i386: prepare shared kernel/kprobes.c

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 0 insertions, 751 deletions

diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c
deleted file mode 100644
index 448a50b..0000000
--- a/arch/i386/kernel/kprobes.c
+++ /dev/null
@@ -1,751 +0,0 @@
-/*
- *  Kernel Probes (KProbes)
- *  arch/i386/kernel/kprobes.c
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- *
- * Copyright (C) IBM Corporation, 2002, 2004
- *
- * 2002-Oct	Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
- *		Probes initial implementation ( includes contributions from
- *		Rusty Russell).
- * 2004-July	Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
- *		interface to access function arguments.
- * 2005-May	Hien Nguyen <hien@us.ibm.com>, Jim Keniston
- *		<jkenisto@us.ibm.com> and Prasanna S Panchamukhi
- *		<prasanna@in.ibm.com> added function-return probes.
- */
-
-#include <linux/kprobes.h>
-#include <linux/ptrace.h>
-#include <linux/preempt.h>
-#include <linux/kdebug.h>
-#include <asm/cacheflush.h>
-#include <asm/desc.h>
-#include <asm/uaccess.h>
-#include <asm/alternative.h>
-
-void jprobe_return_end(void);
-
-DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
-DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
-
-/* insert a jmp code */
-static __always_inline void set_jmp_op(void *from, void *to)
-{
-	struct __arch_jmp_op {
-		char op;
-		long raddr;
-	} __attribute__((packed)) *jop;
-	jop = (struct __arch_jmp_op *)from;
-	jop->raddr = (long)(to) - ((long)(from) + 5);
-	jop->op = RELATIVEJUMP_INSTRUCTION;
-}
-
-/*
- * returns non-zero if opcodes can be boosted.
- */
-static __always_inline int can_boost(kprobe_opcode_t *opcodes)
-{
-#define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf)		      \
-	(((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) |   \
-	  (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) |   \
-	  (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) |   \
-	  (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf))    \
-	 << (row % 32))
-	/*
-	 * Undefined/reserved opcodes, conditional jump, Opcode Extension
-	 * Groups, and some special opcodes can not be boost.
-	 */
-	static const unsigned long twobyte_is_boostable[256 / 32] = {
-		/*      0 1 2 3 4 5 6 7 8 9 a b c d e f         */
-		/*      -------------------------------         */
-		W(0x00, 0,0,1,1,0,0,1,0,1,1,0,0,0,0,0,0)| /* 00 */
-		W(0x10, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 10 */
-		W(0x20, 1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0)| /* 20 */
-		W(0x30, 0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 30 */
-		W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 40 */
-		W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 50 */
-		W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,0,0,1,1)| /* 60 */
-		W(0x70, 0,0,0,0,1,1,1,1,0,0,0,0,0,0,1,1), /* 70 */
-		W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 80 */
-		W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1), /* 90 */
-		W(0xa0, 1,1,0,1,1,1,0,0,1,1,0,1,1,1,0,1)| /* a0 */
-		W(0xb0, 1,1,1,1,1,1,1,1,0,0,0,1,1,1,1,1), /* b0 */
-		W(0xc0, 1,1,0,0,0,0,0,0,1,1,1,1,1,1,1,1)| /* c0 */
-		W(0xd0, 0,1,1,1,0,1,0,0,1,1,0,1,1,1,0,1), /* d0 */
-		W(0xe0, 0,1,1,0,0,1,0,0,1,1,0,1,1,1,0,1)| /* e0 */
-		W(0xf0, 0,1,1,1,0,1,0,0,1,1,1,0,1,1,1,0)  /* f0 */
-		/*      -------------------------------         */
-		/*      0 1 2 3 4 5 6 7 8 9 a b c d e f         */
-	};
-#undef W
-	kprobe_opcode_t opcode;
-	kprobe_opcode_t *orig_opcodes = opcodes;
-retry:
-	if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
-		return 0;
-	opcode = *(opcodes++);
-
-	/* 2nd-byte opcode */
-	if (opcode == 0x0f) {
-		if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
-			return 0;
-		return test_bit(*opcodes, twobyte_is_boostable);
-	}
-
-	switch (opcode & 0xf0) {
-	case 0x60:
-		if (0x63 < opcode && opcode < 0x67)
-			goto retry; /* prefixes */
-		/* can't boost Address-size override and bound */
-		return (opcode != 0x62 && opcode != 0x67);
-	case 0x70:
-		return 0; /* can't boost conditional jump */
-	case 0xc0:
-		/* can't boost software-interruptions */
-		return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf;
-	case 0xd0:
-		/* can boost AA* and XLAT */
-		return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7);
-	case 0xe0:
-		/* can boost in/out and absolute jmps */
-		return ((opcode & 0x04) || opcode == 0xea);
-	case 0xf0:
-		if ((opcode & 0x0c) == 0 && opcode != 0xf1)
-			goto retry; /* lock/rep(ne) prefix */
-		/* clear and set flags can be boost */
-		return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
-	default:
-		if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e)
-			goto retry; /* prefixes */
-		/* can't boost CS override and call */
-		return (opcode != 0x2e && opcode != 0x9a);
-	}
-}
-
-/*
- * returns non-zero if opcode modifies the interrupt flag.
- */
-static int __kprobes is_IF_modifier(kprobe_opcode_t opcode)
-{
-	switch (opcode) {
-	case 0xfa:		/* cli */
-	case 0xfb:		/* sti */
-	case 0xcf:		/* iret/iretd */
-	case 0x9d:		/* popf/popfd */
-		return 1;
-	}
-	return 0;
-}
-
-int __kprobes arch_prepare_kprobe(struct kprobe *p)
-{
-	/* insn: must be on special executable page on i386. */
-	p->ainsn.insn = get_insn_slot();
-	if (!p->ainsn.insn)
-		return -ENOMEM;
-
-	memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
-	p->opcode = *p->addr;
-	if (can_boost(p->addr)) {
-		p->ainsn.boostable = 0;
-	} else {
-		p->ainsn.boostable = -1;
-	}
-	return 0;
-}
-
-void __kprobes arch_arm_kprobe(struct kprobe *p)
-{
-	text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
-}
-
-void __kprobes arch_disarm_kprobe(struct kprobe *p)
-{
-	text_poke(p->addr, &p->opcode, 1);
-}
-
-void __kprobes arch_remove_kprobe(struct kprobe *p)
-{
-	mutex_lock(&kprobe_mutex);
-	free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1));
-	mutex_unlock(&kprobe_mutex);
-}
-
-static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
-{
-	kcb->prev_kprobe.kp = kprobe_running();
-	kcb->prev_kprobe.status = kcb->kprobe_status;
-	kcb->prev_kprobe.old_eflags = kcb->kprobe_old_eflags;
-	kcb->prev_kprobe.saved_eflags = kcb->kprobe_saved_eflags;
-}
-
-static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
-{
-	__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
-	kcb->kprobe_status = kcb->prev_kprobe.status;
-	kcb->kprobe_old_eflags = kcb->prev_kprobe.old_eflags;
-	kcb->kprobe_saved_eflags = kcb->prev_kprobe.saved_eflags;
-}
-
-static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
-				struct kprobe_ctlblk *kcb)
-{
-	__get_cpu_var(current_kprobe) = p;
-	kcb->kprobe_saved_eflags = kcb->kprobe_old_eflags
-		= (regs->eflags & (TF_MASK | IF_MASK));
-	if (is_IF_modifier(p->opcode))
-		kcb->kprobe_saved_eflags &= ~IF_MASK;
-}
-
-static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
-{
-	regs->eflags |= TF_MASK;
-	regs->eflags &= ~IF_MASK;
-	/*single step inline if the instruction is an int3*/
-	if (p->opcode == BREAKPOINT_INSTRUCTION)
-		regs->eip = (unsigned long)p->addr;
-	else
-		regs->eip = (unsigned long)p->ainsn.insn;
-}
-
-/* Called with kretprobe_lock held */
-void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
-				      struct pt_regs *regs)
-{
-	unsigned long *sara = (unsigned long *)&regs->esp;
-
-	ri->ret_addr = (kprobe_opcode_t *) *sara;
-
-	/* Replace the return addr with trampoline addr */
-	*sara = (unsigned long) &kretprobe_trampoline;
-}
-
-/*
- * Interrupts are disabled on entry as trap3 is an interrupt gate and they
- * remain disabled thorough out this function.
- */
-static int __kprobes kprobe_handler(struct pt_regs *regs)
-{
-	struct kprobe *p;
-	int ret = 0;
-	kprobe_opcode_t *addr;
-	struct kprobe_ctlblk *kcb;
-
-	addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
-
-	/*
-	 * We don't want to be preempted for the entire
-	 * duration of kprobe processing
-	 */
-	preempt_disable();
-	kcb = get_kprobe_ctlblk();
-
-	/* Check we're not actually recursing */
-	if (kprobe_running()) {
-		p = get_kprobe(addr);
-		if (p) {
-			if (kcb->kprobe_status == KPROBE_HIT_SS &&
-				*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
-				regs->eflags &= ~TF_MASK;
-				regs->eflags |= kcb->kprobe_saved_eflags;
-				goto no_kprobe;
-			}
-			/* We have reentered the kprobe_handler(), since
-			 * another probe was hit while within the handler.
-			 * We here save the original kprobes variables and
-			 * just single step on the instruction of the new probe
-			 * without calling any user handlers.
-			 */
-			save_previous_kprobe(kcb);
-			set_current_kprobe(p, regs, kcb);
-			kprobes_inc_nmissed_count(p);
-			prepare_singlestep(p, regs);
-			kcb->kprobe_status = KPROBE_REENTER;
-			return 1;
-		} else {
-			if (*addr != BREAKPOINT_INSTRUCTION) {
-			/* The breakpoint instruction was removed by
-			 * another cpu right after we hit, no further
-			 * handling of this interrupt is appropriate
-			 */
-				regs->eip -= sizeof(kprobe_opcode_t);
-				ret = 1;
-				goto no_kprobe;
-			}
-			p = __get_cpu_var(current_kprobe);
-			if (p->break_handler && p->break_handler(p, regs)) {
-				goto ss_probe;
-			}
-		}
-		goto no_kprobe;
-	}
-
-	p = get_kprobe(addr);
-	if (!p) {
-		if (*addr != BREAKPOINT_INSTRUCTION) {
-			/*
-			 * The breakpoint instruction was removed right
-			 * after we hit it.  Another cpu has removed
-			 * either a probepoint or a debugger breakpoint
-			 * at this address.  In either case, no further
-			 * handling of this interrupt is appropriate.
-			 * Back up over the (now missing) int3 and run
-			 * the original instruction.
-			 */
-			regs->eip -= sizeof(kprobe_opcode_t);
-			ret = 1;
-		}
-		/* Not one of ours: let kernel handle it */
-		goto no_kprobe;
-	}
-
-	set_current_kprobe(p, regs, kcb);
-	kcb->kprobe_status = KPROBE_HIT_ACTIVE;
-
-	if (p->pre_handler && p->pre_handler(p, regs))
-		/* handler has already set things up, so skip ss setup */
-		return 1;
-
-ss_probe:
-#if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM)
-	if (p->ainsn.boostable == 1 && !p->post_handler){
-		/* Boost up -- we can execute copied instructions directly */
-		reset_current_kprobe();
-		regs->eip = (unsigned long)p->ainsn.insn;
-		preempt_enable_no_resched();
-		return 1;
-	}
-#endif
-	prepare_singlestep(p, regs);
-	kcb->kprobe_status = KPROBE_HIT_SS;
-	return 1;
-
-no_kprobe:
-	preempt_enable_no_resched();
-	return ret;
-}
-
-/*
- * For function-return probes, init_kprobes() establishes a probepoint
- * here. When a retprobed function returns, this probe is hit and
- * trampoline_probe_handler() runs, calling the kretprobe's handler.
- */
- void __kprobes kretprobe_trampoline_holder(void)
- {
-	asm volatile ( ".global kretprobe_trampoline\n"
-			"kretprobe_trampoline: \n"
-			"	pushf\n"
-			/* skip cs, eip, orig_eax */
-			"	subl $12, %esp\n"
-			"	pushl %fs\n"
-			"	pushl %ds\n"
-			"	pushl %es\n"
-			"	pushl %eax\n"
-			"	pushl %ebp\n"
-			"	pushl %edi\n"
-			"	pushl %esi\n"
-			"	pushl %edx\n"
-			"	pushl %ecx\n"
-			"	pushl %ebx\n"
-			"	movl %esp, %eax\n"
-			"	call trampoline_handler\n"
-			/* move eflags to cs */
-			"	movl 52(%esp), %edx\n"
-			"	movl %edx, 48(%esp)\n"
-			/* save true return address on eflags */
-			"	movl %eax, 52(%esp)\n"
-			"	popl %ebx\n"
-			"	popl %ecx\n"
-			"	popl %edx\n"
-			"	popl %esi\n"
-			"	popl %edi\n"
-			"	popl %ebp\n"
-			"	popl %eax\n"
-			/* skip eip, orig_eax, es, ds, fs */
-			"	addl $20, %esp\n"
-			"	popf\n"
-			"	ret\n");
-}
-
-/*
- * Called from kretprobe_trampoline
- */
-fastcall void *__kprobes trampoline_handler(struct pt_regs *regs)
-{
-	struct kretprobe_instance *ri = NULL;
-	struct hlist_head *head, empty_rp;
-	struct hlist_node *node, *tmp;
-	unsigned long flags, orig_ret_address = 0;
-	unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
-
-	INIT_HLIST_HEAD(&empty_rp);
-	spin_lock_irqsave(&kretprobe_lock, flags);
-	head = kretprobe_inst_table_head(current);
-	/* fixup registers */
-	regs->xcs = __KERNEL_CS | get_kernel_rpl();
-	regs->eip = trampoline_address;
-	regs->orig_eax = 0xffffffff;
-
-	/*
-	 * It is possible to have multiple instances associated with a given
-	 * task either because an multiple functions in the call path
-	 * have a return probe installed on them, and/or more then one return
-	 * return probe was registered for a target function.
-	 *
-	 * We can handle this because:
-	 *     - instances are always inserted at the head of the list
-	 *     - when multiple return probes are registered for the same
-	 *       function, the first instance's ret_addr will point to the
-	 *       real return address, and all the rest will point to
-	 *       kretprobe_trampoline
-	 */
-	hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
-		if (ri->task != current)
-			/* another task is sharing our hash bucket */
-			continue;
-
-		if (ri->rp && ri->rp->handler){
-			__get_cpu_var(current_kprobe) = &ri->rp->kp;
-			get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
-			ri->rp->handler(ri, regs);
-			__get_cpu_var(current_kprobe) = NULL;
-		}
-
-		orig_ret_address = (unsigned long)ri->ret_addr;
-		recycle_rp_inst(ri, &empty_rp);
-
-		if (orig_ret_address != trampoline_address)
-			/*
-			 * This is the real return address. Any other
-			 * instances associated with this task are for
-			 * other calls deeper on the call stack
-			 */
-			break;
-	}
-
-	kretprobe_assert(ri, orig_ret_address, trampoline_address);
-	spin_unlock_irqrestore(&kretprobe_lock, flags);
-
-	hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
-		hlist_del(&ri->hlist);
-		kfree(ri);
-	}
-	return (void*)orig_ret_address;
-}
-
-/*
- * Called after single-stepping.  p->addr is the address of the
- * instruction whose first byte has been replaced by the "int 3"
- * instruction.  To avoid the SMP problems that can occur when we
- * temporarily put back the original opcode to single-step, we
- * single-stepped a copy of the instruction.  The address of this
- * copy is p->ainsn.insn.
- *
- * This function prepares to return from the post-single-step
- * interrupt.  We have to fix up the stack as follows:
- *
- * 0) Except in the case of absolute or indirect jump or call instructions,
- * the new eip is relative to the copied instruction.  We need to make
- * it relative to the original instruction.
- *
- * 1) If the single-stepped instruction was pushfl, then the TF and IF
- * flags are set in the just-pushed eflags, and may need to be cleared.
- *
- * 2) If the single-stepped instruction was a call, the return address
- * that is atop the stack is the address following the copied instruction.
- * We need to make it the address following the original instruction.
- *
- * This function also checks instruction size for preparing direct execution.
- */
-static void __kprobes resume_execution(struct kprobe *p,
-		struct pt_regs *regs, struct kprobe_ctlblk *kcb)
-{
-	unsigned long *tos = (unsigned long *)&regs->esp;
-	unsigned long copy_eip = (unsigned long)p->ainsn.insn;
-	unsigned long orig_eip = (unsigned long)p->addr;
-
-	regs->eflags &= ~TF_MASK;
-	switch (p->ainsn.insn[0]) {
-	case 0x9c:		/* pushfl */
-		*tos &= ~(TF_MASK | IF_MASK);
-		*tos |= kcb->kprobe_old_eflags;
-		break;
-	case 0xc2:		/* iret/ret/lret */
-	case 0xc3:
-	case 0xca:
-	case 0xcb:
-	case 0xcf:
-	case 0xea:		/* jmp absolute -- eip is correct */
-		/* eip is already adjusted, no more changes required */
-		p->ainsn.boostable = 1;
-		goto no_change;
-	case 0xe8:		/* call relative - Fix return addr */
-		*tos = orig_eip + (*tos - copy_eip);
-		break;
-	case 0x9a:		/* call absolute -- same as call absolute, indirect */
-		*tos = orig_eip + (*tos - copy_eip);
-		goto no_change;
-	case 0xff:
-		if ((p->ainsn.insn[1] & 0x30) == 0x10) {
-			/*
-			 * call absolute, indirect
-			 * Fix return addr; eip is correct.
-			 * But this is not boostable
-			 */
-			*tos = orig_eip + (*tos - copy_eip);
-			goto no_change;
-		} else if (((p->ainsn.insn[1] & 0x31) == 0x20) ||	/* jmp near, absolute indirect */
-			   ((p->ainsn.insn[1] & 0x31) == 0x21)) {	/* jmp far, absolute indirect */
-			/* eip is correct. And this is boostable */
-			p->ainsn.boostable = 1;
-			goto no_change;
-		}
-	default:
-		break;
-	}
-
-	if (p->ainsn.boostable == 0) {
-		if ((regs->eip > copy_eip) &&
-		    (regs->eip - copy_eip) + 5 < MAX_INSN_SIZE) {
-			/*
-			 * These instructions can be executed directly if it
-			 * jumps back to correct address.
-			 */
-			set_jmp_op((void *)regs->eip,
-				   (void *)orig_eip + (regs->eip - copy_eip));
-			p->ainsn.boostable = 1;
-		} else {
-			p->ainsn.boostable = -1;
-		}
-	}
-
-	regs->eip = orig_eip + (regs->eip - copy_eip);
-
-no_change:
-	return;
-}
-
-/*
- * Interrupts are disabled on entry as trap1 is an interrupt gate and they
- * remain disabled thoroughout this function.
- */
-static int __kprobes post_kprobe_handler(struct pt_regs *regs)
-{
-	struct kprobe *cur = kprobe_running();
-	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
-	if (!cur)
-		return 0;
-
-	if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
-		kcb->kprobe_status = KPROBE_HIT_SSDONE;
-		cur->post_handler(cur, regs, 0);
-	}
-
-	resume_execution(cur, regs, kcb);
-	regs->eflags |= kcb->kprobe_saved_eflags;
-
-	/*Restore back the original saved kprobes variables and continue. */
-	if (kcb->kprobe_status == KPROBE_REENTER) {
-		restore_previous_kprobe(kcb);
-		goto out;
-	}
-	reset_current_kprobe();
-out:
-	preempt_enable_no_resched();
-
-	/*
-	 * if somebody else is singlestepping across a probe point, eflags
-	 * will have TF set, in which case, continue the remaining processing
-	 * of do_debug, as if this is not a probe hit.
-	 */
-	if (regs->eflags & TF_MASK)
-		return 0;
-
-	return 1;
-}
-
-static int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
-{
-	struct kprobe *cur = kprobe_running();
-	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
-	switch(kcb->kprobe_status) {
-	case KPROBE_HIT_SS:
-	case KPROBE_REENTER:
-		/*
-		 * We are here because the instruction being single
-		 * stepped caused a page fault. We reset the current
-		 * kprobe and the eip points back to the probe address
-		 * and allow the page fault handler to continue as a
-		 * normal page fault.
-		 */
-		regs->eip = (unsigned long)cur->addr;
-		regs->eflags |= kcb->kprobe_old_eflags;
-		if (kcb->kprobe_status == KPROBE_REENTER)
-			restore_previous_kprobe(kcb);
-		else
-			reset_current_kprobe();
-		preempt_enable_no_resched();
-		break;
-	case KPROBE_HIT_ACTIVE:
-	case KPROBE_HIT_SSDONE:
-		/*
-		 * We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accouting
-		 * these specific fault cases.
-		 */
-		kprobes_inc_nmissed_count(cur);
-
-		/*
-		 * We come here because instructions in the pre/post
-		 * handler caused the page_fault, this could happen
-		 * if handler tries to access user space by
-		 * copy_from_user(), get_user() etc. Let the
-		 * user-specified handler try to fix it first.
-		 */
-		if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
-			return 1;
-
-		/*
-		 * In case the user-specified fault handler returned
-		 * zero, try to fix up.
-		 */
-		if (fixup_exception(regs))
-			return 1;
-
-		/*
-		 * fixup_exception() could not handle it,
-		 * Let do_page_fault() fix it.
-		 */
-		break;
-	default:
-		break;
-	}
-	return 0;
-}
-
-/*
- * Wrapper routine to for handling exceptions.
- */
-int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
-				       unsigned long val, void *data)
-{
-	struct die_args *args = (struct die_args *)data;
-	int ret = NOTIFY_DONE;
-
-	if (args->regs && user_mode_vm(args->regs))
-		return ret;
-
-	switch (val) {
-	case DIE_INT3:
-		if (kprobe_handler(args->regs))
-			ret = NOTIFY_STOP;
-		break;
-	case DIE_DEBUG:
-		if (post_kprobe_handler(args->regs))
-			ret = NOTIFY_STOP;
-		break;
-	case DIE_GPF:
-	case DIE_PAGE_FAULT:
-		/* kprobe_running() needs smp_processor_id() */
-		preempt_disable();
-		if (kprobe_running() &&
-		    kprobe_fault_handler(args->regs, args->trapnr))
-			ret = NOTIFY_STOP;
-		preempt_enable();
-		break;
-	default:
-		break;
-	}
-	return ret;
-}
-
-int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
-{
-	struct jprobe *jp = container_of(p, struct jprobe, kp);
-	unsigned long addr;
-	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
-	kcb->jprobe_saved_regs = *regs;
-	kcb->jprobe_saved_esp = &regs->esp;
-	addr = (unsigned long)(kcb->jprobe_saved_esp);
-
-	/*
-	 * TBD: As Linus pointed out, gcc assumes that the callee
-	 * owns the argument space and could overwrite it, e.g.
-	 * tailcall optimization. So, to be absolutely safe
-	 * we also save and restore enough stack bytes to cover
-	 * the argument area.
-	 */
-	memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
-			MIN_STACK_SIZE(addr));
-	regs->eflags &= ~IF_MASK;
-	regs->eip = (unsigned long)(jp->entry);
-	return 1;
-}
-
-void __kprobes jprobe_return(void)
-{
-	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
-	asm volatile ("       xchgl   %%ebx,%%esp     \n"
-		      "       int3			\n"
-		      "       .globl jprobe_return_end	\n"
-		      "       jprobe_return_end:	\n"
-		      "       nop			\n"::"b"
-		      (kcb->jprobe_saved_esp):"memory");
-}
-
-int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
-{
-	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-	u8 *addr = (u8 *) (regs->eip - 1);
-	unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_esp);
-	struct jprobe *jp = container_of(p, struct jprobe, kp);
-
-	if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) {
-		if (&regs->esp != kcb->jprobe_saved_esp) {
-			struct pt_regs *saved_regs =
-			    container_of(kcb->jprobe_saved_esp,
-					    struct pt_regs, esp);
-			printk("current esp %p does not match saved esp %p\n",
-			       &regs->esp, kcb->jprobe_saved_esp);
-			printk("Saved registers for jprobe %p\n", jp);
-			show_registers(saved_regs);
-			printk("Current registers\n");
-			show_registers(regs);
-			BUG();
-		}
-		*regs = kcb->jprobe_saved_regs;
-		memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
-		       MIN_STACK_SIZE(stack_addr));
-		preempt_enable_no_resched();
-		return 1;
-	}
-	return 0;
-}
-
-int __kprobes arch_trampoline_kprobe(struct kprobe *p)
-{
-	return 0;
-}
-
-int __init arch_init_kprobes(void)
-{
-	return 0;
-}