include/linux/kprobes.h

   1 #ifndef _LINUX_KPROBES_H
   2 #define _LINUX_KPROBES_H
   3 /*
   4  *  Kernel Probes (KProbes)
   5  *  include/linux/kprobes.h
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  20  *
  21  * Copyright (C) IBM Corporation, 2002, 2004
  22  *
  23  * 2002-Oct     Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
  24  *              Probes initial implementation ( includes suggestions from
  25  *              Rusty Russell).
  26  * 2004-July    Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
  27  *              interface to access function arguments.
  28  * 2005-May     Hien Nguyen <hien@us.ibm.com> and Jim Keniston
  29  *              <jkenisto@us.ibm.com>  and Prasanna S Panchamukhi
  30  *              <prasanna@in.ibm.com> added function-return probes.
  31  */
  32 #include <linux/config.h>
  33 #include <linux/list.h>
  34 #include <linux/notifier.h>
  35 #include <linux/smp.h>
  36
  37 #include <asm/kprobes.h>
  38
  39 /* kprobe_status settings */
  40 #define KPROBE_HIT_ACTIVE       0x00000001
  41 #define KPROBE_HIT_SS           0x00000002
  42 #define KPROBE_REENTER          0x00000004
  43 #define KPROBE_HIT_SSDONE       0x00000008
  44
  45 struct kprobe;
  46 struct pt_regs;
  47 struct kretprobe;
  48 struct kretprobe_instance;
  49 typedef int (*kprobe_pre_handler_t) (struct kprobe *, struct pt_regs *);
  50 typedef int (*kprobe_break_handler_t) (struct kprobe *, struct pt_regs *);
  51 typedef void (*kprobe_post_handler_t) (struct kprobe *, struct pt_regs *,
  52                                        unsigned long flags);
  53 typedef int (*kprobe_fault_handler_t) (struct kprobe *, struct pt_regs *,
  54                                        int trapnr);
  55 typedef int (*kretprobe_handler_t) (struct kretprobe_instance *,
  56                                     struct pt_regs *);
  57
  58 struct kprobe {
  59         struct hlist_node hlist;
  60
  61         /* list of kprobes for multi-handler support */
  62         struct list_head list;
  63
  64         /*count the number of times this probe was temporarily disarmed */
  65         unsigned long nmissed;
  66
  67         /* location of the probe point */
  68         kprobe_opcode_t *addr;
  69
  70         /* Called before addr is executed. */
  71         kprobe_pre_handler_t pre_handler;
  72
  73         /* Called after addr is executed, unless... */
  74         kprobe_post_handler_t post_handler;
  75
  76         /* ... called if executing addr causes a fault (eg. page fault).
  77          * Return 1 if it handled fault, otherwise kernel will see it. */
  78         kprobe_fault_handler_t fault_handler;
  79
  80         /* ... called if breakpoint trap occurs in probe handler.
  81          * Return 1 if it handled break, otherwise kernel will see it. */
  82         kprobe_break_handler_t break_handler;
  83
  84         /* Saved opcode (which has been replaced with breakpoint) */
  85         kprobe_opcode_t opcode;
  86
  87         /* copy of the original instruction */
  88         struct arch_specific_insn ainsn;
  89 };
  90
  91 /*
  92  * Special probe type that uses setjmp-longjmp type tricks to resume
  93  * execution at a specified entry with a matching prototype corresponding
  94  * to the probed function - a trick to enable arguments to become
  95  * accessible seamlessly by probe handling logic.
  96  * Note:
  97  * Because of the way compilers allocate stack space for local variables
  98  * etc upfront, regardless of sub-scopes within a function, this mirroring
  99  * principle currently works only for probes placed on function entry points.
 100  */
 101 struct jprobe {
 102         struct kprobe kp;
 103         kprobe_opcode_t *entry; /* probe handling code to jump to */
 104 };
 105
 106 #ifdef ARCH_SUPPORTS_KRETPROBES
 107 extern void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs);
 108 #else /* ARCH_SUPPORTS_KRETPROBES */
 109 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
 110                                         struct pt_regs *regs)
 111 {
 112 }
 113 #endif /* ARCH_SUPPORTS_KRETPROBES */
 114 /*
 115  * Function-return probe -
 116  * Note:
 117  * User needs to provide a handler function, and initialize maxactive.
 118  * maxactive - The maximum number of instances of the probed function that
 119  * can be active concurrently.
 120  * nmissed - tracks the number of times the probed function's return was
 121  * ignored, due to maxactive being too low.
 122  *
 123  */
 124 struct kretprobe {
 125         struct kprobe kp;
 126         kretprobe_handler_t handler;
 127         int maxactive;
 128         int nmissed;
 129         struct hlist_head free_instances;
 130         struct hlist_head used_instances;
 131 };
 132
 133 struct kretprobe_instance {
 134         struct hlist_node uflist; /* either on free list or used list */
 135         struct hlist_node hlist;
 136         struct kretprobe *rp;
 137         kprobe_opcode_t *ret_addr;
 138         struct task_struct *task;
 139 };
 140
 141 #ifdef CONFIG_KPROBES
 142 /* Locks kprobe: irq must be disabled */
 143 void lock_kprobes(void);
 144 void unlock_kprobes(void);
 145
 146 /* kprobe running now on this CPU? */
 147 static inline int kprobe_running(void)
 148 {
 149         extern unsigned int kprobe_cpu;
 150         return kprobe_cpu == smp_processor_id();
 151 }
 152
 153 extern int arch_prepare_kprobe(struct kprobe *p);
 154 extern void arch_copy_kprobe(struct kprobe *p);
 155 extern void arch_arm_kprobe(struct kprobe *p);
 156 extern void arch_disarm_kprobe(struct kprobe *p);
 157 extern void arch_remove_kprobe(struct kprobe *p);
 158 extern int arch_init(void);
 159 extern void show_registers(struct pt_regs *regs);
 160 extern kprobe_opcode_t *get_insn_slot(void);
 161 extern void free_insn_slot(kprobe_opcode_t *slot);
 162
 163 /* Get the kprobe at this addr (if any).  Must have called lock_kprobes */
 164 struct kprobe *get_kprobe(void *addr);
 165 struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk);
 166
 167 int register_kprobe(struct kprobe *p);
 168 void unregister_kprobe(struct kprobe *p);
 169 int setjmp_pre_handler(struct kprobe *, struct pt_regs *);
 170 int longjmp_break_handler(struct kprobe *, struct pt_regs *);
 171 int register_jprobe(struct jprobe *p);
 172 void unregister_jprobe(struct jprobe *p);
 173 void jprobe_return(void);
 174
 175 int register_kretprobe(struct kretprobe *rp);
 176 void unregister_kretprobe(struct kretprobe *rp);
 177
 178 struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp);
 179 void add_rp_inst(struct kretprobe_instance *ri);
 180 void kprobe_flush_task(struct task_struct *tk);
 181 void recycle_rp_inst(struct kretprobe_instance *ri);
 182 #else /* CONFIG_KPROBES */
 183 static inline int kprobe_running(void)
 184 {
 185         return 0;
 186 }
 187 static inline int register_kprobe(struct kprobe *p)
 188 {
 189         return -ENOSYS;
 190 }
 191 static inline void unregister_kprobe(struct kprobe *p)
 192 {
 193 }
 194 static inline int register_jprobe(struct jprobe *p)
 195 {
 196         return -ENOSYS;
 197 }
 198 static inline void unregister_jprobe(struct jprobe *p)
 199 {
 200 }
 201 static inline void jprobe_return(void)
 202 {
 203 }
 204 static inline int register_kretprobe(struct kretprobe *rp)
 205 {
 206         return -ENOSYS;
 207 }
 208 static inline void unregister_kretprobe(struct kretprobe *rp)
 209 {
 210 }
 211 static inline void kprobe_flush_task(struct task_struct *tk)
 212 {
 213 }
 214 #endif                          /* CONFIG_KPROBES */
 215 #endif                          /* _LINUX_KPROBES_H */