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 #include <linux/spinlock.h>
  38 #include <linux/rcupdate.h>
  39 #include <linux/mutex.h>
  40
  41 #ifdef CONFIG_KPROBES
  42 #include <asm/kprobes.h>
  43
  44 /* kprobe_status settings */
  45 #define KPROBE_HIT_ACTIVE       0x00000001
  46 #define KPROBE_HIT_SS           0x00000002
  47 #define KPROBE_REENTER          0x00000004
  48 #define KPROBE_HIT_SSDONE       0x00000008
  49
  50 /* Attach to insert probes on any functions which should be ignored*/
  51 #define __kprobes       __attribute__((__section__(".kprobes.text")))
  52
  53 struct kprobe;
  54 struct pt_regs;
  55 struct kretprobe;
  56 struct kretprobe_instance;
  57 typedef int (*kprobe_pre_handler_t) (struct kprobe *, struct pt_regs *);
  58 typedef int (*kprobe_break_handler_t) (struct kprobe *, struct pt_regs *);
  59 typedef void (*kprobe_post_handler_t) (struct kprobe *, struct pt_regs *,
  60                                        unsigned long flags);
  61 typedef int (*kprobe_fault_handler_t) (struct kprobe *, struct pt_regs *,
  62                                        int trapnr);
  63 typedef int (*kretprobe_handler_t) (struct kretprobe_instance *,
  64                                     struct pt_regs *);
  65
  66 struct kprobe {
  67         struct hlist_node hlist;
  68
  69         /* list of kprobes for multi-handler support */
  70         struct list_head list;
  71
  72         /* Indicates that the corresponding module has been ref counted */
  73         unsigned int mod_refcounted;
  74
  75         /*count the number of times this probe was temporarily disarmed */
  76         unsigned long nmissed;
  77
  78         /* location of the probe point */
  79         kprobe_opcode_t *addr;
  80
  81         /* Called before addr is executed. */
  82         kprobe_pre_handler_t pre_handler;
  83
  84         /* Called after addr is executed, unless... */
  85         kprobe_post_handler_t post_handler;
  86
  87         /* ... called if executing addr causes a fault (eg. page fault).
  88          * Return 1 if it handled fault, otherwise kernel will see it. */
  89         kprobe_fault_handler_t fault_handler;
  90
  91         /* ... called if breakpoint trap occurs in probe handler.
  92          * Return 1 if it handled break, otherwise kernel will see it. */
  93         kprobe_break_handler_t break_handler;
  94
  95         /* Saved opcode (which has been replaced with breakpoint) */
  96         kprobe_opcode_t opcode;
  97
  98         /* copy of the original instruction */
  99         struct arch_specific_insn ainsn;
 100 };
 101
 102 /*
 103  * Special probe type that uses setjmp-longjmp type tricks to resume
 104  * execution at a specified entry with a matching prototype corresponding
 105  * to the probed function - a trick to enable arguments to become
 106  * accessible seamlessly by probe handling logic.
 107  * Note:
 108  * Because of the way compilers allocate stack space for local variables
 109  * etc upfront, regardless of sub-scopes within a function, this mirroring
 110  * principle currently works only for probes placed on function entry points.
 111  */
 112 struct jprobe {
 113         struct kprobe kp;
 114         kprobe_opcode_t *entry; /* probe handling code to jump to */
 115 };
 116
 117 DECLARE_PER_CPU(struct kprobe *, current_kprobe);
 118 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 119
 120 #ifdef ARCH_SUPPORTS_KRETPROBES
 121 extern void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs);
 122 #else /* ARCH_SUPPORTS_KRETPROBES */
 123 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
 124                                         struct pt_regs *regs)
 125 {
 126 }
 127 #endif /* ARCH_SUPPORTS_KRETPROBES */
 128 /*
 129  * Function-return probe -
 130  * Note:
 131  * User needs to provide a handler function, and initialize maxactive.
 132  * maxactive - The maximum number of instances of the probed function that
 133  * can be active concurrently.
 134  * nmissed - tracks the number of times the probed function's return was
 135  * ignored, due to maxactive being too low.
 136  *
 137  */
 138 struct kretprobe {
 139         struct kprobe kp;
 140         kretprobe_handler_t handler;
 141         int maxactive;
 142         int nmissed;
 143         struct hlist_head free_instances;
 144         struct hlist_head used_instances;
 145 };
 146
 147 struct kretprobe_instance {
 148         struct hlist_node uflist; /* either on free list or used list */
 149         struct hlist_node hlist;
 150         struct kretprobe *rp;
 151         kprobe_opcode_t *ret_addr;
 152         struct task_struct *task;
 153 };
 154
 155 extern spinlock_t kretprobe_lock;
 156 extern struct mutex kprobe_mutex;
 157 extern int arch_prepare_kprobe(struct kprobe *p);
 158 extern void arch_arm_kprobe(struct kprobe *p);
 159 extern void arch_disarm_kprobe(struct kprobe *p);
 160 extern int arch_init_kprobes(void);
 161 extern void show_registers(struct pt_regs *regs);
 162 extern kprobe_opcode_t *get_insn_slot(void);
 163 extern void free_insn_slot(kprobe_opcode_t *slot);
 164 extern void kprobes_inc_nmissed_count(struct kprobe *p);
 165
 166 /* Get the kprobe at this addr (if any) - called with preemption disabled */
 167 struct kprobe *get_kprobe(void *addr);
 168 struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk);
 169
 170 /* kprobe_running() will just return the current_kprobe on this CPU */
 171 static inline struct kprobe *kprobe_running(void)
 172 {
 173         return (__get_cpu_var(current_kprobe));
 174 }
 175
 176 static inline void reset_current_kprobe(void)
 177 {
 178         __get_cpu_var(current_kprobe) = NULL;
 179 }
 180
 181 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
 182 {
 183         return (&__get_cpu_var(kprobe_ctlblk));
 184 }
 185
 186 int register_kprobe(struct kprobe *p);
 187 void unregister_kprobe(struct kprobe *p);
 188 int setjmp_pre_handler(struct kprobe *, struct pt_regs *);
 189 int longjmp_break_handler(struct kprobe *, struct pt_regs *);
 190 int register_jprobe(struct jprobe *p);
 191 void unregister_jprobe(struct jprobe *p);
 192 void jprobe_return(void);
 193
 194 int register_kretprobe(struct kretprobe *rp);
 195 void unregister_kretprobe(struct kretprobe *rp);
 196
 197 struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp);
 198 void add_rp_inst(struct kretprobe_instance *ri);
 199 void kprobe_flush_task(struct task_struct *tk);
 200 void recycle_rp_inst(struct kretprobe_instance *ri);
 201 #else /* CONFIG_KPROBES */
 202
 203 #define __kprobes       /**/
 204 struct jprobe;
 205 struct kretprobe;
 206
 207 static inline struct kprobe *kprobe_running(void)
 208 {
 209         return NULL;
 210 }
 211 static inline int register_kprobe(struct kprobe *p)
 212 {
 213         return -ENOSYS;
 214 }
 215 static inline void unregister_kprobe(struct kprobe *p)
 216 {
 217 }
 218 static inline int register_jprobe(struct jprobe *p)
 219 {
 220         return -ENOSYS;
 221 }
 222 static inline void unregister_jprobe(struct jprobe *p)
 223 {
 224 }
 225 static inline void jprobe_return(void)
 226 {
 227 }
 228 static inline int register_kretprobe(struct kretprobe *rp)
 229 {
 230         return -ENOSYS;
 231 }
 232 static inline void unregister_kretprobe(struct kretprobe *rp)
 233 {
 234 }
 235 static inline void kprobe_flush_task(struct task_struct *tk)
 236 {
 237 }
 238 #endif                          /* CONFIG_KPROBES */
 239 #endif                          /* _LINUX_KPROBES_H */