1 files changed, 563 insertions, 118 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index b7df302a0204..fa034d29cf73 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -42,8 +42,11 @@
 #include <linux/freezer.h>
 #include <linux/seq_file.h>
 #include <linux/debugfs.h>
+#include <linux/sysctl.h>
 #include <linux/kdebug.h>
 #include <linux/memory.h>
+#include <linux/ftrace.h>
+#include <linux/cpu.h>
 
 #include <asm-generic/sections.h>
 #include <asm/cacheflush.h>
@@ -93,6 +96,7 @@ static struct kprobe_blackpoint kprobe_blacklist[] = {
         {"native_get_debugreg",},
         {"irq_entries_start",},
         {"common_interrupt",},
+        {"mcount",},    /* mcount can be called from everywhere */
         {NULL}    /* Terminator */
 };
 
@@ -103,81 +107,74 @@ static struct kprobe_blackpoint kprobe_blacklist[] = {
  * stepping on the instruction on a vmalloced/kmalloced/data page
  * is a recipe for disaster
  */
-#define INSNS_PER_PAGE  (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
-
 struct kprobe_insn_page {
         struct list_head list;
         kprobe_opcode_t *insns;         /* Page of instruction slots */
-        char slot_used[INSNS_PER_PAGE];
         int nused;
         int ngarbage;
+        char slot_used[];
 };
 
+#define KPROBE_INSN_PAGE_SIZE(slots)                    \
+        (offsetof(struct kprobe_insn_page, slot_used) + \
+         (sizeof(char) * (slots)))
+
+struct kprobe_insn_cache {
+        struct list_head pages; /* list of kprobe_insn_page */
+        size_t insn_size;       /* size of instruction slot */
+        int nr_garbage;
+};
+
+static int slots_per_page(struct kprobe_insn_cache *c)
+{
+        return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
+}
+
 enum kprobe_slot_state {
         SLOT_CLEAN = 0,
         SLOT_DIRTY = 1,
         SLOT_USED = 2,
 };
 
-static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_pages */
-static LIST_HEAD(kprobe_insn_pages);
-static int kprobe_garbage_slots;
-static int collect_garbage_slots(void);
-
-static int __kprobes check_safety(void)
-{
-        int ret = 0;
-#if defined(CONFIG_PREEMPT) && defined(CONFIG_FREEZER)
-        ret = freeze_processes();
-        if (ret == 0) {
-                struct task_struct *p, *q;
-                do_each_thread(p, q) {
-                        if (p != current && p->state == TASK_RUNNING &&
-                            p->pid != 0) {
-                                printk("Check failed: %s is running\n",p->comm);
-                                ret = -1;
-                                goto loop_end;
-                        }
-                } while_each_thread(p, q);
-        }
-loop_end:
-        thaw_processes();
-#else
-        synchronize_sched();
-#endif
-        return ret;
-}
+static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_slots */
+static struct kprobe_insn_cache kprobe_insn_slots = {
+        .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
+        .insn_size = MAX_INSN_SIZE,
+        .nr_garbage = 0,
+};
+static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c);
 
 /**
  * __get_insn_slot() - Find a slot on an executable page for an instruction.
  * We allocate an executable page if there's no room on existing ones.
  */
-static kprobe_opcode_t __kprobes *__get_insn_slot(void)
+static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
 {
         struct kprobe_insn_page *kip;
 
  retry:
-        list_for_each_entry(kip, &kprobe_insn_pages, list) {
-                if (kip->nused < INSNS_PER_PAGE) {
+        list_for_each_entry(kip, &c->pages, list) {
+                if (kip->nused < slots_per_page(c)) {
                         int i;
-                        for (i = 0; i < INSNS_PER_PAGE; i++) {
+                        for (i = 0; i < slots_per_page(c); i++) {
                                 if (kip->slot_used[i] == SLOT_CLEAN) {
                                         kip->slot_used[i] = SLOT_USED;
                                         kip->nused++;
-                                        return kip->insns + (i * MAX_INSN_SIZE);
+                                        return kip->insns + (i * c->insn_size);
                                 }
                         }
-                        /* Surprise!  No unused slots.  Fix kip->nused. */
-                        kip->nused = INSNS_PER_PAGE;
+                        /* kip->nused is broken. Fix it. */
+                        kip->nused = slots_per_page(c);
+                        WARN_ON(1);
                 }
         }
 
         /* If there are any garbage slots, collect it and try again. */
-        if (kprobe_garbage_slots && collect_garbage_slots() == 0) {
+        if (c->nr_garbage && collect_garbage_slots(c) == 0)
                 goto retry;
-        }
-        /* All out of space.  Need to allocate a new page. Use slot 0. */
-        kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL);
+
+        /* All out of space.  Need to allocate a new page. */
+        kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
         if (!kip)
                 return NULL;
 
@@ -192,20 +189,23 @@ static kprobe_opcode_t __kprobes *__get_insn_slot(void)
                 return NULL;
         }
         INIT_LIST_HEAD(&kip->list);
-        list_add(&kip->list, &kprobe_insn_pages);
-        memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE);
+        memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
         kip->slot_used[0] = SLOT_USED;
         kip->nused = 1;
         kip->ngarbage = 0;
+        list_add(&kip->list, &c->pages);
         return kip->insns;
 }
 
+
 kprobe_opcode_t __kprobes *get_insn_slot(void)
 {
-        kprobe_opcode_t *ret;
+        kprobe_opcode_t *ret = NULL;
+
         mutex_lock(&kprobe_insn_mutex);
-        ret = __get_insn_slot();
+        ret = __get_insn_slot(&kprobe_insn_slots);
         mutex_unlock(&kprobe_insn_mutex);
+
         return ret;
 }
 
@@ -221,7 +221,7 @@ static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
                  * so as not to have to set it up again the
                  * next time somebody inserts a probe.
                  */
-                if (!list_is_singular(&kprobe_insn_pages)) {
+                if (!list_is_singular(&kip->list)) {
                         list_del(&kip->list);
                         module_free(NULL, kip->insns);
                         kfree(kip);
@@ -231,52 +231,84 @@ static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
         return 0;
 }
 
-static int __kprobes collect_garbage_slots(void)
+static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c)
 {
         struct kprobe_insn_page *kip, *next;
 
-        /* Ensure no-one is preepmted on the garbages */
-        if (check_safety())
-                return -EAGAIN;
+        /* Ensure no-one is interrupted on the garbages */
+        synchronize_sched();
 
-        list_for_each_entry_safe(kip, next, &kprobe_insn_pages, list) {
+        list_for_each_entry_safe(kip, next, &c->pages, list) {
                 int i;
                 if (kip->ngarbage == 0)
                         continue;
                 kip->ngarbage = 0;      /* we will collect all garbages */
-                for (i = 0; i < INSNS_PER_PAGE; i++) {
+                for (i = 0; i < slots_per_page(c); i++) {
                         if (kip->slot_used[i] == SLOT_DIRTY &&
                             collect_one_slot(kip, i))
                                 break;
                 }
         }
-        kprobe_garbage_slots = 0;
+        c->nr_garbage = 0;
         return 0;
 }
 
-void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
+static void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
+                                       kprobe_opcode_t *slot, int dirty)
 {
         struct kprobe_insn_page *kip;
 
-        mutex_lock(&kprobe_insn_mutex);
-        list_for_each_entry(kip, &kprobe_insn_pages, list) {
-                if (kip->insns <= slot &&
-                    slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
-                        int i = (slot - kip->insns) / MAX_INSN_SIZE;
+        list_for_each_entry(kip, &c->pages, list) {
+                long idx = ((long)slot - (long)kip->insns) / c->insn_size;
+                if (idx >= 0 && idx < slots_per_page(c)) {
+                        WARN_ON(kip->slot_used[idx] != SLOT_USED);
                         if (dirty) {
-                                kip->slot_used[i] = SLOT_DIRTY;
+                                kip->slot_used[idx] = SLOT_DIRTY;
                                 kip->ngarbage++;
+                                if (++c->nr_garbage > slots_per_page(c))
+                                        collect_garbage_slots(c);
                         } else
-                                collect_one_slot(kip, i);
-                        break;
+                                collect_one_slot(kip, idx);
+                        return;
                 }
         }
+        /* Could not free this slot. */
+        WARN_ON(1);
+}
 
-        if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE)
-                collect_garbage_slots();
-
+void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
+{
+        mutex_lock(&kprobe_insn_mutex);
+        __free_insn_slot(&kprobe_insn_slots, slot, dirty);
         mutex_unlock(&kprobe_insn_mutex);
 }
+#ifdef CONFIG_OPTPROBES
+/* For optimized_kprobe buffer */
+static DEFINE_MUTEX(kprobe_optinsn_mutex); /* Protects kprobe_optinsn_slots */
+static struct kprobe_insn_cache kprobe_optinsn_slots = {
+        .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
+        /* .insn_size is initialized later */
+        .nr_garbage = 0,
+};
+/* Get a slot for optimized_kprobe buffer */
+kprobe_opcode_t __kprobes *get_optinsn_slot(void)
+{
+        kprobe_opcode_t *ret = NULL;
+
+        mutex_lock(&kprobe_optinsn_mutex);
+        ret = __get_insn_slot(&kprobe_optinsn_slots);
+        mutex_unlock(&kprobe_optinsn_mutex);
+
+        return ret;
+}
+
+void __kprobes free_optinsn_slot(kprobe_opcode_t * slot, int dirty)
+{
+        mutex_lock(&kprobe_optinsn_mutex);
+        __free_insn_slot(&kprobe_optinsn_slots, slot, dirty);
+        mutex_unlock(&kprobe_optinsn_mutex);
+}
+#endif
 #endif
 
 /* We have preemption disabled.. so it is safe to use __ versions */
@@ -307,23 +339,401 @@ struct kprobe __kprobes *get_kprobe(void *addr)
                 if (p->addr == addr)
                         return p;
         }
+
         return NULL;
 }
 
+static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
+
+/* Return true if the kprobe is an aggregator */
+static inline int kprobe_aggrprobe(struct kprobe *p)
+{
+        return p->pre_handler == aggr_pre_handler;
+}
+
+/*
+ * Keep all fields in the kprobe consistent
+ */
+static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
+{
+        memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
+        memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
+}
+
+#ifdef CONFIG_OPTPROBES
+/* NOTE: change this value only with kprobe_mutex held */
+static bool kprobes_allow_optimization;
+
+/*
+ * Call all pre_handler on the list, but ignores its return value.
+ * This must be called from arch-dep optimized caller.
+ */
+void __kprobes opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+        struct kprobe *kp;
+
+        list_for_each_entry_rcu(kp, &p->list, list) {
+                if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
+                        set_kprobe_instance(kp);
+                        kp->pre_handler(kp, regs);
+                }
+                reset_kprobe_instance();
+        }
+}
+
+/* Return true(!0) if the kprobe is ready for optimization. */
+static inline int kprobe_optready(struct kprobe *p)
+{
+        struct optimized_kprobe *op;
+
+        if (kprobe_aggrprobe(p)) {
+                op = container_of(p, struct optimized_kprobe, kp);
+                return arch_prepared_optinsn(&op->optinsn);
+        }
+
+        return 0;
+}
+
+/*
+ * Return an optimized kprobe whose optimizing code replaces
+ * instructions including addr (exclude breakpoint).
+ */
+struct kprobe *__kprobes get_optimized_kprobe(unsigned long addr)
+{
+        int i;
+        struct kprobe *p = NULL;
+        struct optimized_kprobe *op;
+
+        /* Don't check i == 0, since that is a breakpoint case. */
+        for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
+                p = get_kprobe((void *)(addr - i));
+
+        if (p && kprobe_optready(p)) {
+                op = container_of(p, struct optimized_kprobe, kp);
+                if (arch_within_optimized_kprobe(op, addr))
+                        return p;
+        }
+
+        return NULL;
+}
+
+/* Optimization staging list, protected by kprobe_mutex */
+static LIST_HEAD(optimizing_list);
+
+static void kprobe_optimizer(struct work_struct *work);
+static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
+#define OPTIMIZE_DELAY 5
+
+/* Kprobe jump optimizer */
+static __kprobes void kprobe_optimizer(struct work_struct *work)
+{
+        struct optimized_kprobe *op, *tmp;
+
+        /* Lock modules while optimizing kprobes */
+        mutex_lock(&module_mutex);
+        mutex_lock(&kprobe_mutex);
+        if (kprobes_all_disarmed || !kprobes_allow_optimization)
+                goto end;
+
+        /*
+         * Wait for quiesence period to ensure all running interrupts
+         * are done. Because optprobe may modify multiple instructions
+         * there is a chance that Nth instruction is interrupted. In that
+         * case, running interrupt can return to 2nd-Nth byte of jump
+         * instruction. This wait is for avoiding it.
+         */
+        synchronize_sched();
+
+        /*
+         * The optimization/unoptimization refers online_cpus via
+         * stop_machine() and cpu-hotplug modifies online_cpus.
+         * And same time, text_mutex will be held in cpu-hotplug and here.
+         * This combination can cause a deadlock (cpu-hotplug try to lock
+         * text_mutex but stop_machine can not be done because online_cpus
+         * has been changed)
+         * To avoid this deadlock, we need to call get_online_cpus()
+         * for preventing cpu-hotplug outside of text_mutex locking.
+         */
+        get_online_cpus();
+        mutex_lock(&text_mutex);
+        list_for_each_entry_safe(op, tmp, &optimizing_list, list) {
+                WARN_ON(kprobe_disabled(&op->kp));
+                if (arch_optimize_kprobe(op) < 0)
+                        op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
+                list_del_init(&op->list);
+        }
+        mutex_unlock(&text_mutex);
+        put_online_cpus();
+end:
+        mutex_unlock(&kprobe_mutex);
+        mutex_unlock(&module_mutex);
+}
+
+/* Optimize kprobe if p is ready to be optimized */
+static __kprobes void optimize_kprobe(struct kprobe *p)
+{
+        struct optimized_kprobe *op;
+
+        /* Check if the kprobe is disabled or not ready for optimization. */
+        if (!kprobe_optready(p) || !kprobes_allow_optimization ||
+            (kprobe_disabled(p) || kprobes_all_disarmed))
+                return;
+
+        /* Both of break_handler and post_handler are not supported. */
+        if (p->break_handler || p->post_handler)
+                return;
+
+        op = container_of(p, struct optimized_kprobe, kp);
+
+        /* Check there is no other kprobes at the optimized instructions */
+        if (arch_check_optimized_kprobe(op) < 0)
+                return;
+
+        /* Check if it is already optimized. */
+        if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
+                return;
+
+        op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
+        list_add(&op->list, &optimizing_list);
+        if (!delayed_work_pending(&optimizing_work))
+                schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
+}
+
+/* Unoptimize a kprobe if p is optimized */
+static __kprobes void unoptimize_kprobe(struct kprobe *p)
+{
+        struct optimized_kprobe *op;
+
+        if ((p->flags & KPROBE_FLAG_OPTIMIZED) && kprobe_aggrprobe(p)) {
+                op = container_of(p, struct optimized_kprobe, kp);
+                if (!list_empty(&op->list))
+                        /* Dequeue from the optimization queue */
+                        list_del_init(&op->list);
+                else
+                        /* Replace jump with break */
+                        arch_unoptimize_kprobe(op);
+                op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
+        }
+}
+
+/* Remove optimized instructions */
+static void __kprobes kill_optimized_kprobe(struct kprobe *p)
+{
+        struct optimized_kprobe *op;
+
+        op = container_of(p, struct optimized_kprobe, kp);
+        if (!list_empty(&op->list)) {
+                /* Dequeue from the optimization queue */
+                list_del_init(&op->list);
+                op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
+        }
+        /* Don't unoptimize, because the target code will be freed. */
+        arch_remove_optimized_kprobe(op);
+}
+
+/* Try to prepare optimized instructions */
+static __kprobes void prepare_optimized_kprobe(struct kprobe *p)
+{
+        struct optimized_kprobe *op;
+
+        op = container_of(p, struct optimized_kprobe, kp);
+        arch_prepare_optimized_kprobe(op);
+}
+
+/* Free optimized instructions and optimized_kprobe */
+static __kprobes void free_aggr_kprobe(struct kprobe *p)
+{
+        struct optimized_kprobe *op;
+
+        op = container_of(p, struct optimized_kprobe, kp);
+        arch_remove_optimized_kprobe(op);
+        kfree(op);
+}
+
+/* Allocate new optimized_kprobe and try to prepare optimized instructions */
+static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
+{
+        struct optimized_kprobe *op;
+
+        op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
+        if (!op)
+                return NULL;
+
+        INIT_LIST_HEAD(&op->list);
+        op->kp.addr = p->addr;
+        arch_prepare_optimized_kprobe(op);
+
+        return &op->kp;
+}
+
+static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
+
+/*
+ * Prepare an optimized_kprobe and optimize it
+ * NOTE: p must be a normal registered kprobe
+ */
+static __kprobes void try_to_optimize_kprobe(struct kprobe *p)
+{
+        struct kprobe *ap;
+        struct optimized_kprobe *op;
+
+        ap = alloc_aggr_kprobe(p);
+        if (!ap)
+                return;
+
+        op = container_of(ap, struct optimized_kprobe, kp);
+        if (!arch_prepared_optinsn(&op->optinsn)) {
+                /* If failed to setup optimizing, fallback to kprobe */
+                free_aggr_kprobe(ap);
+                return;
+        }
+
+        init_aggr_kprobe(ap, p);
+        optimize_kprobe(ap);
+}
+
+#ifdef CONFIG_SYSCTL
+static void __kprobes optimize_all_kprobes(void)
+{
+        struct hlist_head *head;
+        struct hlist_node *node;
+        struct kprobe *p;
+        unsigned int i;
+
+        /* If optimization is already allowed, just return */
+        if (kprobes_allow_optimization)
+                return;
+
+        kprobes_allow_optimization = true;
+        mutex_lock(&text_mutex);
+        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
+                head = &kprobe_table[i];
+                hlist_for_each_entry_rcu(p, node, head, hlist)
+                        if (!kprobe_disabled(p))
+                                optimize_kprobe(p);
+        }
+        mutex_unlock(&text_mutex);
+        printk(KERN_INFO "Kprobes globally optimized\n");
+}
+
+static void __kprobes unoptimize_all_kprobes(void)
+{
+        struct hlist_head *head;
+        struct hlist_node *node;
+        struct kprobe *p;
+        unsigned int i;
+
+        /* If optimization is already prohibited, just return */
+        if (!kprobes_allow_optimization)
+                return;
+
+        kprobes_allow_optimization = false;
+        printk(KERN_INFO "Kprobes globally unoptimized\n");
+        get_online_cpus();      /* For avoiding text_mutex deadlock */
+        mutex_lock(&text_mutex);
+        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
+                head = &kprobe_table[i];
+                hlist_for_each_entry_rcu(p, node, head, hlist) {
+                        if (!kprobe_disabled(p))
+                                unoptimize_kprobe(p);
+                }
+        }
+
+        mutex_unlock(&text_mutex);
+        put_online_cpus();
+        /* Allow all currently running kprobes to complete */
+        synchronize_sched();
+}
+
+int sysctl_kprobes_optimization;
+int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
+                                      void __user *buffer, size_t *length,
+                                      loff_t *ppos)
+{
+        int ret;
+
+        mutex_lock(&kprobe_mutex);
+        sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
+        ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
+
+        if (sysctl_kprobes_optimization)
+                optimize_all_kprobes();
+        else
+                unoptimize_all_kprobes();
+        mutex_unlock(&kprobe_mutex);
+
+        return ret;
+}
+#endif /* CONFIG_SYSCTL */
+
+static void __kprobes __arm_kprobe(struct kprobe *p)
+{
+        struct kprobe *old_p;
+
+        /* Check collision with other optimized kprobes */
+        old_p = get_optimized_kprobe((unsigned long)p->addr);
+        if (unlikely(old_p))
+                unoptimize_kprobe(old_p); /* Fallback to unoptimized kprobe */
+
+        arch_arm_kprobe(p);
+        optimize_kprobe(p);     /* Try to optimize (add kprobe to a list) */
+}
+
+static void __kprobes __disarm_kprobe(struct kprobe *p)
+{
+        struct kprobe *old_p;
+
+        unoptimize_kprobe(p);   /* Try to unoptimize */
+        arch_disarm_kprobe(p);
+
+        /* If another kprobe was blocked, optimize it. */
+        old_p = get_optimized_kprobe((unsigned long)p->addr);
+        if (unlikely(old_p))
+                optimize_kprobe(old_p);
+}
+
+#else /* !CONFIG_OPTPROBES */
+
+#define optimize_kprobe(p)                      do {} while (0)
+#define unoptimize_kprobe(p)                    do {} while (0)
+#define kill_optimized_kprobe(p)                do {} while (0)
+#define prepare_optimized_kprobe(p)             do {} while (0)
+#define try_to_optimize_kprobe(p)               do {} while (0)
+#define __arm_kprobe(p)                         arch_arm_kprobe(p)
+#define __disarm_kprobe(p)                      arch_disarm_kprobe(p)
+
+static __kprobes void free_aggr_kprobe(struct kprobe *p)
+{
+        kfree(p);
+}
+
+static __kprobes struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
+{
+        return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
+}
+#endif /* CONFIG_OPTPROBES */
+
 /* Arm a kprobe with text_mutex */
 static void __kprobes arm_kprobe(struct kprobe *kp)
 {
+        /*
+         * Here, since __arm_kprobe() doesn't use stop_machine(),
+         * this doesn't cause deadlock on text_mutex. So, we don't
+         * need get_online_cpus().
+         */
         mutex_lock(&text_mutex);
-        arch_arm_kprobe(kp);
+        __arm_kprobe(kp);
         mutex_unlock(&text_mutex);
 }
 
 /* Disarm a kprobe with text_mutex */
 static void __kprobes disarm_kprobe(struct kprobe *kp)
 {
+        get_online_cpus();      /* For avoiding text_mutex deadlock */
         mutex_lock(&text_mutex);
-        arch_disarm_kprobe(kp);
+        __disarm_kprobe(kp);
         mutex_unlock(&text_mutex);
+        put_online_cpus();
 }
 
 /*
@@ -392,7 +802,7 @@ static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
 {
         struct kprobe *kp;
-        if (p->pre_handler != aggr_pre_handler) {
+        if (!kprobe_aggrprobe(p)) {
                 p->nmissed++;
         } else {
                 list_for_each_entry_rcu(kp, &p->list, list)
@@ -516,21 +926,16 @@ static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
 }
 
 /*
- * Keep all fields in the kprobe consistent
- */
-static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
-{
-        memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
-        memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
-}
-
-/*
 * Add the new probe to ap->list. Fail if this is the
 * second jprobe at the address - two jprobes can't coexist
 */
 static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
 {
         BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
+
+        if (p->break_handler || p->post_handler)
+                unoptimize_kprobe(ap);  /* Fall back to normal kprobe */
+
         if (p->break_handler) {
                 if (ap->break_handler)
                         return -EEXIST;
@@ -545,7 +950,7 @@ static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
                 ap->flags &= ~KPROBE_FLAG_DISABLED;
                 if (!kprobes_all_disarmed)
                         /* Arm the breakpoint again. */
-                        arm_kprobe(ap);
+                        __arm_kprobe(ap);
         }
         return 0;
 }
@@ -554,12 +959,13 @@ static int __kprobes add_new_kprobe(struct kprobe *ap, struct kprobe *p)
  * Fill in the required fields of the "manager kprobe". Replace the
  * earlier kprobe in the hlist with the manager kprobe
  */
-static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
+static void __kprobes init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
 {
+        /* Copy p's insn slot to ap */
         copy_kprobe(p, ap);
         flush_insn_slot(ap);
         ap->addr = p->addr;
-        ap->flags = p->flags;
+        ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
         ap->pre_handler = aggr_pre_handler;
         ap->fault_handler = aggr_fault_handler;
         /* We don't care the kprobe which has gone. */
@@ -569,8 +975,9 @@ static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
                 ap->break_handler = aggr_break_handler;
 
         INIT_LIST_HEAD(&ap->list);
-        list_add_rcu(&p->list, &ap->list);
+        INIT_HLIST_NODE(&ap->hlist);
 
+        list_add_rcu(&p->list, &ap->list);
         hlist_replace_rcu(&p->hlist, &ap->hlist);
 }
 
@@ -584,12 +991,12 @@ static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
         int ret = 0;
         struct kprobe *ap = old_p;
 
-        if (old_p->pre_handler != aggr_pre_handler) {
-                /* If old_p is not an aggr_probe, create new aggr_kprobe. */
-                ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
+        if (!kprobe_aggrprobe(old_p)) {
+                /* If old_p is not an aggr_kprobe, create new aggr_kprobe. */
+                ap = alloc_aggr_kprobe(old_p);
                 if (!ap)
                         return -ENOMEM;
-                add_aggr_kprobe(ap, old_p);
+                init_aggr_kprobe(ap, old_p);
         }
 
         if (kprobe_gone(ap)) {
@@ -608,6 +1015,9 @@ static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
                          */
                         return ret;
 
+                /* Prepare optimized instructions if possible. */
+                prepare_optimized_kprobe(ap);
+
                 /*
                  * Clear gone flag to prevent allocating new slot again, and
                  * set disabled flag because it is not armed yet.
@@ -616,6 +1026,7 @@ static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
                             | KPROBE_FLAG_DISABLED;
         }
 
+        /* Copy ap's insn slot to p */
         copy_kprobe(ap, p);
         return add_new_kprobe(ap, p);
 }
@@ -728,7 +1139,8 @@ int __kprobes register_kprobe(struct kprobe *p)
 
         preempt_disable();
         if (!kernel_text_address((unsigned long) p->addr) ||
-            in_kprobes_functions((unsigned long) p->addr)) {
+            in_kprobes_functions((unsigned long) p->addr) ||
+            ftrace_text_reserved(p->addr, p->addr)) {
                 preempt_enable();
                 return -EINVAL;
         }
@@ -765,27 +1177,34 @@ int __kprobes register_kprobe(struct kprobe *p)
         p->nmissed = 0;
         INIT_LIST_HEAD(&p->list);
         mutex_lock(&kprobe_mutex);
+
+        get_online_cpus();      /* For avoiding text_mutex deadlock. */
+        mutex_lock(&text_mutex);
+
         old_p = get_kprobe(p->addr);
         if (old_p) {
+                /* Since this may unoptimize old_p, locking text_mutex. */
                 ret = register_aggr_kprobe(old_p, p);
                 goto out;
         }
 
-        mutex_lock(&text_mutex);
         ret = arch_prepare_kprobe(p);
         if (ret)
-                goto out_unlock_text;
+                goto out;
 
         INIT_HLIST_NODE(&p->hlist);
         hlist_add_head_rcu(&p->hlist,
                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
 
         if (!kprobes_all_disarmed && !kprobe_disabled(p))
-                arch_arm_kprobe(p);
+                __arm_kprobe(p);
+
+        /* Try to optimize kprobe */
+        try_to_optimize_kprobe(p);
 
-out_unlock_text:
-        mutex_unlock(&text_mutex);
 out:
+        mutex_unlock(&text_mutex);
+        put_online_cpus();
         mutex_unlock(&kprobe_mutex);
 
         if (probed_mod)
@@ -807,7 +1226,7 @@ static int __kprobes __unregister_kprobe_top(struct kprobe *p)
                 return -EINVAL;
 
         if (old_p == p ||
-            (old_p->pre_handler == aggr_pre_handler &&
+            (kprobe_aggrprobe(old_p) &&
              list_is_singular(&old_p->list))) {
                 /*
                  * Only probe on the hash list. Disarm only if kprobes are
@@ -815,7 +1234,7 @@ static int __kprobes __unregister_kprobe_top(struct kprobe *p)
                  * already have been removed. We save on flushing icache.
                  */
                 if (!kprobes_all_disarmed && !kprobe_disabled(old_p))
-                        disarm_kprobe(p);
+                        disarm_kprobe(old_p);
                 hlist_del_rcu(&old_p->hlist);
         } else {
                 if (p->break_handler && !kprobe_gone(p))
@@ -831,8 +1250,13 @@ noclean:
                 list_del_rcu(&p->list);
                 if (!kprobe_disabled(old_p)) {
                         try_to_disable_aggr_kprobe(old_p);
-                        if (!kprobes_all_disarmed && kprobe_disabled(old_p))
-                                disarm_kprobe(old_p);
+                        if (!kprobes_all_disarmed) {
+                                if (kprobe_disabled(old_p))
+                                        disarm_kprobe(old_p);
+                                else
+                                        /* Try to optimize this probe again */
+                                        optimize_kprobe(old_p);
+                        }
                 }
         }
         return 0;
@@ -849,7 +1273,7 @@ static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
                 old_p = list_entry(p->list.next, struct kprobe, list);
                 list_del(&p->list);
                 arch_remove_kprobe(old_p);
-                kfree(old_p);
+                free_aggr_kprobe(old_p);
         }
 }
 
@@ -1145,7 +1569,7 @@ static void __kprobes kill_kprobe(struct kprobe *p)
         struct kprobe *kp;
 
         p->flags |= KPROBE_FLAG_GONE;
-        if (p->pre_handler == aggr_pre_handler) {
+        if (kprobe_aggrprobe(p)) {
                 /*
                  * If this is an aggr_kprobe, we have to list all the
                  * chained probes and mark them GONE.
@@ -1154,6 +1578,7 @@ static void __kprobes kill_kprobe(struct kprobe *p)
                         kp->flags |= KPROBE_FLAG_GONE;
                 p->post_handler = NULL;
                 p->break_handler = NULL;
+                kill_optimized_kprobe(p);
         }
         /*
          * Here, we can remove insn_slot safely, because no thread calls
@@ -1263,6 +1688,15 @@ static int __init init_kprobes(void)
                 }
         }
 
+#if defined(CONFIG_OPTPROBES)
+#if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
+        /* Init kprobe_optinsn_slots */
+        kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
+#endif
+        /* By default, kprobes can be optimized */
+        kprobes_allow_optimization = true;
+#endif
+
         /* By default, kprobes are armed */
         kprobes_all_disarmed = false;
 
@@ -1281,7 +1715,7 @@ static int __init init_kprobes(void)
 
 #ifdef CONFIG_DEBUG_FS
 static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
-                const char *sym, int offset,char *modname)
+                const char *sym, int offset, char *modname, struct kprobe *pp)
 {
         char *kprobe_type;
 
@@ -1291,19 +1725,21 @@ static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
                 kprobe_type = "j";
         else
                 kprobe_type = "k";
+
         if (sym)
-                seq_printf(pi, "%p  %s  %s+0x%x  %s %s%s\n",
+                seq_printf(pi, "%p  %s  %s+0x%x  %s ",
                         p->addr, kprobe_type, sym, offset,
-                        (modname ? modname : " "),
-                        (kprobe_gone(p) ? "[GONE]" : ""),
-                        ((kprobe_disabled(p) && !kprobe_gone(p)) ?
-                         "[DISABLED]" : ""));
+                        (modname ? modname : " "));
         else
-                seq_printf(pi, "%p  %s  %p %s%s\n",
-                        p->addr, kprobe_type, p->addr,
-                        (kprobe_gone(p) ? "[GONE]" : ""),
-                        ((kprobe_disabled(p) && !kprobe_gone(p)) ?
-                         "[DISABLED]" : ""));
+                seq_printf(pi, "%p  %s  %p ",
+                        p->addr, kprobe_type, p->addr);
+
+        if (!pp)
+                pp = p;
+        seq_printf(pi, "%s%s%s\n",
+                (kprobe_gone(p) ? "[GONE]" : ""),
+                ((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
+                (kprobe_optimized(pp) ? "[OPTIMIZED]" : ""));
 }
 
 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
@@ -1339,11 +1775,11 @@ static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
         hlist_for_each_entry_rcu(p, node, head, hlist) {
                 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
                                         &offset, &modname, namebuf);
-                if (p->pre_handler == aggr_pre_handler) {
+                if (kprobe_aggrprobe(p)) {
                         list_for_each_entry_rcu(kp, &p->list, list)
-                                report_probe(pi, kp, sym, offset, modname);
+                                report_probe(pi, kp, sym, offset, modname, p);
                 } else
-                        report_probe(pi, p, sym, offset, modname);
+                        report_probe(pi, p, sym, offset, modname, NULL);
         }
         preempt_enable();
         return 0;
@@ -1421,12 +1857,13 @@ int __kprobes enable_kprobe(struct kprobe *kp)
                 goto out;
         }
 
-        if (!kprobes_all_disarmed && kprobe_disabled(p))
-                arm_kprobe(p);
-
-        p->flags &= ~KPROBE_FLAG_DISABLED;
         if (p != kp)
                 kp->flags &= ~KPROBE_FLAG_DISABLED;
+
+        if (!kprobes_all_disarmed && kprobe_disabled(p)) {
+                p->flags &= ~KPROBE_FLAG_DISABLED;
+                arm_kprobe(p);
+        }
 out:
         mutex_unlock(&kprobe_mutex);
         return ret;
@@ -1446,12 +1883,13 @@ static void __kprobes arm_all_kprobes(void)
         if (!kprobes_all_disarmed)
                 goto already_enabled;
 
+        /* Arming kprobes doesn't optimize kprobe itself */
         mutex_lock(&text_mutex);
         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
                 head = &kprobe_table[i];
                 hlist_for_each_entry_rcu(p, node, head, hlist)
                         if (!kprobe_disabled(p))
-                                arch_arm_kprobe(p);
+                                __arm_kprobe(p);
         }
         mutex_unlock(&text_mutex);
 
@@ -1478,16 +1916,23 @@ static void __kprobes disarm_all_kprobes(void)
 
         kprobes_all_disarmed = true;
         printk(KERN_INFO "Kprobes globally disabled\n");
+
+        /*
+         * Here we call get_online_cpus() for avoiding text_mutex deadlock,
+         * because disarming may also unoptimize kprobes.
+         */
+        get_online_cpus();
         mutex_lock(&text_mutex);
         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
                 head = &kprobe_table[i];
                 hlist_for_each_entry_rcu(p, node, head, hlist) {
                         if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
-                                arch_disarm_kprobe(p);
+                                __disarm_kprobe(p);
                 }
         }
 
         mutex_unlock(&text_mutex);
+        put_online_cpus();
         mutex_unlock(&kprobe_mutex);
         /* Allow all currently running kprobes to complete */
         synchronize_sched();