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/list.h>
  33 #include <linux/notifier.h>
  34 #include <linux/smp.h>
  35 #include <linux/percpu.h>
  36 #include <linux/spinlock.h>
  37 #include <linux/rcupdate.h>
  38 #include <linux/mutex.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         /* Indicates that the corresponding module has been ref counted */
  72         unsigned int mod_refcounted;
  73
  74         /*count the number of times this probe was temporarily disarmed */
  75         unsigned long nmissed;
  76
  77         /* location of the probe point */
  78         kprobe_opcode_t *addr;
  79
  80         /* Called before addr is executed. */
  81         kprobe_pre_handler_t pre_handler;
  82
  83         /* Called after addr is executed, unless... */
  84         kprobe_post_handler_t post_handler;
  85
  86         /* ... called if executing addr causes a fault (eg. page fault).
  87          * Return 1 if it handled fault, otherwise kernel will see it. */
  88         kprobe_fault_handler_t fault_handler;
  89
  90         /* ... called if breakpoint trap occurs in probe handler.
  91          * Return 1 if it handled break, otherwise kernel will see it. */
  92         kprobe_break_handler_t break_handler;
  93
  94         /* Saved opcode (which has been replaced with breakpoint) */
  95         kprobe_opcode_t opcode;
  96
  97         /* copy of the original instruction */
  98         struct arch_specific_insn ainsn;
  99 };
 100
 101 /*
 102  * Special probe type that uses setjmp-longjmp type tricks to resume
 103  * execution at a specified entry with a matching prototype corresponding
 104  * to the probed function - a trick to enable arguments to become
 105  * accessible seamlessly by probe handling logic.
 106  * Note:
 107  * Because of the way compilers allocate stack space for local variables
 108  * etc upfront, regardless of sub-scopes within a function, this mirroring
 109  * principle currently works only for probes placed on function entry points.
 110  */
 111 struct jprobe {
 112         struct kprobe kp;
 113         kprobe_opcode_t *entry; /* probe handling code to jump to */
 114 };
 115
 116 DECLARE_PER_CPU(struct kprobe *, current_kprobe);
 117 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 118
 119 #ifdef ARCH_SUPPORTS_KRETPROBES
 120 extern void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs);
 121 #else /* ARCH_SUPPORTS_KRETPROBES */
 122 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
 123                                         struct pt_regs *regs)
 124 {
 125 }
 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         kprobe_opcode_t *ret_addr;
 151         struct task_struct *task;
 152 };
 153
 154 extern spinlock_t kretprobe_lock;
 155 extern struct mutex kprobe_mutex;
 156 extern int arch_prepare_kprobe(struct kprobe *p);
 157 extern void arch_arm_kprobe(struct kprobe *p);
 158 extern void arch_disarm_kprobe(struct kprobe *p);
 159 extern int arch_init_kprobes(void);
 160 extern void show_registers(struct pt_regs *regs);
 161 extern kprobe_opcode_t *get_insn_slot(void);
 162 extern void free_insn_slot(kprobe_opcode_t *slot);
 163 extern void kprobes_inc_nmissed_count(struct kprobe *p);
 164
 165 /* Get the kprobe at this addr (if any) - called with preemption disabled */
 166 struct kprobe *get_kprobe(void *addr);
 167 struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk);
 168
 169 /* kprobe_running() will just return the current_kprobe on this CPU */
 170 static inline struct kprobe *kprobe_running(void)
 171 {
 172         return (__get_cpu_var(current_kprobe));
 173 }
 174
 175 static inline void reset_current_kprobe(void)
 176 {
 177         __get_cpu_var(current_kprobe) = NULL;
 178 }
 179
 180 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
 181 {
 182         return (&__get_cpu_var(kprobe_ctlblk));
 183 }
 184
 185 int register_kprobe(struct kprobe *p);
 186 void unregister_kprobe(struct kprobe *p);
 187 int setjmp_pre_handler(struct kprobe *, struct pt_regs *);
 188 int longjmp_break_handler(struct kprobe *, struct pt_regs *);
 189 int register_jprobe(struct jprobe *p);
 190 void unregister_jprobe(struct jprobe *p);
 191 void jprobe_return(void);
 192
 193 int register_kretprobe(struct kretprobe *rp);
 194 void unregister_kretprobe(struct kretprobe *rp);
 195
 196 struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp);
 197 void add_rp_inst(struct kretprobe_instance *ri);
 198 void kprobe_flush_task(struct task_struct *tk);
 199 void recycle_rp_inst(struct kretprobe_instance *ri);
 200 #else /* CONFIG_KPROBES */
 201
 202 #define __kprobes       /**/
 203 struct jprobe;
 204 struct kretprobe;
 205
 206 static inline struct kprobe *kprobe_running(void)
 207 {
 208         return NULL;
 209 }
 210 static inline int register_kprobe(struct kprobe *p)
 211 {
 212         return -ENOSYS;
 213 }
 214 static inline void unregister_kprobe(struct kprobe *p)
 215 {
 216 }
 217 static inline int register_jprobe(struct jprobe *p)
 218 {
 219         return -ENOSYS;
 220 }
 221 static inline void unregister_jprobe(struct jprobe *p)
 222 {
 223 }
 224 static inline void jprobe_return(void)
 225 {
 226 }
 227 static inline int register_kretprobe(struct kretprobe *rp)
 228 {
 229         return -ENOSYS;
 230 }
 231 static inline void unregister_kretprobe(struct kretprobe *rp)
 232 {
 233 }
 234 static inline void kprobe_flush_task(struct task_struct *tk)
 235 {
 236 }
 237 #endif                          /* CONFIG_KPROBES */
 238 #endif                          /* _LINUX_KPROBES_H */