ClabureDB: Classified Bug-Reports Database

   /*
    *  Kernel Probes (KProbes)
    *  kernel/kprobes.c
    *
    * This program is free software; you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation; either version 2 of the License, or
    * (at your option) any later version.
    *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   *
   * Copyright (C) IBM Corporation, 2002, 2004
   *
   * 2002-Oct        Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
   *                Probes initial implementation (includes suggestions from
   *                Rusty Russell).
   * 2004-Aug        Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
   *                hlists and exceptions notifier as suggested by Andi Kleen.
   * 2004-July        Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
   *                interface to access function arguments.
   * 2004-Sep        Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
   *                exceptions notifier to be first on the priority list.
   * 2005-May        Hien Nguyen <hien@us.ibm.com>, Jim Keniston
   *                <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
   *                <prasanna@in.ibm.com> added function-return probes.
   */
  #include <linux/kprobes.h>
  #include <linux/hash.h>
  #include <linux/init.h>
  #include <linux/slab.h>
  #include <linux/stddef.h>
  #include <linux/module.h>
  #include <linux/moduleloader.h>
  #include <linux/kallsyms.h>
  #include <linux/freezer.h>
  #include <linux/seq_file.h>
  #include <linux/debugfs.h>
  #include <linux/kdebug.h>
  
  #include <asm-generic/sections.h>
  #include <asm/cacheflush.h>
  #include <asm/errno.h>
  #include <asm/uaccess.h>
  
  #define KPROBE_HASH_BITS 6
  #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
  
  
  /*
   * Some oddball architectures like 64bit powerpc have function descriptors
   * so this must be overridable.
   */
  #ifndef kprobe_lookup_name
  #define kprobe_lookup_name(name, addr) \
          addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
  #endif
  
  static int kprobes_initialized;
  static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
  static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
  
  /* NOTE: change this value only with kprobe_mutex held */
  static bool kprobe_enabled;
  
  DEFINE_MUTEX(kprobe_mutex);                /* Protects kprobe_table */
  static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
  static struct {
          spinlock_t lock ____cacheline_aligned_in_smp;
  } kretprobe_table_locks[KPROBE_TABLE_SIZE];
  
  static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
  {
          return &(kretprobe_table_locks[hash].lock);
  }
  
  /*
   * Normally, functions that we'd want to prohibit kprobes in, are marked
   * __kprobes. But, there are cases where such functions already belong to
   * a different section (__sched for preempt_schedule)
   *
   * For such cases, we now have a blacklist
   */
  static struct kprobe_blackpoint kprobe_blacklist[] = {
          {"preempt_schedule",},
          {NULL}    /* Terminator */
  };
  
  #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
  /*
   * kprobe->ainsn.insn points to the copy of the instruction to be
   * single-stepped. x86_64, POWER4 and above have no-exec support and
   * stepping on the instruction on a vmalloced/kmalloced/data page
  * is a recipe for disaster
  */
 #define INSNS_PER_PAGE        (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
 
 struct kprobe_insn_page {
         struct hlist_node hlist;
         kprobe_opcode_t *insns;                /* Page of instruction slots */
         char slot_used[INSNS_PER_PAGE];
         int nused;
         int ngarbage;
 };
 
 enum kprobe_slot_state {
         SLOT_CLEAN = 0,
         SLOT_DIRTY = 1,
         SLOT_USED = 2,
 };
 
 static struct hlist_head kprobe_insn_pages;
 static int kprobe_garbage_slots;
 static int collect_garbage_slots(void);
 
 static int __kprobes check_safety(void)
 {
         int ret = 0;
 #if defined(CONFIG_PREEMPT) && defined(CONFIG_PM)
         ret = freeze_processes();
         if (ret == 0) {
                 struct task_struct *p, *q;
                 do_each_thread(p, q) {
                         if (p != current && p->state == TASK_RUNNING &&
                             p->pid != 0) {
                                 printk("Check failed: %s is running\n",p->comm);
                                 ret = -1;
                                 goto loop_end;
                         }
                 } while_each_thread(p, q);
         }
 loop_end:
         thaw_processes();
 #else
         synchronize_sched();
 #endif
         return ret;
 }
 
 /**
  * get_insn_slot() - Find a slot on an executable page for an instruction.
  * We allocate an executable page if there's no room on existing ones.
  */
 kprobe_opcode_t __kprobes *get_insn_slot(void)
 {
         struct kprobe_insn_page *kip;
         struct hlist_node *pos;
 
  retry:
         hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) {
                 if (kip->nused < INSNS_PER_PAGE) {
                         int i;
                         for (i = 0; i < INSNS_PER_PAGE; i++) {
                                 if (kip->slot_used[i] == SLOT_CLEAN) {
                                         kip->slot_used[i] = SLOT_USED;
                                         kip->nused++;
                                         return kip->insns + (i * MAX_INSN_SIZE);
                                 }
                         }
                         /* Surprise!  No unused slots.  Fix kip->nused. */
                         kip->nused = INSNS_PER_PAGE;
                 }
         }
 
         /* If there are any garbage slots, collect it and try again. */
         if (kprobe_garbage_slots && collect_garbage_slots() == 0) {
                 goto retry;
         }
         /* All out of space.  Need to allocate a new page. Use slot 0. */
         kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL);
         if (!kip)
                 return NULL;
 
         /*
          * Use module_alloc so this page is within +/- 2GB of where the
          * kernel image and loaded module images reside. This is required
          * so x86_64 can correctly handle the %rip-relative fixups.
          */
         kip->insns = module_alloc(PAGE_SIZE);
         if (!kip->insns) {
                 kfree(kip);
                 return NULL;
         }
         INIT_HLIST_NODE(&kip->hlist);
         hlist_add_head(&kip->hlist, &kprobe_insn_pages);
         memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE);
         kip->slot_used[0] = SLOT_USED;
         kip->nused = 1;
         kip->ngarbage = 0;
         return kip->insns;
 }
 
 /* Return 1 if all garbages are collected, otherwise 0. */
 static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
 {
         kip->slot_used[idx] = SLOT_CLEAN;
         kip->nused--;
         if (kip->nused == 0) {
                 /*
                  * Page is no longer in use.  Free it unless
                  * it's the last one.  We keep the last one
                  * so as not to have to set it up again the
                  * next time somebody inserts a probe.
                  */
                 hlist_del(&kip->hlist);
                 if (hlist_empty(&kprobe_insn_pages)) {
                         INIT_HLIST_NODE(&kip->hlist);
                         hlist_add_head(&kip->hlist,
                                        &kprobe_insn_pages);
                 } else {
                         module_free(NULL, kip->insns);
                         kfree(kip);
                 }
                 return 1;
         }
         return 0;
 }
 
 static int __kprobes collect_garbage_slots(void)
 {
         struct kprobe_insn_page *kip;
         struct hlist_node *pos, *next;
 
         /* Ensure no-one is preepmted on the garbages */
         if (check_safety() != 0)
                 return -EAGAIN;
 
         hlist_for_each_entry_safe(kip, pos, next, &kprobe_insn_pages, hlist) {
                 int i;
                 if (kip->ngarbage == 0)
                         continue;
                 kip->ngarbage = 0;        /* we will collect all garbages */
                 for (i = 0; i < INSNS_PER_PAGE; i++) {
                         if (kip->slot_used[i] == SLOT_DIRTY &&
                             collect_one_slot(kip, i))
                                 break;
                 }
         }
         kprobe_garbage_slots = 0;
         return 0;
 }
 
 void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
 {
         struct kprobe_insn_page *kip;
         struct hlist_node *pos;
 
         hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) {
                 if (kip->insns <= slot &&
                     slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
                         int i = (slot - kip->insns) / MAX_INSN_SIZE;
                         if (dirty) {
                                 kip->slot_used[i] = SLOT_DIRTY;
                                 kip->ngarbage++;
                         } else {
                                 collect_one_slot(kip, i);
                         }
                         break;
                 }
         }
 
         if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE)
                 collect_garbage_slots();
 }
 #endif
 
 /* We have preemption disabled.. so it is safe to use __ versions */
 static inline void set_kprobe_instance(struct kprobe *kp)
 {
         __get_cpu_var(kprobe_instance) = kp;
 }
 
 static inline void reset_kprobe_instance(void)
 {
         __get_cpu_var(kprobe_instance) = NULL;
 }
 
 /*
  * This routine is called either:
  *         - under the kprobe_mutex - during kprobe_[un]register()
  *                                 OR
  *         - with preemption disabled - from arch/xxx/kernel/kprobes.c
  */
 struct kprobe __kprobes *get_kprobe(void *addr)
 {
         struct hlist_head *head;
         struct hlist_node *node;
         struct kprobe *p;
 
         head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
         hlist_for_each_entry_rcu(p, node, head, hlist) {
                 if (p->addr == addr)
                         return p;
         }
         return NULL;
 }
 
 /*
  * Aggregate handlers for multiple kprobes support - these handlers
  * take care of invoking the individual kprobe handlers on p->list
  */
 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
 {
         struct kprobe *kp;
 
         list_for_each_entry_rcu(kp, &p->list, list) {
                 if (kp->pre_handler) {
                         set_kprobe_instance(kp);
                         if (kp->pre_handler(kp, regs))
                                 return 1;
                 }
                 reset_kprobe_instance();
         }
         return 0;
 }
 
 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
                                         unsigned long flags)
 {
         struct kprobe *kp;
 
         list_for_each_entry_rcu(kp, &p->list, list) {
                 if (kp->post_handler) {
                         set_kprobe_instance(kp);
                         kp->post_handler(kp, regs, flags);
                         reset_kprobe_instance();
                 }
         }
 }
 
 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
                                         int trapnr)
 {
         struct kprobe *cur = __get_cpu_var(kprobe_instance);
 
         /*
          * if we faulted "during" the execution of a user specified
          * probe handler, invoke just that probe's fault handler
          */
         if (cur && cur->fault_handler) {
                 if (cur->fault_handler(cur, regs, trapnr))
                         return 1;
         }
         return 0;
 }
 
 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
 {
         struct kprobe *cur = __get_cpu_var(kprobe_instance);
         int ret = 0;
 
         if (cur && cur->break_handler) {
                 if (cur->break_handler(cur, regs))
                         ret = 1;
         }
         reset_kprobe_instance();
         return ret;
 }
 
 /* Walks the list and increments nmissed count for multiprobe case */
 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
 {
         struct kprobe *kp;
         if (p->pre_handler != aggr_pre_handler) {
                 p->nmissed++;
         } else {
                 list_for_each_entry_rcu(kp, &p->list, list)
                         kp->nmissed++;
         }
         return;
 }
 
 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
                                 struct hlist_head *head)
 {
         struct kretprobe *rp = ri->rp;
 
         /* remove rp inst off the rprobe_inst_table */
         hlist_del(&ri->hlist);
         INIT_HLIST_NODE(&ri->hlist);
         if (likely(rp)) {
                 spin_lock(&rp->lock);
                 hlist_add_head(&ri->hlist, &rp->free_instances);
                 spin_unlock(&rp->lock);
         } else
                 /* Unregistering */
                 hlist_add_head(&ri->hlist, head);
 }
 
 void kretprobe_hash_lock(struct task_struct *tsk,
                          struct hlist_head **head, unsigned long *flags)
 {
         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
         spinlock_t *hlist_lock;
 
         *head = &kretprobe_inst_table[hash];
         hlist_lock = kretprobe_table_lock_ptr(hash);
         spin_lock_irqsave(hlist_lock, *flags);
 }
 
 static void kretprobe_table_lock(unsigned long hash, unsigned long *flags)
 {
         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
         spin_lock_irqsave(hlist_lock, *flags);
 }
 
 void kretprobe_hash_unlock(struct task_struct *tsk, unsigned long *flags)
 {
         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
         spinlock_t *hlist_lock;
 
         hlist_lock = kretprobe_table_lock_ptr(hash);
         spin_unlock_irqrestore(hlist_lock, *flags);
 }
 
 void kretprobe_table_unlock(unsigned long hash, unsigned long *flags)
 {
         spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
         spin_unlock_irqrestore(hlist_lock, *flags);
 }
 
 /*
  * This function is called from finish_task_switch when task tk becomes dead,
  * so that we can recycle any function-return probe instances associated
  * with this task. These left over instances represent probed functions
  * that have been called but will never return.
  */
 void __kprobes kprobe_flush_task(struct task_struct *tk)
 {
         struct kretprobe_instance *ri;
         struct hlist_head *head, empty_rp;
         struct hlist_node *node, *tmp;
         unsigned long hash, flags = 0;
 
         if (unlikely(!kprobes_initialized))
                 /* Early boot.  kretprobe_table_locks not yet initialized. */
                 return;
 
         hash = hash_ptr(tk, KPROBE_HASH_BITS);
         head = &kretprobe_inst_table[hash];
         kretprobe_table_lock(hash, &flags);
         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
                 if (ri->task == tk)
                         recycle_rp_inst(ri, &empty_rp);
         }
         kretprobe_table_unlock(hash, &flags);
         INIT_HLIST_HEAD(&empty_rp);
         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
                 hlist_del(&ri->hlist);
                 kfree(ri);
         }
 }
 
 static inline void free_rp_inst(struct kretprobe *rp)
 {
         struct kretprobe_instance *ri;
         struct hlist_node *pos, *next;
 
         hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) {
                 hlist_del(&ri->hlist);
                 kfree(ri);
         }
 }
 
 static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
 {
         unsigned long flags, hash;
         struct kretprobe_instance *ri;
         struct hlist_node *pos, *next;
         struct hlist_head *head;
 
         /* No race here */
         for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
                 kretprobe_table_lock(hash, &flags);
                 head = &kretprobe_inst_table[hash];
                 hlist_for_each_entry_safe(ri, pos, next, head, hlist) {
                         if (ri->rp == rp)
                                 ri->rp = NULL;
                 }
                 kretprobe_table_unlock(hash, &flags);
         }
         free_rp_inst(rp);
 }
 
 /*
  * Keep all fields in the kprobe consistent
  */
 static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
 {
         memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
         memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
 }
 
 /*
 * Add the new probe to old_p->list. Fail if this is the
 * second jprobe at the address - two jprobes can't coexist
 */
 static int __kprobes add_new_kprobe(struct kprobe *old_p, struct kprobe *p)
 {
         if (p->break_handler) {
                 if (old_p->break_handler)
                         return -EEXIST;
                 list_add_tail_rcu(&p->list, &old_p->list);
                 old_p->break_handler = aggr_break_handler;
         } else
                 list_add_rcu(&p->list, &old_p->list);
         if (p->post_handler && !old_p->post_handler)
                 old_p->post_handler = aggr_post_handler;
         return 0;
 }
 
 /*
  * Fill in the required fields of the "manager kprobe". Replace the
  * earlier kprobe in the hlist with the manager kprobe
  */
 static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
 {
         copy_kprobe(p, ap);
         flush_insn_slot(ap);
         ap->addr = p->addr;
         ap->pre_handler = aggr_pre_handler;
         ap->fault_handler = aggr_fault_handler;
         if (p->post_handler)
                 ap->post_handler = aggr_post_handler;
         if (p->break_handler)
                 ap->break_handler = aggr_break_handler;
 
         INIT_LIST_HEAD(&ap->list);
         list_add_rcu(&p->list, &ap->list);
 
         hlist_replace_rcu(&p->hlist, &ap->hlist);
 }
 
 /*
  * This is the second or subsequent kprobe at the address - handle
  * the intricacies
  */
 static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
                                           struct kprobe *p)
 {
         int ret = 0;
         struct kprobe *ap;
 
         if (old_p->pre_handler == aggr_pre_handler) {
                 copy_kprobe(old_p, p);
                 ret = add_new_kprobe(old_p, p);
         } else {
                 ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
                 if (!ap)
                         return -ENOMEM;
                 add_aggr_kprobe(ap, old_p);
                 copy_kprobe(ap, p);
                 ret = add_new_kprobe(ap, p);
         }
         return ret;
 }
 
 static int __kprobes in_kprobes_functions(unsigned long addr)
 {
         struct kprobe_blackpoint *kb;
 
         if (addr >= (unsigned long)__kprobes_text_start &&
             addr < (unsigned long)__kprobes_text_end)
                 return -EINVAL;
         /*
          * If there exists a kprobe_blacklist, verify and
          * fail any probe registration in the prohibited area
          */
         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
                 if (kb->start_addr) {
                         if (addr >= kb->start_addr &&
                             addr < (kb->start_addr + kb->range))
                                 return -EINVAL;
                 }
         }
         return 0;
 }
 
 /*
  * If we have a symbol_name argument, look it up and add the offset field
  * to it. This way, we can specify a relative address to a symbol.
  */
 static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
 {
         kprobe_opcode_t *addr = p->addr;
         if (p->symbol_name) {
                 if (addr)
                         return NULL;
                 kprobe_lookup_name(p->symbol_name, addr);
         }
 
         if (!addr)
                 return NULL;
         return (kprobe_opcode_t *)(((char *)addr) + p->offset);
 }
 
 static int __kprobes __register_kprobe(struct kprobe *p,
         unsigned long called_from)
 {
         int ret = 0;
         struct kprobe *old_p;
         struct module *probed_mod;
         kprobe_opcode_t *addr;
 
         addr = kprobe_addr(p);
         if (!addr)
                 return -EINVAL;
         p->addr = addr;
 
         preempt_disable();
         if (!__kernel_text_address((unsigned long) p->addr) ||
             in_kprobes_functions((unsigned long) p->addr)) {
                 preempt_enable();
                 return -EINVAL;
         }
 
         p->mod_refcounted = 0;
 
         /*
          * Check if are we probing a module.
          */
         probed_mod = __module_text_address((unsigned long) p->addr);
         if (probed_mod) {
                 struct module *calling_mod;
                 calling_mod = __module_text_address(called_from);
                 /*
                  * We must allow modules to probe themself and in this case
                  * avoid incrementing the module refcount, so as to allow
                  * unloading of self probing modules.
                  */
                 if (calling_mod && calling_mod != probed_mod) {
                         if (unlikely(!try_module_get(probed_mod))) {
                                 preempt_enable();
                                 return -EINVAL;
                         }
                         p->mod_refcounted = 1;
                 } else
                         probed_mod = NULL;
         }
         preempt_enable();
 
         p->nmissed = 0;
         INIT_LIST_HEAD(&p->list);
         mutex_lock(&kprobe_mutex);
         old_p = get_kprobe(p->addr);
         if (old_p) {
                 ret = register_aggr_kprobe(old_p, p);
                 goto out;
         }
 
         ret = arch_prepare_kprobe(p);
         if (ret)
                 goto out;
 
         INIT_HLIST_NODE(&p->hlist);
         hlist_add_head_rcu(&p->hlist,
                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
 
         if (kprobe_enabled)
                 arch_arm_kprobe(p);
 
 out:
         mutex_unlock(&kprobe_mutex);
 
         if (ret && probed_mod)
                 module_put(probed_mod);
         return ret;
 }
 
 /*
  * Unregister a kprobe without a scheduler synchronization.
  */
 static int __kprobes __unregister_kprobe_top(struct kprobe *p)
 {
         struct kprobe *old_p, *list_p;
 
         old_p = get_kprobe(p->addr);
         if (unlikely(!old_p))
                 return -EINVAL;
 
         if (p != old_p) {
                 list_for_each_entry_rcu(list_p, &old_p->list, list)
                         if (list_p == p)
                         /* kprobe p is a valid probe */
                                 goto valid_p;
                 return -EINVAL;
         }
 valid_p:
         if (old_p == p ||
             (old_p->pre_handler == aggr_pre_handler &&
              list_is_singular(&old_p->list))) {
                 /*
                  * Only probe on the hash list. Disarm only if kprobes are
                  * enabled - otherwise, the breakpoint would already have
                  * been removed. We save on flushing icache.
                  */
                 if (kprobe_enabled)
                         arch_disarm_kprobe(p);
                 hlist_del_rcu(&old_p->hlist);
         } else {
                 if (p->break_handler)
                         old_p->break_handler = NULL;
                 if (p->post_handler) {
                         list_for_each_entry_rcu(list_p, &old_p->list, list) {
                                 if ((list_p != p) && (list_p->post_handler))
                                         goto noclean;
                         }
                         old_p->post_handler = NULL;
                 }
 noclean:
                 list_del_rcu(&p->list);
         }
         return 0;
 }
 
 static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
 {
         struct module *mod;
         struct kprobe *old_p;
 
         if (p->mod_refcounted) {
                 /*
                  * Since we've already incremented refcount,
                  * we don't need to disable preemption.
                  */
                 mod = module_text_address((unsigned long)p->addr);
                 if (mod)
                         module_put(mod);
         }
 
         if (list_empty(&p->list) || list_is_singular(&p->list)) {
                 if (!list_empty(&p->list)) {
                         /* "p" is the last child of an aggr_kprobe */
                         old_p = list_entry(p->list.next, struct kprobe, list);
                         list_del(&p->list);
                         kfree(old_p);
                 }
                 arch_remove_kprobe(p);
         }
 }
 
 static int __register_kprobes(struct kprobe **kps, int num,
         unsigned long called_from)
 {
         int i, ret = 0;
 
         if (num <= 0)
                 return -EINVAL;
         for (i = 0; i < num; i++) {
                 ret = __register_kprobe(kps[i], called_from);
                 if (ret < 0) {
                         if (i > 0)
                                 unregister_kprobes(kps, i);
                         break;
                 }
         }
         return ret;
 }
 
 /*
  * Registration and unregistration functions for kprobe.
  */
 int __kprobes register_kprobe(struct kprobe *p)
 {
         return __register_kprobes(&p, 1,
                                   (unsigned long)__builtin_return_address(0));
 }
 
 void __kprobes unregister_kprobe(struct kprobe *p)
 {
         unregister_kprobes(&p, 1);
 }
 
 int __kprobes register_kprobes(struct kprobe **kps, int num)
 {
         return __register_kprobes(kps, num,
                                   (unsigned long)__builtin_return_address(0));
 }
 
 void __kprobes unregister_kprobes(struct kprobe **kps, int num)
 {
         int i;
 
         if (num <= 0)
                 return;
         mutex_lock(&kprobe_mutex);
         for (i = 0; i < num; i++)
                 if (__unregister_kprobe_top(kps[i]) < 0)
                         kps[i]->addr = NULL;
         mutex_unlock(&kprobe_mutex);
 
         synchronize_sched();
         for (i = 0; i < num; i++)
                 if (kps[i]->addr)
                         __unregister_kprobe_bottom(kps[i]);
 }
 
 static struct notifier_block kprobe_exceptions_nb = {
         .notifier_call = kprobe_exceptions_notify,
         .priority = 0x7fffffff /* we need to be notified first */
 };
 
 unsigned long __weak arch_deref_entry_point(void *entry)
 {
         return (unsigned long)entry;
 }
 
 static int __register_jprobes(struct jprobe **jps, int num,
         unsigned long called_from)
 {
         struct jprobe *jp;
         int ret = 0, i;
 
         if (num <= 0)
                 return -EINVAL;
         for (i = 0; i < num; i++) {
                 unsigned long addr;
                 jp = jps[i];
                 addr = arch_deref_entry_point(jp->entry);
 
                 if (!kernel_text_address(addr))
                         ret = -EINVAL;
                 else {
                         /* Todo: Verify probepoint is a function entry point */
                         jp->kp.pre_handler = setjmp_pre_handler;
                         jp->kp.break_handler = longjmp_break_handler;
                         ret = __register_kprobe(&jp->kp, called_from);
                 }
                 if (ret < 0) {
                         if (i > 0)
                                 unregister_jprobes(jps, i);
                         break;
                 }
         }
         return ret;
 }
 
 int __kprobes register_jprobe(struct jprobe *jp)
 {
         return __register_jprobes(&jp, 1,
                 (unsigned long)__builtin_return_address(0));
 }
 
 void __kprobes unregister_jprobe(struct jprobe *jp)
 {
         unregister_jprobes(&jp, 1);
 }
 
 int __kprobes register_jprobes(struct jprobe **jps, int num)
 {
         return __register_jprobes(jps, num,
                 (unsigned long)__builtin_return_address(0));
 }
 
 void __kprobes unregister_jprobes(struct jprobe **jps, int num)
 {
         int i;
 
         if (num <= 0)
                 return;
         mutex_lock(&kprobe_mutex);
         for (i = 0; i < num; i++)
                 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
                         jps[i]->kp.addr = NULL;
         mutex_unlock(&kprobe_mutex);
 
         synchronize_sched();
         for (i = 0; i < num; i++) {
                 if (jps[i]->kp.addr)
                         __unregister_kprobe_bottom(&jps[i]->kp);
         }
 }
 
 #ifdef CONFIG_KRETPROBES
 /*
  * This kprobe pre_handler is registered with every kretprobe. When probe
  * hits it will set up the return probe.
  */
 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
                                            struct pt_regs *regs)
 {
         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
         unsigned long hash, flags = 0;
         struct kretprobe_instance *ri;
 
         /*TODO: consider to only swap the RA after the last pre_handler fired */
         hash = hash_ptr(current, KPROBE_HASH_BITS);
         spin_lock_irqsave(&rp->lock, flags);
         if (!hlist_empty(&rp->free_instances)) {
                 ri = hlist_entry(rp->free_instances.first,
                                 struct kretprobe_instance, hlist);
                 hlist_del(&ri->hlist);
                 spin_unlock_irqrestore(&rp->lock, flags);
 
                 ri->rp = rp;
                 ri->task = current;
 
                 if (rp->entry_handler && rp->entry_handler(ri, regs)) {
                         spin_unlock_irqrestore(&rp->lock, flags);
                         return 0;
                 }
 
                 arch_prepare_kretprobe(ri, regs);
 
                 /* XXX(hch): why is there no hlist_move_head? */
                 INIT_HLIST_NODE(&ri->hlist);
                 kretprobe_table_lock(hash, &flags);
                 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
                 kretprobe_table_unlock(hash, &flags);
         } else {
                 rp->nmissed++;
                 spin_unlock_irqrestore(&rp->lock, flags);
         }
         return 0;
 }
 
 static int __kprobes __register_kretprobe(struct kretprobe *rp,
                                           unsigned long called_from)
 {
         int ret = 0;
         struct kretprobe_instance *inst;
         int i;
         void *addr;
 
         if (kretprobe_blacklist_size) {
                 addr = kprobe_addr(&rp->kp);
                 if (!addr)
                         return -EINVAL;
 
                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
                         if (kretprobe_blacklist[i].addr == addr)
                                 return -EINVAL;
                 }
         }
 
         rp->kp.pre_handler = pre_handler_kretprobe;
         rp->kp.post_handler = NULL;
         rp->kp.fault_handler = NULL;
         rp->kp.break_handler = NULL;
 
         /* Pre-allocate memory for max kretprobe instances */
         if (rp->maxactive <= 0) {
 #ifdef CONFIG_PREEMPT
                 rp->maxactive = max(10, 2 * NR_CPUS);
 #else
                 rp->maxactive = NR_CPUS;
 #endif
         }
         spin_lock_init(&rp->lock);
         INIT_HLIST_HEAD(&rp->free_instances);
         for (i = 0; i < rp->maxactive; i++) {
                 inst = kmalloc(sizeof(struct kretprobe_instance) +
                                rp->data_size, GFP_KERNEL);
                 if (inst == NULL) {
                         free_rp_inst(rp);
                         return -ENOMEM;
                 }
                 INIT_HLIST_NODE(&inst->hlist);
                 hlist_add_head(&inst->hlist, &rp->free_instances);
         }
 
         rp->nmissed = 0;
         /* Establish function entry probe point */
         ret = __register_kprobe(&rp->kp, called_from);
         if (ret != 0)
                 free_rp_inst(rp);
         return ret;
 }
 
 static int __register_kretprobes(struct kretprobe **rps, int num,
         unsigned long called_from)
 {
         int ret = 0, i;
 
         if (num <= 0)
                 return -EINVAL;
         for (i = 0; i < num; i++) {
                 ret = __register_kretprobe(rps[i], called_from);
                 if (ret < 0) {
                         if (i > 0)
                                 unregister_kretprobes(rps, i);
                         break;
                 }
         }
         return ret;
 }
 
 int __kprobes register_kretprobe(struct kretprobe *rp)
 {
         return __register_kretprobes(&rp, 1,
                         (unsigned long)__builtin_return_address(0));
 }
 
void __kprobes unregister_kretprobe(struct kretprobe *rp)
{
        unregister_kretprobes(&rp, 1);
}

int __kprobes register_kretprobes(struct kretprobe **rps, int num)
{
        return __register_kretprobes(rps, num,
                        (unsigned long)__builtin_return_address(0));
}

void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
{
        int i;

        if (num <= 0)
                return;
        mutex_lock(&kprobe_mutex);
        for (i = 0; i < num; i++)
                if (__unregister_kprobe_top(&rps[i]->kp) < 0)
                        rps[i]->kp.addr = NULL;
        mutex_unlock(&kprobe_mutex);

        synchronize_sched();
        for (i = 0; i < num; i++) {
                if (rps[i]->kp.addr) {
                        __unregister_kprobe_bottom(&rps[i]->kp);
                        cleanup_rp_inst(rps[i]);
                }
        }
}

#else /* CONFIG_KRETPROBES */
int __kprobes register_kretprobe(struct kretprobe *rp)
{
        return -ENOSYS;
}

int __kprobes register_kretprobes(struct kretprobe **rps, int num)
{
        return -ENOSYS;
}
void __kprobes unregister_kretprobe(struct kretprobe *rp)
{
}

void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
{
}

static int __kprobes pre_handler_kretprobe(struct kprobe *p,
                                           struct pt_regs *regs)
{
        return 0;
}

#endif /* CONFIG_KRETPROBES */

static int __init init_kprobes(void)
{
        int i, err = 0;
        unsigned long offset = 0, size = 0;
        char *modname, namebuf[128];
        const char *symbol_name;
        void *addr;
        struct kprobe_blackpoint *kb;

        /* FIXME allocate the probe table, currently defined statically */
        /* initialize all list heads */
        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
                INIT_HLIST_HEAD(&kprobe_table[i]);
                INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
                spin_lock_init(&(kretprobe_table_locks[i].lock));
        }

        /*
         * Lookup and populate the kprobe_blacklist.
         *
         * Unlike the kretprobe blacklist, we'll need to determine
         * the range of addresses that belong to the said functions,
         * since a kprobe need not necessarily be at the beginning
         * of a function.
         */
        for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
                kprobe_lookup_name(kb->name, addr);
                if (!addr)
                        continue;

                kb->start_addr = (unsigned long)addr;
                symbol_name = kallsyms_lookup(kb->start_addr,
                                &size, &offset, &modname, namebuf);
                if (!symbol_name)
                        kb->range = 0;
                else
                        kb->range = size;
        }

        if (kretprobe_blacklist_size) {
                /* lookup the function address from its name */
                for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
                        kprobe_lookup_name(kretprobe_blacklist[i].name,
                                           kretprobe_blacklist[i].addr);
                        if (!kretprobe_blacklist[i].addr)
                                printk("kretprobe: lookup failed: %s\n",
                                       kretprobe_blacklist[i].name);
                }
        }

        /* By default, kprobes are enabled */
        kprobe_enabled = true;

        err = arch_init_kprobes();
        if (!err)
                err = register_die_notifier(&kprobe_exceptions_nb);
        kprobes_initialized = (err == 0);

        if (!err)
                init_test_probes();
        return err;
}

#ifdef CONFIG_DEBUG_FS
static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
                const char *sym, int offset,char *modname)
{
        char *kprobe_type;

        if (p->pre_handler == pre_handler_kretprobe)
                kprobe_type = "r";
        else if (p->pre_handler == setjmp_pre_handler)
                kprobe_type = "j";
        else
                kprobe_type = "k";
        if (sym)
                seq_printf(pi, "%p  %s  %s+0x%x  %s\n", p->addr, kprobe_type,
                        sym, offset, (modname ? modname : " "));
        else
                seq_printf(pi, "%p  %s  %p\n", p->addr, kprobe_type, p->addr);
}

static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
{
        return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
}

static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
{
        (*pos)++;
        if (*pos >= KPROBE_TABLE_SIZE)
                return NULL;
        return pos;
}

static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
{
        /* Nothing to do */
}

static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
{
        struct hlist_head *head;
        struct hlist_node *node;
        struct kprobe *p, *kp;
        const char *sym = NULL;
        unsigned int i = *(loff_t *) v;
        unsigned long offset = 0;
        char *modname, namebuf[128];

        head = &kprobe_table[i];
        preempt_disable();
        hlist_for_each_entry_rcu(p, node, head, hlist) {
                sym = kallsyms_lookup((unsigned long)p->addr, NULL,
                                        &offset, &modname, namebuf);
                if (p->pre_handler == aggr_pre_handler) {
                        list_for_each_entry_rcu(kp, &p->list, list)
                                report_probe(pi, kp, sym, offset, modname);
                } else
                        report_probe(pi, p, sym, offset, modname);
        }
        preempt_enable();
        return 0;
}

static struct seq_operations kprobes_seq_ops = {
        .start = kprobe_seq_start,
        .next  = kprobe_seq_next,
        .stop  = kprobe_seq_stop,
        .show  = show_kprobe_addr
};

static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
{
        return seq_open(filp, &kprobes_seq_ops);
}

static struct file_operations debugfs_kprobes_operations = {
        .open           = kprobes_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release,
};

static void __kprobes enable_all_kprobes(void)
{
        struct hlist_head *head;
        struct hlist_node *node;
        struct kprobe *p;
        unsigned int i;

        mutex_lock(&kprobe_mutex);

        /* If kprobes are already enabled, just return */
        if (kprobe_enabled)
                goto already_enabled;

        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
                head = &kprobe_table[i];
                hlist_for_each_entry_rcu(p, node, head, hlist)
                        arch_arm_kprobe(p);
        }

        kprobe_enabled = true;
        printk(KERN_INFO "Kprobes globally enabled\n");

already_enabled:
        mutex_unlock(&kprobe_mutex);
        return;
}

static void __kprobes disable_all_kprobes(void)
{
        struct hlist_head *head;
        struct hlist_node *node;
        struct kprobe *p;
        unsigned int i;

        mutex_lock(&kprobe_mutex);

        /* If kprobes are already disabled, just return */
        if (!kprobe_enabled)
                goto already_disabled;

        kprobe_enabled = false;
        printk(KERN_INFO "Kprobes globally disabled\n");
        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
                head = &kprobe_table[i];
                hlist_for_each_entry_rcu(p, node, head, hlist) {
                        if (!arch_trampoline_kprobe(p))
                                arch_disarm_kprobe(p);
                }
        }

        mutex_unlock(&kprobe_mutex);
        /* Allow all currently running kprobes to complete */
        synchronize_sched();
        return;

already_disabled:
        mutex_unlock(&kprobe_mutex);
        return;
}

/*
 * XXX: The debugfs bool file interface doesn't allow for callbacks
 * when the bool state is switched. We can reuse that facility when
 * available
 */
static ssize_t read_enabled_file_bool(struct file *file,
               char __user *user_buf, size_t count, loff_t *ppos)
{
        char buf[3];

        if (kprobe_enabled)
                buf[0] = '1';
        else
                buf[0] = '0';
        buf[1] = '\n';
        buf[2] = 0x00;
        return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
}

static ssize_t write_enabled_file_bool(struct file *file,
               const char __user *user_buf, size_t count, loff_t *ppos)
{
        char buf[32];
        int buf_size;

        buf_size = min(count, (sizeof(buf)-1));
        if (copy_from_user(buf, user_buf, buf_size))
                return -EFAULT;

        switch (buf[0]) {
        case 'y':
        case 'Y':
        case '1':
                enable_all_kprobes();
                break;
        case 'n':
        case 'N':
        case '0':
                disable_all_kprobes();
                break;
        }

        return count;
}

static struct file_operations fops_kp = {
        .read =         read_enabled_file_bool,
        .write =        write_enabled_file_bool,
};

static int __kprobes debugfs_kprobe_init(void)
{
        struct dentry *dir, *file;
        unsigned int value = 1;

        dir = debugfs_create_dir("kprobes", NULL);
        if (!dir)
                return -ENOMEM;

        file = debugfs_create_file("list", 0444, dir, NULL,
                                &debugfs_kprobes_operations);
        if (!file) {
                debugfs_remove(dir);
                return -ENOMEM;
        }

        file = debugfs_create_file("enabled", 0600, dir,
                                        &value, &fops_kp);
        if (!file) {
                debugfs_remove(dir);
                return -ENOMEM;
        }

        return 0;
}

late_initcall(debugfs_kprobe_init);
#endif /* CONFIG_DEBUG_FS */

module_init(init_kprobes);

EXPORT_SYMBOL_GPL(register_kprobe);
EXPORT_SYMBOL_GPL(unregister_kprobe);
EXPORT_SYMBOL_GPL(register_kprobes);
EXPORT_SYMBOL_GPL(unregister_kprobes);
EXPORT_SYMBOL_GPL(register_jprobe);
EXPORT_SYMBOL_GPL(unregister_jprobe);
EXPORT_SYMBOL_GPL(register_jprobes);
EXPORT_SYMBOL_GPL(unregister_jprobes);
EXPORT_SYMBOL_GPL(jprobe_return);
EXPORT_SYMBOL_GPL(register_kretprobe);
EXPORT_SYMBOL_GPL(unregister_kretprobe);
EXPORT_SYMBOL_GPL(register_kretprobes);
EXPORT_SYMBOL_GPL(unregister_kretprobes);