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