The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kernel/kprobes.c

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    1 /*
    2  *  Kernel Probes (KProbes)
    3  *  kernel/kprobes.c
    4  *
    5  * This program is free software; you can redistribute it and/or modify
    6  * it under the terms of the GNU General Public License as published by
    7  * the Free Software Foundation; either version 2 of the License, or
    8  * (at your option) any later version.
    9  *
   10  * This program is distributed in the hope that it will be useful,
   11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   13  * GNU General Public License for more details.
   14  *
   15  * You should have received a copy of the GNU General Public License
   16  * along with this program; if not, write to the Free Software
   17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   18  *
   19  * Copyright (C) IBM Corporation, 2002, 2004
   20  *
   21  * 2002-Oct     Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
   22  *              Probes initial implementation (includes suggestions from
   23  *              Rusty Russell).
   24  * 2004-Aug     Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
   25  *              hlists and exceptions notifier as suggested by Andi Kleen.
   26  * 2004-July    Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
   27  *              interface to access function arguments.
   28  * 2004-Sep     Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
   29  *              exceptions notifier to be first on the priority list.
   30  * 2005-May     Hien Nguyen <hien@us.ibm.com>, Jim Keniston
   31  *              <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
   32  *              <prasanna@in.ibm.com> added function-return probes.
   33  */
   34 #include <linux/kprobes.h>
   35 #include <linux/hash.h>
   36 #include <linux/init.h>
   37 #include <linux/slab.h>
   38 #include <linux/stddef.h>
   39 #include <linux/export.h>
   40 #include <linux/moduleloader.h>
   41 #include <linux/kallsyms.h>
   42 #include <linux/freezer.h>
   43 #include <linux/seq_file.h>
   44 #include <linux/debugfs.h>
   45 #include <linux/sysctl.h>
   46 #include <linux/kdebug.h>
   47 #include <linux/memory.h>
   48 #include <linux/ftrace.h>
   49 #include <linux/cpu.h>
   50 #include <linux/jump_label.h>
   51 
   52 #include <asm-generic/sections.h>
   53 #include <asm/cacheflush.h>
   54 #include <asm/errno.h>
   55 #include <asm/uaccess.h>
   56 
   57 #define KPROBE_HASH_BITS 6
   58 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
   59 
   60 
   61 /*
   62  * Some oddball architectures like 64bit powerpc have function descriptors
   63  * so this must be overridable.
   64  */
   65 #ifndef kprobe_lookup_name
   66 #define kprobe_lookup_name(name, addr) \
   67         addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
   68 #endif
   69 
   70 static int kprobes_initialized;
   71 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
   72 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
   73 
   74 /* NOTE: change this value only with kprobe_mutex held */
   75 static bool kprobes_all_disarmed;
   76 
   77 /* This protects kprobe_table and optimizing_list */
   78 static DEFINE_MUTEX(kprobe_mutex);
   79 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
   80 static struct {
   81         raw_spinlock_t lock ____cacheline_aligned_in_smp;
   82 } kretprobe_table_locks[KPROBE_TABLE_SIZE];
   83 
   84 static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
   85 {
   86         return &(kretprobe_table_locks[hash].lock);
   87 }
   88 
   89 /*
   90  * Normally, functions that we'd want to prohibit kprobes in, are marked
   91  * __kprobes. But, there are cases where such functions already belong to
   92  * a different section (__sched for preempt_schedule)
   93  *
   94  * For such cases, we now have a blacklist
   95  */
   96 static struct kprobe_blackpoint kprobe_blacklist[] = {
   97         {"preempt_schedule",},
   98         {"native_get_debugreg",},
   99         {"irq_entries_start",},
  100         {"common_interrupt",},
  101         {"mcount",},    /* mcount can be called from everywhere */
  102         {NULL}    /* Terminator */
  103 };
  104 
  105 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
  106 /*
  107  * kprobe->ainsn.insn points to the copy of the instruction to be
  108  * single-stepped. x86_64, POWER4 and above have no-exec support and
  109  * stepping on the instruction on a vmalloced/kmalloced/data page
  110  * is a recipe for disaster
  111  */
  112 struct kprobe_insn_page {
  113         struct list_head list;
  114         kprobe_opcode_t *insns;         /* Page of instruction slots */
  115         int nused;
  116         int ngarbage;
  117         char slot_used[];
  118 };
  119 
  120 #define KPROBE_INSN_PAGE_SIZE(slots)                    \
  121         (offsetof(struct kprobe_insn_page, slot_used) + \
  122          (sizeof(char) * (slots)))
  123 
  124 struct kprobe_insn_cache {
  125         struct list_head pages; /* list of kprobe_insn_page */
  126         size_t insn_size;       /* size of instruction slot */
  127         int nr_garbage;
  128 };
  129 
  130 static int slots_per_page(struct kprobe_insn_cache *c)
  131 {
  132         return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
  133 }
  134 
  135 enum kprobe_slot_state {
  136         SLOT_CLEAN = 0,
  137         SLOT_DIRTY = 1,
  138         SLOT_USED = 2,
  139 };
  140 
  141 static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_slots */
  142 static struct kprobe_insn_cache kprobe_insn_slots = {
  143         .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
  144         .insn_size = MAX_INSN_SIZE,
  145         .nr_garbage = 0,
  146 };
  147 static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c);
  148 
  149 /**
  150  * __get_insn_slot() - Find a slot on an executable page for an instruction.
  151  * We allocate an executable page if there's no room on existing ones.
  152  */
  153 static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
  154 {
  155         struct kprobe_insn_page *kip;
  156 
  157  retry:
  158         list_for_each_entry(kip, &c->pages, list) {
  159                 if (kip->nused < slots_per_page(c)) {
  160                         int i;
  161                         for (i = 0; i < slots_per_page(c); i++) {
  162                                 if (kip->slot_used[i] == SLOT_CLEAN) {
  163                                         kip->slot_used[i] = SLOT_USED;
  164                                         kip->nused++;
  165                                         return kip->insns + (i * c->insn_size);
  166                                 }
  167                         }
  168                         /* kip->nused is broken. Fix it. */
  169                         kip->nused = slots_per_page(c);
  170                         WARN_ON(1);
  171                 }
  172         }
  173 
  174         /* If there are any garbage slots, collect it and try again. */
  175         if (c->nr_garbage && collect_garbage_slots(c) == 0)
  176                 goto retry;
  177 
  178         /* All out of space.  Need to allocate a new page. */
  179         kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
  180         if (!kip)
  181                 return NULL;
  182 
  183         /*
  184          * Use module_alloc so this page is within +/- 2GB of where the
  185          * kernel image and loaded module images reside. This is required
  186          * so x86_64 can correctly handle the %rip-relative fixups.
  187          */
  188         kip->insns = module_alloc(PAGE_SIZE);
  189         if (!kip->insns) {
  190                 kfree(kip);
  191                 return NULL;
  192         }
  193         INIT_LIST_HEAD(&kip->list);
  194         memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
  195         kip->slot_used[0] = SLOT_USED;
  196         kip->nused = 1;
  197         kip->ngarbage = 0;
  198         list_add(&kip->list, &c->pages);
  199         return kip->insns;
  200 }
  201 
  202 
  203 kprobe_opcode_t __kprobes *get_insn_slot(void)
  204 {
  205         kprobe_opcode_t *ret = NULL;
  206 
  207         mutex_lock(&kprobe_insn_mutex);
  208         ret = __get_insn_slot(&kprobe_insn_slots);
  209         mutex_unlock(&kprobe_insn_mutex);
  210 
  211         return ret;
  212 }
  213 
  214 /* Return 1 if all garbages are collected, otherwise 0. */
  215 static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
  216 {
  217         kip->slot_used[idx] = SLOT_CLEAN;
  218         kip->nused--;
  219         if (kip->nused == 0) {
  220                 /*
  221                  * Page is no longer in use.  Free it unless
  222                  * it's the last one.  We keep the last one
  223                  * so as not to have to set it up again the
  224                  * next time somebody inserts a probe.
  225                  */
  226                 if (!list_is_singular(&kip->list)) {
  227                         list_del(&kip->list);
  228                         module_free(NULL, kip->insns);
  229                         kfree(kip);
  230                 }
  231                 return 1;
  232         }
  233         return 0;
  234 }
  235 
  236 static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c)
  237 {
  238         struct kprobe_insn_page *kip, *next;
  239 
  240         /* Ensure no-one is interrupted on the garbages */
  241         synchronize_sched();
  242 
  243         list_for_each_entry_safe(kip, next, &c->pages, list) {
  244                 int i;
  245                 if (kip->ngarbage == 0)
  246                         continue;
  247                 kip->ngarbage = 0;      /* we will collect all garbages */
  248                 for (i = 0; i < slots_per_page(c); i++) {
  249                         if (kip->slot_used[i] == SLOT_DIRTY &&
  250                             collect_one_slot(kip, i))
  251                                 break;
  252                 }
  253         }
  254         c->nr_garbage = 0;
  255         return 0;
  256 }
  257 
  258 static void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
  259                                        kprobe_opcode_t *slot, int dirty)
  260 {
  261         struct kprobe_insn_page *kip;
  262 
  263         list_for_each_entry(kip, &c->pages, list) {
  264                 long idx = ((long)slot - (long)kip->insns) /
  265                                 (c->insn_size * sizeof(kprobe_opcode_t));
  266                 if (idx >= 0 && idx < slots_per_page(c)) {
  267                         WARN_ON(kip->slot_used[idx] != SLOT_USED);
  268                         if (dirty) {
  269                                 kip->slot_used[idx] = SLOT_DIRTY;
  270                                 kip->ngarbage++;
  271                                 if (++c->nr_garbage > slots_per_page(c))
  272                                         collect_garbage_slots(c);
  273                         } else
  274                                 collect_one_slot(kip, idx);
  275                         return;
  276                 }
  277         }
  278         /* Could not free this slot. */
  279         WARN_ON(1);
  280 }
  281 
  282 void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
  283 {
  284         mutex_lock(&kprobe_insn_mutex);
  285         __free_insn_slot(&kprobe_insn_slots, slot, dirty);
  286         mutex_unlock(&kprobe_insn_mutex);
  287 }
  288 #ifdef CONFIG_OPTPROBES
  289 /* For optimized_kprobe buffer */
  290 static DEFINE_MUTEX(kprobe_optinsn_mutex); /* Protects kprobe_optinsn_slots */
  291 static struct kprobe_insn_cache kprobe_optinsn_slots = {
  292         .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
  293         /* .insn_size is initialized later */
  294         .nr_garbage = 0,
  295 };
  296 /* Get a slot for optimized_kprobe buffer */
  297 kprobe_opcode_t __kprobes *get_optinsn_slot(void)
  298 {
  299         kprobe_opcode_t *ret = NULL;
  300 
  301         mutex_lock(&kprobe_optinsn_mutex);
  302         ret = __get_insn_slot(&kprobe_optinsn_slots);
  303         mutex_unlock(&kprobe_optinsn_mutex);
  304 
  305         return ret;
  306 }
  307 
  308 void __kprobes free_optinsn_slot(kprobe_opcode_t * slot, int dirty)
  309 {
  310         mutex_lock(&kprobe_optinsn_mutex);
  311         __free_insn_slot(&kprobe_optinsn_slots, slot, dirty);
  312         mutex_unlock(&kprobe_optinsn_mutex);
  313 }
  314 #endif
  315 #endif
  316 
  317 /* We have preemption disabled.. so it is safe to use __ versions */
  318 static inline void set_kprobe_instance(struct kprobe *kp)
  319 {
  320         __this_cpu_write(kprobe_instance, kp);
  321 }
  322 
  323 static inline void reset_kprobe_instance(void)
  324 {
  325         __this_cpu_write(kprobe_instance, NULL);
  326 }
  327 
  328 /*
  329  * This routine is called either:
  330  *      - under the kprobe_mutex - during kprobe_[un]register()
  331  *                              OR
  332  *      - with preemption disabled - from arch/xxx/kernel/kprobes.c
  333  */
  334 struct kprobe __kprobes *get_kprobe(void *addr)
  335 {
  336         struct hlist_head *head;
  337         struct hlist_node *node;
  338         struct kprobe *p;
  339 
  340         head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
  341         hlist_for_each_entry_rcu(p, node, head, hlist) {
  342                 if (p->addr == addr)
  343                         return p;
  344         }
  345 
  346         return NULL;
  347 }
  348 
  349 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
  350 
  351 /* Return true if the kprobe is an aggregator */
  352 static inline int kprobe_aggrprobe(struct kprobe *p)
  353 {
  354         return p->pre_handler == aggr_pre_handler;
  355 }
  356 
  357 /* Return true(!0) if the kprobe is unused */
  358 static inline int kprobe_unused(struct kprobe *p)
  359 {
  360         return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
  361                list_empty(&p->list);
  362 }
  363 
  364 /*
  365  * Keep all fields in the kprobe consistent
  366  */
  367 static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
  368 {
  369         memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
  370         memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
  371 }
  372 
  373 #ifdef CONFIG_OPTPROBES
  374 /* NOTE: change this value only with kprobe_mutex held */
  375 static bool kprobes_allow_optimization;
  376 
  377 /*
  378  * Call all pre_handler on the list, but ignores its return value.
  379  * This must be called from arch-dep optimized caller.
  380  */
  381 void __kprobes opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
  382 {
  383         struct kprobe *kp;
  384 
  385         list_for_each_entry_rcu(kp, &p->list, list) {
  386                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
  387                         set_kprobe_instance(kp);
  388                         kp->pre_handler(kp, regs);
  389                 }
  390                 reset_kprobe_instance();
  391         }
  392 }
  393 
  394 /* Free optimized instructions and optimized_kprobe */
  395 static __kprobes void free_aggr_kprobe(struct kprobe *p)
  396 {
  397         struct optimized_kprobe *op;
  398 
  399         op = container_of(p, struct optimized_kprobe, kp);
  400         arch_remove_optimized_kprobe(op);
  401         arch_remove_kprobe(p);
  402         kfree(op);
  403 }
  404 
  405 /* Return true(!0) if the kprobe is ready for optimization. */
  406 static inline int kprobe_optready(struct kprobe *p)
  407 {
  408         struct optimized_kprobe *op;
  409 
  410         if (kprobe_aggrprobe(p)) {
  411                 op = container_of(p, struct optimized_kprobe, kp);
  412                 return arch_prepared_optinsn(&op->optinsn);
  413         }
  414 
  415         return 0;
  416 }
  417 
  418 /* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
  419 static inline int kprobe_disarmed(struct kprobe *p)
  420 {
  421         struct optimized_kprobe *op;
  422 
  423         /* If kprobe is not aggr/opt probe, just return kprobe is disabled */
  424         if (!kprobe_aggrprobe(p))
  425                 return kprobe_disabled(p);
  426 
  427         op = container_of(p, struct optimized_kprobe, kp);
  428 
  429         return kprobe_disabled(p) && list_empty(&op->list);
  430 }
  431 
  432 /* Return true(!0) if the probe is queued on (un)optimizing lists */
  433 static int __kprobes kprobe_queued(struct kprobe *p)
  434 {
  435         struct optimized_kprobe *op;
  436 
  437         if (kprobe_aggrprobe(p)) {
  438                 op = container_of(p, struct optimized_kprobe, kp);
  439                 if (!list_empty(&op->list))
  440                         return 1;
  441         }
  442         return 0;
  443 }
  444 
  445 /*
  446  * Return an optimized kprobe whose optimizing code replaces
  447  * instructions including addr (exclude breakpoint).
  448  */
  449 static struct kprobe *__kprobes get_optimized_kprobe(unsigned long addr)
  450 {
  451         int i;
  452         struct kprobe *p = NULL;
  453         struct optimized_kprobe *op;
  454 
  455         /* Don't check i == 0, since that is a breakpoint case. */
  456         for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
  457                 p = get_kprobe((void *)(addr - i));
  458 
  459         if (p && kprobe_optready(p)) {
  460                 op = container_of(p, struct optimized_kprobe, kp);
  461                 if (arch_within_optimized_kprobe(op, addr))
  462                         return p;
  463         }
  464 
  465         return NULL;
  466 }
  467 
  468 /* Optimization staging list, protected by kprobe_mutex */
  469 static LIST_HEAD(optimizing_list);
  470 static LIST_HEAD(unoptimizing_list);
  471 
  472 static void kprobe_optimizer(struct work_struct *work);
  473 static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
  474 static DECLARE_COMPLETION(optimizer_comp);
  475 #define OPTIMIZE_DELAY 5
  476 
  477 /*
  478  * Optimize (replace a breakpoint with a jump) kprobes listed on
  479  * optimizing_list.
  480  */
  481 static __kprobes void do_optimize_kprobes(void)
  482 {
  483         /* Optimization never be done when disarmed */
  484         if (kprobes_all_disarmed || !kprobes_allow_optimization ||
  485             list_empty(&optimizing_list))
  486                 return;
  487 
  488         /*
  489          * The optimization/unoptimization refers online_cpus via
  490          * stop_machine() and cpu-hotplug modifies online_cpus.
  491          * And same time, text_mutex will be held in cpu-hotplug and here.
  492          * This combination can cause a deadlock (cpu-hotplug try to lock
  493          * text_mutex but stop_machine can not be done because online_cpus
  494          * has been changed)
  495          * To avoid this deadlock, we need to call get_online_cpus()
  496          * for preventing cpu-hotplug outside of text_mutex locking.
  497          */
  498         get_online_cpus();
  499         mutex_lock(&text_mutex);
  500         arch_optimize_kprobes(&optimizing_list);
  501         mutex_unlock(&text_mutex);
  502         put_online_cpus();
  503 }
  504 
  505 /*
  506  * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
  507  * if need) kprobes listed on unoptimizing_list.
  508  */
  509 static __kprobes void do_unoptimize_kprobes(struct list_head *free_list)
  510 {
  511         struct optimized_kprobe *op, *tmp;
  512 
  513         /* Unoptimization must be done anytime */
  514         if (list_empty(&unoptimizing_list))
  515                 return;
  516 
  517         /* Ditto to do_optimize_kprobes */
  518         get_online_cpus();
  519         mutex_lock(&text_mutex);
  520         arch_unoptimize_kprobes(&unoptimizing_list, free_list);
  521         /* Loop free_list for disarming */
  522         list_for_each_entry_safe(op, tmp, free_list, list) {
  523                 /* Disarm probes if marked disabled */
  524                 if (kprobe_disabled(&op->kp))
  525                         arch_disarm_kprobe(&op->kp);
  526                 if (kprobe_unused(&op->kp)) {
  527                         /*
  528                          * Remove unused probes from hash list. After waiting
  529                          * for synchronization, these probes are reclaimed.
  530                          * (reclaiming is done by do_free_cleaned_kprobes.)
  531                          */
  532                         hlist_del_rcu(&op->kp.hlist);
  533                 } else
  534                         list_del_init(&op->list);
  535         }
  536         mutex_unlock(&text_mutex);
  537         put_online_cpus();
  538 }
  539 
  540 /* Reclaim all kprobes on the free_list */
  541 static __kprobes void do_free_cleaned_kprobes(struct list_head *free_list)
  542 {
  543         struct optimized_kprobe *op, *tmp;
  544 
  545         list_for_each_entry_safe(op, tmp, free_list, list) {
  546                 BUG_ON(!kprobe_unused(&op->kp));
  547                 list_del_init(&op->list);
  548                 free_aggr_kprobe(&op->kp);
  549         }
  550 }
  551 
  552 /* Start optimizer after OPTIMIZE_DELAY passed */
  553 static __kprobes void kick_kprobe_optimizer(void)
  554 {
  555         if (!delayed_work_pending(&optimizing_work))
  556                 schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
  557 }
  558 
  559 /* Kprobe jump optimizer */
  560 static __kprobes void kprobe_optimizer(struct work_struct *work)
  561 {
  562         LIST_HEAD(free_list);
  563 
  564         mutex_lock(&kprobe_mutex);
  565         /* Lock modules while optimizing kprobes */
  566         mutex_lock(&module_mutex);
  567 
  568         /*
  569          * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
  570          * kprobes before waiting for quiesence period.
  571          */
  572         do_unoptimize_kprobes(&free_list);
  573 
  574         /*
  575          * Step 2: Wait for quiesence period to ensure all running interrupts
  576          * are done. Because optprobe may modify multiple instructions
  577          * there is a chance that Nth instruction is interrupted. In that
  578          * case, running interrupt can return to 2nd-Nth byte of jump
  579          * instruction. This wait is for avoiding it.
  580          */
  581         synchronize_sched();
  582 
  583         /* Step 3: Optimize kprobes after quiesence period */
  584         do_optimize_kprobes();
  585 
  586         /* Step 4: Free cleaned kprobes after quiesence period */
  587         do_free_cleaned_kprobes(&free_list);
  588 
  589         mutex_unlock(&module_mutex);
  590         mutex_unlock(&kprobe_mutex);
  591 
  592         /* Step 5: Kick optimizer again if needed */
  593         if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
  594                 kick_kprobe_optimizer();
  595         else
  596                 /* Wake up all waiters */
  597                 complete_all(&optimizer_comp);
  598 }
  599 
  600 /* Wait for completing optimization and unoptimization */
  601 static __kprobes void wait_for_kprobe_optimizer(void)
  602 {
  603         if (delayed_work_pending(&optimizing_work))
  604                 wait_for_completion(&optimizer_comp);
  605 }
  606 
  607 /* Optimize kprobe if p is ready to be optimized */
  608 static __kprobes void optimize_kprobe(struct kprobe *p)
  609 {
  610         struct optimized_kprobe *op;
  611 
  612         /* Check if the kprobe is disabled or not ready for optimization. */
  613         if (!kprobe_optready(p) || !kprobes_allow_optimization ||
  614             (kprobe_disabled(p) || kprobes_all_disarmed))
  615                 return;
  616 
  617         /* Both of break_handler and post_handler are not supported. */
  618         if (p->break_handler || p->post_handler)
  619                 return;
  620 
  621         op = container_of(p, struct optimized_kprobe, kp);
  622 
  623         /* Check there is no other kprobes at the optimized instructions */
  624         if (arch_check_optimized_kprobe(op) < 0)
  625                 return;
  626 
  627         /* Check if it is already optimized. */
  628         if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
  629                 return;
  630         op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
  631 
  632         if (!list_empty(&op->list))
  633                 /* This is under unoptimizing. Just dequeue the probe */
  634                 list_del_init(&op->list);
  635         else {
  636                 list_add(&op->list, &optimizing_list);
  637                 kick_kprobe_optimizer();
  638         }
  639 }
  640 
  641 /* Short cut to direct unoptimizing */
  642 static __kprobes void force_unoptimize_kprobe(struct optimized_kprobe *op)
  643 {
  644         get_online_cpus();
  645         arch_unoptimize_kprobe(op);
  646         put_online_cpus();
  647         if (kprobe_disabled(&op->kp))
  648                 arch_disarm_kprobe(&op->kp);
  649 }
  650 
  651 /* Unoptimize a kprobe if p is optimized */
  652 static __kprobes void unoptimize_kprobe(struct kprobe *p, bool force)
  653 {
  654         struct optimized_kprobe *op;
  655 
  656         if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
  657                 return; /* This is not an optprobe nor optimized */
  658 
  659         op = container_of(p, struct optimized_kprobe, kp);
  660         if (!kprobe_optimized(p)) {
  661                 /* Unoptimized or unoptimizing case */
  662                 if (force && !list_empty(&op->list)) {
  663                         /*
  664                          * Only if this is unoptimizing kprobe and forced,
  665                          * forcibly unoptimize it. (No need to unoptimize
  666                          * unoptimized kprobe again :)
  667                          */
  668                         list_del_init(&op->list);
  669                         force_unoptimize_kprobe(op);
  670                 }
  671                 return;
  672         }
  673 
  674         op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
  675         if (!list_empty(&op->list)) {
  676                 /* Dequeue from the optimization queue */
  677                 list_del_init(&op->list);
  678                 return;
  679         }
  680         /* Optimized kprobe case */
  681         if (force)
  682                 /* Forcibly update the code: this is a special case */
  683                 force_unoptimize_kprobe(op);
  684         else {
  685                 list_add(&op->list, &unoptimizing_list);
  686                 kick_kprobe_optimizer();
  687         }
  688 }
  689 
  690 /* Cancel unoptimizing for reusing */
  691 static void reuse_unused_kprobe(struct kprobe *ap)
  692 {
  693         struct optimized_kprobe *op;
  694 
  695         BUG_ON(!kprobe_unused(ap));
  696         /*
  697          * Unused kprobe MUST be on the way of delayed unoptimizing (means
  698          * there is still a relative jump) and disabled.
  699          */
  700         op = container_of(ap, struct optimized_kprobe, kp);
  701         if (unlikely(list_empty(&op->list)))
  702                 printk(KERN_WARNING "Warning: found a stray unused "
  703                         "aggrprobe@%p\n", ap->addr);
  704         /* Enable the probe again */
  705         ap->flags &= ~KPROBE_FLAG_DISABLED;
  706         /* Optimize it again (remove from op->list) */
  707         BUG_ON(!kprobe_optready(ap));
  708         optimize_kprobe(ap);
  709 }
  710 
  711 /* Remove optimized instructions */
  712 static void __kprobes kill_optimized_kprobe(struct kprobe *p)
  713 {
  714         struct optimized_kprobe *op;
  715 
  716         op = container_of(p, struct optimized_kprobe, kp);
  717         if (!list_empty(&op->list))
  718                 /* Dequeue from the (un)optimization queue */
  719                 list_del_init(&op->list);
  720 
  721         op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
  722         /* Don't touch the code, because it is already freed. */
  723         arch_remove_optimized_kprobe(op);
  724 }
  725 
  726 /* Try to prepare optimized instructions */
  727 static __kprobes void prepare_optimized_kprobe(struct kprobe *p)
  728 {
  729         struct optimized_kprobe *op;
  730 
  731         op = container_of(p, struct optimized_kprobe, kp);
  732         arch_prepare_optimized_kprobe(op);
  733 }
  734 
  735 /* Allocate new optimized_kprobe and try to prepare optimized instructions */
  736 static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
  737 {
  738         struct optimized_kprobe *op;
  739 
  740         op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
  741         if (!op)
  742                 return NULL;
  743 
  744         INIT_LIST_HEAD(&op->list);
  745         op->kp.addr = p->addr;
  746         arch_prepare_optimized_kprobe(op);
  747 
  748         return &op->kp;
  749 }
  750 
  751 static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
  752 
  753 /*
  754  * Prepare an optimized_kprobe and optimize it
  755  * NOTE: p must be a normal registered kprobe
  756  */
  757 static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
  758 {
  759         struct kprobe *ap;
  760         struct optimized_kprobe *op;
  761 
  762         /* Impossible to optimize ftrace-based kprobe */
  763         if (kprobe_ftrace(p))
  764                 return;
  765 
  766         /* For preparing optimization, jump_label_text_reserved() is called */
  767         jump_label_lock();
  768         mutex_lock(&text_mutex);
  769 
  770         ap = alloc_aggr_kprobe(p);
  771         if (!ap)
  772                 goto out;
  773 
  774         op = container_of(ap, struct optimized_kprobe, kp);
  775         if (!arch_prepared_optinsn(&op->optinsn)) {
  776                 /* If failed to setup optimizing, fallback to kprobe */
  777                 arch_remove_optimized_kprobe(op);
  778                 kfree(op);
  779                 goto out;
  780         }
  781 
  782         init_aggr_kprobe(ap, p);
  783         optimize_kprobe(ap);    /* This just kicks optimizer thread */
  784 
  785 out:
  786         mutex_unlock(&text_mutex);
  787         jump_label_unlock();
  788 }
  789 
  790 #ifdef CONFIG_SYSCTL
  791 /* This should be called with kprobe_mutex locked */
  792 static void __kprobes optimize_all_kprobes(void)
  793 {
  794         struct hlist_head *head;
  795         struct hlist_node *node;
  796         struct kprobe *p;
  797         unsigned int i;
  798 
  799         /* If optimization is already allowed, just return */
  800         if (kprobes_allow_optimization)
  801                 return;
  802 
  803         kprobes_allow_optimization = true;
  804         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
  805                 head = &kprobe_table[i];
  806                 hlist_for_each_entry_rcu(p, node, head, hlist)
  807                         if (!kprobe_disabled(p))
  808                                 optimize_kprobe(p);
  809         }
  810         printk(KERN_INFO "Kprobes globally optimized\n");
  811 }
  812 
  813 /* This should be called with kprobe_mutex locked */
  814 static void __kprobes unoptimize_all_kprobes(void)
  815 {
  816         struct hlist_head *head;
  817         struct hlist_node *node;
  818         struct kprobe *p;
  819         unsigned int i;
  820 
  821         /* If optimization is already prohibited, just return */
  822         if (!kprobes_allow_optimization)
  823                 return;
  824 
  825         kprobes_allow_optimization = false;
  826         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
  827                 head = &kprobe_table[i];
  828                 hlist_for_each_entry_rcu(p, node, head, hlist) {
  829                         if (!kprobe_disabled(p))
  830                                 unoptimize_kprobe(p, false);
  831                 }
  832         }
  833         /* Wait for unoptimizing completion */
  834         wait_for_kprobe_optimizer();
  835         printk(KERN_INFO "Kprobes globally unoptimized\n");
  836 }
  837 
  838 int sysctl_kprobes_optimization;
  839 int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
  840                                       void __user *buffer, size_t *length,
  841                                       loff_t *ppos)
  842 {
  843         int ret;
  844 
  845         mutex_lock(&kprobe_mutex);
  846         sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
  847         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
  848 
  849         if (sysctl_kprobes_optimization)
  850                 optimize_all_kprobes();
  851         else
  852                 unoptimize_all_kprobes();
  853         mutex_unlock(&kprobe_mutex);
  854 
  855         return ret;
  856 }
  857 #endif /* CONFIG_SYSCTL */
  858 
  859 /* Put a breakpoint for a probe. Must be called with text_mutex locked */
  860 static void __kprobes __arm_kprobe(struct kprobe *p)
  861 {
  862         struct kprobe *_p;
  863 
  864         /* Check collision with other optimized kprobes */
  865         _p = get_optimized_kprobe((unsigned long)p->addr);
  866         if (unlikely(_p))
  867                 /* Fallback to unoptimized kprobe */
  868                 unoptimize_kprobe(_p, true);
  869 
  870         arch_arm_kprobe(p);
  871         optimize_kprobe(p);     /* Try to optimize (add kprobe to a list) */
  872 }
  873 
  874 /* Remove the breakpoint of a probe. Must be called with text_mutex locked */
  875 static void __kprobes __disarm_kprobe(struct kprobe *p, bool reopt)
  876 {
  877         struct kprobe *_p;
  878 
  879         unoptimize_kprobe(p, false);    /* Try to unoptimize */
  880 
  881         if (!kprobe_queued(p)) {
  882                 arch_disarm_kprobe(p);
  883                 /* If another kprobe was blocked, optimize it. */
  884                 _p = get_optimized_kprobe((unsigned long)p->addr);
  885                 if (unlikely(_p) && reopt)
  886                         optimize_kprobe(_p);
  887         }
  888         /* TODO: reoptimize others after unoptimized this probe */
  889 }
  890 
  891 #else /* !CONFIG_OPTPROBES */
  892 
  893 #define optimize_kprobe(p)                      do {} while (0)
  894 #define unoptimize_kprobe(p, f)                 do {} while (0)
  895 #define kill_optimized_kprobe(p)                do {} while (0)
  896 #define prepare_optimized_kprobe(p)             do {} while (0)
  897 #define try_to_optimize_kprobe(p)               do {} while (0)
  898 #define __arm_kprobe(p)                         arch_arm_kprobe(p)
  899 #define __disarm_kprobe(p, o)                   arch_disarm_kprobe(p)
  900 #define kprobe_disarmed(p)                      kprobe_disabled(p)
  901 #define wait_for_kprobe_optimizer()             do {} while (0)
  902 
  903 /* There should be no unused kprobes can be reused without optimization */
  904 static void reuse_unused_kprobe(struct kprobe *ap)
  905 {
  906         printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
  907         BUG_ON(kprobe_unused(ap));
  908 }
  909 
  910 static __kprobes void free_aggr_kprobe(struct kprobe *p)
  911 {
  912         arch_remove_kprobe(p);
  913         kfree(p);
  914 }
  915 
  916 static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
  917 {
  918         return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
  919 }
  920 #endif /* CONFIG_OPTPROBES */
  921 
  922 #ifdef KPROBES_CAN_USE_FTRACE
  923 static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
  924         .func = kprobe_ftrace_handler,
  925         .flags = FTRACE_OPS_FL_SAVE_REGS,
  926 };
  927 static int kprobe_ftrace_enabled;
  928 
  929 /* Must ensure p->addr is really on ftrace */
  930 static int __kprobes prepare_kprobe(struct kprobe *p)
  931 {
  932         if (!kprobe_ftrace(p))
  933                 return arch_prepare_kprobe(p);
  934 
  935         return arch_prepare_kprobe_ftrace(p);
  936 }
  937 
  938 /* Caller must lock kprobe_mutex */
  939 static void __kprobes arm_kprobe_ftrace(struct kprobe *p)
  940 {
  941         int ret;
  942 
  943         ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
  944                                    (unsigned long)p->addr, 0, 0);
  945         WARN(ret < 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p->addr, ret);
  946         kprobe_ftrace_enabled++;
  947         if (kprobe_ftrace_enabled == 1) {
  948                 ret = register_ftrace_function(&kprobe_ftrace_ops);
  949                 WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
  950         }
  951 }
  952 
  953 /* Caller must lock kprobe_mutex */
  954 static void __kprobes disarm_kprobe_ftrace(struct kprobe *p)
  955 {
  956         int ret;
  957 
  958         kprobe_ftrace_enabled--;
  959         if (kprobe_ftrace_enabled == 0) {
  960                 ret = unregister_ftrace_function(&kprobe_ftrace_ops);
  961                 WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
  962         }
  963         ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
  964                            (unsigned long)p->addr, 1, 0);
  965         WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
  966 }
  967 #else   /* !KPROBES_CAN_USE_FTRACE */
  968 #define prepare_kprobe(p)       arch_prepare_kprobe(p)
  969 #define arm_kprobe_ftrace(p)    do {} while (0)
  970 #define disarm_kprobe_ftrace(p) do {} while (0)
  971 #endif
  972 
  973 /* Arm a kprobe with text_mutex */
  974 static void __kprobes arm_kprobe(struct kprobe *kp)
  975 {
  976         if (unlikely(kprobe_ftrace(kp))) {
  977                 arm_kprobe_ftrace(kp);
  978                 return;
  979         }
  980         /*
  981          * Here, since __arm_kprobe() doesn't use stop_machine(),
  982          * this doesn't cause deadlock on text_mutex. So, we don't
  983          * need get_online_cpus().
  984          */
  985         mutex_lock(&text_mutex);
  986         __arm_kprobe(kp);
  987         mutex_unlock(&text_mutex);
  988 }
  989 
  990 /* Disarm a kprobe with text_mutex */
  991 static void __kprobes disarm_kprobe(struct kprobe *kp, bool reopt)
  992 {
  993         if (unlikely(kprobe_ftrace(kp))) {
  994                 disarm_kprobe_ftrace(kp);
  995                 return;
  996         }
  997         /* Ditto */
  998         mutex_lock(&text_mutex);
  999         __disarm_kprobe(kp, reopt);
 1000         mutex_unlock(&text_mutex);
 1001 }
 1002 
 1003 /*
 1004  * Aggregate handlers for multiple kprobes support - these handlers
 1005  * take care of invoking the individual kprobe handlers on p->list
 1006  */
 1007 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
 1008 {
 1009         struct kprobe *kp;
 1010 
 1011         list_for_each_entry_rcu(kp, &p->list, list) {
 1012                 if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
 1013                         set_kprobe_instance(kp);
 1014                         if (kp->pre_handler(kp, regs))
 1015                                 return 1;
 1016                 }
 1017                 reset_kprobe_instance();
 1018         }
 1019         return 0;
 1020 }
 1021 
 1022 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
 1023                                         unsigned long flags)
 1024 {
 1025         struct kprobe *kp;
 1026 
 1027         list_for_each_entry_rcu(kp, &p->list, list) {
 1028                 if (kp->post_handler && likely(!kprobe_disabled(kp))) {
 1029                         set_kprobe_instance(kp);
 1030                         kp->post_handler(kp, regs, flags);
 1031                         reset_kprobe_instance();
 1032                 }
 1033         }
 1034 }
 1035 
 1036 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
 1037                                         int trapnr)
 1038 {
 1039         struct kprobe *cur = __this_cpu_read(kprobe_instance);
 1040 
 1041         /*
 1042          * if we faulted "during" the execution of a user specified
 1043          * probe handler, invoke just that probe's fault handler
 1044          */
 1045         if (cur && cur->fault_handler) {
 1046                 if (cur->fault_handler(cur, regs, trapnr))
 1047                         return 1;
 1048         }
 1049         return 0;
 1050 }
 1051 
 1052 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
 1053 {
 1054         struct kprobe *cur = __this_cpu_read(kprobe_instance);
 1055         int ret = 0;
 1056 
 1057         if (cur && cur->break_handler) {
 1058                 if (cur->break_handler(cur, regs))
 1059                         ret = 1;
 1060         }
 1061         reset_kprobe_instance();
 1062         return ret;
 1063 }
 1064 
 1065 /* Walks the list and increments nmissed count for multiprobe case */
 1066 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
 1067 {
 1068         struct kprobe *kp;
 1069         if (!kprobe_aggrprobe(p)) {
 1070                 p->nmissed++;
 1071         } else {
 1072                 list_for_each_entry_rcu(kp, &p->list, list)
 1073                         kp->nmissed++;
 1074         }
 1075         return;
 1076 }
 1077 
 1078 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
 1079                                 struct hlist_head *head)
 1080 {
 1081         struct kretprobe *rp = ri->rp;
 1082 
 1083         /* remove rp inst off the rprobe_inst_table */
 1084         hlist_del(&ri->hlist);
 1085         INIT_HLIST_NODE(&ri->hlist);
 1086         if (likely(rp)) {
 1087                 raw_spin_lock(&rp->lock);
 1088                 hlist_add_head(&ri->hlist, &rp->free_instances);
 1089                 raw_spin_unlock(&rp->lock);
 1090         } else
 1091                 /* Unregistering */
 1092                 hlist_add_head(&ri->hlist, head);
 1093 }
 1094 
 1095 void __kprobes 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 
 1107 static void __kprobes kretprobe_table_lock(unsigned long hash,
 1108         unsigned long *flags)
 1109 __acquires(hlist_lock)
 1110 {
 1111         raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
 1112         raw_spin_lock_irqsave(hlist_lock, *flags);
 1113 }
 1114 
 1115 void __kprobes kretprobe_hash_unlock(struct task_struct *tsk,
 1116         unsigned long *flags)
 1117 __releases(hlist_lock)
 1118 {
 1119         unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
 1120         raw_spinlock_t *hlist_lock;
 1121 
 1122         hlist_lock = kretprobe_table_lock_ptr(hash);
 1123         raw_spin_unlock_irqrestore(hlist_lock, *flags);
 1124 }
 1125 
 1126 static void __kprobes kretprobe_table_unlock(unsigned long hash,
 1127        unsigned long *flags)
 1128 __releases(hlist_lock)
 1129 {
 1130         raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
 1131         raw_spin_unlock_irqrestore(hlist_lock, *flags);
 1132 }
 1133 
 1134 /*
 1135  * This function is called from finish_task_switch when task tk becomes dead,
 1136  * so that we can recycle any function-return probe instances associated
 1137  * with this task. These left over instances represent probed functions
 1138  * that have been called but will never return.
 1139  */
 1140 void __kprobes kprobe_flush_task(struct task_struct *tk)
 1141 {
 1142         struct kretprobe_instance *ri;
 1143         struct hlist_head *head, empty_rp;
 1144         struct hlist_node *node, *tmp;
 1145         unsigned long hash, flags = 0;
 1146 
 1147         if (unlikely(!kprobes_initialized))
 1148                 /* Early boot.  kretprobe_table_locks not yet initialized. */
 1149                 return;
 1150 
 1151         INIT_HLIST_HEAD(&empty_rp);
 1152         hash = hash_ptr(tk, KPROBE_HASH_BITS);
 1153         head = &kretprobe_inst_table[hash];
 1154         kretprobe_table_lock(hash, &flags);
 1155         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
 1156                 if (ri->task == tk)
 1157                         recycle_rp_inst(ri, &empty_rp);
 1158         }
 1159         kretprobe_table_unlock(hash, &flags);
 1160         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
 1161                 hlist_del(&ri->hlist);
 1162                 kfree(ri);
 1163         }
 1164 }
 1165 
 1166 static inline void free_rp_inst(struct kretprobe *rp)
 1167 {
 1168         struct kretprobe_instance *ri;
 1169         struct hlist_node *pos, *next;
 1170 
 1171         hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) {
 1172                 hlist_del(&ri->hlist);
 1173                 kfree(ri);
 1174         }
 1175 }
 1176 
 1177 static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
 1178 {
 1179         unsigned long flags, hash;
 1180         struct kretprobe_instance *ri;
 1181         struct hlist_node *pos, *next;
 1182         struct hlist_head *head;
 1183 
 1184         /* No race here */
 1185         for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
 1186                 kretprobe_table_lock(hash, &flags);
 1187                 head = &kretprobe_inst_table[hash];
 1188                 hlist_for_each_entry_safe(ri, pos, next, head, hlist) {
 1189                         if (ri->rp == rp)
 1190                                 ri->rp = NULL;
 1191                 }
 1192                 kretprobe_table_unlock(hash, &flags);
 1193         }
 1194         free_rp_inst(rp);
 1195 }
 1196 
 1197 /*
 1198 * Add the new probe to ap->list. Fail if this is the
 1199 * second jprobe at the address - two jprobes can't coexist
 1200 */
 1201 static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
 1202 {
 1203         BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
 1204 
 1205         if (p->break_handler || p->post_handler)
 1206                 unoptimize_kprobe(ap, true);    /* Fall back to normal kprobe */
 1207 
 1208         if (p->break_handler) {
 1209                 if (ap->break_handler)
 1210                         return -EEXIST;
 1211                 list_add_tail_rcu(&p->list, &ap->list);
 1212                 ap->break_handler = aggr_break_handler;
 1213         } else
 1214                 list_add_rcu(&p->list, &ap->list);
 1215         if (p->post_handler && !ap->post_handler)
 1216                 ap->post_handler = aggr_post_handler;
 1217 
 1218         return 0;
 1219 }
 1220 
 1221 /*
 1222  * Fill in the required fields of the "manager kprobe". Replace the
 1223  * earlier kprobe in the hlist with the manager kprobe
 1224  */
 1225 static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
 1226 {
 1227         /* Copy p's insn slot to ap */
 1228         copy_kprobe(p, ap);
 1229         flush_insn_slot(ap);
 1230         ap->addr = p->addr;
 1231         ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
 1232         ap->pre_handler = aggr_pre_handler;
 1233         ap->fault_handler = aggr_fault_handler;
 1234         /* We don't care the kprobe which has gone. */
 1235         if (p->post_handler && !kprobe_gone(p))
 1236                 ap->post_handler = aggr_post_handler;
 1237         if (p->break_handler && !kprobe_gone(p))
 1238                 ap->break_handler = aggr_break_handler;
 1239 
 1240         INIT_LIST_HEAD(&ap->list);
 1241         INIT_HLIST_NODE(&ap->hlist);
 1242 
 1243         list_add_rcu(&p->list, &ap->list);
 1244         hlist_replace_rcu(&p->hlist, &ap->hlist);
 1245 }
 1246 
 1247 /*
 1248  * This is the second or subsequent kprobe at the address - handle
 1249  * the intricacies
 1250  */
 1251 static int __kprobes register_aggr_kprobe(struct kprobe *orig_p,
 1252                                           struct kprobe *p)
 1253 {
 1254         int ret = 0;
 1255         struct kprobe *ap = orig_p;
 1256 
 1257         /* For preparing optimization, jump_label_text_reserved() is called */
 1258         jump_label_lock();
 1259         /*
 1260          * Get online CPUs to avoid text_mutex deadlock.with stop machine,
 1261          * which is invoked by unoptimize_kprobe() in add_new_kprobe()
 1262          */
 1263         get_online_cpus();
 1264         mutex_lock(&text_mutex);
 1265 
 1266         if (!kprobe_aggrprobe(orig_p)) {
 1267                 /* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
 1268                 ap = alloc_aggr_kprobe(orig_p);
 1269                 if (!ap) {
 1270                         ret = -ENOMEM;
 1271                         goto out;
 1272                 }
 1273                 init_aggr_kprobe(ap, orig_p);
 1274         } else if (kprobe_unused(ap))
 1275                 /* This probe is going to die. Rescue it */
 1276                 reuse_unused_kprobe(ap);
 1277 
 1278         if (kprobe_gone(ap)) {
 1279                 /*
 1280                  * Attempting to insert new probe at the same location that
 1281                  * had a probe in the module vaddr area which already
 1282                  * freed. So, the instruction slot has already been
 1283                  * released. We need a new slot for the new probe.
 1284                  */
 1285                 ret = arch_prepare_kprobe(ap);
 1286                 if (ret)
 1287                         /*
 1288                          * Even if fail to allocate new slot, don't need to
 1289                          * free aggr_probe. It will be used next time, or
 1290                          * freed by unregister_kprobe.
 1291                          */
 1292                         goto out;
 1293 
 1294                 /* Prepare optimized instructions if possible. */
 1295                 prepare_optimized_kprobe(ap);
 1296 
 1297                 /*
 1298                  * Clear gone flag to prevent allocating new slot again, and
 1299                  * set disabled flag because it is not armed yet.
 1300                  */
 1301                 ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
 1302                             | KPROBE_FLAG_DISABLED;
 1303         }
 1304 
 1305         /* Copy ap's insn slot to p */
 1306         copy_kprobe(ap, p);
 1307         ret = add_new_kprobe(ap, p);
 1308 
 1309 out:
 1310         mutex_unlock(&text_mutex);
 1311         put_online_cpus();
 1312         jump_label_unlock();
 1313 
 1314         if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
 1315                 ap->flags &= ~KPROBE_FLAG_DISABLED;
 1316                 if (!kprobes_all_disarmed)
 1317                         /* Arm the breakpoint again. */
 1318                         arm_kprobe(ap);
 1319         }
 1320         return ret;
 1321 }
 1322 
 1323 static int __kprobes in_kprobes_functions(unsigned long addr)
 1324 {
 1325         struct kprobe_blackpoint *kb;
 1326 
 1327         if (addr >= (unsigned long)__kprobes_text_start &&
 1328             addr < (unsigned long)__kprobes_text_end)
 1329                 return -EINVAL;
 1330         /*
 1331          * If there exists a kprobe_blacklist, verify and
 1332          * fail any probe registration in the prohibited area
 1333          */
 1334         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
 1335                 if (kb->start_addr) {
 1336                         if (addr >= kb->start_addr &&
 1337                             addr < (kb->start_addr + kb->range))
 1338                                 return -EINVAL;
 1339                 }
 1340         }
 1341         return 0;
 1342 }
 1343 
 1344 /*
 1345  * If we have a symbol_name argument, look it up and add the offset field
 1346  * to it. This way, we can specify a relative address to a symbol.
 1347  * This returns encoded errors if it fails to look up symbol or invalid
 1348  * combination of parameters.
 1349  */
 1350 static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
 1351 {
 1352         kprobe_opcode_t *addr = p->addr;
 1353 
 1354         if ((p->symbol_name && p->addr) ||
 1355             (!p->symbol_name && !p->addr))
 1356                 goto invalid;
 1357 
 1358         if (p->symbol_name) {
 1359                 kprobe_lookup_name(p->symbol_name, addr);
 1360                 if (!addr)
 1361                         return ERR_PTR(-ENOENT);
 1362         }
 1363 
 1364         addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
 1365         if (addr)
 1366                 return addr;
 1367 
 1368 invalid:
 1369         return ERR_PTR(-EINVAL);
 1370 }
 1371 
 1372 /* Check passed kprobe is valid and return kprobe in kprobe_table. */
 1373 static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)
 1374 {
 1375         struct kprobe *ap, *list_p;
 1376 
 1377         ap = get_kprobe(p->addr);
 1378         if (unlikely(!ap))
 1379                 return NULL;
 1380 
 1381         if (p != ap) {
 1382                 list_for_each_entry_rcu(list_p, &ap->list, list)
 1383                         if (list_p == p)
 1384                         /* kprobe p is a valid probe */
 1385                                 goto valid;
 1386                 return NULL;
 1387         }
 1388 valid:
 1389         return ap;
 1390 }
 1391 
 1392 /* Return error if the kprobe is being re-registered */
 1393 static inline int check_kprobe_rereg(struct kprobe *p)
 1394 {
 1395         int ret = 0;
 1396 
 1397         mutex_lock(&kprobe_mutex);
 1398         if (__get_valid_kprobe(p))
 1399                 ret = -EINVAL;
 1400         mutex_unlock(&kprobe_mutex);
 1401 
 1402         return ret;
 1403 }
 1404 
 1405 static __kprobes int check_kprobe_address_safe(struct kprobe *p,
 1406                                                struct module **probed_mod)
 1407 {
 1408         int ret = 0;
 1409         unsigned long ftrace_addr;
 1410 
 1411         /*
 1412          * If the address is located on a ftrace nop, set the
 1413          * breakpoint to the following instruction.
 1414          */
 1415         ftrace_addr = ftrace_location((unsigned long)p->addr);
 1416         if (ftrace_addr) {
 1417 #ifdef KPROBES_CAN_USE_FTRACE
 1418                 /* Given address is not on the instruction boundary */
 1419                 if ((unsigned long)p->addr != ftrace_addr)
 1420                         return -EILSEQ;
 1421                 p->flags |= KPROBE_FLAG_FTRACE;
 1422 #else   /* !KPROBES_CAN_USE_FTRACE */
 1423                 return -EINVAL;
 1424 #endif
 1425         }
 1426 
 1427         jump_label_lock();
 1428         preempt_disable();
 1429 
 1430         /* Ensure it is not in reserved area nor out of text */
 1431         if (!kernel_text_address((unsigned long) p->addr) ||
 1432             in_kprobes_functions((unsigned long) p->addr) ||
 1433             jump_label_text_reserved(p->addr, p->addr)) {
 1434                 ret = -EINVAL;
 1435                 goto out;
 1436         }
 1437 
 1438         /* Check if are we probing a module */
 1439         *probed_mod = __module_text_address((unsigned long) p->addr);
 1440         if (*probed_mod) {
 1441                 /*
 1442                  * We must hold a refcount of the probed module while updating
 1443                  * its code to prohibit unexpected unloading.
 1444                  */
 1445                 if (unlikely(!try_module_get(*probed_mod))) {
 1446                         ret = -ENOENT;
 1447                         goto out;
 1448                 }
 1449 
 1450                 /*
 1451                  * If the module freed .init.text, we couldn't insert
 1452                  * kprobes in there.
 1453                  */
 1454                 if (within_module_init((unsigned long)p->addr, *probed_mod) &&
 1455                     (*probed_mod)->state != MODULE_STATE_COMING) {
 1456                         module_put(*probed_mod);
 1457                         *probed_mod = NULL;
 1458                         ret = -ENOENT;
 1459                 }
 1460         }
 1461 out:
 1462         preempt_enable();
 1463         jump_label_unlock();
 1464 
 1465         return ret;
 1466 }
 1467 
 1468 int __kprobes register_kprobe(struct kprobe *p)
 1469 {
 1470         int ret;
 1471         struct kprobe *old_p;
 1472         struct module *probed_mod;
 1473         kprobe_opcode_t *addr;
 1474 
 1475         /* Adjust probe address from symbol */
 1476         addr = kprobe_addr(p);
 1477         if (IS_ERR(addr))
 1478                 return PTR_ERR(addr);
 1479         p->addr = addr;
 1480 
 1481         ret = check_kprobe_rereg(p);
 1482         if (ret)
 1483                 return ret;
 1484 
 1485         /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
 1486         p->flags &= KPROBE_FLAG_DISABLED;
 1487         p->nmissed = 0;
 1488         INIT_LIST_HEAD(&p->list);
 1489 
 1490         ret = check_kprobe_address_safe(p, &probed_mod);
 1491         if (ret)
 1492                 return ret;
 1493 
 1494         mutex_lock(&kprobe_mutex);
 1495 
 1496         old_p = get_kprobe(p->addr);
 1497         if (old_p) {
 1498                 /* Since this may unoptimize old_p, locking text_mutex. */
 1499                 ret = register_aggr_kprobe(old_p, p);
 1500                 goto out;
 1501         }
 1502 
 1503         mutex_lock(&text_mutex);        /* Avoiding text modification */
 1504         ret = prepare_kprobe(p);
 1505         mutex_unlock(&text_mutex);
 1506         if (ret)
 1507                 goto out;
 1508 
 1509         INIT_HLIST_NODE(&p->hlist);
 1510         hlist_add_head_rcu(&p->hlist,
 1511                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
 1512 
 1513         if (!kprobes_all_disarmed && !kprobe_disabled(p))
 1514                 arm_kprobe(p);
 1515 
 1516         /* Try to optimize kprobe */
 1517         try_to_optimize_kprobe(p);
 1518 
 1519 out:
 1520         mutex_unlock(&kprobe_mutex);
 1521 
 1522         if (probed_mod)
 1523                 module_put(probed_mod);
 1524 
 1525         return ret;
 1526 }
 1527 EXPORT_SYMBOL_GPL(register_kprobe);
 1528 
 1529 /* Check if all probes on the aggrprobe are disabled */
 1530 static int __kprobes aggr_kprobe_disabled(struct kprobe *ap)
 1531 {
 1532         struct kprobe *kp;
 1533 
 1534         list_for_each_entry_rcu(kp, &ap->list, list)
 1535                 if (!kprobe_disabled(kp))
 1536                         /*
 1537                          * There is an active probe on the list.
 1538                          * We can't disable this ap.
 1539                          */
 1540                         return 0;
 1541 
 1542         return 1;
 1543 }
 1544 
 1545 /* Disable one kprobe: Make sure called under kprobe_mutex is locked */
 1546 static struct kprobe *__kprobes __disable_kprobe(struct kprobe *p)
 1547 {
 1548         struct kprobe *orig_p;
 1549 
 1550         /* Get an original kprobe for return */
 1551         orig_p = __get_valid_kprobe(p);
 1552         if (unlikely(orig_p == NULL))
 1553                 return NULL;
 1554 
 1555         if (!kprobe_disabled(p)) {
 1556                 /* Disable probe if it is a child probe */
 1557                 if (p != orig_p)
 1558                         p->flags |= KPROBE_FLAG_DISABLED;
 1559 
 1560                 /* Try to disarm and disable this/parent probe */
 1561                 if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
 1562                         disarm_kprobe(orig_p, true);
 1563                         orig_p->flags |= KPROBE_FLAG_DISABLED;
 1564                 }
 1565         }
 1566 
 1567         return orig_p;
 1568 }
 1569 
 1570 /*
 1571  * Unregister a kprobe without a scheduler synchronization.
 1572  */
 1573 static int __kprobes __unregister_kprobe_top(struct kprobe *p)
 1574 {
 1575         struct kprobe *ap, *list_p;
 1576 
 1577         /* Disable kprobe. This will disarm it if needed. */
 1578         ap = __disable_kprobe(p);
 1579         if (ap == NULL)
 1580                 return -EINVAL;
 1581 
 1582         if (ap == p)
 1583                 /*
 1584                  * This probe is an independent(and non-optimized) kprobe
 1585                  * (not an aggrprobe). Remove from the hash list.
 1586                  */
 1587                 goto disarmed;
 1588 
 1589         /* Following process expects this probe is an aggrprobe */
 1590         WARN_ON(!kprobe_aggrprobe(ap));
 1591 
 1592         if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
 1593                 /*
 1594                  * !disarmed could be happen if the probe is under delayed
 1595                  * unoptimizing.
 1596                  */
 1597                 goto disarmed;
 1598         else {
 1599                 /* If disabling probe has special handlers, update aggrprobe */
 1600                 if (p->break_handler && !kprobe_gone(p))
 1601                         ap->break_handler = NULL;
 1602                 if (p->post_handler && !kprobe_gone(p)) {
 1603                         list_for_each_entry_rcu(list_p, &ap->list, list) {
 1604                                 if ((list_p != p) && (list_p->post_handler))
 1605                                         goto noclean;
 1606                         }
 1607                         ap->post_handler = NULL;
 1608                 }
 1609 noclean:
 1610                 /*
 1611                  * Remove from the aggrprobe: this path will do nothing in
 1612                  * __unregister_kprobe_bottom().
 1613                  */
 1614                 list_del_rcu(&p->list);
 1615                 if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
 1616                         /*
 1617                          * Try to optimize this probe again, because post
 1618                          * handler may have been changed.
 1619                          */
 1620                         optimize_kprobe(ap);
 1621         }
 1622         return 0;
 1623 
 1624 disarmed:
 1625         BUG_ON(!kprobe_disarmed(ap));
 1626         hlist_del_rcu(&ap->hlist);
 1627         return 0;
 1628 }
 1629 
 1630 static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
 1631 {
 1632         struct kprobe *ap;
 1633 
 1634         if (list_empty(&p->list))
 1635                 /* This is an independent kprobe */
 1636                 arch_remove_kprobe(p);
 1637         else if (list_is_singular(&p->list)) {
 1638                 /* This is the last child of an aggrprobe */
 1639                 ap = list_entry(p->list.next, struct kprobe, list);
 1640                 list_del(&p->list);
 1641                 free_aggr_kprobe(ap);
 1642         }
 1643         /* Otherwise, do nothing. */
 1644 }
 1645 
 1646 int __kprobes register_kprobes(struct kprobe **kps, int num)
 1647 {
 1648         int i, ret = 0;
 1649 
 1650         if (num <= 0)
 1651                 return -EINVAL;
 1652         for (i = 0; i < num; i++) {
 1653                 ret = register_kprobe(kps[i]);
 1654                 if (ret < 0) {
 1655                         if (i > 0)
 1656                                 unregister_kprobes(kps, i);
 1657                         break;
 1658                 }
 1659         }
 1660         return ret;
 1661 }
 1662 EXPORT_SYMBOL_GPL(register_kprobes);
 1663 
 1664 void __kprobes unregister_kprobe(struct kprobe *p)
 1665 {
 1666         unregister_kprobes(&p, 1);
 1667 }
 1668 EXPORT_SYMBOL_GPL(unregister_kprobe);
 1669 
 1670 void __kprobes unregister_kprobes(struct kprobe **kps, int num)
 1671 {
 1672         int i;
 1673 
 1674         if (num <= 0)
 1675                 return;
 1676         mutex_lock(&kprobe_mutex);
 1677         for (i = 0; i < num; i++)
 1678                 if (__unregister_kprobe_top(kps[i]) < 0)
 1679                         kps[i]->addr = NULL;
 1680         mutex_unlock(&kprobe_mutex);
 1681 
 1682         synchronize_sched();
 1683         for (i = 0; i < num; i++)
 1684                 if (kps[i]->addr)
 1685                         __unregister_kprobe_bottom(kps[i]);
 1686 }
 1687 EXPORT_SYMBOL_GPL(unregister_kprobes);
 1688 
 1689 static struct notifier_block kprobe_exceptions_nb = {
 1690         .notifier_call = kprobe_exceptions_notify,
 1691         .priority = 0x7fffffff /* we need to be notified first */
 1692 };
 1693 
 1694 unsigned long __weak arch_deref_entry_point(void *entry)
 1695 {
 1696         return (unsigned long)entry;
 1697 }
 1698 
 1699 int __kprobes register_jprobes(struct jprobe **jps, int num)
 1700 {
 1701         struct jprobe *jp;
 1702         int ret = 0, i;
 1703 
 1704         if (num <= 0)
 1705                 return -EINVAL;
 1706         for (i = 0; i < num; i++) {
 1707                 unsigned long addr, offset;
 1708                 jp = jps[i];
 1709                 addr = arch_deref_entry_point(jp->entry);
 1710 
 1711                 /* Verify probepoint is a function entry point */
 1712                 if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
 1713                     offset == 0) {
 1714                         jp->kp.pre_handler = setjmp_pre_handler;
 1715                         jp->kp.break_handler = longjmp_break_handler;
 1716                         ret = register_kprobe(&jp->kp);
 1717                 } else
 1718                         ret = -EINVAL;
 1719 
 1720                 if (ret < 0) {
 1721                         if (i > 0)
 1722                                 unregister_jprobes(jps, i);
 1723                         break;
 1724                 }
 1725         }
 1726         return ret;
 1727 }
 1728 EXPORT_SYMBOL_GPL(register_jprobes);
 1729 
 1730 int __kprobes register_jprobe(struct jprobe *jp)
 1731 {
 1732         return register_jprobes(&jp, 1);
 1733 }
 1734 EXPORT_SYMBOL_GPL(register_jprobe);
 1735 
 1736 void __kprobes unregister_jprobe(struct jprobe *jp)
 1737 {
 1738         unregister_jprobes(&jp, 1);
 1739 }
 1740 EXPORT_SYMBOL_GPL(unregister_jprobe);
 1741 
 1742 void __kprobes unregister_jprobes(struct jprobe **jps, int num)
 1743 {
 1744         int i;
 1745 
 1746         if (num <= 0)
 1747                 return;
 1748         mutex_lock(&kprobe_mutex);
 1749         for (i = 0; i < num; i++)
 1750                 if (__unregister_kprobe_top(&jps[i]->kp) < 0)
 1751                         jps[i]->kp.addr = NULL;
 1752         mutex_unlock(&kprobe_mutex);
 1753 
 1754         synchronize_sched();
 1755         for (i = 0; i < num; i++) {
 1756                 if (jps[i]->kp.addr)
 1757                         __unregister_kprobe_bottom(&jps[i]->kp);
 1758         }
 1759 }
 1760 EXPORT_SYMBOL_GPL(unregister_jprobes);
 1761 
 1762 #ifdef CONFIG_KRETPROBES
 1763 /*
 1764  * This kprobe pre_handler is registered with every kretprobe. When probe
 1765  * hits it will set up the return probe.
 1766  */
 1767 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
 1768                                            struct pt_regs *regs)
 1769 {
 1770         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
 1771         unsigned long hash, flags = 0;
 1772         struct kretprobe_instance *ri;
 1773 
 1774         /*TODO: consider to only swap the RA after the last pre_handler fired */
 1775         hash = hash_ptr(current, KPROBE_HASH_BITS);
 1776         raw_spin_lock_irqsave(&rp->lock, flags);
 1777         if (!hlist_empty(&rp->free_instances)) {
 1778                 ri = hlist_entry(rp->free_instances.first,
 1779                                 struct kretprobe_instance, hlist);
 1780                 hlist_del(&ri->hlist);
 1781                 raw_spin_unlock_irqrestore(&rp->lock, flags);
 1782 
 1783                 ri->rp = rp;
 1784                 ri->task = current;
 1785 
 1786                 if (rp->entry_handler && rp->entry_handler(ri, regs)) {
 1787                         raw_spin_lock_irqsave(&rp->lock, flags);
 1788                         hlist_add_head(&ri->hlist, &rp->free_instances);
 1789                         raw_spin_unlock_irqrestore(&rp->lock, flags);
 1790                         return 0;
 1791                 }
 1792 
 1793                 arch_prepare_kretprobe(ri, regs);
 1794 
 1795                 /* XXX(hch): why is there no hlist_move_head? */
 1796                 INIT_HLIST_NODE(&ri->hlist);
 1797                 kretprobe_table_lock(hash, &flags);
 1798                 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
 1799                 kretprobe_table_unlock(hash, &flags);
 1800         } else {
 1801                 rp->nmissed++;
 1802                 raw_spin_unlock_irqrestore(&rp->lock, flags);
 1803         }
 1804         return 0;
 1805 }
 1806 
 1807 int __kprobes register_kretprobe(struct kretprobe *rp)
 1808 {
 1809         int ret = 0;
 1810         struct kretprobe_instance *inst;
 1811         int i;
 1812         void *addr;
 1813 
 1814         if (kretprobe_blacklist_size) {
 1815                 addr = kprobe_addr(&rp->kp);
 1816                 if (IS_ERR(addr))
 1817                         return PTR_ERR(addr);
 1818 
 1819                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
 1820                         if (kretprobe_blacklist[i].addr == addr)
 1821                                 return -EINVAL;
 1822                 }
 1823         }
 1824 
 1825         rp->kp.pre_handler = pre_handler_kretprobe;
 1826         rp->kp.post_handler = NULL;
 1827         rp->kp.fault_handler = NULL;
 1828         rp->kp.break_handler = NULL;
 1829 
 1830         /* Pre-allocate memory for max kretprobe instances */
 1831         if (rp->maxactive <= 0) {
 1832 #ifdef CONFIG_PREEMPT
 1833                 rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
 1834 #else
 1835                 rp->maxactive = num_possible_cpus();
 1836 #endif
 1837         }
 1838         raw_spin_lock_init(&rp->lock);
 1839         INIT_HLIST_HEAD(&rp->free_instances);
 1840         for (i = 0; i < rp->maxactive; i++) {
 1841                 inst = kmalloc(sizeof(struct kretprobe_instance) +
 1842                                rp->data_size, GFP_KERNEL);
 1843                 if (inst == NULL) {
 1844                         free_rp_inst(rp);
 1845                         return -ENOMEM;
 1846                 }
 1847                 INIT_HLIST_NODE(&inst->hlist);
 1848                 hlist_add_head(&inst->hlist, &rp->free_instances);
 1849         }
 1850 
 1851         rp->nmissed = 0;
 1852         /* Establish function entry probe point */
 1853         ret = register_kprobe(&rp->kp);
 1854         if (ret != 0)
 1855                 free_rp_inst(rp);
 1856         return ret;
 1857 }
 1858 EXPORT_SYMBOL_GPL(register_kretprobe);
 1859 
 1860 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
 1861 {
 1862         int ret = 0, i;
 1863 
 1864         if (num <= 0)
 1865                 return -EINVAL;
 1866         for (i = 0; i < num; i++) {
 1867                 ret = register_kretprobe(rps[i]);
 1868                 if (ret < 0) {
 1869                         if (i > 0)
 1870                                 unregister_kretprobes(rps, i);
 1871                         break;
 1872                 }
 1873         }
 1874         return ret;
 1875 }
 1876 EXPORT_SYMBOL_GPL(register_kretprobes);
 1877 
 1878 void __kprobes unregister_kretprobe(struct kretprobe *rp)
 1879 {
 1880         unregister_kretprobes(&rp, 1);
 1881 }
 1882 EXPORT_SYMBOL_GPL(unregister_kretprobe);
 1883 
 1884 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
 1885 {
 1886         int i;
 1887 
 1888         if (num <= 0)
 1889                 return;
 1890         mutex_lock(&kprobe_mutex);
 1891         for (i = 0; i < num; i++)
 1892                 if (__unregister_kprobe_top(&rps[i]->kp) < 0)
 1893                         rps[i]->kp.addr = NULL;
 1894         mutex_unlock(&kprobe_mutex);
 1895 
 1896         synchronize_sched();
 1897         for (i = 0; i < num; i++) {
 1898                 if (rps[i]->kp.addr) {
 1899                         __unregister_kprobe_bottom(&rps[i]->kp);
 1900                         cleanup_rp_inst(rps[i]);
 1901                 }
 1902         }
 1903 }
 1904 EXPORT_SYMBOL_GPL(unregister_kretprobes);
 1905 
 1906 #else /* CONFIG_KRETPROBES */
 1907 int __kprobes register_kretprobe(struct kretprobe *rp)
 1908 {
 1909         return -ENOSYS;
 1910 }
 1911 EXPORT_SYMBOL_GPL(register_kretprobe);
 1912 
 1913 int __kprobes register_kretprobes(struct kretprobe **rps, int num)
 1914 {
 1915         return -ENOSYS;
 1916 }
 1917 EXPORT_SYMBOL_GPL(register_kretprobes);
 1918 
 1919 void __kprobes unregister_kretprobe(struct kretprobe *rp)
 1920 {
 1921 }
 1922 EXPORT_SYMBOL_GPL(unregister_kretprobe);
 1923 
 1924 void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
 1925 {
 1926 }
 1927 EXPORT_SYMBOL_GPL(unregister_kretprobes);
 1928 
 1929 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
 1930                                            struct pt_regs *regs)
 1931 {
 1932         return 0;
 1933 }
 1934 
 1935 #endif /* CONFIG_KRETPROBES */
 1936 
 1937 /* Set the kprobe gone and remove its instruction buffer. */
 1938 static void __kprobes kill_kprobe(struct kprobe *p)
 1939 {
 1940         struct kprobe *kp;
 1941 
 1942         p->flags |= KPROBE_FLAG_GONE;
 1943         if (kprobe_aggrprobe(p)) {
 1944                 /*
 1945                  * If this is an aggr_kprobe, we have to list all the
 1946                  * chained probes and mark them GONE.
 1947                  */
 1948                 list_for_each_entry_rcu(kp, &p->list, list)
 1949                         kp->flags |= KPROBE_FLAG_GONE;
 1950                 p->post_handler = NULL;
 1951                 p->break_handler = NULL;
 1952                 kill_optimized_kprobe(p);
 1953         }
 1954         /*
 1955          * Here, we can remove insn_slot safely, because no thread calls
 1956          * the original probed function (which will be freed soon) any more.
 1957          */
 1958         arch_remove_kprobe(p);
 1959 }
 1960 
 1961 /* Disable one kprobe */
 1962 int __kprobes disable_kprobe(struct kprobe *kp)
 1963 {
 1964         int ret = 0;
 1965 
 1966         mutex_lock(&kprobe_mutex);
 1967 
 1968         /* Disable this kprobe */
 1969         if (__disable_kprobe(kp) == NULL)
 1970                 ret = -EINVAL;
 1971 
 1972         mutex_unlock(&kprobe_mutex);
 1973         return ret;
 1974 }
 1975 EXPORT_SYMBOL_GPL(disable_kprobe);
 1976 
 1977 /* Enable one kprobe */
 1978 int __kprobes enable_kprobe(struct kprobe *kp)
 1979 {
 1980         int ret = 0;
 1981         struct kprobe *p;
 1982 
 1983         mutex_lock(&kprobe_mutex);
 1984 
 1985         /* Check whether specified probe is valid. */
 1986         p = __get_valid_kprobe(kp);
 1987         if (unlikely(p == NULL)) {
 1988                 ret = -EINVAL;
 1989                 goto out;
 1990         }
 1991 
 1992         if (kprobe_gone(kp)) {
 1993                 /* This kprobe has gone, we couldn't enable it. */
 1994                 ret = -EINVAL;
 1995                 goto out;
 1996         }
 1997 
 1998         if (p != kp)
 1999                 kp->flags &= ~KPROBE_FLAG_DISABLED;
 2000 
 2001         if (!kprobes_all_disarmed && kprobe_disabled(p)) {
 2002                 p->flags &= ~KPROBE_FLAG_DISABLED;
 2003                 arm_kprobe(p);
 2004         }
 2005 out:
 2006         mutex_unlock(&kprobe_mutex);
 2007         return ret;
 2008 }
 2009 EXPORT_SYMBOL_GPL(enable_kprobe);
 2010 
 2011 void __kprobes dump_kprobe(struct kprobe *kp)
 2012 {
 2013         printk(KERN_WARNING "Dumping kprobe:\n");
 2014         printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
 2015                kp->symbol_name, kp->addr, kp->offset);
 2016 }
 2017 
 2018 /* Module notifier call back, checking kprobes on the module */
 2019 static int __kprobes kprobes_module_callback(struct notifier_block *nb,
 2020                                              unsigned long val, void *data)
 2021 {
 2022         struct module *mod = data;
 2023         struct hlist_head *head;
 2024         struct hlist_node *node;
 2025         struct kprobe *p;
 2026         unsigned int i;
 2027         int checkcore = (val == MODULE_STATE_GOING);
 2028 
 2029         if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
 2030                 return NOTIFY_DONE;
 2031 
 2032         /*
 2033          * When MODULE_STATE_GOING was notified, both of module .text and
 2034          * .init.text sections would be freed. When MODULE_STATE_LIVE was
 2035          * notified, only .init.text section would be freed. We need to
 2036          * disable kprobes which have been inserted in the sections.
 2037          */
 2038         mutex_lock(&kprobe_mutex);
 2039         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 2040                 head = &kprobe_table[i];
 2041                 hlist_for_each_entry_rcu(p, node, head, hlist)
 2042                         if (within_module_init((unsigned long)p->addr, mod) ||
 2043                             (checkcore &&
 2044                              within_module_core((unsigned long)p->addr, mod))) {
 2045                                 /*
 2046                                  * The vaddr this probe is installed will soon
 2047                                  * be vfreed buy not synced to disk. Hence,
 2048                                  * disarming the breakpoint isn't needed.
 2049                                  */
 2050                                 kill_kprobe(p);
 2051                         }
 2052         }
 2053         mutex_unlock(&kprobe_mutex);
 2054         return NOTIFY_DONE;
 2055 }
 2056 
 2057 static struct notifier_block kprobe_module_nb = {
 2058         .notifier_call = kprobes_module_callback,
 2059         .priority = 0
 2060 };
 2061 
 2062 static int __init init_kprobes(void)
 2063 {
 2064         int i, err = 0;
 2065         unsigned long offset = 0, size = 0;
 2066         char *modname, namebuf[128];
 2067         const char *symbol_name;
 2068         void *addr;
 2069         struct kprobe_blackpoint *kb;
 2070 
 2071         /* FIXME allocate the probe table, currently defined statically */
 2072         /* initialize all list heads */
 2073         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 2074                 INIT_HLIST_HEAD(&kprobe_table[i]);
 2075                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
 2076                 raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
 2077         }
 2078 
 2079         /*
 2080          * Lookup and populate the kprobe_blacklist.
 2081          *
 2082          * Unlike the kretprobe blacklist, we'll need to determine
 2083          * the range of addresses that belong to the said functions,
 2084          * since a kprobe need not necessarily be at the beginning
 2085          * of a function.
 2086          */
 2087         for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
 2088                 kprobe_lookup_name(kb->name, addr);
 2089                 if (!addr)
 2090                         continue;
 2091 
 2092                 kb->start_addr = (unsigned long)addr;
 2093                 symbol_name = kallsyms_lookup(kb->start_addr,
 2094                                 &size, &offset, &modname, namebuf);
 2095                 if (!symbol_name)
 2096                         kb->range = 0;
 2097                 else
 2098                         kb->range = size;
 2099         }
 2100 
 2101         if (kretprobe_blacklist_size) {
 2102                 /* lookup the function address from its name */
 2103                 for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
 2104                         kprobe_lookup_name(kretprobe_blacklist[i].name,
 2105                                            kretprobe_blacklist[i].addr);
 2106                         if (!kretprobe_blacklist[i].addr)
 2107                                 printk("kretprobe: lookup failed: %s\n",
 2108                                        kretprobe_blacklist[i].name);
 2109                 }
 2110         }
 2111 
 2112 #if defined(CONFIG_OPTPROBES)
 2113 #if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
 2114         /* Init kprobe_optinsn_slots */
 2115         kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
 2116 #endif
 2117         /* By default, kprobes can be optimized */
 2118         kprobes_allow_optimization = true;
 2119 #endif
 2120 
 2121         /* By default, kprobes are armed */
 2122         kprobes_all_disarmed = false;
 2123 
 2124         err = arch_init_kprobes();
 2125         if (!err)
 2126                 err = register_die_notifier(&kprobe_exceptions_nb);
 2127         if (!err)
 2128                 err = register_module_notifier(&kprobe_module_nb);
 2129 
 2130         kprobes_initialized = (err == 0);
 2131 
 2132         if (!err)
 2133                 init_test_probes();
 2134         return err;
 2135 }
 2136 
 2137 #ifdef CONFIG_DEBUG_FS
 2138 static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
 2139                 const char *sym, int offset, char *modname, struct kprobe *pp)
 2140 {
 2141         char *kprobe_type;
 2142 
 2143         if (p->pre_handler == pre_handler_kretprobe)
 2144                 kprobe_type = "r";
 2145         else if (p->pre_handler == setjmp_pre_handler)
 2146                 kprobe_type = "j";
 2147         else
 2148                 kprobe_type = "k";
 2149 
 2150         if (sym)
 2151                 seq_printf(pi, "%p  %s  %s+0x%x  %s ",
 2152                         p->addr, kprobe_type, sym, offset,
 2153                         (modname ? modname : " "));
 2154         else
 2155                 seq_printf(pi, "%p  %s  %p ",
 2156                         p->addr, kprobe_type, p->addr);
 2157 
 2158         if (!pp)
 2159                 pp = p;
 2160         seq_printf(pi, "%s%s%s%s\n",
 2161                 (kprobe_gone(p) ? "[GONE]" : ""),
 2162                 ((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
 2163                 (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""),
 2164                 (kprobe_ftrace(pp) ? "[FTRACE]" : ""));
 2165 }
 2166 
 2167 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
 2168 {
 2169         return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
 2170 }
 2171 
 2172 static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
 2173 {
 2174         (*pos)++;
 2175         if (*pos >= KPROBE_TABLE_SIZE)
 2176                 return NULL;
 2177         return pos;
 2178 }
 2179 
 2180 static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
 2181 {
 2182         /* Nothing to do */
 2183 }
 2184 
 2185 static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
 2186 {
 2187         struct hlist_head *head;
 2188         struct hlist_node *node;
 2189         struct kprobe *p, *kp;
 2190         const char *sym = NULL;
 2191         unsigned int i = *(loff_t *) v;
 2192         unsigned long offset = 0;
 2193         char *modname, namebuf[128];
 2194 
 2195         head = &kprobe_table[i];
 2196         preempt_disable();
 2197         hlist_for_each_entry_rcu(p, node, head, hlist) {
 2198                 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
 2199                                         &offset, &modname, namebuf);
 2200                 if (kprobe_aggrprobe(p)) {
 2201                         list_for_each_entry_rcu(kp, &p->list, list)
 2202                                 report_probe(pi, kp, sym, offset, modname, p);
 2203                 } else
 2204                         report_probe(pi, p, sym, offset, modname, NULL);
 2205         }
 2206         preempt_enable();
 2207         return 0;
 2208 }
 2209 
 2210 static const struct seq_operations kprobes_seq_ops = {
 2211         .start = kprobe_seq_start,
 2212         .next  = kprobe_seq_next,
 2213         .stop  = kprobe_seq_stop,
 2214         .show  = show_kprobe_addr
 2215 };
 2216 
 2217 static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
 2218 {
 2219         return seq_open(filp, &kprobes_seq_ops);
 2220 }
 2221 
 2222 static const struct file_operations debugfs_kprobes_operations = {
 2223         .open           = kprobes_open,
 2224         .read           = seq_read,
 2225         .llseek         = seq_lseek,
 2226         .release        = seq_release,
 2227 };
 2228 
 2229 static void __kprobes arm_all_kprobes(void)
 2230 {
 2231         struct hlist_head *head;
 2232         struct hlist_node *node;
 2233         struct kprobe *p;
 2234         unsigned int i;
 2235 
 2236         mutex_lock(&kprobe_mutex);
 2237 
 2238         /* If kprobes are armed, just return */
 2239         if (!kprobes_all_disarmed)
 2240                 goto already_enabled;
 2241 
 2242         /* Arming kprobes doesn't optimize kprobe itself */
 2243         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 2244                 head = &kprobe_table[i];
 2245                 hlist_for_each_entry_rcu(p, node, head, hlist)
 2246                         if (!kprobe_disabled(p))
 2247                                 arm_kprobe(p);
 2248         }
 2249 
 2250         kprobes_all_disarmed = false;
 2251         printk(KERN_INFO "Kprobes globally enabled\n");
 2252 
 2253 already_enabled:
 2254         mutex_unlock(&kprobe_mutex);
 2255         return;
 2256 }
 2257 
 2258 static void __kprobes disarm_all_kprobes(void)
 2259 {
 2260         struct hlist_head *head;
 2261         struct hlist_node *node;
 2262         struct kprobe *p;
 2263         unsigned int i;
 2264 
 2265         mutex_lock(&kprobe_mutex);
 2266 
 2267         /* If kprobes are already disarmed, just return */
 2268         if (kprobes_all_disarmed) {
 2269                 mutex_unlock(&kprobe_mutex);
 2270                 return;
 2271         }
 2272 
 2273         kprobes_all_disarmed = true;
 2274         printk(KERN_INFO "Kprobes globally disabled\n");
 2275 
 2276         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 2277                 head = &kprobe_table[i];
 2278                 hlist_for_each_entry_rcu(p, node, head, hlist) {
 2279                         if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
 2280                                 disarm_kprobe(p, false);
 2281                 }
 2282         }
 2283         mutex_unlock(&kprobe_mutex);
 2284 
 2285         /* Wait for disarming all kprobes by optimizer */
 2286         wait_for_kprobe_optimizer();
 2287 }
 2288 
 2289 /*
 2290  * XXX: The debugfs bool file interface doesn't allow for callbacks
 2291  * when the bool state is switched. We can reuse that facility when
 2292  * available
 2293  */
 2294 static ssize_t read_enabled_file_bool(struct file *file,
 2295                char __user *user_buf, size_t count, loff_t *ppos)
 2296 {
 2297         char buf[3];
 2298 
 2299         if (!kprobes_all_disarmed)
 2300                 buf[0] = '1';
 2301         else
 2302                 buf[0] = '';
 2303         buf[1] = '\n';
 2304         buf[2] = 0x00;
 2305         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
 2306 }
 2307 
 2308 static ssize_t write_enabled_file_bool(struct file *file,
 2309                const char __user *user_buf, size_t count, loff_t *ppos)
 2310 {
 2311         char buf[32];
 2312         size_t buf_size;
 2313 
 2314         buf_size = min(count, (sizeof(buf)-1));
 2315         if (copy_from_user(buf, user_buf, buf_size))
 2316                 return -EFAULT;
 2317 
 2318         switch (buf[0]) {
 2319         case 'y':
 2320         case 'Y':
 2321         case '1':
 2322                 arm_all_kprobes();
 2323                 break;
 2324         case 'n':
 2325         case 'N':
 2326         case '':
 2327                 disarm_all_kprobes();
 2328                 break;
 2329         }
 2330 
 2331         return count;
 2332 }
 2333 
 2334 static const struct file_operations fops_kp = {
 2335         .read =         read_enabled_file_bool,
 2336         .write =        write_enabled_file_bool,
 2337         .llseek =       default_llseek,
 2338 };
 2339 
 2340 static int __kprobes debugfs_kprobe_init(void)
 2341 {
 2342         struct dentry *dir, *file;
 2343         unsigned int value = 1;
 2344 
 2345         dir = debugfs_create_dir("kprobes", NULL);
 2346         if (!dir)
 2347                 return -ENOMEM;
 2348 
 2349         file = debugfs_create_file("list", 0444, dir, NULL,
 2350                                 &debugfs_kprobes_operations);
 2351         if (!file) {
 2352                 debugfs_remove(dir);
 2353                 return -ENOMEM;
 2354         }
 2355 
 2356         file = debugfs_create_file("enabled", 0600, dir,
 2357                                         &value, &fops_kp);
 2358         if (!file) {
 2359                 debugfs_remove(dir);
 2360                 return -ENOMEM;
 2361         }
 2362 
 2363         return 0;
 2364 }
 2365 
 2366 late_initcall(debugfs_kprobe_init);
 2367 #endif /* CONFIG_DEBUG_FS */
 2368 
 2369 module_init(init_kprobes);
 2370 
 2371 /* defined in arch/.../kernel/kprobes.c */
 2372 EXPORT_SYMBOL_GPL(jprobe_return);

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