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![Michael Ellerman](/assets/img/avatar_default.png)
I realise jprobes are a razor-blades-included type of interface, but that doesn't mean we can't try and make them safer to use. This guy I know once wrote code like this: struct jprobe jp = { .kp.symbol_name = "foo", .entry = "jprobe_foo" }; And then his kernel exploded. Oops. This patch adds an arch hook, arch_deref_entry_point() (I don't like it either) which takes the void * in a struct jprobe, and gives back the text address that it represents. We can then use that in register_jprobe() to check that the entry point we're passed is actually in the kernel text, rather than just some random value. Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
262 lines
8 KiB
C
262 lines
8 KiB
C
#ifndef _LINUX_KPROBES_H
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#define _LINUX_KPROBES_H
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/*
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* Kernel Probes (KProbes)
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* include/linux/kprobes.h
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (C) IBM Corporation, 2002, 2004
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*
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* 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
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* Probes initial implementation ( includes suggestions from
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* Rusty Russell).
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* 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
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* interface to access function arguments.
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* 2005-May Hien Nguyen <hien@us.ibm.com> and Jim Keniston
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* <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
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* <prasanna@in.ibm.com> added function-return probes.
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*/
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#include <linux/list.h>
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#include <linux/notifier.h>
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#include <linux/smp.h>
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#include <linux/percpu.h>
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#include <linux/spinlock.h>
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#include <linux/rcupdate.h>
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#include <linux/mutex.h>
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#ifdef CONFIG_KPROBES
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#include <asm/kprobes.h>
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/* kprobe_status settings */
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#define KPROBE_HIT_ACTIVE 0x00000001
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#define KPROBE_HIT_SS 0x00000002
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#define KPROBE_REENTER 0x00000004
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#define KPROBE_HIT_SSDONE 0x00000008
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/* Attach to insert probes on any functions which should be ignored*/
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#define __kprobes __attribute__((__section__(".kprobes.text")))
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struct kprobe;
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struct pt_regs;
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struct kretprobe;
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struct kretprobe_instance;
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typedef int (*kprobe_pre_handler_t) (struct kprobe *, struct pt_regs *);
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typedef int (*kprobe_break_handler_t) (struct kprobe *, struct pt_regs *);
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typedef void (*kprobe_post_handler_t) (struct kprobe *, struct pt_regs *,
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unsigned long flags);
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typedef int (*kprobe_fault_handler_t) (struct kprobe *, struct pt_regs *,
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int trapnr);
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typedef int (*kretprobe_handler_t) (struct kretprobe_instance *,
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struct pt_regs *);
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struct kprobe {
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struct hlist_node hlist;
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/* list of kprobes for multi-handler support */
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struct list_head list;
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/* Indicates that the corresponding module has been ref counted */
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unsigned int mod_refcounted;
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/*count the number of times this probe was temporarily disarmed */
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unsigned long nmissed;
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/* location of the probe point */
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kprobe_opcode_t *addr;
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/* Allow user to indicate symbol name of the probe point */
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const char *symbol_name;
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/* Offset into the symbol */
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unsigned int offset;
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/* Called before addr is executed. */
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kprobe_pre_handler_t pre_handler;
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/* Called after addr is executed, unless... */
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kprobe_post_handler_t post_handler;
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/* ... called if executing addr causes a fault (eg. page fault).
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* Return 1 if it handled fault, otherwise kernel will see it. */
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kprobe_fault_handler_t fault_handler;
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/* ... called if breakpoint trap occurs in probe handler.
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* Return 1 if it handled break, otherwise kernel will see it. */
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kprobe_break_handler_t break_handler;
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/* Saved opcode (which has been replaced with breakpoint) */
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kprobe_opcode_t opcode;
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/* copy of the original instruction */
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struct arch_specific_insn ainsn;
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};
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/*
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* Special probe type that uses setjmp-longjmp type tricks to resume
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* execution at a specified entry with a matching prototype corresponding
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* to the probed function - a trick to enable arguments to become
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* accessible seamlessly by probe handling logic.
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* Note:
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* Because of the way compilers allocate stack space for local variables
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* etc upfront, regardless of sub-scopes within a function, this mirroring
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* principle currently works only for probes placed on function entry points.
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*/
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struct jprobe {
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struct kprobe kp;
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void *entry; /* probe handling code to jump to */
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};
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/* For backward compatibility with old code using JPROBE_ENTRY() */
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#define JPROBE_ENTRY(handler) (handler)
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DECLARE_PER_CPU(struct kprobe *, current_kprobe);
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DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
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#ifdef ARCH_SUPPORTS_KRETPROBES
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extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
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struct pt_regs *regs);
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extern int arch_trampoline_kprobe(struct kprobe *p);
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#else /* ARCH_SUPPORTS_KRETPROBES */
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static inline void arch_prepare_kretprobe(struct kretprobe *rp,
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struct pt_regs *regs)
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{
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}
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static inline int arch_trampoline_kprobe(struct kprobe *p)
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{
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return 0;
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}
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#endif /* ARCH_SUPPORTS_KRETPROBES */
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/*
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* Function-return probe -
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* Note:
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* User needs to provide a handler function, and initialize maxactive.
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* maxactive - The maximum number of instances of the probed function that
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* can be active concurrently.
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* nmissed - tracks the number of times the probed function's return was
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* ignored, due to maxactive being too low.
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*
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*/
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struct kretprobe {
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struct kprobe kp;
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kretprobe_handler_t handler;
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int maxactive;
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int nmissed;
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struct hlist_head free_instances;
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struct hlist_head used_instances;
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};
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struct kretprobe_instance {
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struct hlist_node uflist; /* either on free list or used list */
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struct hlist_node hlist;
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struct kretprobe *rp;
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kprobe_opcode_t *ret_addr;
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struct task_struct *task;
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};
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static inline void kretprobe_assert(struct kretprobe_instance *ri,
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unsigned long orig_ret_address, unsigned long trampoline_address)
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{
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if (!orig_ret_address || (orig_ret_address == trampoline_address)) {
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printk("kretprobe BUG!: Processing kretprobe %p @ %p\n",
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ri->rp, ri->rp->kp.addr);
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BUG();
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}
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}
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extern spinlock_t kretprobe_lock;
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extern struct mutex kprobe_mutex;
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extern int arch_prepare_kprobe(struct kprobe *p);
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extern void arch_arm_kprobe(struct kprobe *p);
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extern void arch_disarm_kprobe(struct kprobe *p);
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extern int arch_init_kprobes(void);
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extern void show_registers(struct pt_regs *regs);
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extern kprobe_opcode_t *get_insn_slot(void);
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extern void free_insn_slot(kprobe_opcode_t *slot, int dirty);
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extern void kprobes_inc_nmissed_count(struct kprobe *p);
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/* Get the kprobe at this addr (if any) - called with preemption disabled */
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struct kprobe *get_kprobe(void *addr);
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struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk);
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/* kprobe_running() will just return the current_kprobe on this CPU */
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static inline struct kprobe *kprobe_running(void)
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{
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return (__get_cpu_var(current_kprobe));
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}
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static inline void reset_current_kprobe(void)
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{
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__get_cpu_var(current_kprobe) = NULL;
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}
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static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
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{
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return (&__get_cpu_var(kprobe_ctlblk));
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}
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int register_kprobe(struct kprobe *p);
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void unregister_kprobe(struct kprobe *p);
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int setjmp_pre_handler(struct kprobe *, struct pt_regs *);
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int longjmp_break_handler(struct kprobe *, struct pt_regs *);
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int register_jprobe(struct jprobe *p);
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void unregister_jprobe(struct jprobe *p);
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void jprobe_return(void);
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unsigned long arch_deref_entry_point(void *);
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int register_kretprobe(struct kretprobe *rp);
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void unregister_kretprobe(struct kretprobe *rp);
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void kprobe_flush_task(struct task_struct *tk);
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void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head);
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#else /* CONFIG_KPROBES */
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#define __kprobes /**/
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struct jprobe;
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struct kretprobe;
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static inline struct kprobe *kprobe_running(void)
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{
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return NULL;
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}
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static inline int register_kprobe(struct kprobe *p)
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{
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return -ENOSYS;
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}
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static inline void unregister_kprobe(struct kprobe *p)
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{
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}
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static inline int register_jprobe(struct jprobe *p)
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{
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return -ENOSYS;
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}
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static inline void unregister_jprobe(struct jprobe *p)
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{
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}
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static inline void jprobe_return(void)
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{
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}
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static inline int register_kretprobe(struct kretprobe *rp)
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{
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return -ENOSYS;
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}
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static inline void unregister_kretprobe(struct kretprobe *rp)
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{
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}
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static inline void kprobe_flush_task(struct task_struct *tk)
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{
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}
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#endif /* CONFIG_KPROBES */
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#endif /* _LINUX_KPROBES_H */
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