 64;
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void printk_address(unsigned long address, int reliable)
{
#ifdef CONFIG_KALLSYMS
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	char namebuf[KSYM_NAME_LEN];
	unsigned long offset = 0;
	unsigned long symsize;
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	const char *symname;
	char reliab[4] = "";
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	char *delim = ":";
	char *modname;
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	symname = kallsyms_lookup(address, &symsize, &offset,
					&modname, namebuf);
	if (!symname) {
		printk(" [<%08lx>]\n", address);
		return;
	}
	if (!reliable)
		strcpy(reliab, "? ");

	if (!modname)
		modname = delim = "";
	printk(" [<%08lx>] %s%s%s%s%s+0x%lx/0x%lx\n",
		address, reliab, delim, modname, delim, symname, offset, symsize);
#else
	printk(" [<%08lx>]\n", address);
#endif
}

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static inline int valid_stack_ptr(struct thread_info *tinfo, void *p, unsigned size)
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{
	return	p > (void *)tinfo &&
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		p <= (void *)tinfo + THREAD_SIZE - size;
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}

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/* The form of the top of the frame on the stack */
struct stack_frame {
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	struct stack_frame	*next_frame;
	unsigned long		return_address;
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};

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static inline unsigned long
print_context_stack(struct thread_info *tinfo,
		    unsigned long *stack, unsigned long bp,
		    const struct stacktrace_ops *ops, void *data)
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{
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	struct stack_frame *frame = (struct stack_frame *)bp;
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	while (valid_stack_ptr(tinfo, stack, sizeof(*stack))) {
		unsigned long addr;

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		addr = *stack;
		if (__kernel_text_address(addr)) {
			if ((unsigned long) stack == bp + 4) {
				ops->address(data, addr, 1);
				frame = frame->next_frame;
				bp = (unsigned long) frame;
			} else {
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				ops->address(data, addr, bp == 0);
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			}
		}
		stack++;
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	}
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	return bp;
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}

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#define MSG(msg)		ops->warning(data, msg)
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void dump_trace(struct task_struct *task, struct pt_regs *regs,
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		unsigned long *stack, unsigned long bp,
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		const struct stacktrace_ops *ops, void *data)
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{
	if (!task)
		task = current;

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	if (!stack) {
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		unsigned long dummy;
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		stack = &dummy;
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		if (task != current)
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			stack = (unsigned long *)task->thread.sp;
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	}

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#ifdef CONFIG_FRAME_POINTER
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	if (!bp) {
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		if (task == current) {
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			/* Grab bp right from our regs */
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			asm("movl %%ebp, %0" : "=r" (bp) :);
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		} else {
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			/* bp is the last reg pushed by switch_to */
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			bp = *(unsigned long *) task->thread.sp;
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		}
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	}
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#endif
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	while (1) {
		struct thread_info *context;
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		context = (struct thread_info *)
			((unsigned long)stack & (~(THREAD_SIZE - 1)));
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		bp = print_context_stack(context, stack, bp, ops, data);
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		/*
		 * Should be after the line below, but somewhere
		 * in early boot context comes out corrupted and we
		 * can't reference it:
		 */
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		if (ops->stack(data, "IRQ") < 0)
			break;
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		stack = (unsigned long *)context->previous_esp;
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		if (!stack)
			break;
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		touch_nmi_watchdog();
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	}
}
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EXPORT_SYMBOL(dump_trace);

static void
print_trace_warning_symbol(void *data, char *msg, unsigned long symbol)
{
	printk(data);
	print_symbol(msg, symbol);
	printk("\n");
}

static void print_trace_warning(void *data, char *msg)
{
	printk("%s%s\n", (char *)data, msg);
}

static int print_trace_stack(void *data, char *name)
{
	return 0;
}

/*
 * Print one address/symbol entries per line.
 */
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static void print_trace_address(void *data, unsigned long addr, int reliable)
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{
	printk("%s [<%08lx>] ", (char *)data, addr);
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	if (!reliable)
		printk("? ");
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	print_symbol("%s\n", addr);
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	touch_nmi_watchdog();
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}

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static const struct stacktrace_ops print_trace_ops = {
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	.warning		= print_trace_warning,
	.warning_symbol		= print_trace_warning_symbol,
	.stack			= print_trace_stack,
	.address		= print_trace_address,
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};

static void
show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
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		   unsigned long *stack, unsigned long bp, char *log_lvl)
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{
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	dump_trace(task, regs, stack, bp, &print_trace_ops, log_lvl);
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	printk("%s =======================\n", log_lvl);
}
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void show_trace(struct task_struct *task, struct pt_regs *regs,
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		unsigned long *stack, unsigned long bp)
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{
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	show_trace_log_lvl(task, regs, stack, bp, "");
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}

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static void
show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
		   unsigned long *sp, unsigned long bp, char *log_lvl)
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{
	unsigned long *stack;
	int i;

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	if (sp == NULL) {
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		if (task)
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			sp = (unsigned long *)task->thread.sp;
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		else
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			sp = (unsigned long *)&sp;
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	}

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	stack = sp;
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	for (i = 0; i < kstack_depth_to_print; i++) {
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		if (kstack_end(stack))
			break;
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		if (i && ((i % 8) == 0))
			printk("\n%s       ", log_lvl);
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		printk("%08lx ", *stack++);
	}
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	printk("\n%sCall Trace:\n", log_lvl);
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	show_trace_log_lvl(task, regs, sp, bp, log_lvl);
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}

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void show_stack(struct task_struct *task, unsigned long *sp)
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{
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	printk("       ");
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	show_stack_log_lvl(task, NULL, sp, 0, "");
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}

/*
 * The architecture-independent dump_stack generator
 */
void dump_stack(void)
{
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	unsigned long bp = 0;
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	unsigned long stack;
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#ifdef CONFIG_FRAME_POINTER
	if (!bp)
		asm("movl %%ebp, %0" : "=r" (bp):);
#endif
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	printk("Pid: %d, comm: %.20s %s %s %.*s\n",
		current->pid, current->comm, print_tainted(),
		init_utsname()->release,
		(int)strcspn(init_utsname()->version, " "),
		init_utsname()->version);
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	show_trace(current, NULL, &stack, bp);
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}

EXPORT_SYMBOL(dump_stack);

void show_registers(struct pt_regs *regs)
{
	int i;
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	print_modules();
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	__show_registers(regs, 0);
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	printk(KERN_EMERG "Process %.*s (pid: %d, ti=%p task=%p task.ti=%p)",
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		TASK_COMM_LEN, current->comm, task_pid_nr(current),
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		current_thread_info(), current, task_thread_info(current));
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	/*
	 * When in-kernel, we also print out the stack and code at the
	 * time of the fault..
	 */
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	if (!user_mode_vm(regs)) {
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		unsigned int code_prologue = code_bytes * 43 / 64;
		unsigned int code_len = code_bytes;
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		unsigned char c;
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		u8 *ip;
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		printk("\n" KERN_EMERG "Stack: ");
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		show_stack_log_lvl(NULL, regs, &regs->sp, 0, KERN_EMERG);
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		printk(KERN_EMERG "Code: ");
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		ip = (u8 *)regs->ip - code_prologue;
		if (ip < (u8 *)PAGE_OFFSET ||
			probe_kernel_address(ip, c)) {
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			/* try starting at EIP */
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			ip = (u8 *)regs->ip;
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			code_len = code_len - code_prologue + 1;
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		}
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		for (i = 0; i < code_len; i++, ip++) {
			if (ip < (u8 *)PAGE_OFFSET ||
				probe_kernel_address(ip, c)) {
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				printk(" Bad EIP value.");
				break;
			}
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			if (ip == (u8 *)regs->ip)
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				printk("<%02x> ", c);
			else
				printk("%02x ", c);
		}
	}
	printk("\n");
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}
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int is_valid_bugaddr(unsigned long ip)
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{
	unsigned short ud2;

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	if (ip < PAGE_OFFSET)
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		return 0;
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	if (probe_kernel_address((unsigned short *)ip, ud2))
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		return 0;
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	return ud2 == 0x0b0f;
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}

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static int die_counter;

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int __kprobes __die(const char *str, struct pt_regs *regs, long err)
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{
	unsigned short ss;
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	unsigned long sp;
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	printk(KERN_EMERG "%s: %04lx [#%d] ", str, err & 0xffff, ++die_counter);
#ifdef CONFIG_PREEMPT
	printk("PREEMPT ");
#endif
#ifdef CONFIG_SMP
	printk("SMP ");
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
	printk("DEBUG_PAGEALLOC");
#endif
	printk("\n");

	if (notify_die(DIE_OOPS, str, regs, err,
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			current->thread.trap_no, SIGSEGV) != NOTIFY_STOP) {

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		show_registers(regs);
		/* Executive summary in case the oops scrolled away */
		sp = (unsigned long) (&regs->sp);
		savesegment(ss, ss);
		if (user_mode(regs)) {
			sp = regs->sp;
			ss = regs->ss & 0xffff;
		}
		printk(KERN_EMERG "EIP: [<%08lx>] ", regs->ip);
		print_symbol("%s", regs->ip);
		printk(" SS:ESP %04x:%08lx\n", ss, sp);
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		return 0;
	}
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	return 1;
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}

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/*
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 * This is gone through when something in the kernel has done something bad
 * and is about to be terminated:
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 */
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void die(const char *str, struct pt_regs *regs, long err)
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{
	static struct {
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		raw_spinlock_t lock;
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		u32 lock_owner;
		int lock_owner_depth;
	} die = {
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		.lock =			__RAW_SPIN_LOCK_UNLOCKED,
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		.lock_owner =		-1,
		.lock_owner_depth =	0
	};
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	unsigned long flags;
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	oops_enter();

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	if (die.lock_owner != raw_smp_processor_id()) {
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		console_verbose();
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		raw_local_irq_save(flags);
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		__raw_spin_lock(&die.lock);
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		die.lock_owner = smp_processor_id();
		die.lock_owner_depth = 0;
		bust_spinlocks(1);
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	} else {
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		raw_local_irq_save(flags);
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	}
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	if (++die.lock_owner_depth < 3) {
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		report_bug(regs->ip, regs);
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		if (__die(str, regs, err))
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			regs = NULL;
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	} else {
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		printk(KERN_EMERG "Recursive die() failure, output suppressed\n");
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	}
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	bust_spinlocks(0);
	die.lock_owner = -1;
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	add_taint(TAINT_DIE);
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	__raw_spin_unlock(&die.lock);
	raw_local_irq_restore(flags);
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	if (!regs)
		return;

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	if (kexec_should_crash(current))
		crash_kexec(regs);

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	if (in_interrupt())
		panic("Fatal exception in interrupt");

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	if (panic_on_oops)
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		panic("Fatal exception");
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	oops_exit();
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	do_exit(SIGSEGV);
}

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static inline void
die_if_kernel(const char *str, struct pt_regs *regs, long err)
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{
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	if (!user_mode_vm(regs))
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		die(str, regs, err);
}

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static void __kprobes
do_trap(int trapnr, int signr, char *str, int vm86, struct pt_regs *regs,
	long error_code, siginfo_t *info)
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{
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	struct task_struct *tsk = current;

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	if (regs->flags & X86_VM_MASK) {
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		if (vm86)
			goto vm86_trap;
		goto trap_signal;
	}

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	if (!user_mode(regs))
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		goto kernel_trap;

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trap_signal:
	/*
	 * We want error_code and trap_no set for userspace faults and
	 * kernelspace faults which result in die(), but not
	 * kernelspace faults which are fixed up.  die() gives the
	 * process no chance to handle the signal and notice the
	 * kernel fault information, so that won't result in polluting
	 * the information about previously queued, but not yet
	 * delivered, faults.  See also do_general_protection below.
	 */
	tsk->thread.error_code = error_code;
	tsk->thread.trap_no = trapnr;
522

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	if (info)
		force_sig_info(signr, info, tsk);
	else
		force_sig(signr, tsk);
	return;
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kernel_trap:
	if (!fixup_exception(regs)) {
		tsk->thread.error_code = error_code;
		tsk->thread.trap_no = trapnr;
		die(str, regs, error_code);
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	}
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	return;
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vm86_trap:
	if (handle_vm86_trap((struct kernel_vm86_regs *) regs,
						error_code, trapnr))
		goto trap_signal;
	return;
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}

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#define DO_ERROR(trapnr, signr, str, name)				\
void do_##name(struct pt_regs *regs, long error_code)			\
{									\
	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)	\
						== NOTIFY_STOP)		\
		return;							\
	do_trap(trapnr, signr, str, 0, regs, error_code, NULL);		\
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}

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#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr, irq)	\
void do_##name(struct pt_regs *regs, long error_code)			\
{									\
	siginfo_t info;							\
	if (irq)							\
		local_irq_enable();					\
	info.si_signo = signr;						\
	info.si_errno = 0;						\
	info.si_code = sicode;						\
	info.si_addr = (void __user *)siaddr;				\
	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)	\
						== NOTIFY_STOP)		\
		return;							\
	do_trap(trapnr, signr, str, 0, regs, error_code, &info);	\
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}

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#define DO_VM86_ERROR(trapnr, signr, str, name)				\
void do_##name(struct pt_regs *regs, long error_code)			\
{									\
	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)	\
						== NOTIFY_STOP)		\
		return;							\
	do_trap(trapnr, signr, str, 1, regs, error_code, NULL);		\
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}

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#define DO_VM86_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr)	\
void do_##name(struct pt_regs *regs, long error_code)			\
{									\
	siginfo_t info;							\
	info.si_signo = signr;						\
	info.si_errno = 0;						\
	info.si_code = sicode;						\
	info.si_addr = (void __user *)siaddr;				\
	trace_hardirqs_fixup();						\
	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)	\
						== NOTIFY_STOP)		\
		return;							\
	do_trap(trapnr, signr, str, 1, regs, error_code, &info);	\
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}

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DO_VM86_ERROR_INFO(0, SIGFPE,  "divide error", divide_error, FPE_INTDIV, regs->ip)
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#ifndef CONFIG_KPROBES
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DO_VM86_ERROR(3, SIGTRAP, "int3", int3)
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#endif
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DO_VM86_ERROR(4, SIGSEGV, "overflow", overflow)
DO_VM86_ERROR(5, SIGSEGV, "bounds", bounds)
DO_ERROR_INFO(6, SIGILL,  "invalid opcode", invalid_op, ILL_ILLOPN, regs->ip, 0)
DO_ERROR(9, SIGFPE,  "coprocessor segment overrun", coprocessor_segment_overrun)
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DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS)
DO_ERROR(11, SIGBUS,  "segment not present", segment_not_present)
DO_ERROR(12, SIGBUS,  "stack segment", stack_segment)
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DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0, 0)
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DO_ERROR_INFO(32, SIGILL, "iret exception", iret_error, ILL_BADSTK, 0, 1)
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void __kprobes do_general_protection(struct pt_regs *regs, long error_code)
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{
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	struct thread_struct *thread;
	struct tss_struct *tss;
	int cpu;

	cpu = get_cpu();
	tss = &per_cpu(init_tss, cpu);
	thread = &current->thread;
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	/*
	 * Perform the lazy TSS's I/O bitmap copy. If the TSS has an
	 * invalid offset set (the LAZY one) and the faulting thread has
	 * a valid I/O bitmap pointer, we copy the I/O bitmap in the TSS
	 * and we set the offset field correctly. Then we let the CPU to
	 * restart the faulting instruction.
	 */
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	if (tss->x86_tss.io_bitmap_base == INVALID_IO_BITMAP_OFFSET_LAZY &&
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	    thread->io_bitmap_ptr) {
		memcpy(tss->io_bitmap, thread->io_bitmap_ptr,
		       thread->io_bitmap_max);
		/*
		 * If the previously set map was extending to higher ports
		 * than the current one, pad extra space with 0xff (no access).
		 */
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		if (thread->io_bitmap_max < tss->io_bitmap_max) {
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			memset((char *) tss->io_bitmap +
				thread->io_bitmap_max, 0xff,
				tss->io_bitmap_max - thread->io_bitmap_max);
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		}
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		tss->io_bitmap_max = thread->io_bitmap_max;
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		tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
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		tss->io_bitmap_owner = thread;
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		put_cpu();
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		return;
	}
	put_cpu();

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	if (regs->flags & X86_VM_MASK)
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		goto gp_in_vm86;

649
	if (!user_mode(regs))
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		goto gp_in_kernel;

	current->thread.error_code = error_code;
	current->thread.trap_no = 13;
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	if (show_unhandled_signals && unhandled_signal(current, SIGSEGV) &&
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	    printk_ratelimit()) {
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		printk(KERN_INFO
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		    "%s[%d] general protection ip:%lx sp:%lx error:%lx",
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		    current->comm, task_pid_nr(current),
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		    regs->ip, regs->sp, error_code);
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		print_vma_addr(" in ", regs->ip);
		printk("\n");
	}
664

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	force_sig(SIGSEGV, current);
	return;

gp_in_vm86:
	local_irq_enable();
	handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
	return;

gp_in_kernel:
	if (!fixup_exception(regs)) {
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		current->thread.error_code = error_code;
		current->thread.trap_no = 13;
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		if (notify_die(DIE_GPF, "general protection fault", regs,
				error_code, 13, SIGSEGV) == NOTIFY_STOP)
			return;
		die("general protection fault", regs, error_code);
	}
}

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static notrace __kprobes void
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mem_parity_error(unsigned char reason, struct pt_regs *regs)
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{
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	printk(KERN_EMERG
		"Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
			reason, smp_processor_id());

	printk(KERN_EMERG
		"You have some hardware problem, likely on the PCI bus.\n");
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#if defined(CONFIG_EDAC)
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	if (edac_handler_set()) {
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		edac_atomic_assert_error();
		return;
	}
#endif

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	if (panic_on_unrecovered_nmi)
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		panic("NMI: Not continuing");
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	printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
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	/* Clear and disable the memory parity error line. */
	clear_mem_error(reason);
}

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static notrace __kprobes void
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io_check_error(unsigned char reason, struct pt_regs *regs)
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{
	unsigned long i;

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	printk(KERN_EMERG "NMI: IOCK error (debug interrupt?)\n");
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	show_registers(regs);

	/* Re-enable the IOCK line, wait for a few seconds */
	reason = (reason & 0xf) | 8;
	outb(reason, 0x61);
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	i = 2000;
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	while (--i)
		udelay(1000);

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	reason &= ~8;
	outb(reason, 0x61);
}

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static notrace __kprobes void
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unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
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{
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	if (notify_die(DIE_NMIUNKNOWN, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP)
		return;
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#ifdef CONFIG_MCA
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	/*
	 * Might actually be able to figure out what the guilty party
	 * is:
	 */
	if (MCA_bus) {
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		mca_handle_nmi();
		return;
	}
#endif
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	printk(KERN_EMERG
		"Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
			reason, smp_processor_id());

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	printk(KERN_EMERG "Do you have a strange power saving mode enabled?\n");
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	if (panic_on_unrecovered_nmi)
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		panic("NMI: Not continuing");
752

753
	printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
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}

static DEFINE_SPINLOCK(nmi_print_lock);

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void notrace __kprobes die_nmi(struct pt_regs *regs, const char *msg)
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{
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	if (notify_die(DIE_NMIWATCHDOG, msg, regs, 0, 2, SIGINT) == NOTIFY_STOP)
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		return;

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	spin_lock(&nmi_print_lock);
	/*
	* We are in trouble anyway, lets at least try
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	* to get a message out:
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	*/
	bust_spinlocks(1);
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	printk(KERN_EMERG "%s", msg);
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	printk(" on CPU%d, ip %08lx, registers:\n",
		smp_processor_id(), regs->ip);
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	show_registers(regs);
	console_silent();
	spin_unlock(&nmi_print_lock);
	bust_spinlocks(0);
776

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	/*
	 * If we are in kernel we are probably nested up pretty bad
	 * and might aswell get out now while we still can:
	 */
781
	if (!user_mode_vm(regs)) {
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		current->thread.trap_no = 2;
		crash_kexec(regs);
	}

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	do_exit(SIGSEGV);
}

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static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
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{
	unsigned char reason = 0;

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	/* Only the BSP gets external NMIs from the system: */
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	if (!smp_processor_id())
		reason = get_nmi_reason();
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	if (!(reason & 0xc0)) {
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		if (notify_die(DIE_NMI_IPI, "nmi_ipi", regs, reason, 2, SIGINT)
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							== NOTIFY_STOP)
			return;
#ifdef CONFIG_X86_LOCAL_APIC
		/*
		 * Ok, so this is none of the documented NMI sources,
		 * so it must be the NMI watchdog.
		 */
806
		if (nmi_watchdog_tick(regs, reason))
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			return;
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		if (!do_nmi_callback(regs, smp_processor_id()))
809
			unknown_nmi_error(reason, regs);
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#else
		unknown_nmi_error(reason, regs);
#endif
813

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		return;
	}
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	if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP)
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		return;
	if (reason & 0x80)
		mem_parity_error(reason, regs);
	if (reason & 0x40)
		io_check_error(reason, regs);
	/*
	 * Reassert NMI in case it became active meanwhile
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	 * as it's edge-triggered:
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	 */
	reassert_nmi();
}

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static int ignore_nmis;

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notrace __kprobes void do_nmi(struct pt_regs *regs, long error_code)
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{
	int cpu;

	nmi_enter();

	cpu = smp_processor_id();
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	++nmi_count(cpu);

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	if (!ignore_nmis)
		default_do_nmi(regs);
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	nmi_exit();
}

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void stop_nmi(void)
{
	acpi_nmi_disable();
	ignore_nmis++;
}

void restart_nmi(void)
{
	ignore_nmis--;
	acpi_nmi_enable();
}

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#ifdef CONFIG_KPROBES
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void __kprobes do_int3(struct pt_regs *regs, long error_code)
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{
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	trace_hardirqs_fixup();

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	if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
			== NOTIFY_STOP)
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		return;
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	/*
	 * This is an interrupt gate, because kprobes wants interrupts
	 * disabled. Normal trap handlers don't.
	 */
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	restore_interrupts(regs);
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	do_trap(3, SIGTRAP, "int3", 1, regs, error_code, NULL);
}
#endif

/*
 * Our handling of the processor debug registers is non-trivial.
 * We do not clear them on entry and exit from the kernel. Therefore
 * it is possible to get a watchpoint trap here from inside the kernel.
 * However, the code in ./ptrace.c has ensured that the user can
 * only set watchpoints on userspace addresses. Therefore the in-kernel
 * watchpoint trap can only occur in code which is reading/writing
 * from user space. Such code must not hold kernel locks (since it
 * can equally take a page fault), therefore it is safe to call
 * force_sig_info even though that claims and releases locks.
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 *
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 * Code in ./signal.c ensures that the debug control register
 * is restored before we deliver any signal, and therefore that
 * user code runs with the correct debug control register even though
 * we clear it here.
 *
 * Being careful here means that we don't have to be as careful in a
 * lot of more complicated places (task switching can be a bit lazy
 * about restoring all the debug state, and ptrace doesn't have to
 * find every occurrence of the TF bit that could be saved away even
 * by user code)
 */
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void __kprobes do_debug(struct pt_regs *regs, long error_code)
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{
	struct task_struct *tsk = current;
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	unsigned int condition;
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	trace_hardirqs_fixup();

906
	get_debugreg(condition, 6);
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	/*
	 * The processor cleared BTF, so don't mark that we need it set.
	 */
	clear_tsk_thread_flag(tsk, TIF_DEBUGCTLMSR);
	tsk->thread.debugctlmsr = 0;

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	if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
					SIGTRAP) == NOTIFY_STOP)
		return;
	/* It's safe to allow irq's after DR6 has been saved */
918
	if (regs->flags & X86_EFLAGS_IF)
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		local_irq_enable();

	/* Mask out spurious debug traps due to lazy DR7 setting */
	if (condition & (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)) {
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		if (!tsk->thread.debugreg7)
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			goto clear_dr7;
	}

927
	if (regs->flags & X86_VM_MASK)
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		goto debug_vm86;

	/* Save debug status register where ptrace can see it */
931
	tsk->thread.debugreg6 = condition;
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	/*
	 * Single-stepping through TF: make sure we ignore any events in
	 * kernel space (but re-enable TF when returning to user mode).
	 */
	if (condition & DR_STEP) {
		/*
		 * We already checked v86 mode above, so we can
		 * check for kernel mode by just checking the CPL
		 * of CS.
		 */
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		if (!user_mode(regs))
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			goto clear_TF_reenable;
	}

	/* Ok, finally something we can handle */
	send_sigtrap(tsk, regs, error_code);

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	/*
	 * Disable additional traps. They'll be re-enabled when
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	 * the signal is delivered.
	 */
clear_dr7:
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	set_debugreg(0, 7);
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	return;

debug_vm86:
	handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, 1);
	return;

clear_TF_reenable:
	set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
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	regs->flags &= ~X86_EFLAGS_TF;
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	return;
}

/*
 * Note that we play around with the 'TS' bit in an attempt to get
 * the correct behaviour even in the presence of the asynchronous
 * IRQ13 behaviour
 */
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void math_error(void __user *ip)
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{
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	struct task_struct *task;
	unsigned short cwd;
	unsigned short swd;
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	siginfo_t info;

	/*
	 * Save the info for the exception handler and clear the error.
	 */
	task = current;
	save_init_fpu(task);
	task->thread.trap_no = 16;
	task->thread.error_code = 0;
	info.si_signo = SIGFPE;
	info.si_errno = 0;
	info.si_code = __SI_FAULT;
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	info.si_addr = ip;
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	/*
	 * (~cwd & swd) will mask out exceptions that are not set to unmasked
	 * status.  0x3f is the exception bits in these regs, 0x200 is the
	 * C1 reg you need in case of a stack fault, 0x040 is the stack
	 * fault bit.  We should only be taking one exception at a time,
	 * so if this combination doesn't produce any single exception,
	 * then we have a bad program that isn't syncronizing its FPU usage
	 * and it will suffer the consequences since we won't be able to
	 * fully reproduce the context of the exception
	 */