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0001 /*
0002  *  Kernel Probes (KProbes)
0003  *  kernel/kprobes.c
0004  *
0005  * This program is free software; you can redistribute it and/or modify
0006  * it under the terms of the GNU General Public License as published by
0007  * the Free Software Foundation; either version 2 of the License, or
0008  * (at your option) any later version.
0009  *
0010  * This program is distributed in the hope that it will be useful,
0011  * but WITHOUT ANY WARRANTY; without even the implied warranty of
0012  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
0013  * GNU General Public License for more details.
0014  *
0015  * You should have received a copy of the GNU General Public License
0016  * along with this program; if not, write to the Free Software
0017  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
0018  *
0019  * Copyright (C) IBM Corporation, 2002, 2004
0020  *
0021  * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
0022  *      Probes initial implementation (includes suggestions from
0023  *      Rusty Russell).
0024  * 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
0025  *      hlists and exceptions notifier as suggested by Andi Kleen.
0026  * 2004-July    Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
0027  *      interface to access function arguments.
0028  * 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
0029  *      exceptions notifier to be first on the priority list.
0030  * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
0031  *      <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
0032  *      <prasanna@in.ibm.com> added function-return probes.
0033  */
0034 #include <linux/kprobes.h>
0035 #include <linux/hash.h>
0036 #include <linux/init.h>
0037 #include <linux/slab.h>
0038 #include <linux/stddef.h>
0039 #include <linux/export.h>
0040 #include <linux/moduleloader.h>
0041 #include <linux/kallsyms.h>
0042 #include <linux/freezer.h>
0043 #include <linux/seq_file.h>
0044 #include <linux/debugfs.h>
0045 #include <linux/sysctl.h>
0046 #include <linux/kdebug.h>
0047 #include <linux/memory.h>
0048 #include <linux/ftrace.h>
0049 #include <linux/cpu.h>
0050 #include <linux/jump_label.h>
0051 
0052 #include <asm/sections.h>
0053 #include <asm/cacheflush.h>
0054 #include <asm/errno.h>
0055 #include <linux/uaccess.h>
0056 
0057 #define KPROBE_HASH_BITS 6
0058 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
0059 
0060 
0061 /*
0062  * Some oddball architectures like 64bit powerpc have function descriptors
0063  * so this must be overridable.
0064  */
0065 #ifndef kprobe_lookup_name
0066 #define kprobe_lookup_name(name, addr) \
0067     addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
0068 #endif
0069 
0070 static int kprobes_initialized;
0071 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
0072 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
0073 
0074 /* NOTE: change this value only with kprobe_mutex held */
0075 static bool kprobes_all_disarmed;
0076 
0077 /* This protects kprobe_table and optimizing_list */
0078 static DEFINE_MUTEX(kprobe_mutex);
0079 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
0080 static struct {
0081     raw_spinlock_t lock ____cacheline_aligned_in_smp;
0082 } kretprobe_table_locks[KPROBE_TABLE_SIZE];
0083 
0084 static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
0085 {
0086     return &(kretprobe_table_locks[hash].lock);
0087 }
0088 
0089 /* Blacklist -- list of struct kprobe_blacklist_entry */
0090 static LIST_HEAD(kprobe_blacklist);
0091 
0092 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
0093 /*
0094  * kprobe->ainsn.insn points to the copy of the instruction to be
0095  * single-stepped. x86_64, POWER4 and above have no-exec support and
0096  * stepping on the instruction on a vmalloced/kmalloced/data page
0097  * is a recipe for disaster
0098  */
0099 struct kprobe_insn_page {
0100     struct list_head list;
0101     kprobe_opcode_t *insns;     /* Page of instruction slots */
0102     struct kprobe_insn_cache *cache;
0103     int nused;
0104     int ngarbage;
0105     char slot_used[];
0106 };
0107 
0108 #define KPROBE_INSN_PAGE_SIZE(slots)            \
0109     (offsetof(struct kprobe_insn_page, slot_used) + \
0110      (sizeof(char) * (slots)))
0111 
0112 static int slots_per_page(struct kprobe_insn_cache *c)
0113 {
0114     return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
0115 }
0116 
0117 enum kprobe_slot_state {
0118     SLOT_CLEAN = 0,
0119     SLOT_DIRTY = 1,
0120     SLOT_USED = 2,
0121 };
0122 
0123 static void *alloc_insn_page(void)
0124 {
0125     return module_alloc(PAGE_SIZE);
0126 }
0127 
0128 static void free_insn_page(void *page)
0129 {
0130     module_memfree(page);
0131 }
0132 
0133 struct kprobe_insn_cache kprobe_insn_slots = {
0134     .mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex),
0135     .alloc = alloc_insn_page,
0136     .free = free_insn_page,
0137     .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
0138     .insn_size = MAX_INSN_SIZE,
0139     .nr_garbage = 0,
0140 };
0141 static int collect_garbage_slots(struct kprobe_insn_cache *c);
0142 
0143 /**
0144  * __get_insn_slot() - Find a slot on an executable page for an instruction.
0145  * We allocate an executable page if there's no room on existing ones.
0146  */
0147 kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
0148 {
0149     struct kprobe_insn_page *kip;
0150     kprobe_opcode_t *slot = NULL;
0151 
0152     mutex_lock(&c->mutex);
0153  retry:
0154     list_for_each_entry(kip, &c->pages, list) {
0155         if (kip->nused < slots_per_page(c)) {
0156             int i;
0157             for (i = 0; i < slots_per_page(c); i++) {
0158                 if (kip->slot_used[i] == SLOT_CLEAN) {
0159                     kip->slot_used[i] = SLOT_USED;
0160                     kip->nused++;
0161                     slot = kip->insns + (i * c->insn_size);
0162                     goto out;
0163                 }
0164             }
0165             /* kip->nused is broken. Fix it. */
0166             kip->nused = slots_per_page(c);
0167             WARN_ON(1);
0168         }
0169     }
0170 
0171     /* If there are any garbage slots, collect it and try again. */
0172     if (c->nr_garbage && collect_garbage_slots(c) == 0)
0173         goto retry;
0174 
0175     /* All out of space.  Need to allocate a new page. */
0176     kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
0177     if (!kip)
0178         goto out;
0179 
0180     /*
0181      * Use module_alloc so this page is within +/- 2GB of where the
0182      * kernel image and loaded module images reside. This is required
0183      * so x86_64 can correctly handle the %rip-relative fixups.
0184      */
0185     kip->insns = c->alloc();
0186     if (!kip->insns) {
0187         kfree(kip);
0188         goto out;
0189     }
0190     INIT_LIST_HEAD(&kip->list);
0191     memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
0192     kip->slot_used[0] = SLOT_USED;
0193     kip->nused = 1;
0194     kip->ngarbage = 0;
0195     kip->cache = c;
0196     list_add(&kip->list, &c->pages);
0197     slot = kip->insns;
0198 out:
0199     mutex_unlock(&c->mutex);
0200     return slot;
0201 }
0202 
0203 /* Return 1 if all garbages are collected, otherwise 0. */
0204 static int collect_one_slot(struct kprobe_insn_page *kip, int idx)
0205 {
0206     kip->slot_used[idx] = SLOT_CLEAN;
0207     kip->nused--;
0208     if (kip->nused == 0) {
0209         /*
0210          * Page is no longer in use.  Free it unless
0211          * it's the last one.  We keep the last one
0212          * so as not to have to set it up again the
0213          * next time somebody inserts a probe.
0214          */
0215         if (!list_is_singular(&kip->list)) {
0216             list_del(&kip->list);
0217             kip->cache->free(kip->insns);
0218             kfree(kip);
0219         }
0220         return 1;
0221     }
0222     return 0;
0223 }
0224 
0225 static int collect_garbage_slots(struct kprobe_insn_cache *c)
0226 {
0227     struct kprobe_insn_page *kip, *next;
0228 
0229     /* Ensure no-one is interrupted on the garbages */
0230     synchronize_sched();
0231 
0232     list_for_each_entry_safe(kip, next, &c->pages, list) {
0233         int i;
0234         if (kip->ngarbage == 0)
0235             continue;
0236         kip->ngarbage = 0;  /* we will collect all garbages */
0237         for (i = 0; i < slots_per_page(c); i++) {
0238             if (kip->slot_used[i] == SLOT_DIRTY &&
0239                 collect_one_slot(kip, i))
0240                 break;
0241         }
0242     }
0243     c->nr_garbage = 0;
0244     return 0;
0245 }
0246 
0247 void __free_insn_slot(struct kprobe_insn_cache *c,
0248               kprobe_opcode_t *slot, int dirty)
0249 {
0250     struct kprobe_insn_page *kip;
0251 
0252     mutex_lock(&c->mutex);
0253     list_for_each_entry(kip, &c->pages, list) {
0254         long idx = ((long)slot - (long)kip->insns) /
0255                 (c->insn_size * sizeof(kprobe_opcode_t));
0256         if (idx >= 0 && idx < slots_per_page(c)) {
0257             WARN_ON(kip->slot_used[idx] != SLOT_USED);
0258             if (dirty) {
0259                 kip->slot_used[idx] = SLOT_DIRTY;
0260                 kip->ngarbage++;
0261                 if (++c->nr_garbage > slots_per_page(c))
0262                     collect_garbage_slots(c);
0263             } else
0264                 collect_one_slot(kip, idx);
0265             goto out;
0266         }
0267     }
0268     /* Could not free this slot. */
0269     WARN_ON(1);
0270 out:
0271     mutex_unlock(&c->mutex);
0272 }
0273 
0274 #ifdef CONFIG_OPTPROBES
0275 /* For optimized_kprobe buffer */
0276 struct kprobe_insn_cache kprobe_optinsn_slots = {
0277     .mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
0278     .alloc = alloc_insn_page,
0279     .free = free_insn_page,
0280     .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
0281     /* .insn_size is initialized later */
0282     .nr_garbage = 0,
0283 };
0284 #endif
0285 #endif
0286 
0287 /* We have preemption disabled.. so it is safe to use __ versions */
0288 static inline void set_kprobe_instance(struct kprobe *kp)
0289 {
0290     __this_cpu_write(kprobe_instance, kp);
0291 }
0292 
0293 static inline void reset_kprobe_instance(void)
0294 {
0295     __this_cpu_write(kprobe_instance, NULL);
0296 }
0297 
0298 /*
0299  * This routine is called either:
0300  *  - under the kprobe_mutex - during kprobe_[un]register()
0301  *              OR
0302  *  - with preemption disabled - from arch/xxx/kernel/kprobes.c
0303  */
0304 struct kprobe *get_kprobe(void *addr)
0305 {
0306     struct hlist_head *head;
0307     struct kprobe *p;
0308 
0309     head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
0310     hlist_for_each_entry_rcu(p, head, hlist) {
0311         if (p->addr == addr)
0312             return p;
0313     }
0314 
0315     return NULL;
0316 }
0317 NOKPROBE_SYMBOL(get_kprobe);
0318 
0319 static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
0320 
0321 /* Return true if the kprobe is an aggregator */
0322 static inline int kprobe_aggrprobe(struct kprobe *p)
0323 {
0324     return p->pre_handler == aggr_pre_handler;
0325 }
0326 
0327 /* Return true(!0) if the kprobe is unused */
0328 static inline int kprobe_unused(struct kprobe *p)
0329 {
0330     return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
0331            list_empty(&p->list);
0332 }
0333 
0334 /*
0335  * Keep all fields in the kprobe consistent
0336  */
0337 static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
0338 {
0339     memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
0340     memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
0341 }
0342 
0343 #ifdef CONFIG_OPTPROBES
0344 /* NOTE: change this value only with kprobe_mutex held */
0345 static bool kprobes_allow_optimization;
0346 
0347 /*
0348  * Call all pre_handler on the list, but ignores its return value.
0349  * This must be called from arch-dep optimized caller.
0350  */
0351 void opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
0352 {
0353     struct kprobe *kp;
0354 
0355     list_for_each_entry_rcu(kp, &p->list, list) {
0356         if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
0357             set_kprobe_instance(kp);
0358             kp->pre_handler(kp, regs);
0359         }
0360         reset_kprobe_instance();
0361     }
0362 }
0363 NOKPROBE_SYMBOL(opt_pre_handler);
0364 
0365 /* Free optimized instructions and optimized_kprobe */
0366 static void free_aggr_kprobe(struct kprobe *p)
0367 {
0368     struct optimized_kprobe *op;
0369 
0370     op = container_of(p, struct optimized_kprobe, kp);
0371     arch_remove_optimized_kprobe(op);
0372     arch_remove_kprobe(p);
0373     kfree(op);
0374 }
0375 
0376 /* Return true(!0) if the kprobe is ready for optimization. */
0377 static inline int kprobe_optready(struct kprobe *p)
0378 {
0379     struct optimized_kprobe *op;
0380 
0381     if (kprobe_aggrprobe(p)) {
0382         op = container_of(p, struct optimized_kprobe, kp);
0383         return arch_prepared_optinsn(&op->optinsn);
0384     }
0385 
0386     return 0;
0387 }
0388 
0389 /* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
0390 static inline int kprobe_disarmed(struct kprobe *p)
0391 {
0392     struct optimized_kprobe *op;
0393 
0394     /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
0395     if (!kprobe_aggrprobe(p))
0396         return kprobe_disabled(p);
0397 
0398     op = container_of(p, struct optimized_kprobe, kp);
0399 
0400     return kprobe_disabled(p) && list_empty(&op->list);
0401 }
0402 
0403 /* Return true(!0) if the probe is queued on (un)optimizing lists */
0404 static int kprobe_queued(struct kprobe *p)
0405 {
0406     struct optimized_kprobe *op;
0407 
0408     if (kprobe_aggrprobe(p)) {
0409         op = container_of(p, struct optimized_kprobe, kp);
0410         if (!list_empty(&op->list))
0411             return 1;
0412     }
0413     return 0;
0414 }
0415 
0416 /*
0417  * Return an optimized kprobe whose optimizing code replaces
0418  * instructions including addr (exclude breakpoint).
0419  */
0420 static struct kprobe *get_optimized_kprobe(unsigned long addr)
0421 {
0422     int i;
0423     struct kprobe *p = NULL;
0424     struct optimized_kprobe *op;
0425 
0426     /* Don't check i == 0, since that is a breakpoint case. */
0427     for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
0428         p = get_kprobe((void *)(addr - i));
0429 
0430     if (p && kprobe_optready(p)) {
0431         op = container_of(p, struct optimized_kprobe, kp);
0432         if (arch_within_optimized_kprobe(op, addr))
0433             return p;
0434     }
0435 
0436     return NULL;
0437 }
0438 
0439 /* Optimization staging list, protected by kprobe_mutex */
0440 static LIST_HEAD(optimizing_list);
0441 static LIST_HEAD(unoptimizing_list);
0442 static LIST_HEAD(freeing_list);
0443 
0444 static void kprobe_optimizer(struct work_struct *work);
0445 static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
0446 #define OPTIMIZE_DELAY 5
0447 
0448 /*
0449  * Optimize (replace a breakpoint with a jump) kprobes listed on
0450  * optimizing_list.
0451  */
0452 static void do_optimize_kprobes(void)
0453 {
0454     /* Optimization never be done when disarmed */
0455     if (kprobes_all_disarmed || !kprobes_allow_optimization ||
0456         list_empty(&optimizing_list))
0457         return;
0458 
0459     /*
0460      * The optimization/unoptimization refers online_cpus via
0461      * stop_machine() and cpu-hotplug modifies online_cpus.
0462      * And same time, text_mutex will be held in cpu-hotplug and here.
0463      * This combination can cause a deadlock (cpu-hotplug try to lock
0464      * text_mutex but stop_machine can not be done because online_cpus
0465      * has been changed)
0466      * To avoid this deadlock, we need to call get_online_cpus()
0467      * for preventing cpu-hotplug outside of text_mutex locking.
0468      */
0469     get_online_cpus();
0470     mutex_lock(&text_mutex);
0471     arch_optimize_kprobes(&optimizing_list);
0472     mutex_unlock(&text_mutex);
0473     put_online_cpus();
0474 }
0475 
0476 /*
0477  * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
0478  * if need) kprobes listed on unoptimizing_list.
0479  */
0480 static void do_unoptimize_kprobes(void)
0481 {
0482     struct optimized_kprobe *op, *tmp;
0483 
0484     /* Unoptimization must be done anytime */
0485     if (list_empty(&unoptimizing_list))
0486         return;
0487 
0488     /* Ditto to do_optimize_kprobes */
0489     get_online_cpus();
0490     mutex_lock(&text_mutex);
0491     arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
0492     /* Loop free_list for disarming */
0493     list_for_each_entry_safe(op, tmp, &freeing_list, list) {
0494         /* Disarm probes if marked disabled */
0495         if (kprobe_disabled(&op->kp))
0496             arch_disarm_kprobe(&op->kp);
0497         if (kprobe_unused(&op->kp)) {
0498             /*
0499              * Remove unused probes from hash list. After waiting
0500              * for synchronization, these probes are reclaimed.
0501              * (reclaiming is done by do_free_cleaned_kprobes.)
0502              */
0503             hlist_del_rcu(&op->kp.hlist);
0504         } else
0505             list_del_init(&op->list);
0506     }
0507     mutex_unlock(&text_mutex);
0508     put_online_cpus();
0509 }
0510 
0511 /* Reclaim all kprobes on the free_list */
0512 static void do_free_cleaned_kprobes(void)
0513 {
0514     struct optimized_kprobe *op, *tmp;
0515 
0516     list_for_each_entry_safe(op, tmp, &freeing_list, list) {
0517         BUG_ON(!kprobe_unused(&op->kp));
0518         list_del_init(&op->list);
0519         free_aggr_kprobe(&op->kp);
0520     }
0521 }
0522 
0523 /* Start optimizer after OPTIMIZE_DELAY passed */
0524 static void kick_kprobe_optimizer(void)
0525 {
0526     schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
0527 }
0528 
0529 /* Kprobe jump optimizer */
0530 static void kprobe_optimizer(struct work_struct *work)
0531 {
0532     mutex_lock(&kprobe_mutex);
0533     /* Lock modules while optimizing kprobes */
0534     mutex_lock(&module_mutex);
0535 
0536     /*
0537      * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
0538      * kprobes before waiting for quiesence period.
0539      */
0540     do_unoptimize_kprobes();
0541 
0542     /*
0543      * Step 2: Wait for quiesence period to ensure all running interrupts
0544      * are done. Because optprobe may modify multiple instructions
0545      * there is a chance that Nth instruction is interrupted. In that
0546      * case, running interrupt can return to 2nd-Nth byte of jump
0547      * instruction. This wait is for avoiding it.
0548      */
0549     synchronize_sched();
0550 
0551     /* Step 3: Optimize kprobes after quiesence period */
0552     do_optimize_kprobes();
0553 
0554     /* Step 4: Free cleaned kprobes after quiesence period */
0555     do_free_cleaned_kprobes();
0556 
0557     mutex_unlock(&module_mutex);
0558     mutex_unlock(&kprobe_mutex);
0559 
0560     /* Step 5: Kick optimizer again if needed */
0561     if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
0562         kick_kprobe_optimizer();
0563 }
0564 
0565 /* Wait for completing optimization and unoptimization */
0566 static void wait_for_kprobe_optimizer(void)
0567 {
0568     mutex_lock(&kprobe_mutex);
0569 
0570     while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
0571         mutex_unlock(&kprobe_mutex);
0572 
0573         /* this will also make optimizing_work execute immmediately */
0574         flush_delayed_work(&optimizing_work);
0575         /* @optimizing_work might not have been queued yet, relax */
0576         cpu_relax();
0577 
0578         mutex_lock(&kprobe_mutex);
0579     }
0580 
0581     mutex_unlock(&kprobe_mutex);
0582 }
0583 
0584 /* Optimize kprobe if p is ready to be optimized */
0585 static void optimize_kprobe(struct kprobe *p)
0586 {
0587     struct optimized_kprobe *op;
0588 
0589     /* Check if the kprobe is disabled or not ready for optimization. */
0590     if (!kprobe_optready(p) || !kprobes_allow_optimization ||
0591         (kprobe_disabled(p) || kprobes_all_disarmed))
0592         return;
0593 
0594     /* Both of break_handler and post_handler are not supported. */
0595     if (p->break_handler || p->post_handler)
0596         return;
0597 
0598     op = container_of(p, struct optimized_kprobe, kp);
0599 
0600     /* Check there is no other kprobes at the optimized instructions */
0601     if (arch_check_optimized_kprobe(op) < 0)
0602         return;
0603 
0604     /* Check if it is already optimized. */
0605     if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
0606         return;
0607     op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
0608 
0609     if (!list_empty(&op->list))
0610         /* This is under unoptimizing. Just dequeue the probe */
0611         list_del_init(&op->list);
0612     else {
0613         list_add(&op->list, &optimizing_list);
0614         kick_kprobe_optimizer();
0615     }
0616 }
0617 
0618 /* Short cut to direct unoptimizing */
0619 static void force_unoptimize_kprobe(struct optimized_kprobe *op)
0620 {
0621     get_online_cpus();
0622     arch_unoptimize_kprobe(op);
0623     put_online_cpus();
0624     if (kprobe_disabled(&op->kp))
0625         arch_disarm_kprobe(&op->kp);
0626 }
0627 
0628 /* Unoptimize a kprobe if p is optimized */
0629 static void unoptimize_kprobe(struct kprobe *p, bool force)
0630 {
0631     struct optimized_kprobe *op;
0632 
0633     if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
0634         return; /* This is not an optprobe nor optimized */
0635 
0636     op = container_of(p, struct optimized_kprobe, kp);
0637     if (!kprobe_optimized(p)) {
0638         /* Unoptimized or unoptimizing case */
0639         if (force && !list_empty(&op->list)) {
0640             /*
0641              * Only if this is unoptimizing kprobe and forced,
0642              * forcibly unoptimize it. (No need to unoptimize
0643              * unoptimized kprobe again :)
0644              */
0645             list_del_init(&op->list);
0646             force_unoptimize_kprobe(op);
0647         }
0648         return;
0649     }
0650 
0651     op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
0652     if (!list_empty(&op->list)) {
0653         /* Dequeue from the optimization queue */
0654         list_del_init(&op->list);
0655         return;
0656     }
0657     /* Optimized kprobe case */
0658     if (force)
0659         /* Forcibly update the code: this is a special case */
0660         force_unoptimize_kprobe(op);
0661     else {
0662         list_add(&op->list, &unoptimizing_list);
0663         kick_kprobe_optimizer();
0664     }
0665 }
0666 
0667 /* Cancel unoptimizing for reusing */
0668 static void reuse_unused_kprobe(struct kprobe *ap)
0669 {
0670     struct optimized_kprobe *op;
0671 
0672     BUG_ON(!kprobe_unused(ap));
0673     /*
0674      * Unused kprobe MUST be on the way of delayed unoptimizing (means
0675      * there is still a relative jump) and disabled.
0676      */
0677     op = container_of(ap, struct optimized_kprobe, kp);
0678     if (unlikely(list_empty(&op->list)))
0679         printk(KERN_WARNING "Warning: found a stray unused "
0680             "aggrprobe@%p\n", ap->addr);
0681     /* Enable the probe again */
0682     ap->flags &= ~KPROBE_FLAG_DISABLED;
0683     /* Optimize it again (remove from op->list) */
0684     BUG_ON(!kprobe_optready(ap));
0685     optimize_kprobe(ap);
0686 }
0687 
0688 /* Remove optimized instructions */
0689 static void kill_optimized_kprobe(struct kprobe *p)
0690 {
0691     struct optimized_kprobe *op;
0692 
0693     op = container_of(p, struct optimized_kprobe, kp);
0694     if (!list_empty(&op->list))
0695         /* Dequeue from the (un)optimization queue */
0696         list_del_init(&op->list);
0697     op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
0698 
0699     if (kprobe_unused(p)) {
0700         /* Enqueue if it is unused */
0701         list_add(&op->list, &freeing_list);
0702         /*
0703          * Remove unused probes from the hash list. After waiting
0704          * for synchronization, this probe is reclaimed.
0705          * (reclaiming is done by do_free_cleaned_kprobes().)
0706          */
0707         hlist_del_rcu(&op->kp.hlist);
0708     }
0709 
0710     /* Don't touch the code, because it is already freed. */
0711     arch_remove_optimized_kprobe(op);
0712 }
0713 
0714 /* Try to prepare optimized instructions */
0715 static void prepare_optimized_kprobe(struct kprobe *p)
0716 {
0717     struct optimized_kprobe *op;
0718 
0719     op = container_of(p, struct optimized_kprobe, kp);
0720     arch_prepare_optimized_kprobe(op, p);
0721 }
0722 
0723 /* Allocate new optimized_kprobe and try to prepare optimized instructions */
0724 static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
0725 {
0726     struct optimized_kprobe *op;
0727 
0728     op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
0729     if (!op)
0730         return NULL;
0731 
0732     INIT_LIST_HEAD(&op->list);
0733     op->kp.addr = p->addr;
0734     arch_prepare_optimized_kprobe(op, p);
0735 
0736     return &op->kp;
0737 }
0738 
0739 static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
0740 
0741 /*
0742  * Prepare an optimized_kprobe and optimize it
0743  * NOTE: p must be a normal registered kprobe
0744  */
0745 static void try_to_optimize_kprobe(struct kprobe *p)
0746 {
0747     struct kprobe *ap;
0748     struct optimized_kprobe *op;
0749 
0750     /* Impossible to optimize ftrace-based kprobe */
0751     if (kprobe_ftrace(p))
0752         return;
0753 
0754     /* For preparing optimization, jump_label_text_reserved() is called */
0755     jump_label_lock();
0756     mutex_lock(&text_mutex);
0757 
0758     ap = alloc_aggr_kprobe(p);
0759     if (!ap)
0760         goto out;
0761 
0762     op = container_of(ap, struct optimized_kprobe, kp);
0763     if (!arch_prepared_optinsn(&op->optinsn)) {
0764         /* If failed to setup optimizing, fallback to kprobe */
0765         arch_remove_optimized_kprobe(op);
0766         kfree(op);
0767         goto out;
0768     }
0769 
0770     init_aggr_kprobe(ap, p);
0771     optimize_kprobe(ap);    /* This just kicks optimizer thread */
0772 
0773 out:
0774     mutex_unlock(&text_mutex);
0775     jump_label_unlock();
0776 }
0777 
0778 #ifdef CONFIG_SYSCTL
0779 static void optimize_all_kprobes(void)
0780 {
0781     struct hlist_head *head;
0782     struct kprobe *p;
0783     unsigned int i;
0784 
0785     mutex_lock(&kprobe_mutex);
0786     /* If optimization is already allowed, just return */
0787     if (kprobes_allow_optimization)
0788         goto out;
0789 
0790     kprobes_allow_optimization = true;
0791     for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
0792         head = &kprobe_table[i];
0793         hlist_for_each_entry_rcu(p, head, hlist)
0794             if (!kprobe_disabled(p))
0795                 optimize_kprobe(p);
0796     }
0797     printk(KERN_INFO "Kprobes globally optimized\n");
0798 out:
0799     mutex_unlock(&kprobe_mutex);
0800 }
0801 
0802 static void unoptimize_all_kprobes(void)
0803 {
0804     struct hlist_head *head;
0805     struct kprobe *p;
0806     unsigned int i;
0807 
0808     mutex_lock(&kprobe_mutex);
0809     /* If optimization is already prohibited, just return */
0810     if (!kprobes_allow_optimization) {
0811         mutex_unlock(&kprobe_mutex);
0812         return;
0813     }
0814 
0815     kprobes_allow_optimization = false;
0816     for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
0817         head = &kprobe_table[i];
0818         hlist_for_each_entry_rcu(p, head, hlist) {
0819             if (!kprobe_disabled(p))
0820                 unoptimize_kprobe(p, false);
0821         }
0822     }
0823     mutex_unlock(&kprobe_mutex);
0824 
0825     /* Wait for unoptimizing completion */
0826     wait_for_kprobe_optimizer();
0827     printk(KERN_INFO "Kprobes globally unoptimized\n");
0828 }
0829 
0830 static DEFINE_MUTEX(kprobe_sysctl_mutex);
0831 int sysctl_kprobes_optimization;
0832 int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
0833                       void __user *buffer, size_t *length,
0834                       loff_t *ppos)
0835 {
0836     int ret;
0837 
0838     mutex_lock(&kprobe_sysctl_mutex);
0839     sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
0840     ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
0841 
0842     if (sysctl_kprobes_optimization)
0843         optimize_all_kprobes();
0844     else
0845         unoptimize_all_kprobes();
0846     mutex_unlock(&kprobe_sysctl_mutex);
0847 
0848     return ret;
0849 }
0850 #endif /* CONFIG_SYSCTL */
0851 
0852 /* Put a breakpoint for a probe. Must be called with text_mutex locked */
0853 static void __arm_kprobe(struct kprobe *p)
0854 {
0855     struct kprobe *_p;
0856 
0857     /* Check collision with other optimized kprobes */
0858     _p = get_optimized_kprobe((unsigned long)p->addr);
0859     if (unlikely(_p))
0860         /* Fallback to unoptimized kprobe */
0861         unoptimize_kprobe(_p, true);
0862 
0863     arch_arm_kprobe(p);
0864     optimize_kprobe(p); /* Try to optimize (add kprobe to a list) */
0865 }
0866 
0867 /* Remove the breakpoint of a probe. Must be called with text_mutex locked */
0868 static void __disarm_kprobe(struct kprobe *p, bool reopt)
0869 {
0870     struct kprobe *_p;
0871 
0872     /* Try to unoptimize */
0873     unoptimize_kprobe(p, kprobes_all_disarmed);
0874 
0875     if (!kprobe_queued(p)) {
0876         arch_disarm_kprobe(p);
0877         /* If another kprobe was blocked, optimize it. */
0878         _p = get_optimized_kprobe((unsigned long)p->addr);
0879         if (unlikely(_p) && reopt)
0880             optimize_kprobe(_p);
0881     }
0882     /* TODO: reoptimize others after unoptimized this probe */
0883 }
0884 
0885 #else /* !CONFIG_OPTPROBES */
0886 
0887 #define optimize_kprobe(p)          do {} while (0)
0888 #define unoptimize_kprobe(p, f)         do {} while (0)
0889 #define kill_optimized_kprobe(p)        do {} while (0)
0890 #define prepare_optimized_kprobe(p)     do {} while (0)
0891 #define try_to_optimize_kprobe(p)       do {} while (0)
0892 #define __arm_kprobe(p)             arch_arm_kprobe(p)
0893 #define __disarm_kprobe(p, o)           arch_disarm_kprobe(p)
0894 #define kprobe_disarmed(p)          kprobe_disabled(p)
0895 #define wait_for_kprobe_optimizer()     do {} while (0)
0896 
0897 /* There should be no unused kprobes can be reused without optimization */
0898 static void reuse_unused_kprobe(struct kprobe *ap)
0899 {
0900     printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
0901     BUG_ON(kprobe_unused(ap));
0902 }
0903 
0904 static void free_aggr_kprobe(struct kprobe *p)
0905 {
0906     arch_remove_kprobe(p);
0907     kfree(p);
0908 }
0909 
0910 static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
0911 {
0912     return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
0913 }
0914 #endif /* CONFIG_OPTPROBES */
0915 
0916 #ifdef CONFIG_KPROBES_ON_FTRACE
0917 static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
0918     .func = kprobe_ftrace_handler,
0919     .flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY,
0920 };
0921 static int kprobe_ftrace_enabled;
0922 
0923 /* Must ensure p->addr is really on ftrace */
0924 static int prepare_kprobe(struct kprobe *p)
0925 {
0926     if (!kprobe_ftrace(p))
0927         return arch_prepare_kprobe(p);
0928 
0929     return arch_prepare_kprobe_ftrace(p);
0930 }
0931 
0932 /* Caller must lock kprobe_mutex */
0933 static void arm_kprobe_ftrace(struct kprobe *p)
0934 {
0935     int ret;
0936 
0937     ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
0938                    (unsigned long)p->addr, 0, 0);
0939     WARN(ret < 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p->addr, ret);
0940     kprobe_ftrace_enabled++;
0941     if (kprobe_ftrace_enabled == 1) {
0942         ret = register_ftrace_function(&kprobe_ftrace_ops);
0943         WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
0944     }
0945 }
0946 
0947 /* Caller must lock kprobe_mutex */
0948 static void disarm_kprobe_ftrace(struct kprobe *p)
0949 {
0950     int ret;
0951 
0952     kprobe_ftrace_enabled--;
0953     if (kprobe_ftrace_enabled == 0) {
0954         ret = unregister_ftrace_function(&kprobe_ftrace_ops);
0955         WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
0956     }
0957     ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
0958                (unsigned long)p->addr, 1, 0);
0959     WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
0960 }
0961 #else   /* !CONFIG_KPROBES_ON_FTRACE */
0962 #define prepare_kprobe(p)   arch_prepare_kprobe(p)
0963 #define arm_kprobe_ftrace(p)    do {} while (0)
0964 #define disarm_kprobe_ftrace(p) do {} while (0)
0965 #endif
0966 
0967 /* Arm a kprobe with text_mutex */
0968 static void arm_kprobe(struct kprobe *kp)
0969 {
0970     if (unlikely(kprobe_ftrace(kp))) {
0971         arm_kprobe_ftrace(kp);
0972         return;
0973     }
0974     /*
0975      * Here, since __arm_kprobe() doesn't use stop_machine(),
0976      * this doesn't cause deadlock on text_mutex. So, we don't
0977      * need get_online_cpus().
0978      */
0979     mutex_lock(&text_mutex);
0980     __arm_kprobe(kp);
0981     mutex_unlock(&text_mutex);
0982 }
0983 
0984 /* Disarm a kprobe with text_mutex */
0985 static void disarm_kprobe(struct kprobe *kp, bool reopt)
0986 {
0987     if (unlikely(kprobe_ftrace(kp))) {
0988         disarm_kprobe_ftrace(kp);
0989         return;
0990     }
0991     /* Ditto */
0992     mutex_lock(&text_mutex);
0993     __disarm_kprobe(kp, reopt);
0994     mutex_unlock(&text_mutex);
0995 }
0996 
0997 /*
0998  * Aggregate handlers for multiple kprobes support - these handlers
0999  * take care of invoking the individual kprobe handlers on p->list
1000  */
1001 static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
1002 {
1003     struct kprobe *kp;
1004 
1005     list_for_each_entry_rcu(kp, &p->list, list) {
1006         if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
1007             set_kprobe_instance(kp);
1008             if (kp->pre_handler(kp, regs))
1009                 return 1;
1010         }
1011         reset_kprobe_instance();
1012     }
1013     return 0;
1014 }
1015 NOKPROBE_SYMBOL(aggr_pre_handler);
1016 
1017 static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
1018                   unsigned long flags)
1019 {
1020     struct kprobe *kp;
1021 
1022     list_for_each_entry_rcu(kp, &p->list, list) {
1023         if (kp->post_handler && likely(!kprobe_disabled(kp))) {
1024             set_kprobe_instance(kp);
1025             kp->post_handler(kp, regs, flags);
1026             reset_kprobe_instance();
1027         }
1028     }
1029 }
1030 NOKPROBE_SYMBOL(aggr_post_handler);
1031 
1032 static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
1033                   int trapnr)
1034 {
1035     struct kprobe *cur = __this_cpu_read(kprobe_instance);
1036 
1037     /*
1038      * if we faulted "during" the execution of a user specified
1039      * probe handler, invoke just that probe's fault handler
1040      */
1041     if (cur && cur->fault_handler) {
1042         if (cur->fault_handler(cur, regs, trapnr))
1043             return 1;
1044     }
1045     return 0;
1046 }
1047 NOKPROBE_SYMBOL(aggr_fault_handler);
1048 
1049 static int aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
1050 {
1051     struct kprobe *cur = __this_cpu_read(kprobe_instance);
1052     int ret = 0;
1053 
1054     if (cur && cur->break_handler) {
1055         if (cur->break_handler(cur, regs))
1056             ret = 1;
1057     }
1058     reset_kprobe_instance();
1059     return ret;
1060 }
1061 NOKPROBE_SYMBOL(aggr_break_handler);
1062 
1063 /* Walks the list and increments nmissed count for multiprobe case */
1064 void kprobes_inc_nmissed_count(struct kprobe *p)
1065 {
1066     struct kprobe *kp;
1067     if (!kprobe_aggrprobe(p)) {
1068         p->nmissed++;
1069     } else {
1070         list_for_each_entry_rcu(kp, &p->list, list)
1071             kp->nmissed++;
1072     }
1073     return;
1074 }
1075 NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
1076 
1077 void recycle_rp_inst(struct kretprobe_instance *ri,
1078              struct hlist_head *head)
1079 {
1080     struct kretprobe *rp = ri->rp;
1081 
1082     /* remove rp inst off the rprobe_inst_table */
1083     hlist_del(&ri->hlist);
1084     INIT_HLIST_NODE(&ri->hlist);
1085     if (likely(rp)) {
1086         raw_spin_lock(&rp->lock);
1087         hlist_add_head(&ri->hlist, &rp->free_instances);
1088         raw_spin_unlock(&rp->lock);
1089     } else
1090         /* Unregistering */
1091         hlist_add_head(&ri->hlist, head);
1092 }
1093 NOKPROBE_SYMBOL(recycle_rp_inst);
1094 
1095 void kretprobe_hash_lock(struct task_struct *tsk,
1096              struct hlist_head **head, unsigned long *flags)
1097 __acquires(hlist_lock)
1098 {
1099     unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1100     raw_spinlock_t *hlist_lock;
1101 
1102     *head = &kretprobe_inst_table[hash];
1103     hlist_lock = kretprobe_table_lock_ptr(hash);
1104     raw_spin_lock_irqsave(hlist_lock, *flags);
1105 }
1106 NOKPROBE_SYMBOL(kretprobe_hash_lock);
1107 
1108 static void kretprobe_table_lock(unsigned long hash,
1109                  unsigned long *flags)
1110 __acquires(hlist_lock)
1111 {
1112     raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1113     raw_spin_lock_irqsave(hlist_lock, *flags);
1114 }
1115 NOKPROBE_SYMBOL(kretprobe_table_lock);
1116 
1117 void kretprobe_hash_unlock(struct task_struct *tsk,
1118                unsigned long *flags)
1119 __releases(hlist_lock)
1120 {
1121     unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
1122     raw_spinlock_t *hlist_lock;
1123 
1124     hlist_lock = kretprobe_table_lock_ptr(hash);
1125     raw_spin_unlock_irqrestore(hlist_lock, *flags);
1126 }
1127 NOKPROBE_SYMBOL(kretprobe_hash_unlock);
1128 
1129 static void kretprobe_table_unlock(unsigned long hash,
1130                    unsigned long *flags)
1131 __releases(hlist_lock)
1132 {
1133     raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
1134     raw_spin_unlock_irqrestore(hlist_lock, *flags);
1135 }
1136 NOKPROBE_SYMBOL(kretprobe_table_unlock);
1137 
1138 /*
1139  * This function is called from finish_task_switch when task tk becomes dead,
1140  * so that we can recycle any function-return probe instances associated
1141  * with this task. These left over instances represent probed functions
1142  * that have been called but will never return.
1143  */
1144 void kprobe_flush_task(struct task_struct *tk)
1145 {
1146     struct kretprobe_instance *ri;
1147     struct hlist_head *head, empty_rp;
1148     struct hlist_node *tmp;
1149     unsigned long hash, flags = 0;
1150 
1151     if (unlikely(!kprobes_initialized))
1152         /* Early boot.  kretprobe_table_locks not yet initialized. */
1153         return;
1154 
1155     INIT_HLIST_HEAD(&empty_rp);
1156     hash = hash_ptr(tk, KPROBE_HASH_BITS);
1157     head = &kretprobe_inst_table[hash];
1158     kretprobe_table_lock(hash, &flags);
1159     hlist_for_each_entry_safe(ri, tmp, head, hlist) {
1160         if (ri->task == tk)
1161             recycle_rp_inst(ri, &empty_rp);
1162     }
1163     kretprobe_table_unlock(hash, &flags);
1164     hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
1165         hlist_del(&ri->hlist);
1166         kfree(ri);
1167     }
1168 }
1169 NOKPROBE_SYMBOL(kprobe_flush_task);
1170 
1171 static inline void free_rp_inst(struct kretprobe *rp)
1172 {
1173     struct kretprobe_instance *ri;
1174     struct hlist_node *next;
1175 
1176     hlist_for_each_entry_safe(ri, next, &rp->free_instances, hlist) {
1177         hlist_del(&ri->hlist);
1178         kfree(ri);
1179     }
1180 }
1181 
1182 static void cleanup_rp_inst(struct kretprobe *rp)
1183 {
1184     unsigned long flags, hash;
1185     struct kretprobe_instance *ri;
1186     struct hlist_node *next;
1187     struct hlist_head *head;
1188 
1189     /* No race here */
1190     for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
1191         kretprobe_table_lock(hash, &flags);
1192         head = &kretprobe_inst_table[hash];
1193         hlist_for_each_entry_safe(ri, next, head, hlist) {
1194             if (ri->rp == rp)
1195                 ri->rp = NULL;
1196         }
1197         kretprobe_table_unlock(hash, &flags);
1198     }
1199     free_rp_inst(rp);
1200 }
1201 NOKPROBE_SYMBOL(cleanup_rp_inst);
1202 
1203 /*
1204 * Add the new probe to ap->list. Fail if this is the
1205 * second jprobe at the address - two jprobes can't coexist
1206 */
1207 static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
1208 {
1209     BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
1210 
1211     if (p->break_handler || p->post_handler)
1212         unoptimize_kprobe(ap, true);    /* Fall back to normal kprobe */
1213 
1214     if (p->break_handler) {
1215         if (ap->break_handler)
1216             return -EEXIST;
1217         list_add_tail_rcu(&p->list, &ap->list);
1218         ap->break_handler = aggr_break_handler;
1219     } else
1220         list_add_rcu(&p->list, &ap->list);
1221     if (p->post_handler && !ap->post_handler)
1222         ap->post_handler = aggr_post_handler;
1223 
1224     return 0;
1225 }
1226 
1227 /*
1228  * Fill in the required fields of the "manager kprobe". Replace the
1229  * earlier kprobe in the hlist with the manager kprobe
1230  */
1231 static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
1232 {
1233     /* Copy p's insn slot to ap */
1234     copy_kprobe(p, ap);
1235     flush_insn_slot(ap);
1236     ap->addr = p->addr;
1237     ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
1238     ap->pre_handler = aggr_pre_handler;
1239     ap->fault_handler = aggr_fault_handler;
1240     /* We don't care the kprobe which has gone. */
1241     if (p->post_handler && !kprobe_gone(p))
1242         ap->post_handler = aggr_post_handler;
1243     if (p->break_handler && !kprobe_gone(p))
1244         ap->break_handler = aggr_break_handler;
1245 
1246     INIT_LIST_HEAD(&ap->list);
1247     INIT_HLIST_NODE(&ap->hlist);
1248 
1249     list_add_rcu(&p->list, &ap->list);
1250     hlist_replace_rcu(&p->hlist, &ap->hlist);
1251 }
1252 
1253 /*
1254  * This is the second or subsequent kprobe at the address - handle
1255  * the intricacies
1256  */
1257 static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
1258 {
1259     int ret = 0;
1260     struct kprobe *ap = orig_p;
1261 
1262     /* For preparing optimization, jump_label_text_reserved() is called */
1263     jump_label_lock();
1264     /*
1265      * Get online CPUs to avoid text_mutex deadlock.with stop machine,
1266      * which is invoked by unoptimize_kprobe() in add_new_kprobe()
1267      */
1268     get_online_cpus();
1269     mutex_lock(&text_mutex);
1270 
1271     if (!kprobe_aggrprobe(orig_p)) {
1272         /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
1273         ap = alloc_aggr_kprobe(orig_p);
1274         if (!ap) {
1275             ret = -ENOMEM;
1276             goto out;
1277         }
1278         init_aggr_kprobe(ap, orig_p);
1279     } else if (kprobe_unused(ap))
1280         /* This probe is going to die. Rescue it */
1281         reuse_unused_kprobe(ap);
1282 
1283     if (kprobe_gone(ap)) {
1284         /*
1285          * Attempting to insert new probe at the same location that
1286          * had a probe in the module vaddr area which already
1287          * freed. So, the instruction slot has already been
1288          * released. We need a new slot for the new probe.
1289          */
1290         ret = arch_prepare_kprobe(ap);
1291         if (ret)
1292             /*
1293              * Even if fail to allocate new slot, don't need to
1294              * free aggr_probe. It will be used next time, or
1295              * freed by unregister_kprobe.
1296              */
1297             goto out;
1298 
1299         /* Prepare optimized instructions if possible. */
1300         prepare_optimized_kprobe(ap);
1301 
1302         /*
1303          * Clear gone flag to prevent allocating new slot again, and
1304          * set disabled flag because it is not armed yet.
1305          */
1306         ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
1307                 | KPROBE_FLAG_DISABLED;
1308     }
1309 
1310     /* Copy ap's insn slot to p */
1311     copy_kprobe(ap, p);
1312     ret = add_new_kprobe(ap, p);
1313 
1314 out:
1315     mutex_unlock(&text_mutex);
1316     put_online_cpus();
1317     jump_label_unlock();
1318 
1319     if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
1320         ap->flags &= ~KPROBE_FLAG_DISABLED;
1321         if (!kprobes_all_disarmed)
1322             /* Arm the breakpoint again. */
1323             arm_kprobe(ap);
1324     }
1325     return ret;
1326 }
1327 
1328 bool __weak arch_within_kprobe_blacklist(unsigned long addr)
1329 {
1330     /* The __kprobes marked functions and entry code must not be probed */
1331     return addr >= (unsigned long)__kprobes_text_start &&
1332            addr < (unsigned long)__kprobes_text_end;
1333 }
1334 
1335 bool within_kprobe_blacklist(unsigned long addr)
1336 {
1337     struct kprobe_blacklist_entry *ent;
1338 
1339     if (arch_within_kprobe_blacklist(addr))
1340         return true;
1341     /*
1342      * If there exists a kprobe_blacklist, verify and
1343      * fail any probe registration in the prohibited area
1344      */
1345     list_for_each_entry(ent, &kprobe_blacklist, list) {
1346         if (addr >= ent->start_addr && addr < ent->end_addr)
1347             return true;
1348     }
1349 
1350     return false;
1351 }
1352 
1353 /*
1354  * If we have a symbol_name argument, look it up and add the offset field
1355  * to it. This way, we can specify a relative address to a symbol.
1356  * This returns encoded errors if it fails to look up symbol or invalid
1357  * combination of parameters.
1358  */
1359 static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
1360 {
1361     kprobe_opcode_t *addr = p->addr;
1362 
1363     if ((p->symbol_name && p->addr) ||
1364         (!p->symbol_name && !p->addr))
1365         goto invalid;
1366 
1367     if (p->symbol_name) {
1368         kprobe_lookup_name(p->symbol_name, addr);
1369         if (!addr)
1370             return ERR_PTR(-ENOENT);
1371     }
1372 
1373     addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
1374     if (addr)
1375         return addr;
1376 
1377 invalid:
1378     return ERR_PTR(-EINVAL);
1379 }
1380 
1381 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
1382 static struct kprobe *__get_valid_kprobe(struct kprobe *p)
1383 {
1384     struct kprobe *ap, *list_p;
1385 
1386     ap = get_kprobe(p->addr);
1387     if (unlikely(!ap))
1388         return NULL;
1389 
1390     if (p != ap) {
1391         list_for_each_entry_rcu(list_p, &ap->list, list)
1392             if (list_p == p)
1393             /* kprobe p is a valid probe */
1394                 goto valid;
1395         return NULL;
1396     }
1397 valid:
1398     return ap;
1399 }
1400 
1401 /* Return error if the kprobe is being re-registered */
1402 static inline int check_kprobe_rereg(struct kprobe *p)
1403 {
1404     int ret = 0;
1405 
1406     mutex_lock(&kprobe_mutex);
1407     if (__get_valid_kprobe(p))
1408         ret = -EINVAL;
1409     mutex_unlock(&kprobe_mutex);
1410 
1411     return ret;
1412 }
1413 
1414 int __weak arch_check_ftrace_location(struct kprobe *p)
1415 {
1416     unsigned long ftrace_addr;
1417 
1418     ftrace_addr = ftrace_location((unsigned long)p->addr);
1419     if (ftrace_addr) {
1420 #ifdef CONFIG_KPROBES_ON_FTRACE
1421         /* Given address is not on the instruction boundary */
1422         if ((unsigned long)p->addr != ftrace_addr)
1423             return -EILSEQ;
1424         p->flags |= KPROBE_FLAG_FTRACE;
1425 #else   /* !CONFIG_KPROBES_ON_FTRACE */
1426         return -EINVAL;
1427 #endif
1428     }
1429     return 0;
1430 }
1431 
1432 static int check_kprobe_address_safe(struct kprobe *p,
1433                      struct module **probed_mod)
1434 {
1435     int ret;
1436 
1437     ret = arch_check_ftrace_location(p);
1438     if (ret)
1439         return ret;
1440     jump_label_lock();
1441     preempt_disable();
1442 
1443     /* Ensure it is not in reserved area nor out of text */
1444     if (!kernel_text_address((unsigned long) p->addr) ||
1445         within_kprobe_blacklist((unsigned long) p->addr) ||
1446         jump_label_text_reserved(p->addr, p->addr)) {
1447         ret = -EINVAL;
1448         goto out;
1449     }
1450 
1451     /* Check if are we probing a module */
1452     *probed_mod = __module_text_address((unsigned long) p->addr);
1453     if (*probed_mod) {
1454         /*
1455          * We must hold a refcount of the probed module while updating
1456          * its code to prohibit unexpected unloading.
1457          */
1458         if (unlikely(!try_module_get(*probed_mod))) {
1459             ret = -ENOENT;
1460             goto out;
1461         }
1462 
1463         /*
1464          * If the module freed .init.text, we couldn't insert
1465          * kprobes in there.
1466          */
1467         if (within_module_init((unsigned long)p->addr, *probed_mod) &&
1468             (*probed_mod)->state != MODULE_STATE_COMING) {
1469             module_put(*probed_mod);
1470             *probed_mod = NULL;
1471             ret = -ENOENT;
1472         }
1473     }
1474 out:
1475     preempt_enable();
1476     jump_label_unlock();
1477 
1478     return ret;
1479 }
1480 
1481 int register_kprobe(struct kprobe *p)
1482 {
1483     int ret;
1484     struct kprobe *old_p;
1485     struct module *probed_mod;
1486     kprobe_opcode_t *addr;
1487 
1488     /* Adjust probe address from symbol */
1489     addr = kprobe_addr(p);
1490     if (IS_ERR(addr))
1491         return PTR_ERR(addr);
1492     p->addr = addr;
1493 
1494     ret = check_kprobe_rereg(p);
1495     if (ret)
1496         return ret;
1497 
1498     /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
1499     p->flags &= KPROBE_FLAG_DISABLED;
1500     p->nmissed = 0;
1501     INIT_LIST_HEAD(&p->list);
1502 
1503     ret = check_kprobe_address_safe(p, &probed_mod);
1504     if (ret)
1505         return ret;
1506 
1507     mutex_lock(&kprobe_mutex);
1508 
1509     old_p = get_kprobe(p->addr);
1510     if (old_p) {
1511         /* Since this may unoptimize old_p, locking text_mutex. */
1512         ret = register_aggr_kprobe(old_p, p);
1513         goto out;
1514     }
1515 
1516     mutex_lock(&text_mutex);    /* Avoiding text modification */
1517     ret = prepare_kprobe(p);
1518     mutex_unlock(&text_mutex);
1519     if (ret)
1520         goto out;
1521 
1522     INIT_HLIST_NODE(&p->hlist);
1523     hlist_add_head_rcu(&p->hlist,
1524                &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
1525 
1526     if (!kprobes_all_disarmed && !kprobe_disabled(p))
1527         arm_kprobe(p);
1528 
1529     /* Try to optimize kprobe */
1530     try_to_optimize_kprobe(p);
1531 
1532 out:
1533     mutex_unlock(&kprobe_mutex);
1534 
1535     if (probed_mod)
1536         module_put(probed_mod);
1537 
1538     return ret;
1539 }
1540 EXPORT_SYMBOL_GPL(register_kprobe);
1541 
1542 /* Check if all probes on the aggrprobe are disabled */
1543 static int aggr_kprobe_disabled(struct kprobe *ap)
1544 {
1545     struct kprobe *kp;
1546 
1547     list_for_each_entry_rcu(kp, &ap->list, list)
1548         if (!kprobe_disabled(kp))
1549             /*
1550              * There is an active probe on the list.
1551              * We can't disable this ap.
1552              */
1553             return 0;
1554 
1555     return 1;
1556 }
1557 
1558 /* Disable one kprobe: Make sure called under kprobe_mutex is locked */
1559 static struct kprobe *__disable_kprobe(struct kprobe *p)
1560 {
1561     struct kprobe *orig_p;
1562 
1563     /* Get an original kprobe for return */
1564     orig_p = __get_valid_kprobe(p);
1565     if (unlikely(orig_p == NULL))
1566         return NULL;
1567 
1568     if (!kprobe_disabled(p)) {
1569         /* Disable probe if it is a child probe */
1570         if (p != orig_p)
1571             p->flags |= KPROBE_FLAG_DISABLED;
1572 
1573         /* Try to disarm and disable this/parent probe */
1574         if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
1575             /*
1576              * If kprobes_all_disarmed is set, orig_p
1577              * should have already been disarmed, so
1578              * skip unneed disarming process.
1579              */
1580             if (!kprobes_all_disarmed)
1581                 disarm_kprobe(orig_p, true);
1582             orig_p->flags |= KPROBE_FLAG_DISABLED;
1583         }
1584     }
1585 
1586     return orig_p;
1587 }
1588 
1589 /*
1590  * Unregister a kprobe without a scheduler synchronization.
1591  */
1592 static int __unregister_kprobe_top(struct kprobe *p)
1593 {
1594     struct kprobe *ap, *list_p;
1595 
1596     /* Disable kprobe. This will disarm it if needed. */
1597     ap = __disable_kprobe(p);
1598     if (ap == NULL)
1599         return -EINVAL;
1600 
1601     if (ap == p)
1602         /*
1603          * This probe is an independent(and non-optimized) kprobe
1604          * (not an aggrprobe). Remove from the hash list.
1605          */
1606         goto disarmed;
1607 
1608     /* Following process expects this probe is an aggrprobe */
1609     WARN_ON(!kprobe_aggrprobe(ap));
1610 
1611     if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
1612         /*
1613          * !disarmed could be happen if the probe is under delayed
1614          * unoptimizing.
1615          */
1616         goto disarmed;
1617     else {
1618         /* If disabling probe has special handlers, update aggrprobe */
1619         if (p->break_handler && !kprobe_gone(p))
1620             ap->break_handler = NULL;
1621         if (p->post_handler && !kprobe_gone(p)) {
1622             list_for_each_entry_rcu(list_p, &ap->list, list) {
1623                 if ((list_p != p) && (list_p->post_handler))
1624                     goto noclean;
1625             }
1626             ap->post_handler = NULL;
1627         }
1628 noclean:
1629         /*
1630          * Remove from the aggrprobe: this path will do nothing in
1631          * __unregister_kprobe_bottom().
1632          */
1633         list_del_rcu(&p->list);
1634         if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
1635             /*
1636              * Try to optimize this probe again, because post
1637              * handler may have been changed.
1638              */
1639             optimize_kprobe(ap);
1640     }
1641     return 0;
1642 
1643 disarmed:
1644     BUG_ON(!kprobe_disarmed(ap));
1645     hlist_del_rcu(&ap->hlist);
1646     return 0;
1647 }
1648 
1649 static void __unregister_kprobe_bottom(struct kprobe *p)
1650 {
1651     struct kprobe *ap;
1652 
1653     if (list_empty(&p->list))
1654         /* This is an independent kprobe */
1655         arch_remove_kprobe(p);
1656     else if (list_is_singular(&p->list)) {
1657         /* This is the last child of an aggrprobe */
1658         ap = list_entry(p->list.next, struct kprobe, list);
1659         list_del(&p->list);
1660         free_aggr_kprobe(ap);
1661     }
1662     /* Otherwise, do nothing. */
1663 }
1664 
1665 int register_kprobes(struct kprobe **kps, int num)
1666 {
1667     int i, ret = 0;
1668 
1669     if (num <= 0)
1670         return -EINVAL;
1671     for (i = 0; i < num; i++) {
1672         ret = register_kprobe(kps[i]);
1673         if (ret < 0) {
1674             if (i > 0)
1675                 unregister_kprobes(kps, i);
1676             break;
1677         }
1678     }
1679     return ret;
1680 }
1681 EXPORT_SYMBOL_GPL(register_kprobes);
1682 
1683 void unregister_kprobe(struct kprobe *p)
1684 {
1685     unregister_kprobes(&p, 1);
1686 }
1687 EXPORT_SYMBOL_GPL(unregister_kprobe);
1688 
1689 void unregister_kprobes(struct kprobe **kps, int num)
1690 {
1691     int i;
1692 
1693     if (num <= 0)
1694         return;
1695     mutex_lock(&kprobe_mutex);
1696     for (i = 0; i < num; i++)
1697         if (__unregister_kprobe_top(kps[i]) < 0)
1698             kps[i]->addr = NULL;
1699     mutex_unlock(&kprobe_mutex);
1700 
1701     synchronize_sched();
1702     for (i = 0; i < num; i++)
1703         if (kps[i]->addr)
1704             __unregister_kprobe_bottom(kps[i]);
1705 }
1706 EXPORT_SYMBOL_GPL(unregister_kprobes);
1707 
1708 static struct notifier_block kprobe_exceptions_nb = {
1709     .notifier_call = kprobe_exceptions_notify,
1710     .priority = 0x7fffffff /* we need to be notified first */
1711 };
1712 
1713 unsigned long __weak arch_deref_entry_point(void *entry)
1714 {
1715     return (unsigned long)entry;
1716 }
1717 
1718 int register_jprobes(struct jprobe **jps, int num)
1719 {
1720     struct jprobe *jp;
1721     int ret = 0, i;
1722 
1723     if (num <= 0)
1724         return -EINVAL;
1725     for (i = 0; i < num; i++) {
1726         unsigned long addr, offset;
1727         jp = jps[i];
1728         addr = arch_deref_entry_point(jp->entry);
1729 
1730         /* Verify probepoint is a function entry point */
1731         if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
1732             offset == 0) {
1733             jp->kp.pre_handler = setjmp_pre_handler;
1734             jp->kp.break_handler = longjmp_break_handler;
1735             ret = register_kprobe(&jp->kp);
1736         } else
1737             ret = -EINVAL;
1738 
1739         if (ret < 0) {
1740             if (i > 0)
1741                 unregister_jprobes(jps, i);
1742             break;
1743         }
1744     }
1745     return ret;
1746 }
1747 EXPORT_SYMBOL_GPL(register_jprobes);
1748 
1749 int register_jprobe(struct jprobe *jp)
1750 {
1751     return register_jprobes(&jp, 1);
1752 }
1753 EXPORT_SYMBOL_GPL(register_jprobe);
1754 
1755 void unregister_jprobe(struct jprobe *jp)
1756 {
1757     unregister_jprobes(&jp, 1);
1758 }
1759 EXPORT_SYMBOL_GPL(unregister_jprobe);
1760 
1761 void unregister_jprobes(struct jprobe **jps, int num)
1762 {
1763     int i;
1764 
1765     if (num <= 0)
1766         return;
1767     mutex_lock(&kprobe_mutex);
1768     for (i = 0; i < num; i++)
1769         if (__unregister_kprobe_top(&jps[i]->kp) < 0)
1770             jps[i]->kp.addr = NULL;
1771     mutex_unlock(&kprobe_mutex);
1772 
1773     synchronize_sched();
1774     for (i = 0; i < num; i++) {
1775         if (jps[i]->kp.addr)
1776             __unregister_kprobe_bottom(&jps[i]->kp);
1777     }
1778 }
1779 EXPORT_SYMBOL_GPL(unregister_jprobes);
1780 
1781 #ifdef CONFIG_KRETPROBES
1782 /*
1783  * This kprobe pre_handler is registered with every kretprobe. When probe
1784  * hits it will set up the return probe.
1785  */
1786 static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
1787 {
1788     struct kretprobe *rp = container_of(p, struct kretprobe, kp);
1789     unsigned long hash, flags = 0;
1790     struct kretprobe_instance *ri;
1791 
1792     /*
1793      * To avoid deadlocks, prohibit return probing in NMI contexts,
1794      * just skip the probe and increase the (inexact) 'nmissed'
1795      * statistical counter, so that the user is informed that
1796      * something happened:
1797      */
1798     if (unlikely(in_nmi())) {
1799         rp->nmissed++;
1800         return 0;
1801     }
1802 
1803     /* TODO: consider to only swap the RA after the last pre_handler fired */
1804     hash = hash_ptr(current, KPROBE_HASH_BITS);
1805     raw_spin_lock_irqsave(&rp->lock, flags);
1806     if (!hlist_empty(&rp->free_instances)) {
1807         ri = hlist_entry(rp->free_instances.first,
1808                 struct kretprobe_instance, hlist);
1809         hlist_del(&ri->hlist);
1810         raw_spin_unlock_irqrestore(&rp->lock, flags);
1811 
1812         ri->rp = rp;
1813         ri->task = current;
1814 
1815         if (rp->entry_handler && rp->entry_handler(ri, regs)) {
1816             raw_spin_lock_irqsave(&rp->lock, flags);
1817             hlist_add_head(&ri->hlist, &rp->free_instances);
1818             raw_spin_unlock_irqrestore(&rp->lock, flags);
1819             return 0;
1820         }
1821 
1822         arch_prepare_kretprobe(ri, regs);
1823 
1824         /* XXX(hch): why is there no hlist_move_head? */
1825         INIT_HLIST_NODE(&ri->hlist);
1826         kretprobe_table_lock(hash, &flags);
1827         hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
1828         kretprobe_table_unlock(hash, &flags);
1829     } else {
1830         rp->nmissed++;
1831         raw_spin_unlock_irqrestore(&rp->lock, flags);
1832     }
1833     return 0;
1834 }
1835 NOKPROBE_SYMBOL(pre_handler_kretprobe);
1836 
1837 int register_kretprobe(struct kretprobe *rp)
1838 {
1839     int ret = 0;
1840     struct kretprobe_instance *inst;
1841     int i;
1842     void *addr;
1843 
1844     if (kretprobe_blacklist_size) {
1845         addr = kprobe_addr(&rp->kp);
1846         if (IS_ERR(addr))
1847             return PTR_ERR(addr);
1848 
1849         for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
1850             if (kretprobe_blacklist[i].addr == addr)
1851                 return -EINVAL;
1852         }
1853     }
1854 
1855     rp->kp.pre_handler = pre_handler_kretprobe;
1856     rp->kp.post_handler = NULL;
1857     rp->kp.fault_handler = NULL;
1858     rp->kp.break_handler = NULL;
1859 
1860     /* Pre-allocate memory for max kretprobe instances */
1861     if (rp->maxactive <= 0) {
1862 #ifdef CONFIG_PREEMPT
1863         rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
1864 #else
1865         rp->maxactive = num_possible_cpus();
1866 #endif
1867     }
1868     raw_spin_lock_init(&rp->lock);
1869     INIT_HLIST_HEAD(&rp->free_instances);
1870     for (i = 0; i < rp->maxactive; i++) {
1871         inst = kmalloc(sizeof(struct kretprobe_instance) +
1872                    rp->data_size, GFP_KERNEL);
1873         if (inst == NULL) {
1874             free_rp_inst(rp);
1875             return -ENOMEM;
1876         }
1877         INIT_HLIST_NODE(&inst->hlist);
1878         hlist_add_head(&inst->hlist, &rp->free_instances);
1879     }
1880 
1881     rp->nmissed = 0;
1882     /* Establish function entry probe point */
1883     ret = register_kprobe(&rp->kp);
1884     if (ret != 0)
1885         free_rp_inst(rp);
1886     return ret;
1887 }
1888 EXPORT_SYMBOL_GPL(register_kretprobe);
1889 
1890 int register_kretprobes(struct kretprobe **rps, int num)
1891 {
1892     int ret = 0, i;
1893 
1894     if (num <= 0)
1895         return -EINVAL;
1896     for (i = 0; i < num; i++) {
1897         ret = register_kretprobe(rps[i]);
1898         if (ret < 0) {
1899             if (i > 0)
1900                 unregister_kretprobes(rps, i);
1901             break;
1902         }
1903     }
1904     return ret;
1905 }
1906 EXPORT_SYMBOL_GPL(register_kretprobes);
1907 
1908 void unregister_kretprobe(struct kretprobe *rp)
1909 {
1910     unregister_kretprobes(&rp, 1);
1911 }
1912 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1913 
1914 void unregister_kretprobes(struct kretprobe **rps, int num)
1915 {
1916     int i;
1917 
1918     if (num <= 0)
1919         return;
1920     mutex_lock(&kprobe_mutex);
1921     for (i = 0; i < num; i++)
1922         if (__unregister_kprobe_top(&rps[i]->kp) < 0)
1923             rps[i]->kp.addr = NULL;
1924     mutex_unlock(&kprobe_mutex);
1925 
1926     synchronize_sched();
1927     for (i = 0; i < num; i++) {
1928         if (rps[i]->kp.addr) {
1929             __unregister_kprobe_bottom(&rps[i]->kp);
1930             cleanup_rp_inst(rps[i]);
1931         }
1932     }
1933 }
1934 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1935 
1936 #else /* CONFIG_KRETPROBES */
1937 int register_kretprobe(struct kretprobe *rp)
1938 {
1939     return -ENOSYS;
1940 }
1941 EXPORT_SYMBOL_GPL(register_kretprobe);
1942 
1943 int register_kretprobes(struct kretprobe **rps, int num)
1944 {
1945     return -ENOSYS;
1946 }
1947 EXPORT_SYMBOL_GPL(register_kretprobes);
1948 
1949 void unregister_kretprobe(struct kretprobe *rp)
1950 {
1951 }
1952 EXPORT_SYMBOL_GPL(unregister_kretprobe);
1953 
1954 void unregister_kretprobes(struct kretprobe **rps, int num)
1955 {
1956 }
1957 EXPORT_SYMBOL_GPL(unregister_kretprobes);
1958 
1959 static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
1960 {
1961     return 0;
1962 }
1963 NOKPROBE_SYMBOL(pre_handler_kretprobe);
1964 
1965 #endif /* CONFIG_KRETPROBES */
1966 
1967 /* Set the kprobe gone and remove its instruction buffer. */
1968 static void kill_kprobe(struct kprobe *p)
1969 {
1970     struct kprobe *kp;
1971 
1972     p->flags |= KPROBE_FLAG_GONE;
1973     if (kprobe_aggrprobe(p)) {
1974         /*
1975          * If this is an aggr_kprobe, we have to list all the
1976          * chained probes and mark them GONE.
1977          */
1978         list_for_each_entry_rcu(kp, &p->list, list)
1979             kp->flags |= KPROBE_FLAG_GONE;
1980         p->post_handler = NULL;
1981         p->break_handler = NULL;
1982         kill_optimized_kprobe(p);
1983     }
1984     /*
1985      * Here, we can remove insn_slot safely, because no thread calls
1986      * the original probed function (which will be freed soon) any more.
1987      */
1988     arch_remove_kprobe(p);
1989 }
1990 
1991 /* Disable one kprobe */
1992 int disable_kprobe(struct kprobe *kp)
1993 {
1994     int ret = 0;
1995 
1996     mutex_lock(&kprobe_mutex);
1997 
1998     /* Disable this kprobe */
1999     if (__disable_kprobe(kp) == NULL)
2000         ret = -EINVAL;
2001 
2002     mutex_unlock(&kprobe_mutex);
2003     return ret;
2004 }
2005 EXPORT_SYMBOL_GPL(disable_kprobe);
2006 
2007 /* Enable one kprobe */
2008 int enable_kprobe(struct kprobe *kp)
2009 {
2010     int ret = 0;
2011     struct kprobe *p;
2012 
2013     mutex_lock(&kprobe_mutex);
2014 
2015     /* Check whether specified probe is valid. */
2016     p = __get_valid_kprobe(kp);
2017     if (unlikely(p == NULL)) {
2018         ret = -EINVAL;
2019         goto out;
2020     }
2021 
2022     if (kprobe_gone(kp)) {
2023         /* This kprobe has gone, we couldn't enable it. */
2024         ret = -EINVAL;
2025         goto out;
2026     }
2027 
2028     if (p != kp)
2029         kp->flags &= ~KPROBE_FLAG_DISABLED;
2030 
2031     if (!kprobes_all_disarmed && kprobe_disabled(p)) {
2032         p->flags &= ~KPROBE_FLAG_DISABLED;
2033         arm_kprobe(p);
2034     }
2035 out:
2036     mutex_unlock(&kprobe_mutex);
2037     return ret;
2038 }
2039 EXPORT_SYMBOL_GPL(enable_kprobe);
2040 
2041 void dump_kprobe(struct kprobe *kp)
2042 {
2043     printk(KERN_WARNING "Dumping kprobe:\n");
2044     printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
2045            kp->symbol_name, kp->addr, kp->offset);
2046 }
2047 NOKPROBE_SYMBOL(dump_kprobe);
2048 
2049 /*
2050  * Lookup and populate the kprobe_blacklist.
2051  *
2052  * Unlike the kretprobe blacklist, we'll need to determine
2053  * the range of addresses that belong to the said functions,
2054  * since a kprobe need not necessarily be at the beginning
2055  * of a function.
2056  */
2057 static int __init populate_kprobe_blacklist(unsigned long *start,
2058                          unsigned long *end)
2059 {
2060     unsigned long *iter;
2061     struct kprobe_blacklist_entry *ent;
2062     unsigned long entry, offset = 0, size = 0;
2063 
2064     for (iter = start; iter < end; iter++) {
2065         entry = arch_deref_entry_point((void *)*iter);
2066 
2067         if (!kernel_text_address(entry) ||
2068             !kallsyms_lookup_size_offset(entry, &size, &offset)) {
2069             pr_err("Failed to find blacklist at %p\n",
2070                 (void *)entry);
2071             continue;
2072         }
2073 
2074         ent = kmalloc(sizeof(*ent), GFP_KERNEL);
2075         if (!ent)
2076             return -ENOMEM;
2077         ent->start_addr = entry;
2078         ent->end_addr = entry + size;
2079         INIT_LIST_HEAD(&ent->list);
2080         list_add_tail(&ent->list, &kprobe_blacklist);
2081     }
2082     return 0;
2083 }
2084 
2085 /* Module notifier call back, checking kprobes on the module */
2086 static int kprobes_module_callback(struct notifier_block *nb,
2087                    unsigned long val, void *data)
2088 {
2089     struct module *mod = data;
2090     struct hlist_head *head;
2091     struct kprobe *p;
2092     unsigned int i;
2093     int checkcore = (val == MODULE_STATE_GOING);
2094 
2095     if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
2096         return NOTIFY_DONE;
2097 
2098     /*
2099      * When MODULE_STATE_GOING was notified, both of module .text and
2100      * .init.text sections would be freed. When MODULE_STATE_LIVE was
2101      * notified, only .init.text section would be freed. We need to
2102      * disable kprobes which have been inserted in the sections.
2103      */
2104     mutex_lock(&kprobe_mutex);
2105     for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2106         head = &kprobe_table[i];
2107         hlist_for_each_entry_rcu(p, head, hlist)
2108             if (within_module_init((unsigned long)p->addr, mod) ||
2109                 (checkcore &&
2110                  within_module_core((unsigned long)p->addr, mod))) {
2111                 /*
2112                  * The vaddr this probe is installed will soon
2113                  * be vfreed buy not synced to disk. Hence,
2114                  * disarming the breakpoint isn't needed.
2115                  */
2116                 kill_kprobe(p);
2117             }
2118     }
2119     mutex_unlock(&kprobe_mutex);
2120     return NOTIFY_DONE;
2121 }
2122 
2123 static struct notifier_block kprobe_module_nb = {
2124     .notifier_call = kprobes_module_callback,
2125     .priority = 0
2126 };
2127 
2128 /* Markers of _kprobe_blacklist section */
2129 extern unsigned long __start_kprobe_blacklist[];
2130 extern unsigned long __stop_kprobe_blacklist[];
2131 
2132 static int __init init_kprobes(void)
2133 {
2134     int i, err = 0;
2135 
2136     /* FIXME allocate the probe table, currently defined statically */
2137     /* initialize all list heads */
2138     for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2139         INIT_HLIST_HEAD(&kprobe_table[i]);
2140         INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
2141         raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
2142     }
2143 
2144     err = populate_kprobe_blacklist(__start_kprobe_blacklist,
2145                     __stop_kprobe_blacklist);
2146     if (err) {
2147         pr_err("kprobes: failed to populate blacklist: %d\n", err);
2148         pr_err("Please take care of using kprobes.\n");
2149     }
2150 
2151     if (kretprobe_blacklist_size) {
2152         /* lookup the function address from its name */
2153         for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
2154             kprobe_lookup_name(kretprobe_blacklist[i].name,
2155                        kretprobe_blacklist[i].addr);
2156             if (!kretprobe_blacklist[i].addr)
2157                 printk("kretprobe: lookup failed: %s\n",
2158                        kretprobe_blacklist[i].name);
2159         }
2160     }
2161 
2162 #if defined(CONFIG_OPTPROBES)
2163 #if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
2164     /* Init kprobe_optinsn_slots */
2165     kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
2166 #endif
2167     /* By default, kprobes can be optimized */
2168     kprobes_allow_optimization = true;
2169 #endif
2170 
2171     /* By default, kprobes are armed */
2172     kprobes_all_disarmed = false;
2173 
2174     err = arch_init_kprobes();
2175     if (!err)
2176         err = register_die_notifier(&kprobe_exceptions_nb);
2177     if (!err)
2178         err = register_module_notifier(&kprobe_module_nb);
2179 
2180     kprobes_initialized = (err == 0);
2181 
2182     if (!err)
2183         init_test_probes();
2184     return err;
2185 }
2186 
2187 #ifdef CONFIG_DEBUG_FS
2188 static void report_probe(struct seq_file *pi, struct kprobe *p,
2189         const char *sym, int offset, char *modname, struct kprobe *pp)
2190 {
2191     char *kprobe_type;
2192 
2193     if (p->pre_handler == pre_handler_kretprobe)
2194         kprobe_type = "r";
2195     else if (p->pre_handler == setjmp_pre_handler)
2196         kprobe_type = "j";
2197     else
2198         kprobe_type = "k";
2199 
2200     if (sym)
2201         seq_printf(pi, "%p  %s  %s+0x%x  %s ",
2202             p->addr, kprobe_type, sym, offset,
2203             (modname ? modname : " "));
2204     else
2205         seq_printf(pi, "%p  %s  %p ",
2206             p->addr, kprobe_type, p->addr);
2207 
2208     if (!pp)
2209         pp = p;
2210     seq_printf(pi, "%s%s%s%s\n",
2211         (kprobe_gone(p) ? "[GONE]" : ""),
2212         ((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
2213         (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""),
2214         (kprobe_ftrace(pp) ? "[FTRACE]" : ""));
2215 }
2216 
2217 static void *kprobe_seq_start(struct seq_file *f, loff_t *pos)
2218 {
2219     return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
2220 }
2221 
2222 static void *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
2223 {
2224     (*pos)++;
2225     if (*pos >= KPROBE_TABLE_SIZE)
2226         return NULL;
2227     return pos;
2228 }
2229 
2230 static void kprobe_seq_stop(struct seq_file *f, void *v)
2231 {
2232     /* Nothing to do */
2233 }
2234 
2235 static int show_kprobe_addr(struct seq_file *pi, void *v)
2236 {
2237     struct hlist_head *head;
2238     struct kprobe *p, *kp;
2239     const char *sym = NULL;
2240     unsigned int i = *(loff_t *) v;
2241     unsigned long offset = 0;
2242     char *modname, namebuf[KSYM_NAME_LEN];
2243 
2244     head = &kprobe_table[i];
2245     preempt_disable();
2246     hlist_for_each_entry_rcu(p, head, hlist) {
2247         sym = kallsyms_lookup((unsigned long)p->addr, NULL,
2248                     &offset, &modname, namebuf);
2249         if (kprobe_aggrprobe(p)) {
2250             list_for_each_entry_rcu(kp, &p->list, list)
2251                 report_probe(pi, kp, sym, offset, modname, p);
2252         } else
2253             report_probe(pi, p, sym, offset, modname, NULL);
2254     }
2255     preempt_enable();
2256     return 0;
2257 }
2258 
2259 static const struct seq_operations kprobes_seq_ops = {
2260     .start = kprobe_seq_start,
2261     .next  = kprobe_seq_next,
2262     .stop  = kprobe_seq_stop,
2263     .show  = show_kprobe_addr
2264 };
2265 
2266 static int kprobes_open(struct inode *inode, struct file *filp)
2267 {
2268     return seq_open(filp, &kprobes_seq_ops);
2269 }
2270 
2271 static const struct file_operations debugfs_kprobes_operations = {
2272     .open           = kprobes_open,
2273     .read           = seq_read,
2274     .llseek         = seq_lseek,
2275     .release        = seq_release,
2276 };
2277 
2278 /* kprobes/blacklist -- shows which functions can not be probed */
2279 static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
2280 {
2281     return seq_list_start(&kprobe_blacklist, *pos);
2282 }
2283 
2284 static void *kprobe_blacklist_seq_next(struct seq_file *m, void *v, loff_t *pos)
2285 {
2286     return seq_list_next(v, &kprobe_blacklist, pos);
2287 }
2288 
2289 static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
2290 {
2291     struct kprobe_blacklist_entry *ent =
2292         list_entry(v, struct kprobe_blacklist_entry, list);
2293 
2294     seq_printf(m, "0x%p-0x%p\t%ps\n", (void *)ent->start_addr,
2295            (void *)ent->end_addr, (void *)ent->start_addr);
2296     return 0;
2297 }
2298 
2299 static const struct seq_operations kprobe_blacklist_seq_ops = {
2300     .start = kprobe_blacklist_seq_start,
2301     .next  = kprobe_blacklist_seq_next,
2302     .stop  = kprobe_seq_stop,   /* Reuse void function */
2303     .show  = kprobe_blacklist_seq_show,
2304 };
2305 
2306 static int kprobe_blacklist_open(struct inode *inode, struct file *filp)
2307 {
2308     return seq_open(filp, &kprobe_blacklist_seq_ops);
2309 }
2310 
2311 static const struct file_operations debugfs_kprobe_blacklist_ops = {
2312     .open           = kprobe_blacklist_open,
2313     .read           = seq_read,
2314     .llseek         = seq_lseek,
2315     .release        = seq_release,
2316 };
2317 
2318 static void arm_all_kprobes(void)
2319 {
2320     struct hlist_head *head;
2321     struct kprobe *p;
2322     unsigned int i;
2323 
2324     mutex_lock(&kprobe_mutex);
2325 
2326     /* If kprobes are armed, just return */
2327     if (!kprobes_all_disarmed)
2328         goto already_enabled;
2329 
2330     /*
2331      * optimize_kprobe() called by arm_kprobe() checks
2332      * kprobes_all_disarmed, so set kprobes_all_disarmed before
2333      * arm_kprobe.
2334      */
2335     kprobes_all_disarmed = false;
2336     /* Arming kprobes doesn't optimize kprobe itself */
2337     for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2338         head = &kprobe_table[i];
2339         hlist_for_each_entry_rcu(p, head, hlist)
2340             if (!kprobe_disabled(p))
2341                 arm_kprobe(p);
2342     }
2343 
2344     printk(KERN_INFO "Kprobes globally enabled\n");
2345 
2346 already_enabled:
2347     mutex_unlock(&kprobe_mutex);
2348     return;
2349 }
2350 
2351 static void disarm_all_kprobes(void)
2352 {
2353     struct hlist_head *head;
2354     struct kprobe *p;
2355     unsigned int i;
2356 
2357     mutex_lock(&kprobe_mutex);
2358 
2359     /* If kprobes are already disarmed, just return */
2360     if (kprobes_all_disarmed) {
2361         mutex_unlock(&kprobe_mutex);
2362         return;
2363     }
2364 
2365     kprobes_all_disarmed = true;
2366     printk(KERN_INFO "Kprobes globally disabled\n");
2367 
2368     for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
2369         head = &kprobe_table[i];
2370         hlist_for_each_entry_rcu(p, head, hlist) {
2371             if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
2372                 disarm_kprobe(p, false);
2373         }
2374     }
2375     mutex_unlock(&kprobe_mutex);
2376 
2377     /* Wait for disarming all kprobes by optimizer */
2378     wait_for_kprobe_optimizer();
2379 }
2380 
2381 /*
2382  * XXX: The debugfs bool file interface doesn't allow for callbacks
2383  * when the bool state is switched. We can reuse that facility when
2384  * available
2385  */
2386 static ssize_t read_enabled_file_bool(struct file *file,
2387            char __user *user_buf, size_t count, loff_t *ppos)
2388 {
2389     char buf[3];
2390 
2391     if (!kprobes_all_disarmed)
2392         buf[0] = '1';
2393     else
2394         buf[0] = '0';
2395     buf[1] = '\n';
2396     buf[2] = 0x00;
2397     return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
2398 }
2399 
2400 static ssize_t write_enabled_file_bool(struct file *file,
2401            const char __user *user_buf, size_t count, loff_t *ppos)
2402 {
2403     char buf[32];
2404     size_t buf_size;
2405 
2406     buf_size = min(count, (sizeof(buf)-1));
2407     if (copy_from_user(buf, user_buf, buf_size))
2408         return -EFAULT;
2409 
2410     buf[buf_size] = '\0';
2411     switch (buf[0]) {
2412     case 'y':
2413     case 'Y':
2414     case '1':
2415         arm_all_kprobes();
2416         break;
2417     case 'n':
2418     case 'N':
2419     case '0':
2420         disarm_all_kprobes();
2421         break;
2422     default:
2423         return -EINVAL;
2424     }
2425 
2426     return count;
2427 }
2428 
2429 static const struct file_operations fops_kp = {
2430     .read =         read_enabled_file_bool,
2431     .write =        write_enabled_file_bool,
2432     .llseek =   default_llseek,
2433 };
2434 
2435 static int __init debugfs_kprobe_init(void)
2436 {
2437     struct dentry *dir, *file;
2438     unsigned int value = 1;
2439 
2440     dir = debugfs_create_dir("kprobes", NULL);
2441     if (!dir)
2442         return -ENOMEM;
2443 
2444     file = debugfs_create_file("list", 0444, dir, NULL,
2445                 &debugfs_kprobes_operations);
2446     if (!file)
2447         goto error;
2448 
2449     file = debugfs_create_file("enabled", 0600, dir,
2450                     &value, &fops_kp);
2451     if (!file)
2452         goto error;
2453 
2454     file = debugfs_create_file("blacklist", 0444, dir, NULL,
2455                 &debugfs_kprobe_blacklist_ops);
2456     if (!file)
2457         goto error;
2458 
2459     return 0;
2460 
2461 error:
2462     debugfs_remove(dir);
2463     return -ENOMEM;
2464 }
2465 
2466 late_initcall(debugfs_kprobe_init);
2467 #endif /* CONFIG_DEBUG_FS */
2468 
2469 module_init(init_kprobes);
2470 
2471 /* defined in arch/.../kernel/kprobes.c */
2472 EXPORT_SYMBOL_GPL(jprobe_return);