arch/x86/kernel/traps.c - maze/linux - Git at Google

 /*
  *  Copyright (C) 1991, 1992  Linus Torvalds
  *  Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
  *
  *  Pentium III FXSR, SSE support
  *	Gareth Hughes <gareth@valinux.com>, May 2000
  */

 /*
  * Handle hardware traps and faults.
  */
 #include <linux/interrupt.h>
 #include <linux/kallsyms.h>
 #include <linux/spinlock.h>
 #include <linux/kprobes.h>
 #include <linux/uaccess.h>
 #include <linux/kdebug.h>
 #include <linux/kgdb.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/ptrace.h>
 #include <linux/string.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/kexec.h>
 #include <linux/sched.h>
 #include <linux/timer.h>
 #include <linux/init.h>
 #include <linux/bug.h>
 #include <linux/nmi.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
 #include <linux/io.h>

 #ifdef CONFIG_EISA
 #include <linux/ioport.h>
 #include <linux/eisa.h>
 #endif

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

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

 #include <asm/kmemcheck.h>
 #include <asm/stacktrace.h>
 #include <asm/processor.h>
 #include <asm/debugreg.h>
 #include <linux/atomic.h>
 #include <asm/system.h>
 #include <asm/traps.h>
 #include <asm/desc.h>
 #include <asm/i387.h>
 #include <asm/mce.h>

 #include <asm/mach_traps.h>

 #ifdef CONFIG_X86_64
 #include <asm/x86_init.h>
 #include <asm/pgalloc.h>
 #include <asm/proto.h>
 #else
 #include <asm/processor-flags.h>
 #include <asm/setup.h>

 asmlinkage int system_call(void);

 /* Do we ignore FPU interrupts ? */
 char ignore_fpu_irq;

 /*
  * The IDT has to be page-aligned to simplify the Pentium
  * F0 0F bug workaround.
  */
 gate_desc idt_table[NR_VECTORS] __page_aligned_data = { { { { 0, 0 } } }, };
 #endif

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

 static inline void conditional_sti(struct pt_regs *regs)
 {
 	if (regs->flags & X86_EFLAGS_IF)
 		local_irq_enable();
 }

 static inline void preempt_conditional_sti(struct pt_regs *regs)
 {
 	inc_preempt_count();
 	if (regs->flags & X86_EFLAGS_IF)
 		local_irq_enable();
 }

 static inline void conditional_cli(struct pt_regs *regs)
 {
 	if (regs->flags & X86_EFLAGS_IF)
 		local_irq_disable();
 }

 static inline void preempt_conditional_cli(struct pt_regs *regs)
 {
 	if (regs->flags & X86_EFLAGS_IF)
 		local_irq_disable();
 	dec_preempt_count();
 }

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

 #ifdef CONFIG_X86_32
 	if (regs->flags & X86_VM_MASK) {
 		/*
 		 * traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
 		 * On nmi (interrupt 2), do_trap should not be called.
 		 */
 		if (trapnr < 6)
 			goto vm86_trap;
 		goto trap_signal;
 	}
 #endif

 	if (!user_mode(regs))
 		goto kernel_trap;

 #ifdef CONFIG_X86_32
 trap_signal:
 #endif
 	/*
 	 * 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;

 #ifdef CONFIG_X86_64
 	if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
 	    printk_ratelimit()) {
 		printk(KERN_INFO
 		       "%s[%d] trap %s ip:%lx sp:%lx error:%lx",
 		       tsk->comm, tsk->pid, str,
 		       regs->ip, regs->sp, error_code);
 		print_vma_addr(" in ", regs->ip);
 		printk("\n");
 	}
 #endif

 	if (info)
 		force_sig_info(signr, info, tsk);
 	else
 		force_sig(signr, tsk);
 	return;

 kernel_trap:
 	if (!fixup_exception(regs)) {
 		tsk->thread.error_code = error_code;
 		tsk->thread.trap_no = trapnr;
 		die(str, regs, error_code);
 	}
 	return;

 #ifdef CONFIG_X86_32
 vm86_trap:
 	if (handle_vm86_trap((struct kernel_vm86_regs *) regs,
 						error_code, trapnr))
 		goto trap_signal;
 	return;
 #endif
 }

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

 #define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr)		\
 dotraplinkage 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;				\
 	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)	\
 							== NOTIFY_STOP)	\
 		return;							\
 	conditional_sti(regs);						\
 	do_trap(trapnr, signr, str, regs, error_code, &info);		\
 }

 DO_ERROR_INFO(0, SIGFPE, "divide error", divide_error, FPE_INTDIV, regs->ip)
 DO_ERROR(4, SIGSEGV, "overflow", overflow)
 DO_ERROR(5, SIGSEGV, "bounds", bounds)
 DO_ERROR_INFO(6, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN, regs->ip)
 DO_ERROR(9, SIGFPE, "coprocessor segment overrun", coprocessor_segment_overrun)
 DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS)
 DO_ERROR(11, SIGBUS, "segment not present", segment_not_present)
 #ifdef CONFIG_X86_32
 DO_ERROR(12, SIGBUS, "stack segment", stack_segment)
 #endif
 DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)

 #ifdef CONFIG_X86_64
 /* Runs on IST stack */
 dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
 {
 	if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
 			12, SIGBUS) == NOTIFY_STOP)
 		return;
 	preempt_conditional_sti(regs);
 	do_trap(12, SIGBUS, "stack segment", regs, error_code, NULL);
 	preempt_conditional_cli(regs);
 }

 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 {
 	static const char str[] = "double fault";
 	struct task_struct *tsk = current;

 	/* Return not checked because double check cannot be ignored */
 	notify_die(DIE_TRAP, str, regs, error_code, 8, SIGSEGV);

 	tsk->thread.error_code = error_code;
 	tsk->thread.trap_no = 8;

 	/*
 	 * This is always a kernel trap and never fixable (and thus must
 	 * never return).
 	 */
 	for (;;)
 		die(str, regs, error_code);
 }
 #endif

 dotraplinkage void __kprobes
 do_general_protection(struct pt_regs *regs, long error_code)
 {
 	struct task_struct *tsk;

 	conditional_sti(regs);

 #ifdef CONFIG_X86_32
 	if (regs->flags & X86_VM_MASK)
 		goto gp_in_vm86;
 #endif

 	tsk = current;
 	if (!user_mode(regs))
 		goto gp_in_kernel;

 	tsk->thread.error_code = error_code;
 	tsk->thread.trap_no = 13;

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

 	force_sig(SIGSEGV, tsk);
 	return;

 #ifdef CONFIG_X86_32
 gp_in_vm86:
 	local_irq_enable();
 	handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
 	return;
 #endif

 gp_in_kernel:
 	if (fixup_exception(regs))
 		return;

 	tsk->thread.error_code = error_code;
 	tsk->thread.trap_no = 13;
 	if (notify_die(DIE_GPF, "general protection fault", regs,
 				error_code, 13, SIGSEGV) == NOTIFY_STOP)
 		return;
 	die("general protection fault", regs, error_code);
 }

 /* May run on IST stack. */
 dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
 {
 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
 	if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
 			== NOTIFY_STOP)
 		return;
 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */

 	if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
 			== NOTIFY_STOP)
 		return;

 	/*
 	 * Let others (NMI) know that the debug stack is in use
 	 * as we may switch to the interrupt stack.
 	 */
 	debug_stack_usage_inc();
 	preempt_conditional_sti(regs);
 	do_trap(3, SIGTRAP, "int3", regs, error_code, NULL);
 	preempt_conditional_cli(regs);
 	debug_stack_usage_dec();
 }

 #ifdef CONFIG_X86_64
 /*
  * Help handler running on IST stack to switch back to user stack
  * for scheduling or signal handling. The actual stack switch is done in
  * entry.S
  */
 asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
 {
 	struct pt_regs *regs = eregs;
 	/* Did already sync */
 	if (eregs == (struct pt_regs *)eregs->sp)
 		;
 	/* Exception from user space */
 	else if (user_mode(eregs))
 		regs = task_pt_regs(current);
 	/*
 	 * Exception from kernel and interrupts are enabled. Move to
 	 * kernel process stack.
 	 */
 	else if (eregs->flags & X86_EFLAGS_IF)
 		regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
 	if (eregs != regs)
 		*regs = *eregs;
 	return regs;
 }
 #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.
  *
  * 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)
  *
  * May run on IST stack.
  */
 dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 {
 	struct task_struct *tsk = current;
 	int user_icebp = 0;
 	unsigned long dr6;
 	int si_code;

 	get_debugreg(dr6, 6);

 	/* Filter out all the reserved bits which are preset to 1 */
 	dr6 &= ~DR6_RESERVED;

 	/*
 	 * If dr6 has no reason to give us about the origin of this trap,
 	 * then it's very likely the result of an icebp/int01 trap.
 	 * User wants a sigtrap for that.
 	 */
 	if (!dr6 && user_mode(regs))
 		user_icebp = 1;

 	/* Catch kmemcheck conditions first of all! */
 	if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
 		return;

 	/* DR6 may or may not be cleared by the CPU */
 	set_debugreg(0, 6);

 	/*
 	 * The processor cleared BTF, so don't mark that we need it set.
 	 */
 	clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);

 	/* Store the virtualized DR6 value */
 	tsk->thread.debugreg6 = dr6;

 	if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,
 							SIGTRAP) == NOTIFY_STOP)
 		return;

 	/*
 	 * Let others (NMI) know that the debug stack is in use
 	 * as we may switch to the interrupt stack.
 	 */
 	debug_stack_usage_inc();

 	/* It's safe to allow irq's after DR6 has been saved */
 	preempt_conditional_sti(regs);

 	if (regs->flags & X86_VM_MASK) {
 		handle_vm86_trap((struct kernel_vm86_regs *) regs,
 				error_code, 1);
 		preempt_conditional_cli(regs);
 		debug_stack_usage_dec();
 		return;
 	}

 	/*
 	 * Single-stepping through system calls: ignore any exceptions in
 	 * kernel space, but re-enable TF when returning to user mode.
 	 *
 	 * We already checked v86 mode above, so we can check for kernel mode
 	 * by just checking the CPL of CS.
 	 */
 	if ((dr6 & DR_STEP) && !user_mode(regs)) {
 		tsk->thread.debugreg6 &= ~DR_STEP;
 		set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
 		regs->flags &= ~X86_EFLAGS_TF;
 	}
 	si_code = get_si_code(tsk->thread.debugreg6);
 	if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
 		send_sigtrap(tsk, regs, error_code, si_code);
 	preempt_conditional_cli(regs);
 	debug_stack_usage_dec();

 	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
  */
 void math_error(struct pt_regs *regs, int error_code, int trapnr)
 {
 	struct task_struct *task = current;
 	siginfo_t info;
 	unsigned short err;
 	char *str = (trapnr == 16) ? "fpu exception" : "simd exception";

 	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
 		return;
 	conditional_sti(regs);

 	if (!user_mode_vm(regs))
 	{
 		if (!fixup_exception(regs)) {
 			task->thread.error_code = error_code;
 			task->thread.trap_no = trapnr;
 			die(str, regs, error_code);
 		}
 		return;
 	}

 	/*
 	 * Save the info for the exception handler and clear the error.
 	 */
 	save_init_fpu(task);
 	task->thread.trap_no = trapnr;
 	task->thread.error_code = error_code;
 	info.si_signo = SIGFPE;
 	info.si_errno = 0;
 	info.si_addr = (void __user *)regs->ip;
 	if (trapnr == 16) {
 		unsigned short cwd, swd;
 		/*
 		 * (~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 synchronizing its FPU usage
 		 * and it will suffer the consequences since we won't be able to
 		 * fully reproduce the context of the exception
 		 */
 		cwd = get_fpu_cwd(task);
 		swd = get_fpu_swd(task);

 		err = swd & ~cwd;
 	} else {
 		/*
 		 * The SIMD FPU exceptions are handled a little differently, as there
 		 * is only a single status/control register.  Thus, to determine which
 		 * unmasked exception was caught we must mask the exception mask bits
 		 * at 0x1f80, and then use these to mask the exception bits at 0x3f.
 		 */
 		unsigned short mxcsr = get_fpu_mxcsr(task);
 		err = ~(mxcsr >> 7) & mxcsr;
 	}

 	if (err & 0x001) {	/* Invalid op */
 		/*
 		 * swd & 0x240 == 0x040: Stack Underflow
 		 * swd & 0x240 == 0x240: Stack Overflow
 		 * User must clear the SF bit (0x40) if set
 		 */
 		info.si_code = FPE_FLTINV;
 	} else if (err & 0x004) { /* Divide by Zero */
 		info.si_code = FPE_FLTDIV;
 	} else if (err & 0x008) { /* Overflow */
 		info.si_code = FPE_FLTOVF;
 	} else if (err & 0x012) { /* Denormal, Underflow */
 		info.si_code = FPE_FLTUND;
 	} else if (err & 0x020) { /* Precision */
 		info.si_code = FPE_FLTRES;
 	} else {
 		/*
 		 * If we're using IRQ 13, or supposedly even some trap 16
 		 * implementations, it's possible we get a spurious trap...
 		 */
 		return;		/* Spurious trap, no error */
 	}
 	force_sig_info(SIGFPE, &info, task);
 }

 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
 {
 #ifdef CONFIG_X86_32
 	ignore_fpu_irq = 1;
 #endif

 	math_error(regs, error_code, 16);
 }

 dotraplinkage void
 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
 {
 	math_error(regs, error_code, 19);
 }

 dotraplinkage void
 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
 {
 	conditional_sti(regs);
 #if 0
 	/* No need to warn about this any longer. */
 	printk(KERN_INFO "Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
 #endif
 }

 asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
 {
 }

 asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void)
 {
 }

 /*
  * 'math_state_restore()' saves the current math information in the
  * old math state array, and gets the new ones from the current task
  *
  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
  * Don't touch unless you *really* know how it works.
  *
  * Must be called with kernel preemption disabled (eg with local
  * local interrupts as in the case of do_device_not_available).
  */
 void math_state_restore(void)
 {
 	struct task_struct *tsk = current;

 	if (!tsk_used_math(tsk)) {
 		local_irq_enable();
 		/*
 		 * does a slab alloc which can sleep
 		 */
 		if (init_fpu(tsk)) {
 			/*
 			 * ran out of memory!
 			 */
 			do_group_exit(SIGKILL);
 			return;
 		}
 		local_irq_disable();
 	}

 	__thread_fpu_begin(tsk);
 	/*
 	 * Paranoid restore. send a SIGSEGV if we fail to restore the state.
 	 */
 	if (unlikely(restore_fpu_checking(tsk))) {
 		__thread_fpu_end(tsk);
 		force_sig(SIGSEGV, tsk);
 		return;
 	}

 	tsk->fpu_counter++;
 }
 EXPORT_SYMBOL_GPL(math_state_restore);

 dotraplinkage void __kprobes
 do_device_not_available(struct pt_regs *regs, long error_code)
 {
 #ifdef CONFIG_MATH_EMULATION
 	if (read_cr0() & X86_CR0_EM) {
 		struct math_emu_info info = { };

 		conditional_sti(regs);

 		info.regs = regs;
 		math_emulate(&info);
 		return;
 	}
 #endif
 	math_state_restore(); /* interrupts still off */
 #ifdef CONFIG_X86_32
 	conditional_sti(regs);
 #endif
 }

 #ifdef CONFIG_X86_32
 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
 {
 	siginfo_t info;
 	local_irq_enable();

 	info.si_signo = SIGILL;
 	info.si_errno = 0;
 	info.si_code = ILL_BADSTK;
 	info.si_addr = NULL;
 	if (notify_die(DIE_TRAP, "iret exception",
 			regs, error_code, 32, SIGILL) == NOTIFY_STOP)
 		return;
 	do_trap(32, SIGILL, "iret exception", regs, error_code, &info);
 }
 #endif

 /* Set of traps needed for early debugging. */
 void __init early_trap_init(void)
 {
 	set_intr_gate_ist(1, &debug, DEBUG_STACK);
 	/* int3 can be called from all */
 	set_system_intr_gate_ist(3, &int3, DEBUG_STACK);
 	set_intr_gate(14, &page_fault);
 	load_idt(&idt_descr);
 }

 void __init trap_init(void)
 {
 	int i;

 #ifdef CONFIG_EISA
 	void __iomem *p = early_ioremap(0x0FFFD9, 4);

 	if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
 		EISA_bus = 1;
 	early_iounmap(p, 4);
 #endif

 	set_intr_gate(0, &divide_error);
 	set_intr_gate_ist(2, &nmi, NMI_STACK);
 	/* int4 can be called from all */
 	set_system_intr_gate(4, &overflow);
 	set_intr_gate(5, &bounds);
 	set_intr_gate(6, &invalid_op);
 	set_intr_gate(7, &device_not_available);
 #ifdef CONFIG_X86_32
 	set_task_gate(8, GDT_ENTRY_DOUBLEFAULT_TSS);
 #else
 	set_intr_gate_ist(8, &double_fault, DOUBLEFAULT_STACK);
 #endif
 	set_intr_gate(9, &coprocessor_segment_overrun);
 	set_intr_gate(10, &invalid_TSS);
 	set_intr_gate(11, &segment_not_present);
 	set_intr_gate_ist(12, &stack_segment, STACKFAULT_STACK);
 	set_intr_gate(13, &general_protection);
 	set_intr_gate(15, &spurious_interrupt_bug);
 	set_intr_gate(16, &coprocessor_error);
 	set_intr_gate(17, &alignment_check);
 #ifdef CONFIG_X86_MCE
 	set_intr_gate_ist(18, &machine_check, MCE_STACK);
 #endif
 	set_intr_gate(19, &simd_coprocessor_error);

 	/* Reserve all the builtin and the syscall vector: */
 	for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
 		set_bit(i, used_vectors);

 #ifdef CONFIG_IA32_EMULATION
 	set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
 	set_bit(IA32_SYSCALL_VECTOR, used_vectors);
 #endif

 #ifdef CONFIG_X86_32
 	set_system_trap_gate(SYSCALL_VECTOR, &system_call);
 	set_bit(SYSCALL_VECTOR, used_vectors);
 #endif

 	/*
 	 * Should be a barrier for any external CPU state:
 	 */
 	cpu_init();

 	x86_init.irqs.trap_init();

 #ifdef CONFIG_X86_64
 	memcpy(&nmi_idt_table, &idt_table, IDT_ENTRIES * 16);
 	set_nmi_gate(1, &debug);
 	set_nmi_gate(3, &int3);
 #endif
 }
	/*
	* Copyright (C) 1991, 1992 Linus Torvalds
	* Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
	*
	* Pentium III FXSR, SSE support
	* Gareth Hughes <gareth@valinux.com>, May 2000
	*/

	/*
	* Handle hardware traps and faults.
	*/
	#include <linux/interrupt.h>
	#include <linux/kallsyms.h>
	#include <linux/spinlock.h>
	#include <linux/kprobes.h>
	#include <linux/uaccess.h>
	#include <linux/kdebug.h>
	#include <linux/kgdb.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/ptrace.h>
	#include <linux/string.h>
	#include <linux/delay.h>
	#include <linux/errno.h>
	#include <linux/kexec.h>
	#include <linux/sched.h>
	#include <linux/timer.h>
	#include <linux/init.h>
	#include <linux/bug.h>
	#include <linux/nmi.h>
	#include <linux/mm.h>
	#include <linux/smp.h>
	#include <linux/io.h>

	#ifdef CONFIG_EISA
	#include <linux/ioport.h>
	#include <linux/eisa.h>
	#endif

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

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

	#include <asm/kmemcheck.h>
	#include <asm/stacktrace.h>
	#include <asm/processor.h>
	#include <asm/debugreg.h>
	#include <linux/atomic.h>
	#include <asm/system.h>
	#include <asm/traps.h>
	#include <asm/desc.h>
	#include <asm/i387.h>
	#include <asm/mce.h>

	#include <asm/mach_traps.h>

	#ifdef CONFIG_X86_64
	#include <asm/x86_init.h>
	#include <asm/pgalloc.h>
	#include <asm/proto.h>
	#else
	#include <asm/processor-flags.h>
	#include <asm/setup.h>

	asmlinkage int system_call(void);

	/* Do we ignore FPU interrupts ? */
	char ignore_fpu_irq;

	/*
	* The IDT has to be page-aligned to simplify the Pentium
	* F0 0F bug workaround.
	*/
	gate_desc idt_table[NR_VECTORS] __page_aligned_data = { { { { 0, 0 } } }, };
	#endif

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

	static inline void conditional_sti(struct pt_regs *regs)
	{
	if (regs->flags & X86_EFLAGS_IF)
	local_irq_enable();
	}

	static inline void preempt_conditional_sti(struct pt_regs *regs)
	{
	inc_preempt_count();
	if (regs->flags & X86_EFLAGS_IF)
	local_irq_enable();
	}

	static inline void conditional_cli(struct pt_regs *regs)
	{
	if (regs->flags & X86_EFLAGS_IF)
	local_irq_disable();
	}

	static inline void preempt_conditional_cli(struct pt_regs *regs)
	{
	if (regs->flags & X86_EFLAGS_IF)
	local_irq_disable();
	dec_preempt_count();
	}

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

	#ifdef CONFIG_X86_32
	if (regs->flags & X86_VM_MASK) {
	/*
	* traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
	* On nmi (interrupt 2), do_trap should not be called.
	*/
	if (trapnr < 6)
	goto vm86_trap;
	goto trap_signal;
	}
	#endif

	if (!user_mode(regs))
	goto kernel_trap;

	#ifdef CONFIG_X86_32
	trap_signal:
	#endif
	/*
	* 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;

	#ifdef CONFIG_X86_64
	if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
	printk_ratelimit()) {
	printk(KERN_INFO
	"%s[%d] trap %s ip:%lx sp:%lx error:%lx",
	tsk->comm, tsk->pid, str,
	regs->ip, regs->sp, error_code);
	print_vma_addr(" in ", regs->ip);
	printk("\n");
	}
	#endif

	if (info)
	force_sig_info(signr, info, tsk);
	else
	force_sig(signr, tsk);
	return;

	kernel_trap:
	if (!fixup_exception(regs)) {
	tsk->thread.error_code = error_code;
	tsk->thread.trap_no = trapnr;
	die(str, regs, error_code);
	}
	return;

	#ifdef CONFIG_X86_32
	vm86_trap:
	if (handle_vm86_trap((struct kernel_vm86_regs *) regs,
	error_code, trapnr))
	goto trap_signal;
	return;
	#endif
	}

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

	#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
	dotraplinkage 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; \
	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
	== NOTIFY_STOP) \
	return; \
	conditional_sti(regs); \
	do_trap(trapnr, signr, str, regs, error_code, &info); \
	}

	DO_ERROR_INFO(0, SIGFPE, "divide error", divide_error, FPE_INTDIV, regs->ip)
	DO_ERROR(4, SIGSEGV, "overflow", overflow)
	DO_ERROR(5, SIGSEGV, "bounds", bounds)
	DO_ERROR_INFO(6, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN, regs->ip)
	DO_ERROR(9, SIGFPE, "coprocessor segment overrun", coprocessor_segment_overrun)
	DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS)
	DO_ERROR(11, SIGBUS, "segment not present", segment_not_present)
	#ifdef CONFIG_X86_32
	DO_ERROR(12, SIGBUS, "stack segment", stack_segment)
	#endif
	DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)

	#ifdef CONFIG_X86_64
	/* Runs on IST stack */
	dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
	{
	if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
	12, SIGBUS) == NOTIFY_STOP)
	return;
	preempt_conditional_sti(regs);
	do_trap(12, SIGBUS, "stack segment", regs, error_code, NULL);
	preempt_conditional_cli(regs);
	}

	dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
	{
	static const char str[] = "double fault";
	struct task_struct *tsk = current;

	/* Return not checked because double check cannot be ignored */
	notify_die(DIE_TRAP, str, regs, error_code, 8, SIGSEGV);

	tsk->thread.error_code = error_code;
	tsk->thread.trap_no = 8;

	/*
	* This is always a kernel trap and never fixable (and thus must
	* never return).
	*/
	for (;;)
	die(str, regs, error_code);
	}
	#endif

	dotraplinkage void __kprobes
	do_general_protection(struct pt_regs *regs, long error_code)
	{
	struct task_struct *tsk;

	conditional_sti(regs);

	#ifdef CONFIG_X86_32
	if (regs->flags & X86_VM_MASK)
	goto gp_in_vm86;
	#endif

	tsk = current;
	if (!user_mode(regs))
	goto gp_in_kernel;

	tsk->thread.error_code = error_code;
	tsk->thread.trap_no = 13;

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

	force_sig(SIGSEGV, tsk);
	return;

	#ifdef CONFIG_X86_32
	gp_in_vm86:
	local_irq_enable();
	handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
	return;
	#endif

	gp_in_kernel:
	if (fixup_exception(regs))
	return;

	tsk->thread.error_code = error_code;
	tsk->thread.trap_no = 13;
	if (notify_die(DIE_GPF, "general protection fault", regs,
	error_code, 13, SIGSEGV) == NOTIFY_STOP)
	return;
	die("general protection fault", regs, error_code);
	}

	/* May run on IST stack. */
	dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
	{
	#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
	if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
	== NOTIFY_STOP)
	return;
	#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */

	if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
	== NOTIFY_STOP)
	return;

	/*
	* Let others (NMI) know that the debug stack is in use
	* as we may switch to the interrupt stack.
	*/
	debug_stack_usage_inc();
	preempt_conditional_sti(regs);
	do_trap(3, SIGTRAP, "int3", regs, error_code, NULL);
	preempt_conditional_cli(regs);
	debug_stack_usage_dec();
	}

	#ifdef CONFIG_X86_64
	/*
	* Help handler running on IST stack to switch back to user stack
	* for scheduling or signal handling. The actual stack switch is done in
	* entry.S
	*/
	asmlinkage __kprobes struct pt_regs sync_regs(struct pt_regs eregs)
	{
	struct pt_regs *regs = eregs;
	/* Did already sync */
	if (eregs == (struct pt_regs *)eregs->sp)
	;
	/* Exception from user space */
	else if (user_mode(eregs))
	regs = task_pt_regs(current);
	/*
	* Exception from kernel and interrupts are enabled. Move to
	* kernel process stack.
	*/
	else if (eregs->flags & X86_EFLAGS_IF)
	regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
	if (eregs != regs)
	regs = eregs;
	return regs;
	}
	#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.
	*
	* 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)
	*
	* May run on IST stack.
	*/
	dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
	{
	struct task_struct *tsk = current;
	int user_icebp = 0;
	unsigned long dr6;
	int si_code;

	get_debugreg(dr6, 6);

	/* Filter out all the reserved bits which are preset to 1 */
	dr6 &= ~DR6_RESERVED;

	/*
	* If dr6 has no reason to give us about the origin of this trap,
	* then it's very likely the result of an icebp/int01 trap.
	* User wants a sigtrap for that.
	*/
	if (!dr6 && user_mode(regs))
	user_icebp = 1;

	/* Catch kmemcheck conditions first of all! */
	if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
	return;

	/* DR6 may or may not be cleared by the CPU */
	set_debugreg(0, 6);

	/*
	* The processor cleared BTF, so don't mark that we need it set.
	*/
	clear_tsk_thread_flag(tsk, TIF_BLOCKSTEP);

	/* Store the virtualized DR6 value */
	tsk->thread.debugreg6 = dr6;

	if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,
	SIGTRAP) == NOTIFY_STOP)
	return;

	/*
	* Let others (NMI) know that the debug stack is in use
	* as we may switch to the interrupt stack.
	*/
	debug_stack_usage_inc();

	/* It's safe to allow irq's after DR6 has been saved */
	preempt_conditional_sti(regs);

	if (regs->flags & X86_VM_MASK) {
	handle_vm86_trap((struct kernel_vm86_regs *) regs,
	error_code, 1);
	preempt_conditional_cli(regs);
	debug_stack_usage_dec();
	return;
	}

	/*
	* Single-stepping through system calls: ignore any exceptions in
	* kernel space, but re-enable TF when returning to user mode.
	*
	* We already checked v86 mode above, so we can check for kernel mode
	* by just checking the CPL of CS.
	*/
	if ((dr6 & DR_STEP) && !user_mode(regs)) {
	tsk->thread.debugreg6 &= ~DR_STEP;
	set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
	regs->flags &= ~X86_EFLAGS_TF;
	}
	si_code = get_si_code(tsk->thread.debugreg6);
	if (tsk->thread.debugreg6 & (DR_STEP \| DR_TRAP_BITS) \|\| user_icebp)
	send_sigtrap(tsk, regs, error_code, si_code);
	preempt_conditional_cli(regs);
	debug_stack_usage_dec();

	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
	*/
	void math_error(struct pt_regs *regs, int error_code, int trapnr)
	{
	struct task_struct *task = current;
	siginfo_t info;
	unsigned short err;
	char *str = (trapnr == 16) ? "fpu exception" : "simd exception";

	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, SIGFPE) == NOTIFY_STOP)
	return;
	conditional_sti(regs);

	if (!user_mode_vm(regs))
	{
	if (!fixup_exception(regs)) {
	task->thread.error_code = error_code;
	task->thread.trap_no = trapnr;
	die(str, regs, error_code);
	}
	return;
	}

	/*
	* Save the info for the exception handler and clear the error.
	*/
	save_init_fpu(task);
	task->thread.trap_no = trapnr;
	task->thread.error_code = error_code;
	info.si_signo = SIGFPE;
	info.si_errno = 0;
	info.si_addr = (void __user *)regs->ip;
	if (trapnr == 16) {
	unsigned short cwd, swd;
	/*
	* (~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 synchronizing its FPU usage
	* and it will suffer the consequences since we won't be able to
	* fully reproduce the context of the exception
	*/
	cwd = get_fpu_cwd(task);
	swd = get_fpu_swd(task);

	err = swd & ~cwd;
	} else {
	/*
	* The SIMD FPU exceptions are handled a little differently, as there
	* is only a single status/control register. Thus, to determine which
	* unmasked exception was caught we must mask the exception mask bits
	* at 0x1f80, and then use these to mask the exception bits at 0x3f.
	*/
	unsigned short mxcsr = get_fpu_mxcsr(task);
	err = ~(mxcsr >> 7) & mxcsr;
	}

	if (err & 0x001) { /* Invalid op */
	/*
	* swd & 0x240 == 0x040: Stack Underflow
	* swd & 0x240 == 0x240: Stack Overflow
	* User must clear the SF bit (0x40) if set
	*/
	info.si_code = FPE_FLTINV;
	} else if (err & 0x004) { /* Divide by Zero */
	info.si_code = FPE_FLTDIV;
	} else if (err & 0x008) { /* Overflow */
	info.si_code = FPE_FLTOVF;
	} else if (err & 0x012) { /* Denormal, Underflow */
	info.si_code = FPE_FLTUND;
	} else if (err & 0x020) { /* Precision */
	info.si_code = FPE_FLTRES;
	} else {
	/*
	* If we're using IRQ 13, or supposedly even some trap 16
	* implementations, it's possible we get a spurious trap...
	*/
	return; /* Spurious trap, no error */
	}
	force_sig_info(SIGFPE, &info, task);
	}

	dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
	{
	#ifdef CONFIG_X86_32
	ignore_fpu_irq = 1;
	#endif

	math_error(regs, error_code, 16);
	}

	dotraplinkage void
	do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
	{
	math_error(regs, error_code, 19);
	}

	dotraplinkage void
	do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
	{
	conditional_sti(regs);
	#if 0
	/* No need to warn about this any longer. */
	printk(KERN_INFO "Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
	#endif
	}

	asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
	{
	}

	asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void)
	{
	}

	/*
	* 'math_state_restore()' saves the current math information in the
	* old math state array, and gets the new ones from the current task
	*
	* Careful.. There are problems with IBM-designed IRQ13 behaviour.
	* Don't touch unless you really know how it works.
	*
	* Must be called with kernel preemption disabled (eg with local
	* local interrupts as in the case of do_device_not_available).
	*/
	void math_state_restore(void)
	{
	struct task_struct *tsk = current;

	if (!tsk_used_math(tsk)) {
	local_irq_enable();
	/*
	* does a slab alloc which can sleep
	*/
	if (init_fpu(tsk)) {
	/*
	* ran out of memory!
	*/
	do_group_exit(SIGKILL);
	return;
	}
	local_irq_disable();
	}

	__thread_fpu_begin(tsk);
	/*
	* Paranoid restore. send a SIGSEGV if we fail to restore the state.
	*/
	if (unlikely(restore_fpu_checking(tsk))) {
	__thread_fpu_end(tsk);
	force_sig(SIGSEGV, tsk);
	return;
	}

	tsk->fpu_counter++;
	}
	EXPORT_SYMBOL_GPL(math_state_restore);

	dotraplinkage void __kprobes
	do_device_not_available(struct pt_regs *regs, long error_code)
	{
	#ifdef CONFIG_MATH_EMULATION
	if (read_cr0() & X86_CR0_EM) {
	struct math_emu_info info = { };

	conditional_sti(regs);

	info.regs = regs;
	math_emulate(&info);
	return;
	}
	#endif
	math_state_restore(); /* interrupts still off */
	#ifdef CONFIG_X86_32
	conditional_sti(regs);
	#endif
	}

	#ifdef CONFIG_X86_32
	dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
	{
	siginfo_t info;
	local_irq_enable();

	info.si_signo = SIGILL;
	info.si_errno = 0;
	info.si_code = ILL_BADSTK;
	info.si_addr = NULL;
	if (notify_die(DIE_TRAP, "iret exception",
	regs, error_code, 32, SIGILL) == NOTIFY_STOP)
	return;
	do_trap(32, SIGILL, "iret exception", regs, error_code, &info);
	}
	#endif

	/* Set of traps needed for early debugging. */
	void __init early_trap_init(void)
	{
	set_intr_gate_ist(1, &debug, DEBUG_STACK);
	/* int3 can be called from all */
	set_system_intr_gate_ist(3, &int3, DEBUG_STACK);
	set_intr_gate(14, &page_fault);
	load_idt(&idt_descr);
	}

	void __init trap_init(void)
	{
	int i;

	#ifdef CONFIG_EISA
	void __iomem *p = early_ioremap(0x0FFFD9, 4);

	if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
	EISA_bus = 1;
	early_iounmap(p, 4);
	#endif

	set_intr_gate(0, &divide_error);
	set_intr_gate_ist(2, &nmi, NMI_STACK);
	/* int4 can be called from all */
	set_system_intr_gate(4, &overflow);
	set_intr_gate(5, &bounds);
	set_intr_gate(6, &invalid_op);
	set_intr_gate(7, &device_not_available);
	#ifdef CONFIG_X86_32
	set_task_gate(8, GDT_ENTRY_DOUBLEFAULT_TSS);
	#else
	set_intr_gate_ist(8, &double_fault, DOUBLEFAULT_STACK);
	#endif
	set_intr_gate(9, &coprocessor_segment_overrun);
	set_intr_gate(10, &invalid_TSS);
	set_intr_gate(11, &segment_not_present);
	set_intr_gate_ist(12, &stack_segment, STACKFAULT_STACK);
	set_intr_gate(13, &general_protection);
	set_intr_gate(15, &spurious_interrupt_bug);
	set_intr_gate(16, &coprocessor_error);
	set_intr_gate(17, &alignment_check);
	#ifdef CONFIG_X86_MCE
	set_intr_gate_ist(18, &machine_check, MCE_STACK);
	#endif
	set_intr_gate(19, &simd_coprocessor_error);

	/* Reserve all the builtin and the syscall vector: */
	for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
	set_bit(i, used_vectors);

	#ifdef CONFIG_IA32_EMULATION
	set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
	set_bit(IA32_SYSCALL_VECTOR, used_vectors);
	#endif

	#ifdef CONFIG_X86_32
	set_system_trap_gate(SYSCALL_VECTOR, &system_call);
	set_bit(SYSCALL_VECTOR, used_vectors);
	#endif

	/*
	* Should be a barrier for any external CPU state:
	*/
	cpu_init();

	x86_init.irqs.trap_init();

	#ifdef CONFIG_X86_64
	memcpy(&nmi_idt_table, &idt_table, IDT_ENTRIES * 16);
	set_nmi_gate(1, &debug);
	set_nmi_gate(3, &int3);
	#endif
	}