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/percpu.h>
  37
  38 #include <asm/kprobes.h>
  39
  40 /* kprobe_status settings */
  41 #define KPROBE_HIT_ACTIVE       0x00000001
  42 #define KPROBE_HIT_SS           0x00000002
  43 #define KPROBE_REENTER          0x00000004
  44 #define KPROBE_HIT_SSDONE       0x00000008
  45
  46 /* Attach to insert probes on any functions which should be ignored*/
  47 #define __kprobes       __attribute__((__section__(".kprobes.text")))
  48
  49 struct kprobe;
  50 struct pt_regs;
  51 struct kretprobe;
  52 struct kretprobe_instance;
  53 typedef int (*kprobe_pre_handler_t) (struct kprobe *, struct pt_regs *);
  54 typedef int (*kprobe_break_handler_t) (struct kprobe *, struct pt_regs *);
  55 typedef void (*kprobe_post_handler_t) (struct kprobe *, struct pt_regs *,
  56                                        unsigned long flags);
  57 typedef int (*kprobe_fault_handler_t) (struct kprobe *, struct pt_regs *,
  58                                        int trapnr);
  59 typedef int (*kretprobe_handler_t) (struct kretprobe_instance *,
  60                                     struct pt_regs *);
  61
  62 struct kprobe {
  63         struct hlist_node hlist;
  64
  65         /* list of kprobes for multi-handler support */
  66         struct list_head list;
  67
  68         /*count the number of times this probe was temporarily disarmed */
  69         unsigned long nmissed;
  70
  71         /* location of the probe point */
  72         kprobe_opcode_t *addr;
  73
  74         /* Called before addr is executed. */
  75         kprobe_pre_handler_t pre_handler;
  76
  77         /* Called after addr is executed, unless... */
  78         kprobe_post_handler_t post_handler;
  79
  80         /* ... called if executing addr causes a fault (eg. page fault).
  81          * Return 1 if it handled fault, otherwise kernel will see it. */
  82         kprobe_fault_handler_t fault_handler;
  83
  84         /* ... called if breakpoint trap occurs in probe handler.
  85          * Return 1 if it handled break, otherwise kernel will see it. */
  86         kprobe_break_handler_t break_handler;
  87
  88         /* Saved opcode (which has been replaced with breakpoint) */
  89         kprobe_opcode_t opcode;
  90
  91         /* copy of the original instruction */
  92         struct arch_specific_insn ainsn;
  93 };
  94
  95 /*
  96  * Special probe type that uses setjmp-longjmp type tricks to resume
  97  * execution at a specified entry with a matching prototype corresponding
  98  * to the probed function - a trick to enable arguments to become
  99  * accessible seamlessly by probe handling logic.
 100  * Note:
 101  * Because of the way compilers allocate stack space for local variables
 102  * etc upfront, regardless of sub-scopes within a function, this mirroring
 103  * principle currently works only for probes placed on function entry points.
 104  */
 105 struct jprobe {
 106         struct kprobe kp;
 107         kprobe_opcode_t *entry; /* probe handling code to jump to */
 108 };
 109
 110 DECLARE_PER_CPU(struct kprobe *, current_kprobe);
 111 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 112
 113 #ifdef ARCH_SUPPORTS_KRETPROBES
 114 extern void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs);
 115 #else /* ARCH_SUPPORTS_KRETPROBES */
 116 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
 117                                         struct pt_regs *regs)
 118 {
 119 }
 120 #endif /* ARCH_SUPPORTS_KRETPROBES */
 121 /*
 122  * Function-return probe -
 123  * Note:
 124  * User needs to provide a handler function, and initialize maxactive.
 125  * maxactive - The maximum number of instances of the probed function that
 126  * can be active concurrently.
 127  * nmissed - tracks the number of times the probed function's return was
 128  * ignored, due to maxactive being too low.
 129  *
 130  */
 131 struct kretprobe {
 132         struct kprobe kp;
 133         kretprobe_handler_t handler;
 134         int maxactive;
 135         int nmissed;
 136         struct hlist_head free_instances;
 137         struct hlist_head used_instances;
 138 };
 139
 140 struct kretprobe_instance {
 141         struct hlist_node uflist; /* either on free list or used list */
 142         struct hlist_node hlist;
 143         struct kretprobe *rp;
 144         kprobe_opcode_t *ret_addr;
 145         struct task_struct *task;
 146 };
 147
 148 #ifdef CONFIG_KPROBES
 149 /* Locks kprobe: irq must be disabled */
 150 void lock_kprobes(void);
 151 void unlock_kprobes(void);
 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_kprobes(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 /* kprobe_running() will just return the current_kprobe on this CPU */
 168 static inline struct kprobe *kprobe_running(void)
 169 {
 170         return (__get_cpu_var(current_kprobe));
 171 }
 172
 173 static inline void reset_current_kprobe(void)
 174 {
 175         __get_cpu_var(current_kprobe) = NULL;
 176 }
 177
 178 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
 179 {
 180         return (&__get_cpu_var(kprobe_ctlblk));
 181 }
 182
 183 int register_kprobe(struct kprobe *p);
 184 void unregister_kprobe(struct kprobe *p);
 185 int setjmp_pre_handler(struct kprobe *, struct pt_regs *);
 186 int longjmp_break_handler(struct kprobe *, struct pt_regs *);
 187 int register_jprobe(struct jprobe *p);
 188 void unregister_jprobe(struct jprobe *p);
 189 void jprobe_return(void);
 190
 191 int register_kretprobe(struct kretprobe *rp);
 192 void unregister_kretprobe(struct kretprobe *rp);
 193
 194 struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp);
 195 void add_rp_inst(struct kretprobe_instance *ri);
 196 void kprobe_flush_task(struct task_struct *tk);
 197 void recycle_rp_inst(struct kretprobe_instance *ri);
 198 #else /* CONFIG_KPROBES */
 199 static inline struct kprobe *kprobe_running(void)
 200 {
 201         return NULL;
 202 }
 203 static inline int register_kprobe(struct kprobe *p)
 204 {
 205         return -ENOSYS;
 206 }
 207 static inline void unregister_kprobe(struct kprobe *p)
 208 {
 209 }
 210 static inline int register_jprobe(struct jprobe *p)
 211 {
 212         return -ENOSYS;
 213 }
 214 static inline void unregister_jprobe(struct jprobe *p)
 215 {
 216 }
 217 static inline void jprobe_return(void)
 218 {
 219 }
 220 static inline int register_kretprobe(struct kretprobe *rp)
 221 {
 222         return -ENOSYS;
 223 }
 224 static inline void unregister_kretprobe(struct kretprobe *rp)
 225 {
 226 }
 227 static inline void kprobe_flush_task(struct task_struct *tk)
 228 {
 229 }
 230 #endif                          /* CONFIG_KPROBES */
 231 #endif                          /* _LINUX_KPROBES_H */