1 files changed, 377 insertions, 504 deletions

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 33399176512..0d0e922fafc 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -9,15 +9,21 @@
 /*
  * Handle hardware traps and faults.
  */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/context_tracking.h>
 #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/uprobes.h>
 #include <linux/string.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
@@ -36,10 +42,6 @@
 #include <linux/eisa.h>
 #endif
 
-#ifdef CONFIG_MCA
-#include <linux/mca.h>
-#endif
-
 #if defined(CONFIG_EDAC)
 #include <linux/edac.h>
 #endif
@@ -48,40 +50,37 @@
 #include <asm/stacktrace.h>
 #include <asm/processor.h>
 #include <asm/debugreg.h>
-#include <asm/atomic.h>
-#include <asm/system.h>
+#include <linux/atomic.h>
+#include <asm/ftrace.h>
 #include <asm/traps.h>
 #include <asm/desc.h>
 #include <asm/i387.h>
+#include <asm/fpu-internal.h>
 #include <asm/mce.h>
-
+#include <asm/fixmap.h>
 #include <asm/mach_traps.h>
+#include <asm/alternative.h>
 
 #ifdef CONFIG_X86_64
 #include <asm/x86_init.h>
 #include <asm/pgalloc.h>
 #include <asm/proto.h>
+
+/* No need to be aligned, but done to keep all IDTs defined the same way. */
+gate_desc debug_idt_table[NR_VECTORS] __page_aligned_bss;
 #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
 
+/* Must be page-aligned because the real IDT is used in a fixmap. */
+gate_desc idt_table[NR_VECTORS] __page_aligned_bss;
+
 DECLARE_BITMAP(used_vectors, NR_VECTORS);
 EXPORT_SYMBOL_GPL(used_vectors);
 
-static int ignore_nmis;
-
 static inline void conditional_sti(struct pt_regs *regs)
 {
 	if (regs->flags & X86_EFLAGS_IF)
@@ -90,7 +89,7 @@ static inline void conditional_sti(struct pt_regs *regs)
 
 static inline void preempt_conditional_sti(struct pt_regs *regs)
 {
-	inc_preempt_count();
+	preempt_count_inc();
 	if (regs->flags & X86_EFLAGS_IF)
 		local_irq_enable();
 }
@@ -105,44 +104,81 @@ static inline void preempt_conditional_cli(struct pt_regs *regs)
 {
 	if (regs->flags & X86_EFLAGS_IF)
 		local_irq_disable();
-	dec_preempt_count();
+	preempt_count_dec();
 }
 
-#ifdef CONFIG_X86_32
-static inline void
-die_if_kernel(const char *str, struct pt_regs *regs, long err)
-{
-	if (!user_mode_vm(regs))
-		die(str, regs, err);
-}
-#endif
-
-static void __kprobes
-do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
-	long error_code, siginfo_t *info)
+static nokprobe_inline int
+do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
+		  struct pt_regs *regs,	long error_code)
 {
-	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.
+		 * 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;
+		if (trapnr < X86_TRAP_UD) {
+			if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
+						error_code, trapnr))
+				return 0;
+		}
+		return -1;
 	}
 #endif
+	if (!user_mode(regs)) {
+		if (!fixup_exception(regs)) {
+			tsk->thread.error_code = error_code;
+			tsk->thread.trap_nr = trapnr;
+			die(str, regs, error_code);
+		}
+		return 0;
+	}
+
+	return -1;
+}
 
-	if (!user_mode(regs))
-		goto kernel_trap;
+static siginfo_t *fill_trap_info(struct pt_regs *regs, int signr, int trapnr,
+				siginfo_t *info)
+{
+	unsigned long siaddr;
+	int sicode;
 
-#ifdef CONFIG_X86_32
-trap_signal:
-#endif
+	switch (trapnr) {
+	default:
+		return SEND_SIG_PRIV;
+
+	case X86_TRAP_DE:
+		sicode = FPE_INTDIV;
+		siaddr = uprobe_get_trap_addr(regs);
+		break;
+	case X86_TRAP_UD:
+		sicode = ILL_ILLOPN;
+		siaddr = uprobe_get_trap_addr(regs);
+		break;
+	case X86_TRAP_AC:
+		sicode = BUS_ADRALN;
+		siaddr = 0;
+		break;
+	}
+
+	info->si_signo = signr;
+	info->si_errno = 0;
+	info->si_code = sicode;
+	info->si_addr = (void __user *)siaddr;
+	return info;
+}
+
+static void
+do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
+	long error_code, siginfo_t *info)
+{
+	struct task_struct *tsk = current;
+
+
+	if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
+		return;
 	/*
-	 * We want error_code and trap_no set for userspace faults and
+	 * We want error_code and trap_nr 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
@@ -151,90 +187,71 @@ trap_signal:
 	 * delivered, faults.  See also do_general_protection below.
 	 */
 	tsk->thread.error_code = error_code;
-	tsk->thread.trap_no = trapnr;
+	tsk->thread.trap_nr = 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);
+		pr_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");
+		pr_cont("\n");
 	}
 #endif
 
-	if (info)
-		force_sig_info(signr, info, tsk);
-	else
-		force_sig(signr, tsk);
-	return;
+	force_sig_info(signr, info ?: SEND_SIG_PRIV, tsk);
+}
+NOKPROBE_SYMBOL(do_trap);
 
-kernel_trap:
-	if (!fixup_exception(regs)) {
-		tsk->thread.error_code = error_code;
-		tsk->thread.trap_no = trapnr;
-		die(str, regs, error_code);
+static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
+			  unsigned long trapnr, int signr)
+{
+	enum ctx_state prev_state = exception_enter();
+	siginfo_t info;
+
+	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
+			NOTIFY_STOP) {
+		conditional_sti(regs);
+		do_trap(trapnr, signr, str, regs, error_code,
+			fill_trap_info(regs, signr, trapnr, &info));
 	}
-	return;
 
-#ifdef CONFIG_X86_32
-vm86_trap:
-	if (handle_vm86_trap((struct kernel_vm86_regs *) regs,
-						error_code, trapnr))
-		goto trap_signal;
-	return;
-#endif
+	exception_exit(prev_state);
 }
 
 #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);		\
+	do_error_trap(regs, error_code, str, trapnr, signr);		\
 }
 
-#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)
+DO_ERROR(X86_TRAP_DE,     SIGFPE,  "divide error",		divide_error)
+DO_ERROR(X86_TRAP_OF,     SIGSEGV, "overflow",			overflow)
+DO_ERROR(X86_TRAP_BR,     SIGSEGV, "bounds",			bounds)
+DO_ERROR(X86_TRAP_UD,     SIGILL,  "invalid opcode",		invalid_op)
+DO_ERROR(X86_TRAP_OLD_MF, SIGFPE,  "coprocessor segment overrun",coprocessor_segment_overrun)
+DO_ERROR(X86_TRAP_TS,     SIGSEGV, "invalid TSS",		invalid_TSS)
+DO_ERROR(X86_TRAP_NP,     SIGBUS,  "segment not present",	segment_not_present)
 #ifdef CONFIG_X86_32
-DO_ERROR(12, SIGBUS, "stack segment", stack_segment)
+DO_ERROR(X86_TRAP_SS,     SIGBUS,  "stack segment",		stack_segment)
 #endif
-DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)
+DO_ERROR(X86_TRAP_AC,     SIGBUS,  "alignment check",		alignment_check)
 
 #ifdef CONFIG_X86_64
 /* Runs on IST stack */
 dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
 {
+	enum ctx_state prev_state;
+
+	prev_state = exception_enter();
 	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);
+		       X86_TRAP_SS, SIGBUS) != NOTIFY_STOP) {
+		preempt_conditional_sti(regs);
+		do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
+		preempt_conditional_cli(regs);
+	}
+	exception_exit(prev_state);
 }
 
 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
@@ -242,12 +259,16 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 	static const char str[] = "double fault";
 	struct task_struct *tsk = current;
 
+	exception_enter();
 	/* Return not checked because double check cannot be ignored */
-	notify_die(DIE_TRAP, str, regs, error_code, 8, SIGSEGV);
+	notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
 
 	tsk->thread.error_code = error_code;
-	tsk->thread.trap_no = 8;
+	tsk->thread.trap_nr = X86_TRAP_DF;
 
+#ifdef CONFIG_DOUBLEFAULT
+	df_debug(regs, error_code);
+#endif
 	/*
 	 * This is always a kernel trap and never fixable (and thus must
 	 * never return).
@@ -257,223 +278,100 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 }
 #endif
 
-dotraplinkage void __kprobes
+dotraplinkage void
 do_general_protection(struct pt_regs *regs, long error_code)
 {
 	struct task_struct *tsk;
+	enum ctx_state prev_state;
 
+	prev_state = exception_enter();
 	conditional_sti(regs);
 
 #ifdef CONFIG_X86_32
-	if (regs->flags & X86_VM_MASK)
-		goto gp_in_vm86;
+	if (regs->flags & X86_VM_MASK) {
+		local_irq_enable();
+		handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
+		goto exit;
+	}
 #endif
 
 	tsk = current;
-	if (!user_mode(regs))
-		goto gp_in_kernel;
+	if (!user_mode(regs)) {
+		if (fixup_exception(regs))
+			goto exit;
+
+		tsk->thread.error_code = error_code;
+		tsk->thread.trap_nr = X86_TRAP_GP;
+		if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
+			       X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
+			die("general protection fault", regs, error_code);
+		goto exit;
+	}
 
 	tsk->thread.error_code = error_code;
-	tsk->thread.trap_no = 13;
+	tsk->thread.trap_nr = X86_TRAP_GP;
 
 	if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
 			printk_ratelimit()) {
-		printk(KERN_INFO
-			"%s[%d] general protection ip:%lx sp:%lx error:%lx",
+		pr_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);
-}
-
-static notrace __kprobes void
-mem_parity_error(unsigned char reason, struct pt_regs *regs)
-{
-	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");
-
-#if defined(CONFIG_EDAC)
-	if (edac_handler_set()) {
-		edac_atomic_assert_error();
-		return;
+		pr_cont("\n");
 	}
-#endif
-
-	if (panic_on_unrecovered_nmi)
-		panic("NMI: Not continuing");
 
-	printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
-
-	/* Clear and disable the memory parity error line. */
-	reason = (reason & 0xf) | 4;
-	outb(reason, 0x61);
+	force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
+exit:
+	exception_exit(prev_state);
 }
+NOKPROBE_SYMBOL(do_general_protection);
 
-static notrace __kprobes void
-io_check_error(unsigned char reason, struct pt_regs *regs)
+/* May run on IST stack. */
+dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
 {
-	unsigned long i;
-
-	printk(KERN_EMERG "NMI: IOCK error (debug interrupt?)\n");
-	show_registers(regs);
-
-	if (panic_on_io_nmi)
-		panic("NMI IOCK error: Not continuing");
+	enum ctx_state prev_state;
 
-	/* Re-enable the IOCK line, wait for a few seconds */
-	reason = (reason & 0xf) | 8;
-	outb(reason, 0x61);
-
-	i = 2000;
-	while (--i)
-		udelay(1000);
-
-	reason &= ~8;
-	outb(reason, 0x61);
-}
-
-static notrace __kprobes void
-unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
-{
-	if (notify_die(DIE_NMIUNKNOWN, "nmi", regs, reason, 2, SIGINT) ==
-			NOTIFY_STOP)
-		return;
-#ifdef CONFIG_MCA
+#ifdef CONFIG_DYNAMIC_FTRACE
 	/*
-	 * Might actually be able to figure out what the guilty party
-	 * is:
+	 * ftrace must be first, everything else may cause a recursive crash.
+	 * See note by declaration of modifying_ftrace_code in ftrace.c
 	 */
-	if (MCA_bus) {
-		mca_handle_nmi();
+	if (unlikely(atomic_read(&modifying_ftrace_code)) &&
+	    ftrace_int3_handler(regs))
 		return;
-	}
 #endif
-	printk(KERN_EMERG
-		"Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
-			reason, smp_processor_id());
-
-	printk(KERN_EMERG "Do you have a strange power saving mode enabled?\n");
-	if (panic_on_unrecovered_nmi)
-		panic("NMI: Not continuing");
-
-	printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
-}
-
-static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
-{
-	unsigned char reason = 0;
-	int cpu;
-
-	cpu = smp_processor_id();
+	if (poke_int3_handler(regs))
+		return;
 
-	/* Only the BSP gets external NMIs from the system. */
-	if (!cpu)
-		reason = get_nmi_reason();
+	prev_state = exception_enter();
+#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
+	if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
+				SIGTRAP) == NOTIFY_STOP)
+		goto exit;
+#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
 
-	if (!(reason & 0xc0)) {
-		if (notify_die(DIE_NMI_IPI, "nmi_ipi", regs, reason, 2, SIGINT)
-								== 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.
-		 */
-		if (nmi_watchdog_tick(regs, reason))
-			return;
-		if (!do_nmi_callback(regs, cpu))
-			unknown_nmi_error(reason, regs);
-#else
-		unknown_nmi_error(reason, regs);
+#ifdef CONFIG_KPROBES
+	if (kprobe_int3_handler(regs))
+		goto exit;
 #endif
 
-		return;
-	}
-	if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP)
-		return;
+	if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
+			SIGTRAP) == NOTIFY_STOP)
+		goto exit;
 
-	/* AK: following checks seem to be broken on modern chipsets. FIXME */
-	if (reason & 0x80)
-		mem_parity_error(reason, regs);
-	if (reason & 0x40)
-		io_check_error(reason, regs);
-#ifdef CONFIG_X86_32
 	/*
-	 * Reassert NMI in case it became active meanwhile
-	 * as it's edge-triggered:
+	 * Let others (NMI) know that the debug stack is in use
+	 * as we may switch to the interrupt stack.
 	 */
-	reassert_nmi();
-#endif
-}
-
-dotraplinkage notrace __kprobes void
-do_nmi(struct pt_regs *regs, long error_code)
-{
-	nmi_enter();
-
-	inc_irq_stat(__nmi_count);
-
-	if (!ignore_nmis)
-		default_do_nmi(regs);
-
-	nmi_exit();
-}
-
-void stop_nmi(void)
-{
-	acpi_nmi_disable();
-	ignore_nmis++;
-}
-
-void restart_nmi(void)
-{
-	ignore_nmis--;
-	acpi_nmi_enable();
-}
-
-/* May run on IST stack. */
-dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
-{
-#ifdef CONFIG_KPROBES
-	if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
-			== NOTIFY_STOP)
-		return;
-#else
-	if (notify_die(DIE_TRAP, "int3", regs, error_code, 3, SIGTRAP)
-			== NOTIFY_STOP)
-		return;
-#endif
-
+	debug_stack_usage_inc();
 	preempt_conditional_sti(regs);
-	do_trap(3, SIGTRAP, "int3", regs, error_code, NULL);
+	do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
 	preempt_conditional_cli(regs);
+	debug_stack_usage_dec();
+exit:
+	exception_exit(prev_state);
 }
+NOKPROBE_SYMBOL(do_int3);
 
 #ifdef CONFIG_X86_64
 /*
@@ -481,7 +379,7 @@ dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
  * 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)
+asmlinkage __visible struct pt_regs *sync_regs(struct pt_regs *eregs)
 {
 	struct pt_regs *regs = eregs;
 	/* Did already sync */
@@ -500,6 +398,7 @@ asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
 		*regs = *eregs;
 	return regs;
 }
+NOKPROBE_SYMBOL(sync_regs);
 #endif
 
 /*
@@ -526,40 +425,68 @@ asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
  *
  * May run on IST stack.
  */
-dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
+dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
 {
 	struct task_struct *tsk = current;
+	enum ctx_state prev_state;
+	int user_icebp = 0;
 	unsigned long dr6;
 	int si_code;
 
+	prev_state = exception_enter();
+
 	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;
+		goto exit;
 
 	/* 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_DEBUGCTLMSR);
-	tsk->thread.debugctlmsr = 0;
+	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,
+#ifdef CONFIG_KPROBES
+	if (kprobe_debug_handler(regs))
+		goto exit;
+#endif
+
+	if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
 							SIGTRAP) == NOTIFY_STOP)
-		return;
+		goto exit;
+
+	/*
+	 * 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);
-		return;
+		handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
+					X86_TRAP_DB);
+		preempt_conditional_cli(regs);
+		debug_stack_usage_dec();
+		goto exit;
 	}
 
 	/*
@@ -575,62 +502,78 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 		regs->flags &= ~X86_EFLAGS_TF;
 	}
 	si_code = get_si_code(tsk->thread.debugreg6);
-	if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS))
+	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;
+exit:
+	exception_exit(prev_state);
 }
-
-#ifdef CONFIG_X86_64
-static int kernel_math_error(struct pt_regs *regs, const char *str, int trapnr)
-{
-	if (fixup_exception(regs))
-		return 1;
-
-	notify_die(DIE_GPF, str, regs, 0, trapnr, SIGFPE);
-	/* Illegal floating point operation in the kernel */
-	current->thread.trap_no = trapnr;
-	die(str, regs, 0);
-	return 0;
-}
-#endif
+NOKPROBE_SYMBOL(do_debug);
 
 /*
  * 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(void __user *ip)
+static void math_error(struct pt_regs *regs, int error_code, int trapnr)
 {
-	struct task_struct *task;
+	struct task_struct *task = current;
 	siginfo_t info;
-	unsigned short cwd, swd, err;
+	unsigned short err;
+	char *str = (trapnr == X86_TRAP_MF) ? "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_nr = trapnr;
+			die(str, regs, error_code);
+		}
+		return;
+	}
 
 	/*
 	 * 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;
+	task->thread.trap_nr = trapnr;
+	task->thread.error_code = error_code;
 	info.si_signo = SIGFPE;
 	info.si_errno = 0;
-	info.si_addr = ip;
-	/*
-	 * (~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);
+	info.si_addr = (void __user *)uprobe_get_trap_addr(regs);
+	if (trapnr == X86_TRAP_MF) {
+		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;
+		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 */
 		/*
@@ -649,107 +592,32 @@ void math_error(void __user *ip)
 		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...
+		 * If we're using IRQ 13, or supposedly even some trap
+		 * X86_TRAP_MF implementations, it's possible
+		 * we get a spurious trap, which is not an error.
 		 */
-		return;		/* Spurious trap, no error */
+		return;
 	}
 	force_sig_info(SIGFPE, &info, task);
 }
 
 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
 {
-	conditional_sti(regs);
-
-#ifdef CONFIG_X86_32
-	ignore_fpu_irq = 1;
-#else
-	if (!user_mode(regs) &&
-	    kernel_math_error(regs, "kernel x87 math error", 16))
-		return;
-#endif
+	enum ctx_state prev_state;
 
-	math_error((void __user *)regs->ip);
-}
-
-static void simd_math_error(void __user *ip)
-{
-	struct task_struct *task;
-	siginfo_t info;
-	unsigned short mxcsr;
-
-	/*
-	 * Save the info for the exception handler and clear the error.
-	 */
-	task = current;
-	save_init_fpu(task);
-	task->thread.trap_no = 19;
-	task->thread.error_code = 0;
-	info.si_signo = SIGFPE;
-	info.si_errno = 0;
-	info.si_code = __SI_FAULT;
-	info.si_addr = ip;
-	/*
-	 * 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.
-	 */
-	mxcsr = get_fpu_mxcsr(task);
-	switch (~((mxcsr & 0x1f80) >> 7) & (mxcsr & 0x3f)) {
-	case 0x000:
-	default:
-		break;
-	case 0x001: /* Invalid Op */
-		info.si_code = FPE_FLTINV;
-		break;
-	case 0x002: /* Denormalize */
-	case 0x010: /* Underflow */
-		info.si_code = FPE_FLTUND;
-		break;
-	case 0x004: /* Zero Divide */
-		info.si_code = FPE_FLTDIV;
-		break;
-	case 0x008: /* Overflow */
-		info.si_code = FPE_FLTOVF;
-		break;
-	case 0x020: /* Precision */
-		info.si_code = FPE_FLTRES;
-		break;
-	}
-	force_sig_info(SIGFPE, &info, task);
+	prev_state = exception_enter();
+	math_error(regs, error_code, X86_TRAP_MF);
+	exception_exit(prev_state);
 }
 
 dotraplinkage void
 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
 {
-	conditional_sti(regs);
+	enum ctx_state prev_state;
 
-#ifdef CONFIG_X86_32
-	if (cpu_has_xmm) {
-		/* Handle SIMD FPU exceptions on PIII+ processors. */
-		ignore_fpu_irq = 1;
-		simd_math_error((void __user *)regs->ip);
-		return;
-	}
-	/*
-	 * Handle strange cache flush from user space exception
-	 * in all other cases.  This is undocumented behaviour.
-	 */
-	if (regs->flags & X86_VM_MASK) {
-		handle_vm86_fault((struct kernel_vm86_regs *)regs, error_code);
-		return;
-	}
-	current->thread.trap_no = 19;
-	current->thread.error_code = error_code;
-	die_if_kernel("cache flush denied", regs, error_code);
-	force_sig(SIGSEGV, current);
-#else
-	if (!user_mode(regs) &&
-			kernel_math_error(regs, "kernel simd math error", 19))
-		return;
-	simd_math_error((void __user *)regs->ip);
-#endif
+	prev_state = exception_enter();
+	math_error(regs, error_code, X86_TRAP_XF);
+	exception_exit(prev_state);
 }
 
 dotraplinkage void
@@ -758,38 +626,16 @@ 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");
+	pr_info("Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
 #endif
 }
 
-asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
+asmlinkage __visible void __attribute__((weak)) smp_thermal_interrupt(void)
 {
 }
 
-asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void)
-{
-}
-
-/*
- * __math_state_restore assumes that cr0.TS is already clear and the
- * fpu state is all ready for use.  Used during context switch.
- */
-void __math_state_restore(void)
+asmlinkage __visible void __attribute__((weak)) smp_threshold_interrupt(void)
 {
-	struct thread_info *thread = current_thread_info();
-	struct task_struct *tsk = thread->task;
-
-	/*
-	 * Paranoid restore. send a SIGSEGV if we fail to restore the state.
-	 */
-	if (unlikely(restore_fpu_checking(tsk))) {
-		stts();
-		force_sig(SIGSEGV, tsk);
-		return;
-	}
-
-	thread->status |= TS_USEDFPU;	/* So we fnsave on switch_to() */
-	tsk->fpu_counter++;
 }
 
 /*
@@ -799,13 +645,12 @@ void __math_state_restore(void)
  * 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 (in this case,
- * local interrupts are disabled at the call-site in entry.S).
+ * Must be called with kernel preemption disabled (eg with local
+ * local interrupts as in the case of do_device_not_available).
  */
-asmlinkage void math_state_restore(void)
+void math_state_restore(void)
 {
-	struct thread_info *thread = current_thread_info();
-	struct task_struct *tsk = thread->task;
+	struct task_struct *tsk = current;
 
 	if (!tsk_used_math(tsk)) {
 		local_irq_enable();
@@ -822,27 +667,30 @@ asmlinkage void math_state_restore(void)
 		local_irq_disable();
 	}
 
-	clts();				/* Allow maths ops (or we recurse) */
+	__thread_fpu_begin(tsk);
 
-	__math_state_restore();
-}
-EXPORT_SYMBOL_GPL(math_state_restore);
+	/*
+	 * Paranoid restore. send a SIGSEGV if we fail to restore the state.
+	 */
+	if (unlikely(restore_fpu_checking(tsk))) {
+		drop_init_fpu(tsk);
+		force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
+		return;
+	}
 
-#ifndef CONFIG_MATH_EMULATION
-void math_emulate(struct math_emu_info *info)
-{
-	printk(KERN_EMERG
-		"math-emulation not enabled and no coprocessor found.\n");
-	printk(KERN_EMERG "killing %s.\n", current->comm);
-	force_sig(SIGFPE, current);
-	schedule();
+	tsk->thread.fpu_counter++;
 }
-#endif /* CONFIG_MATH_EMULATION */
+EXPORT_SYMBOL_GPL(math_state_restore);
 
-dotraplinkage void __kprobes
+dotraplinkage void
 do_device_not_available(struct pt_regs *regs, long error_code)
 {
-#ifdef CONFIG_X86_32
+	enum ctx_state prev_state;
+
+	prev_state = exception_enter();
+	BUG_ON(use_eager_fpu());
+
+#ifdef CONFIG_MATH_EMULATION
 	if (read_cr0() & X86_CR0_EM) {
 		struct math_emu_info info = { };
 
@@ -850,32 +698,59 @@ do_device_not_available(struct pt_regs *regs, long error_code)
 
 		info.regs = regs;
 		math_emulate(&info);
-	} else {
-		math_state_restore(); /* interrupts still off */
-		conditional_sti(regs);
+		exception_exit(prev_state);
+		return;
 	}
-#else
-	math_state_restore();
 #endif
+	math_state_restore(); /* interrupts still off */
+#ifdef CONFIG_X86_32
+	conditional_sti(regs);
+#endif
+	exception_exit(prev_state);
 }
+NOKPROBE_SYMBOL(do_device_not_available);
 
 #ifdef CONFIG_X86_32
 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
 {
 	siginfo_t info;
+	enum ctx_state prev_state;
+
+	prev_state = exception_enter();
 	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);
+	if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
+			X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
+		do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
+			&info);
+	}
+	exception_exit(prev_state);
 }
 #endif
 
+/* Set of traps needed for early debugging. */
+void __init early_trap_init(void)
+{
+	set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
+	/* int3 can be called from all */
+	set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
+#ifdef CONFIG_X86_32
+	set_intr_gate(X86_TRAP_PF, page_fault);
+#endif
+	load_idt(&idt_descr);
+}
+
+void __init early_trap_pf_init(void)
+{
+#ifdef CONFIG_X86_64
+	set_intr_gate(X86_TRAP_PF, page_fault);
+#endif
+}
+
 void __init trap_init(void)
 {
 	int i;
@@ -888,34 +763,30 @@ void __init trap_init(void)
 	early_iounmap(p, 4);
 #endif
 
-	set_intr_gate(0, &divide_error);
-	set_intr_gate_ist(1, &debug, DEBUG_STACK);
-	set_intr_gate_ist(2, &nmi, NMI_STACK);
-	/* int3 can be called from all */
-	set_system_intr_gate_ist(3, &int3, DEBUG_STACK);
+	set_intr_gate(X86_TRAP_DE, divide_error);
+	set_intr_gate_ist(X86_TRAP_NMI, &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);
+	set_system_intr_gate(X86_TRAP_OF, &overflow);
+	set_intr_gate(X86_TRAP_BR, bounds);
+	set_intr_gate(X86_TRAP_UD, invalid_op);
+	set_intr_gate(X86_TRAP_NM, device_not_available);
 #ifdef CONFIG_X86_32
-	set_task_gate(8, GDT_ENTRY_DOUBLEFAULT_TSS);
+	set_task_gate(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS);
 #else
-	set_intr_gate_ist(8, &double_fault, DOUBLEFAULT_STACK);
+	set_intr_gate_ist(X86_TRAP_DF, &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(14, &page_fault);
-	set_intr_gate(15, &spurious_interrupt_bug);
-	set_intr_gate(16, &coprocessor_error);
-	set_intr_gate(17, &alignment_check);
+	set_intr_gate(X86_TRAP_OLD_MF, coprocessor_segment_overrun);
+	set_intr_gate(X86_TRAP_TS, invalid_TSS);
+	set_intr_gate(X86_TRAP_NP, segment_not_present);
+	set_intr_gate_ist(X86_TRAP_SS, &stack_segment, STACKFAULT_STACK);
+	set_intr_gate(X86_TRAP_GP, general_protection);
+	set_intr_gate(X86_TRAP_SPURIOUS, spurious_interrupt_bug);
+	set_intr_gate(X86_TRAP_MF, coprocessor_error);
+	set_intr_gate(X86_TRAP_AC, alignment_check);
 #ifdef CONFIG_X86_MCE
-	set_intr_gate_ist(18, &machine_check, MCE_STACK);
+	set_intr_gate_ist(X86_TRAP_MC, &machine_check, MCE_STACK);
 #endif
-	set_intr_gate(19, &simd_coprocessor_error);
+	set_intr_gate(X86_TRAP_XF, simd_coprocessor_error);
 
 	/* Reserve all the builtin and the syscall vector: */
 	for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
@@ -927,26 +798,28 @@ void __init trap_init(void)
 #endif
 
 #ifdef CONFIG_X86_32
-	if (cpu_has_fxsr) {
-		printk(KERN_INFO "Enabling fast FPU save and restore... ");
-		set_in_cr4(X86_CR4_OSFXSR);
-		printk("done.\n");
-	}
-	if (cpu_has_xmm) {
-		printk(KERN_INFO
-			"Enabling unmasked SIMD FPU exception support... ");
-		set_in_cr4(X86_CR4_OSXMMEXCPT);
-		printk("done.\n");
-	}
-
 	set_system_trap_gate(SYSCALL_VECTOR, &system_call);
 	set_bit(SYSCALL_VECTOR, used_vectors);
 #endif
 
 	/*
+	 * Set the IDT descriptor to a fixed read-only location, so that the
+	 * "sidt" instruction will not leak the location of the kernel, and
+	 * to defend the IDT against arbitrary memory write vulnerabilities.
+	 * It will be reloaded in cpu_init() */
+	__set_fixmap(FIX_RO_IDT, __pa_symbol(idt_table), PAGE_KERNEL_RO);
+	idt_descr.address = fix_to_virt(FIX_RO_IDT);
+
+	/*
 	 * Should be a barrier for any external CPU state:
 	 */
 	cpu_init();
 
 	x86_init.irqs.trap_init();
+
+#ifdef CONFIG_X86_64
+	memcpy(&debug_idt_table, &idt_table, IDT_ENTRIES * 16);
+	set_nmi_gate(X86_TRAP_DB, &debug);
+	set_nmi_gate(X86_TRAP_BP, &int3);
+#endif
 }