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 #include <linux/spinlock.h>
  37
  38 #include <asm/kprobes.h>
  39
  40 struct kprobe;
  41 struct pt_regs;
  42 struct kretprobe;
  43 struct kretprobe_instance;
  44 typedef int (*kprobe_pre_handler_t) (struct kprobe *, struct pt_regs *);
  45 typedef int (*kprobe_break_handler_t) (struct kprobe *, struct pt_regs *);
  46 typedef void (*kprobe_post_handler_t) (struct kprobe *, struct pt_regs *,
  47                                        unsigned long flags);
  48 typedef int (*kprobe_fault_handler_t) (struct kprobe *, struct pt_regs *,
  49                                        int trapnr);
  50 typedef int (*kretprobe_handler_t) (struct kretprobe_instance *,
  51                                     struct pt_regs *);
  52
  53 struct kprobe {
  54         struct hlist_node hlist;
  55
  56         /* list of kprobes for multi-handler support */
  57         struct list_head list;
  58
  59         /* location of the probe point */
  60         kprobe_opcode_t *addr;
  61
  62         /* Called before addr is executed. */
  63         kprobe_pre_handler_t pre_handler;
  64
  65         /* Called after addr is executed, unless... */
  66         kprobe_post_handler_t post_handler;
  67
  68         /* ... called if executing addr causes a fault (eg. page fault).
  69          * Return 1 if it handled fault, otherwise kernel will see it. */
  70         kprobe_fault_handler_t fault_handler;
  71
  72         /* ... called if breakpoint trap occurs in probe handler.
  73          * Return 1 if it handled break, otherwise kernel will see it. */
  74         kprobe_break_handler_t break_handler;
  75
  76         /* Saved opcode (which has been replaced with breakpoint) */
  77         kprobe_opcode_t opcode;
  78
  79         /* copy of the original instruction */
  80         struct arch_specific_insn ainsn;
  81 };
  82
  83 /*
  84  * Special probe type that uses setjmp-longjmp type tricks to resume
  85  * execution at a specified entry with a matching prototype corresponding
  86  * to the probed function - a trick to enable arguments to become
  87  * accessible seamlessly by probe handling logic.
  88  * Note:
  89  * Because of the way compilers allocate stack space for local variables
  90  * etc upfront, regardless of sub-scopes within a function, this mirroring
  91  * principle currently works only for probes placed on function entry points.
  92  */
  93 struct jprobe {
  94         struct kprobe kp;
  95         kprobe_opcode_t *entry; /* probe handling code to jump to */
  96 };
  97
  98 #ifdef ARCH_SUPPORTS_KRETPROBES
  99 extern int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs);
 100 extern void trampoline_post_handler(struct kprobe *p, struct pt_regs *regs,
 101                                                         unsigned long flags);
 102 extern struct task_struct *arch_get_kprobe_task(void *ptr);
 103 extern void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs);
 104 extern void arch_kprobe_flush_task(struct task_struct *tk, spinlock_t *kp_lock);
 105 #else /* ARCH_SUPPORTS_KRETPROBES */
 106 static inline void kretprobe_trampoline(void)
 107 {
 108 }
 109 static inline int trampoline_probe_handler(struct kprobe *p,
 110                                                 struct pt_regs *regs)
 111 {
 112         return 0;
 113 }
 114 static inline void trampoline_post_handler(struct kprobe *p,
 115                                 struct pt_regs *regs, unsigned long flags)
 116 {
 117 }
 118 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
 119                                         struct pt_regs *regs)
 120 {
 121 }
 122 static inline void arch_kprobe_flush_task(struct task_struct *tk)
 123 {
 124 }
 125 #define arch_get_kprobe_task(ptr) ((struct task_struct *)NULL)
 126 #endif /* ARCH_SUPPORTS_KRETPROBES */
 127 /*
 128  * Function-return probe -
 129  * Note:
 130  * User needs to provide a handler function, and initialize maxactive.
 131  * maxactive - The maximum number of instances of the probed function that
 132  * can be active concurrently.
 133  * nmissed - tracks the number of times the probed function's return was
 134  * ignored, due to maxactive being too low.
 135  *
 136  */
 137 struct kretprobe {
 138         struct kprobe kp;
 139         kretprobe_handler_t handler;
 140         int maxactive;
 141         int nmissed;
 142         struct hlist_head free_instances;
 143         struct hlist_head used_instances;
 144 };
 145
 146 struct kretprobe_instance {
 147         struct hlist_node uflist; /* either on free list or used list */
 148         struct hlist_node hlist;
 149         struct kretprobe *rp;
 150         void *ret_addr;
 151         void *stack_addr;
 152 };
 153
 154 #ifdef CONFIG_KPROBES
 155 /* Locks kprobe: irq must be disabled */
 156 void lock_kprobes(void);
 157 void unlock_kprobes(void);
 158
 159 /* kprobe running now on this CPU? */
 160 static inline int kprobe_running(void)
 161 {
 162         extern unsigned int kprobe_cpu;
 163         return kprobe_cpu == smp_processor_id();
 164 }
 165
 166 extern int arch_prepare_kprobe(struct kprobe *p);
 167 extern void arch_copy_kprobe(struct kprobe *p);
 168 extern void arch_remove_kprobe(struct kprobe *p);
 169 extern void show_registers(struct pt_regs *regs);
 170
 171 /* Get the kprobe at this addr (if any).  Must have called lock_kprobes */
 172 struct kprobe *get_kprobe(void *addr);
 173 struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk);
 174
 175 int register_kprobe(struct kprobe *p);
 176 void unregister_kprobe(struct kprobe *p);
 177 int setjmp_pre_handler(struct kprobe *, struct pt_regs *);
 178 int longjmp_break_handler(struct kprobe *, struct pt_regs *);
 179 int register_jprobe(struct jprobe *p);
 180 void unregister_jprobe(struct jprobe *p);
 181 void jprobe_return(void);
 182
 183 int register_kretprobe(struct kretprobe *rp);
 184 void unregister_kretprobe(struct kretprobe *rp);
 185
 186 struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp);
 187 struct kretprobe_instance *get_rp_inst(void *sara);
 188 struct kretprobe_instance *get_rp_inst_tsk(struct task_struct *tk);
 189 void add_rp_inst(struct kretprobe_instance *ri);
 190 void kprobe_flush_task(struct task_struct *tk);
 191 void recycle_rp_inst(struct kretprobe_instance *ri);
 192 #else /* CONFIG_KPROBES */
 193 static inline int kprobe_running(void)
 194 {
 195         return 0;
 196 }
 197 static inline int register_kprobe(struct kprobe *p)
 198 {
 199         return -ENOSYS;
 200 }
 201 static inline void unregister_kprobe(struct kprobe *p)
 202 {
 203 }
 204 static inline int register_jprobe(struct jprobe *p)
 205 {
 206         return -ENOSYS;
 207 }
 208 static inline void unregister_jprobe(struct jprobe *p)
 209 {
 210 }
 211 static inline void jprobe_return(void)
 212 {
 213 }
 214 static inline int register_kretprobe(struct kretprobe *rp)
 215 {
 216         return -ENOSYS;
 217 }
 218 static inline void unregister_kretprobe(struct kretprobe *rp)
 219 {
 220 }
 221 static inline void kprobe_flush_task(struct task_struct *tk)
 222 {
 223 }
 224 #endif                          /* CONFIG_KPROBES */
 225 #endif                          /* _LINUX_KPROBES_H */