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         /* Allow user to indicate symbol name of the probe point */
  81         const char *symbol_name;
  82
  83         /* Offset into the symbol */
  84         unsigned int offset;
  85
  86         /* Called before addr is executed. */
  87         kprobe_pre_handler_t pre_handler;
  88
  89         /* Called after addr is executed, unless... */
  90         kprobe_post_handler_t post_handler;
  91
  92         /* ... called if executing addr causes a fault (eg. page fault).
  93          * Return 1 if it handled fault, otherwise kernel will see it. */
  94         kprobe_fault_handler_t fault_handler;
  95
  96         /* ... called if breakpoint trap occurs in probe handler.
  97          * Return 1 if it handled break, otherwise kernel will see it. */
  98         kprobe_break_handler_t break_handler;
  99
 100         /* Saved opcode (which has been replaced with breakpoint) */
 101         kprobe_opcode_t opcode;
 102
 103         /* copy of the original instruction */
 104         struct arch_specific_insn ainsn;
 105 };
 106
 107 /*
 108  * Special probe type that uses setjmp-longjmp type tricks to resume
 109  * execution at a specified entry with a matching prototype corresponding
 110  * to the probed function - a trick to enable arguments to become
 111  * accessible seamlessly by probe handling logic.
 112  * Note:
 113  * Because of the way compilers allocate stack space for local variables
 114  * etc upfront, regardless of sub-scopes within a function, this mirroring
 115  * principle currently works only for probes placed on function entry points.
 116  */
 117 struct jprobe {
 118         struct kprobe kp;
 119         kprobe_opcode_t *entry; /* probe handling code to jump to */
 120 };
 121
 122 DECLARE_PER_CPU(struct kprobe *, current_kprobe);
 123 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 124
 125 #ifdef ARCH_SUPPORTS_KRETPROBES
 126 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
 127                                    struct pt_regs *regs);
 128 extern int arch_trampoline_kprobe(struct kprobe *p);
 129 #else /* ARCH_SUPPORTS_KRETPROBES */
 130 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
 131                                         struct pt_regs *regs)
 132 {
 133 }
 134 static inline int arch_trampoline_kprobe(struct kprobe *p)
 135 {
 136         return 0;
 137 }
 138 #endif /* ARCH_SUPPORTS_KRETPROBES */
 139 /*
 140  * Function-return probe -
 141  * Note:
 142  * User needs to provide a handler function, and initialize maxactive.
 143  * maxactive - The maximum number of instances of the probed function that
 144  * can be active concurrently.
 145  * nmissed - tracks the number of times the probed function's return was
 146  * ignored, due to maxactive being too low.
 147  *
 148  */
 149 struct kretprobe {
 150         struct kprobe kp;
 151         kretprobe_handler_t handler;
 152         int maxactive;
 153         int nmissed;
 154         struct hlist_head free_instances;
 155         struct hlist_head used_instances;
 156 };
 157
 158 struct kretprobe_instance {
 159         struct hlist_node uflist; /* either on free list or used list */
 160         struct hlist_node hlist;
 161         struct kretprobe *rp;
 162         kprobe_opcode_t *ret_addr;
 163         struct task_struct *task;
 164 };
 165
 166 static inline void kretprobe_assert(struct kretprobe_instance *ri,
 167         unsigned long orig_ret_address, unsigned long trampoline_address)
 168 {
 169         if (!orig_ret_address || (orig_ret_address == trampoline_address)) {
 170                 printk("kretprobe BUG!: Processing kretprobe %p @ %p\n",
 171                                 ri->rp, ri->rp->kp.addr);
 172                 BUG();
 173         }
 174 }
 175
 176 extern spinlock_t kretprobe_lock;
 177 extern struct mutex kprobe_mutex;
 178 extern int arch_prepare_kprobe(struct kprobe *p);
 179 extern void arch_arm_kprobe(struct kprobe *p);
 180 extern void arch_disarm_kprobe(struct kprobe *p);
 181 extern int arch_init_kprobes(void);
 182 extern void show_registers(struct pt_regs *regs);
 183 extern kprobe_opcode_t *get_insn_slot(void);
 184 extern void free_insn_slot(kprobe_opcode_t *slot, int dirty);
 185 extern void kprobes_inc_nmissed_count(struct kprobe *p);
 186
 187 /* Get the kprobe at this addr (if any) - called with preemption disabled */
 188 struct kprobe *get_kprobe(void *addr);
 189 struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk);
 190
 191 /* kprobe_running() will just return the current_kprobe on this CPU */
 192 static inline struct kprobe *kprobe_running(void)
 193 {
 194         return (__get_cpu_var(current_kprobe));
 195 }
 196
 197 static inline void reset_current_kprobe(void)
 198 {
 199         __get_cpu_var(current_kprobe) = NULL;
 200 }
 201
 202 static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
 203 {
 204         return (&__get_cpu_var(kprobe_ctlblk));
 205 }
 206
 207 int register_kprobe(struct kprobe *p);
 208 void unregister_kprobe(struct kprobe *p);
 209 int setjmp_pre_handler(struct kprobe *, struct pt_regs *);
 210 int longjmp_break_handler(struct kprobe *, struct pt_regs *);
 211 int register_jprobe(struct jprobe *p);
 212 void unregister_jprobe(struct jprobe *p);
 213 void jprobe_return(void);
 214
 215 int register_kretprobe(struct kretprobe *rp);
 216 void unregister_kretprobe(struct kretprobe *rp);
 217
 218 void kprobe_flush_task(struct task_struct *tk);
 219 void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head);
 220 #else /* CONFIG_KPROBES */
 221
 222 #define __kprobes       /**/
 223 struct jprobe;
 224 struct kretprobe;
 225
 226 static inline struct kprobe *kprobe_running(void)
 227 {
 228         return NULL;
 229 }
 230 static inline int register_kprobe(struct kprobe *p)
 231 {
 232         return -ENOSYS;
 233 }
 234 static inline void unregister_kprobe(struct kprobe *p)
 235 {
 236 }
 237 static inline int register_jprobe(struct jprobe *p)
 238 {
 239         return -ENOSYS;
 240 }
 241 static inline void unregister_jprobe(struct jprobe *p)
 242 {
 243 }
 244 static inline void jprobe_return(void)
 245 {
 246 }
 247 static inline int register_kretprobe(struct kretprobe *rp)
 248 {
 249         return -ENOSYS;
 250 }
 251 static inline void unregister_kretprobe(struct kretprobe *rp)
 252 {
 253 }
 254 static inline void kprobe_flush_task(struct task_struct *tk)
 255 {
 256 }
 257 #endif                          /* CONFIG_KPROBES */
 258 #endif                          /* _LINUX_KPROBES_H */