kprobes/x86: Move kprobes stuff under arch/x86/kernel/kprobes/

Move arch-dep kprobes stuff under arch/x86/kernel/kprobes.

Link: http://lkml.kernel.org/r/20120928081522.3560.75469.stgit@ltc138.sdl.hitachi.co.jp

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
[ fixed whitespace and s/__attribute__((packed))/__packed/ ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 0 insertions, 1064 deletions

diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
deleted file mode 100644
index 18114bf..0000000
--- a/arch/x86/kernel/kprobes.c
+++ /dev/null
@@ -1,1064 +0,0 @@
-/*
- *  Kernel Probes (KProbes)
- *
- * 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.
- * 2004-Oct	Jim Keniston <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
- *		<prasanna@in.ibm.com> adapted for x86_64 from i386.
- * 2005-Mar	Roland McGrath <roland@redhat.com>
- *		Fixed to handle %rip-relative addressing mode correctly.
- * 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.
- * 2005-May	Rusty Lynch <rusty.lynch@intel.com>
- *		Added function return probes functionality
- * 2006-Feb	Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> added
- *		kprobe-booster and kretprobe-booster for i386.
- * 2007-Dec	Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster
- *		and kretprobe-booster for x86-64
- * 2007-Dec	Masami Hiramatsu <mhiramat@redhat.com>, Arjan van de Ven
- *		<arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com>
- *		unified x86 kprobes code.
- */
-#include <linux/kprobes.h>
-#include <linux/ptrace.h>
-#include <linux/string.h>
-#include <linux/slab.h>
-#include <linux/hardirq.h>
-#include <linux/preempt.h>
-#include <linux/module.h>
-#include <linux/kdebug.h>
-#include <linux/kallsyms.h>
-#include <linux/ftrace.h>
-
-#include <asm/cacheflush.h>
-#include <asm/desc.h>
-#include <asm/pgtable.h>
-#include <asm/uaccess.h>
-#include <asm/alternative.h>
-#include <asm/insn.h>
-#include <asm/debugreg.h>
-
-#include "kprobes-common.h"
-
-void jprobe_return_end(void);
-
-DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
-DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
-
-#define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs))
-
-#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 boost.
-	 * This is non-const and volatile to keep gcc from statically
-	 * optimizing it out, as variable_test_bit makes gcc think only
-	 * *(unsigned long*) is used. 
-	 */
-static volatile u32 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
-
-struct kretprobe_blackpoint kretprobe_blacklist[] = {
-	{"__switch_to", }, /* This function switches only current task, but
-			      doesn't switch kernel stack.*/
-	{NULL, NULL}	/* Terminator */
-};
-
-const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist);
-
-static void __kprobes __synthesize_relative_insn(void *from, void *to, u8 op)
-{
-	struct __arch_relative_insn {
-		u8 op;
-		s32 raddr;
-	} __attribute__((packed)) *insn;
-
-	insn = (struct __arch_relative_insn *)from;
-	insn->raddr = (s32)((long)(to) - ((long)(from) + 5));
-	insn->op = op;
-}
-
-/* Insert a jump instruction at address 'from', which jumps to address 'to'.*/
-void __kprobes synthesize_reljump(void *from, void *to)
-{
-	__synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE);
-}
-
-/* Insert a call instruction at address 'from', which calls address 'to'.*/
-void __kprobes synthesize_relcall(void *from, void *to)
-{
-	__synthesize_relative_insn(from, to, RELATIVECALL_OPCODE);
-}
-
-/*
- * Skip the prefixes of the instruction.
- */
-static kprobe_opcode_t *__kprobes skip_prefixes(kprobe_opcode_t *insn)
-{
-	insn_attr_t attr;
-
-	attr = inat_get_opcode_attribute((insn_byte_t)*insn);
-	while (inat_is_legacy_prefix(attr)) {
-		insn++;
-		attr = inat_get_opcode_attribute((insn_byte_t)*insn);
-	}
-#ifdef CONFIG_X86_64
-	if (inat_is_rex_prefix(attr))
-		insn++;
-#endif
-	return insn;
-}
-
-/*
- * Returns non-zero if opcode is boostable.
- * RIP relative instructions are adjusted at copying time in 64 bits mode
- */
-int __kprobes can_boost(kprobe_opcode_t *opcodes)
-{
-	kprobe_opcode_t opcode;
-	kprobe_opcode_t *orig_opcodes = opcodes;
-
-	if (search_exception_tables((unsigned long)opcodes))
-		return 0;	/* Page fault may occur on this address. */
-
-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,
-				(unsigned long *)twobyte_is_boostable);
-	}
-
-	switch (opcode & 0xf0) {
-#ifdef CONFIG_X86_64
-	case 0x40:
-		goto retry; /* REX prefix is boostable */
-#endif
-	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 are boostable */
-		return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
-	default:
-		/* segment override prefixes are boostable */
-		if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e)
-			goto retry; /* prefixes */
-		/* CS override prefix and call are not boostable */
-		return (opcode != 0x2e && opcode != 0x9a);
-	}
-}
-
-static unsigned long
-__recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr)
-{
-	struct kprobe *kp;
-
-	kp = get_kprobe((void *)addr);
-	/* There is no probe, return original address */
-	if (!kp)
-		return addr;
-
-	/*
-	 *  Basically, kp->ainsn.insn has an original instruction.
-	 *  However, RIP-relative instruction can not do single-stepping
-	 *  at different place, __copy_instruction() tweaks the displacement of
-	 *  that instruction. In that case, we can't recover the instruction
-	 *  from the kp->ainsn.insn.
-	 *
-	 *  On the other hand, kp->opcode has a copy of the first byte of
-	 *  the probed instruction, which is overwritten by int3. And
-	 *  the instruction at kp->addr is not modified by kprobes except
-	 *  for the first byte, we can recover the original instruction
-	 *  from it and kp->opcode.
-	 */
-	memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
-	buf[0] = kp->opcode;
-	return (unsigned long)buf;
-}
-
-/*
- * Recover the probed instruction at addr for further analysis.
- * Caller must lock kprobes by kprobe_mutex, or disable preemption
- * for preventing to release referencing kprobes.
- */
-unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr)
-{
-	unsigned long __addr;
-
-	__addr = __recover_optprobed_insn(buf, addr);
-	if (__addr != addr)
-		return __addr;
-
-	return __recover_probed_insn(buf, addr);
-}
-
-/* Check if paddr is at an instruction boundary */
-static int __kprobes can_probe(unsigned long paddr)
-{
-	unsigned long addr, __addr, offset = 0;
-	struct insn insn;
-	kprobe_opcode_t buf[MAX_INSN_SIZE];
-
-	if (!kallsyms_lookup_size_offset(paddr, NULL, &offset))
-		return 0;
-
-	/* Decode instructions */
-	addr = paddr - offset;
-	while (addr < paddr) {
-		/*
-		 * Check if the instruction has been modified by another
-		 * kprobe, in which case we replace the breakpoint by the
-		 * original instruction in our buffer.
-		 * Also, jump optimization will change the breakpoint to
-		 * relative-jump. Since the relative-jump itself is
-		 * normally used, we just go through if there is no kprobe.
-		 */
-		__addr = recover_probed_instruction(buf, addr);
-		kernel_insn_init(&insn, (void *)__addr);
-		insn_get_length(&insn);
-
-		/*
-		 * Another debugging subsystem might insert this breakpoint.
-		 * In that case, we can't recover it.
-		 */
-		if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
-			return 0;
-		addr += insn.length;
-	}
-
-	return (addr == paddr);
-}
-
-/*
- * Returns non-zero if opcode modifies the interrupt flag.
- */
-static int __kprobes is_IF_modifier(kprobe_opcode_t *insn)
-{
-	/* Skip prefixes */
-	insn = skip_prefixes(insn);
-
-	switch (*insn) {
-	case 0xfa:		/* cli */
-	case 0xfb:		/* sti */
-	case 0xcf:		/* iret/iretd */
-	case 0x9d:		/* popf/popfd */
-		return 1;
-	}
-
-	return 0;
-}
-
-/*
- * Copy an instruction and adjust the displacement if the instruction
- * uses the %rip-relative addressing mode.
- * If it does, Return the address of the 32-bit displacement word.
- * If not, return null.
- * Only applicable to 64-bit x86.
- */
-int __kprobes __copy_instruction(u8 *dest, u8 *src)
-{
-	struct insn insn;
-	kprobe_opcode_t buf[MAX_INSN_SIZE];
-
-	kernel_insn_init(&insn, (void *)recover_probed_instruction(buf, (unsigned long)src));
-	insn_get_length(&insn);
-	/* Another subsystem puts a breakpoint, failed to recover */
-	if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
-		return 0;
-	memcpy(dest, insn.kaddr, insn.length);
-
-#ifdef CONFIG_X86_64
-	if (insn_rip_relative(&insn)) {
-		s64 newdisp;
-		u8 *disp;
-		kernel_insn_init(&insn, dest);
-		insn_get_displacement(&insn);
-		/*
-		 * The copied instruction uses the %rip-relative addressing
-		 * mode.  Adjust the displacement for the difference between
-		 * the original location of this instruction and the location
-		 * of the copy that will actually be run.  The tricky bit here
-		 * is making sure that the sign extension happens correctly in
-		 * this calculation, since we need a signed 32-bit result to
-		 * be sign-extended to 64 bits when it's added to the %rip
-		 * value and yield the same 64-bit result that the sign-
-		 * extension of the original signed 32-bit displacement would
-		 * have given.
-		 */
-		newdisp = (u8 *) src + (s64) insn.displacement.value - (u8 *) dest;
-		BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check.  */
-		disp = (u8 *) dest + insn_offset_displacement(&insn);
-		*(s32 *) disp = (s32) newdisp;
-	}
-#endif
-	return insn.length;
-}
-
-static void __kprobes arch_copy_kprobe(struct kprobe *p)
-{
-	/* Copy an instruction with recovering if other optprobe modifies it.*/
-	__copy_instruction(p->ainsn.insn, p->addr);
-
-	/*
-	 * __copy_instruction can modify the displacement of the instruction,
-	 * but it doesn't affect boostable check.
-	 */
-	if (can_boost(p->ainsn.insn))
-		p->ainsn.boostable = 0;
-	else
-		p->ainsn.boostable = -1;
-
-	/* Also, displacement change doesn't affect the first byte */
-	p->opcode = p->ainsn.insn[0];
-}
-
-int __kprobes arch_prepare_kprobe(struct kprobe *p)
-{
-	if (alternatives_text_reserved(p->addr, p->addr))
-		return -EINVAL;
-
-	if (!can_probe((unsigned long)p->addr))
-		return -EILSEQ;
-	/* insn: must be on special executable page on x86. */
-	p->ainsn.insn = get_insn_slot();
-	if (!p->ainsn.insn)
-		return -ENOMEM;
-	arch_copy_kprobe(p);
-	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)
-{
-	if (p->ainsn.insn) {
-		free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1));
-		p->ainsn.insn = NULL;
-	}
-}
-
-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_flags = kcb->kprobe_old_flags;
-	kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags;
-}
-
-static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
-{
-	__this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
-	kcb->kprobe_status = kcb->prev_kprobe.status;
-	kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags;
-	kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags;
-}
-
-static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
-				struct kprobe_ctlblk *kcb)
-{
-	__this_cpu_write(current_kprobe, p);
-	kcb->kprobe_saved_flags = kcb->kprobe_old_flags
-		= (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF));
-	if (is_IF_modifier(p->ainsn.insn))
-		kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF;
-}
-
-static void __kprobes clear_btf(void)
-{
-	if (test_thread_flag(TIF_BLOCKSTEP)) {
-		unsigned long debugctl = get_debugctlmsr();
-
-		debugctl &= ~DEBUGCTLMSR_BTF;
-		update_debugctlmsr(debugctl);
-	}
-}
-
-static void __kprobes restore_btf(void)
-{
-	if (test_thread_flag(TIF_BLOCKSTEP)) {
-		unsigned long debugctl = get_debugctlmsr();
-
-		debugctl |= DEBUGCTLMSR_BTF;
-		update_debugctlmsr(debugctl);
-	}
-}
-
-void __kprobes
-arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
-{
-	unsigned long *sara = stack_addr(regs);
-
-	ri->ret_addr = (kprobe_opcode_t *) *sara;
-
-	/* Replace the return addr with trampoline addr */
-	*sara = (unsigned long) &kretprobe_trampoline;
-}
-
-static void __kprobes
-setup_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb, int reenter)
-{
-	if (setup_detour_execution(p, regs, reenter))
-		return;
-
-#if !defined(CONFIG_PREEMPT)
-	if (p->ainsn.boostable == 1 && !p->post_handler) {
-		/* Boost up -- we can execute copied instructions directly */
-		if (!reenter)
-			reset_current_kprobe();
-		/*
-		 * Reentering boosted probe doesn't reset current_kprobe,
-		 * nor set current_kprobe, because it doesn't use single
-		 * stepping.
-		 */
-		regs->ip = (unsigned long)p->ainsn.insn;
-		preempt_enable_no_resched();
-		return;
-	}
-#endif
-	if (reenter) {
-		save_previous_kprobe(kcb);
-		set_current_kprobe(p, regs, kcb);
-		kcb->kprobe_status = KPROBE_REENTER;
-	} else
-		kcb->kprobe_status = KPROBE_HIT_SS;
-	/* Prepare real single stepping */
-	clear_btf();
-	regs->flags |= X86_EFLAGS_TF;
-	regs->flags &= ~X86_EFLAGS_IF;
-	/* single step inline if the instruction is an int3 */
-	if (p->opcode == BREAKPOINT_INSTRUCTION)
-		regs->ip = (unsigned long)p->addr;
-	else
-		regs->ip = (unsigned long)p->ainsn.insn;
-}
-
-/*
- * We have reentered the kprobe_handler(), since another probe was hit while
- * within the handler. We save the original kprobes variables and just single
- * step on the instruction of the new probe without calling any user handlers.
- */
-static int __kprobes
-reenter_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
-{
-	switch (kcb->kprobe_status) {
-	case KPROBE_HIT_SSDONE:
-	case KPROBE_HIT_ACTIVE:
-		kprobes_inc_nmissed_count(p);
-		setup_singlestep(p, regs, kcb, 1);
-		break;
-	case KPROBE_HIT_SS:
-		/* A probe has been hit in the codepath leading up to, or just
-		 * after, single-stepping of a probed instruction. This entire
-		 * codepath should strictly reside in .kprobes.text section.
-		 * Raise a BUG or we'll continue in an endless reentering loop
-		 * and eventually a stack overflow.
-		 */
-		printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n",
-		       p->addr);
-		dump_kprobe(p);
-		BUG();
-	default:
-		/* impossible cases */
-		WARN_ON(1);
-		return 0;
-	}
-
-	return 1;
-}
-
-/*
- * Interrupts are disabled on entry as trap3 is an interrupt gate and they
- * remain disabled throughout this function.
- */
-static int __kprobes kprobe_handler(struct pt_regs *regs)
-{
-	kprobe_opcode_t *addr;
-	struct kprobe *p;
-	struct kprobe_ctlblk *kcb;
-
-	addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t));
-	/*
-	 * We don't want to be preempted for the entire
-	 * duration of kprobe processing. We conditionally
-	 * re-enable preemption at the end of this function,
-	 * and also in reenter_kprobe() and setup_singlestep().
-	 */
-	preempt_disable();
-
-	kcb = get_kprobe_ctlblk();
-	p = get_kprobe(addr);
-
-	if (p) {
-		if (kprobe_running()) {
-			if (reenter_kprobe(p, regs, kcb))
-				return 1;
-		} else {
-			set_current_kprobe(p, regs, kcb);
-			kcb->kprobe_status = KPROBE_HIT_ACTIVE;
-
-			/*
-			 * If we have no pre-handler or it returned 0, we
-			 * continue with normal processing.  If we have a
-			 * pre-handler and it returned non-zero, it prepped
-			 * for calling the break_handler below on re-entry
-			 * for jprobe processing, so get out doing nothing
-			 * more here.
-			 */
-			if (!p->pre_handler || !p->pre_handler(p, regs))
-				setup_singlestep(p, regs, kcb, 0);
-			return 1;
-		}
-	} else 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->ip = (unsigned long)addr;
-		preempt_enable_no_resched();
-		return 1;
-	} else if (kprobe_running()) {
-		p = __this_cpu_read(current_kprobe);
-		if (p->break_handler && p->break_handler(p, regs)) {
-			if (!skip_singlestep(p, regs, kcb))
-				setup_singlestep(p, regs, kcb, 0);
-			return 1;
-		}
-	} /* else: not a kprobe fault; let the kernel handle it */
-
-	preempt_enable_no_resched();
-	return 0;
-}
-
-/*
- * When a retprobed function returns, this code saves registers and
- * calls trampoline_handler() runs, which calls the kretprobe's handler.
- */
-static void __used __kprobes kretprobe_trampoline_holder(void)
-{
-	asm volatile (
-			".global kretprobe_trampoline\n"
-			"kretprobe_trampoline: \n"
-#ifdef CONFIG_X86_64
-			/* We don't bother saving the ss register */
-			"	pushq %rsp\n"
-			"	pushfq\n"
-			SAVE_REGS_STRING
-			"	movq %rsp, %rdi\n"
-			"	call trampoline_handler\n"
-			/* Replace saved sp with true return address. */
-			"	movq %rax, 152(%rsp)\n"
-			RESTORE_REGS_STRING
-			"	popfq\n"
-#else
-			"	pushf\n"
-			SAVE_REGS_STRING
-			"	movl %esp, %eax\n"
-			"	call trampoline_handler\n"
-			/* Move flags to cs */
-			"	movl 56(%esp), %edx\n"
-			"	movl %edx, 52(%esp)\n"
-			/* Replace saved flags with true return address. */
-			"	movl %eax, 56(%esp)\n"
-			RESTORE_REGS_STRING
-			"	popf\n"
-#endif
-			"	ret\n");
-}
-
-/*
- * Called from kretprobe_trampoline
- */
-static __used __kprobes void *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;
-	kprobe_opcode_t *correct_ret_addr = NULL;
-
-	INIT_HLIST_HEAD(&empty_rp);
-	kretprobe_hash_lock(current, &head, &flags);
-	/* fixup registers */
-#ifdef CONFIG_X86_64
-	regs->cs = __KERNEL_CS;
-#else
-	regs->cs = __KERNEL_CS | get_kernel_rpl();
-	regs->gs = 0;
-#endif
-	regs->ip = trampoline_address;
-	regs->orig_ax = ~0UL;
-
-	/*
-	 * It is possible to have multiple instances associated with a given
-	 * task either because multiple functions in the call path have
-	 * return probes installed on them, and/or more than one
-	 * return probe was registered for a target function.
-	 *
-	 * We can handle this because:
-	 *     - instances are always pushed into the head of the list
-	 *     - when multiple return probes are registered for the same
-	 *	 function, the (chronologically) first instance's ret_addr
-	 *	 will be 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;
-
-		orig_ret_address = (unsigned long)ri->ret_addr;
-
-		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);
-
-	correct_ret_addr = ri->ret_addr;
-	hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
-		if (ri->task != current)
-			/* another task is sharing our hash bucket */
-			continue;
-
-		orig_ret_address = (unsigned long)ri->ret_addr;
-		if (ri->rp && ri->rp->handler) {
-			__this_cpu_write(current_kprobe, &ri->rp->kp);
-			get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
-			ri->ret_addr = correct_ret_addr;
-			ri->rp->handler(ri, regs);
-			__this_cpu_write(current_kprobe, NULL);
-		}
-
-		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_hash_unlock(current, &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 ip 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 flags, 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.
- *
- * If this is the first time we've single-stepped the instruction at
- * this probepoint, and the instruction is boostable, boost it: add a
- * jump instruction after the copied instruction, that jumps to the next
- * instruction after the probepoint.
- */
-static void __kprobes
-resume_execution(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
-{
-	unsigned long *tos = stack_addr(regs);
-	unsigned long copy_ip = (unsigned long)p->ainsn.insn;
-	unsigned long orig_ip = (unsigned long)p->addr;
-	kprobe_opcode_t *insn = p->ainsn.insn;
-
-	/* Skip prefixes */
-	insn = skip_prefixes(insn);
-
-	regs->flags &= ~X86_EFLAGS_TF;
-	switch (*insn) {
-	case 0x9c:	/* pushfl */
-		*tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF);
-		*tos |= kcb->kprobe_old_flags;
-		break;
-	case 0xc2:	/* iret/ret/lret */
-	case 0xc3:
-	case 0xca:
-	case 0xcb:
-	case 0xcf:
-	case 0xea:	/* jmp absolute -- ip is correct */
-		/* ip is already adjusted, no more changes required */
-		p->ainsn.boostable = 1;
-		goto no_change;
-	case 0xe8:	/* call relative - Fix return addr */
-		*tos = orig_ip + (*tos - copy_ip);
-		break;
-#ifdef CONFIG_X86_32
-	case 0x9a:	/* call absolute -- same as call absolute, indirect */
-		*tos = orig_ip + (*tos - copy_ip);
-		goto no_change;
-#endif
-	case 0xff:
-		if ((insn[1] & 0x30) == 0x10) {
-			/*
-			 * call absolute, indirect
-			 * Fix return addr; ip is correct.
-			 * But this is not boostable
-			 */
-			*tos = orig_ip + (*tos - copy_ip);
-			goto no_change;
-		} else if (((insn[1] & 0x31) == 0x20) ||
-			   ((insn[1] & 0x31) == 0x21)) {
-			/*
-			 * jmp near and far, absolute indirect
-			 * ip is correct. And this is boostable
-			 */
-			p->ainsn.boostable = 1;
-			goto no_change;
-		}
-	default:
-		break;
-	}
-
-	if (p->ainsn.boostable == 0) {
-		if ((regs->ip > copy_ip) &&
-		    (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) {
-			/*
-			 * These instructions can be executed directly if it
-			 * jumps back to correct address.
-			 */
-			synthesize_reljump((void *)regs->ip,
-				(void *)orig_ip + (regs->ip - copy_ip));
-			p->ainsn.boostable = 1;
-		} else {
-			p->ainsn.boostable = -1;
-		}
-	}
-
-	regs->ip += orig_ip - copy_ip;
-
-no_change:
-	restore_btf();
-}
-
-/*
- * Interrupts are disabled on entry as trap1 is an interrupt gate and they
- * remain disabled throughout 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;
-
-	resume_execution(cur, regs, kcb);
-	regs->flags |= kcb->kprobe_saved_flags;
-
-	if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
-		kcb->kprobe_status = KPROBE_HIT_SSDONE;
-		cur->post_handler(cur, regs, 0);
-	}
-
-	/* 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, flags
-	 * will have TF set, in which case, continue the remaining processing
-	 * of do_debug, as if this is not a probe hit.
-	 */
-	if (regs->flags & X86_EFLAGS_TF)
-		return 0;
-
-	return 1;
-}
-
-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 ip points back to the probe address
-		 * and allow the page fault handler to continue as a
-		 * normal page fault.
-		 */
-		regs->ip = (unsigned long)cur->addr;
-		regs->flags |= kcb->kprobe_old_flags;
-		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 accounting
-		 * 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 routine could not handle it,
-		 * Let do_page_fault() fix it.
-		 */
-		break;
-	default:
-		break;
-	}
-	return 0;
-}
-
-/*
- * Wrapper routine for handling exceptions.
- */
-int __kprobes
-kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data)
-{
-	struct die_args *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)) {
-			/*
-			 * Reset the BS bit in dr6 (pointed by args->err) to
-			 * denote completion of processing
-			 */
-			(*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
-			ret = NOTIFY_STOP;
-		}
-		break;
-	case DIE_GPF:
-		/*
-		 * To be potentially processing a kprobe fault and to
-		 * trust the result from kprobe_running(), we have
-		 * be non-preemptible.
-		 */
-		if (!preemptible() && kprobe_running() &&
-		    kprobe_fault_handler(args->regs, args->trapnr))
-			ret = NOTIFY_STOP;
-		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_sp = stack_addr(regs);
-	addr = (unsigned long)(kcb->jprobe_saved_sp);
-
-	/*
-	 * 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->flags &= ~X86_EFLAGS_IF;
-	trace_hardirqs_off();
-	regs->ip = (unsigned long)(jp->entry);
-	return 1;
-}
-
-void __kprobes jprobe_return(void)
-{
-	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
-	asm volatile (
-#ifdef CONFIG_X86_64
-			"       xchg   %%rbx,%%rsp	\n"
-#else
-			"       xchgl   %%ebx,%%esp	\n"
-#endif
-			"       int3			\n"
-			"       .globl jprobe_return_end\n"
-			"       jprobe_return_end:	\n"
-			"       nop			\n"::"b"
-			(kcb->jprobe_saved_sp):"memory");
-}
-
-int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
-{
-	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-	u8 *addr = (u8 *) (regs->ip - 1);
-	struct jprobe *jp = container_of(p, struct jprobe, kp);
-
-	if ((addr > (u8 *) jprobe_return) &&
-	    (addr < (u8 *) jprobe_return_end)) {
-		if (stack_addr(regs) != kcb->jprobe_saved_sp) {
-			struct pt_regs *saved_regs = &kcb->jprobe_saved_regs;
-			printk(KERN_ERR
-			       "current sp %p does not match saved sp %p\n",
-			       stack_addr(regs), kcb->jprobe_saved_sp);
-			printk(KERN_ERR "Saved registers for jprobe %p\n", jp);
-			show_regs(saved_regs);
-			printk(KERN_ERR "Current registers\n");
-			show_regs(regs);
-			BUG();
-		}
-		*regs = kcb->jprobe_saved_regs;
-		memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp),
-		       kcb->jprobes_stack,
-		       MIN_STACK_SIZE(kcb->jprobe_saved_sp));
-		preempt_enable_no_resched();
-		return 1;
-	}
-	return 0;
-}
-
-int __init arch_init_kprobes(void)
-{
-	return arch_init_optprobes();
-}
-
-int __kprobes arch_trampoline_kprobe(struct kprobe *p)
-{
-	return 0;
-}