Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3041 insertions, 0 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
new file mode 100644
index 000000000..b48650476
--- /dev/null
+++ b/kernel/kprobes.c
@@ -0,0 +1,3041 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Kernel Probes (KProbes)
+ *
+ * Copyright (C) IBM Corporation, 2002, 2004
+ *
+ * 2002-Oct	Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
+ *		Probes initial implementation (includes suggestions from
+ *		Rusty Russell).
+ * 2004-Aug	Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
+ *		hlists and exceptions notifier as suggested by Andi Kleen.
+ * 2004-July	Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
+ *		interface to access function arguments.
+ * 2004-Sep	Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
+ *		exceptions notifier to be first on the priority list.
+ * 2005-May	Hien Nguyen <hien@us.ibm.com>, Jim Keniston
+ *		<jkenisto@us.ibm.com> and Prasanna S Panchamukhi
+ *		<prasanna@in.ibm.com> added function-return probes.
+ */
+
+#define pr_fmt(fmt) "kprobes: " fmt
+
+#include <linux/kprobes.h>
+#include <linux/hash.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/stddef.h>
+#include <linux/export.h>
+#include <linux/moduleloader.h>
+#include <linux/kallsyms.h>
+#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 <linux/jump_label.h>
+#include <linux/static_call.h>
+#include <linux/perf_event.h>
+
+#include <asm/sections.h>
+#include <asm/cacheflush.h>
+#include <asm/errno.h>
+#include <linux/uaccess.h>
+
+#define KPROBE_HASH_BITS 6
+#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
+
+#if !defined(CONFIG_OPTPROBES) || !defined(CONFIG_SYSCTL)
+#define kprobe_sysctls_init() do { } while (0)
+#endif
+
+static int kprobes_initialized;
+/* kprobe_table can be accessed by
+ * - Normal hlist traversal and RCU add/del under 'kprobe_mutex' is held.
+ * Or
+ * - RCU hlist traversal under disabling preempt (breakpoint handlers)
+ */
+static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
+
+/* NOTE: change this value only with 'kprobe_mutex' held */
+static bool kprobes_all_disarmed;
+
+/* This protects 'kprobe_table' and 'optimizing_list' */
+static DEFINE_MUTEX(kprobe_mutex);
+static DEFINE_PER_CPU(struct kprobe *, kprobe_instance);
+
+kprobe_opcode_t * __weak kprobe_lookup_name(const char *name,
+					unsigned int __unused)
+{
+	return ((kprobe_opcode_t *)(kallsyms_lookup_name(name)));
+}
+
+/*
+ * Blacklist -- list of 'struct kprobe_blacklist_entry' to store info where
+ * kprobes can not probe.
+ */
+static LIST_HEAD(kprobe_blacklist);
+
+#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
+/*
+ * 'kprobe::ainsn.insn' points to the copy of the instruction to be
+ * single-stepped. x86_64, POWER4 and above have no-exec support and
+ * stepping on the instruction on a vmalloced/kmalloced/data page
+ * is a recipe for disaster
+ */
+struct kprobe_insn_page {
+	struct list_head list;
+	kprobe_opcode_t *insns;		/* Page of instruction slots */
+	struct kprobe_insn_cache *cache;
+	int nused;
+	int ngarbage;
+	char slot_used[];
+};
+
+#define KPROBE_INSN_PAGE_SIZE(slots)			\
+	(offsetof(struct kprobe_insn_page, slot_used) +	\
+	 (sizeof(char) * (slots)))
+
+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,
+};
+
+void __weak *alloc_insn_page(void)
+{
+	/*
+	 * Use module_alloc() so this page is within +/- 2GB of where the
+	 * kernel image and loaded module images reside. This is required
+	 * for most of the architectures.
+	 * (e.g. x86-64 needs this to handle the %rip-relative fixups.)
+	 */
+	return module_alloc(PAGE_SIZE);
+}
+
+static void free_insn_page(void *page)
+{
+	module_memfree(page);
+}
+
+struct kprobe_insn_cache kprobe_insn_slots = {
+	.mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex),
+	.alloc = alloc_insn_page,
+	.free = free_insn_page,
+	.sym = KPROBE_INSN_PAGE_SYM,
+	.pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
+	.insn_size = MAX_INSN_SIZE,
+	.nr_garbage = 0,
+};
+static int 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.
+ */
+kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
+{
+	struct kprobe_insn_page *kip;
+	kprobe_opcode_t *slot = NULL;
+
+	/* Since the slot array is not protected by rcu, we need a mutex */
+	mutex_lock(&c->mutex);
+ retry:
+	rcu_read_lock();
+	list_for_each_entry_rcu(kip, &c->pages, list) {
+		if (kip->nused < slots_per_page(c)) {
+			int 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++;
+					slot = kip->insns + (i * c->insn_size);
+					rcu_read_unlock();
+					goto out;
+				}
+			}
+			/* kip->nused is broken. Fix it. */
+			kip->nused = slots_per_page(c);
+			WARN_ON(1);
+		}
+	}
+	rcu_read_unlock();
+
+	/* If there are any garbage slots, collect it and try again. */
+	if (c->nr_garbage && collect_garbage_slots(c) == 0)
+		goto retry;
+
+	/* All out of space.  Need to allocate a new page. */
+	kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
+	if (!kip)
+		goto out;
+
+	kip->insns = c->alloc();
+	if (!kip->insns) {
+		kfree(kip);
+		goto out;
+	}
+	INIT_LIST_HEAD(&kip->list);
+	memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
+	kip->slot_used[0] = SLOT_USED;
+	kip->nused = 1;
+	kip->ngarbage = 0;
+	kip->cache = c;
+	list_add_rcu(&kip->list, &c->pages);
+	slot = kip->insns;
+
+	/* Record the perf ksymbol register event after adding the page */
+	perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL, (unsigned long)kip->insns,
+			   PAGE_SIZE, false, c->sym);
+out:
+	mutex_unlock(&c->mutex);
+	return slot;
+}
+
+/* Return true if all garbages are collected, otherwise false. */
+static bool collect_one_slot(struct kprobe_insn_page *kip, int idx)
+{
+	kip->slot_used[idx] = SLOT_CLEAN;
+	kip->nused--;
+	if (kip->nused == 0) {
+		/*
+		 * Page is no longer in use.  Free it unless
+		 * it's the last one.  We keep the last one
+		 * so as not to have to set it up again the
+		 * next time somebody inserts a probe.
+		 */
+		if (!list_is_singular(&kip->list)) {
+			/*
+			 * Record perf ksymbol unregister event before removing
+			 * the page.
+			 */
+			perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL,
+					   (unsigned long)kip->insns, PAGE_SIZE, true,
+					   kip->cache->sym);
+			list_del_rcu(&kip->list);
+			synchronize_rcu();
+			kip->cache->free(kip->insns);
+			kfree(kip);
+		}
+		return true;
+	}
+	return false;
+}
+
+static int collect_garbage_slots(struct kprobe_insn_cache *c)
+{
+	struct kprobe_insn_page *kip, *next;
+
+	/* Ensure no-one is interrupted on the garbages */
+	synchronize_rcu();
+
+	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 < slots_per_page(c); i++) {
+			if (kip->slot_used[i] == SLOT_DIRTY && collect_one_slot(kip, i))
+				break;
+		}
+	}
+	c->nr_garbage = 0;
+	return 0;
+}
+
+void __free_insn_slot(struct kprobe_insn_cache *c,
+		      kprobe_opcode_t *slot, int dirty)
+{
+	struct kprobe_insn_page *kip;
+	long idx;
+
+	mutex_lock(&c->mutex);
+	rcu_read_lock();
+	list_for_each_entry_rcu(kip, &c->pages, list) {
+		idx = ((long)slot - (long)kip->insns) /
+			(c->insn_size * sizeof(kprobe_opcode_t));
+		if (idx >= 0 && idx < slots_per_page(c))
+			goto out;
+	}
+	/* Could not find this slot. */
+	WARN_ON(1);
+	kip = NULL;
+out:
+	rcu_read_unlock();
+	/* Mark and sweep: this may sleep */
+	if (kip) {
+		/* Check double free */
+		WARN_ON(kip->slot_used[idx] != SLOT_USED);
+		if (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, idx);
+		}
+	}
+	mutex_unlock(&c->mutex);
+}
+
+/*
+ * Check given address is on the page of kprobe instruction slots.
+ * This will be used for checking whether the address on a stack
+ * is on a text area or not.
+ */
+bool __is_insn_slot_addr(struct kprobe_insn_cache *c, unsigned long addr)
+{
+	struct kprobe_insn_page *kip;
+	bool ret = false;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(kip, &c->pages, list) {
+		if (addr >= (unsigned long)kip->insns &&
+		    addr < (unsigned long)kip->insns + PAGE_SIZE) {
+			ret = true;
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	return ret;
+}
+
+int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
+			     unsigned long *value, char *type, char *sym)
+{
+	struct kprobe_insn_page *kip;
+	int ret = -ERANGE;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(kip, &c->pages, list) {
+		if ((*symnum)--)
+			continue;
+		strscpy(sym, c->sym, KSYM_NAME_LEN);
+		*type = 't';
+		*value = (unsigned long)kip->insns;
+		ret = 0;
+		break;
+	}
+	rcu_read_unlock();
+
+	return ret;
+}
+
+#ifdef CONFIG_OPTPROBES
+void __weak *alloc_optinsn_page(void)
+{
+	return alloc_insn_page();
+}
+
+void __weak free_optinsn_page(void *page)
+{
+	free_insn_page(page);
+}
+
+/* For optimized_kprobe buffer */
+struct kprobe_insn_cache kprobe_optinsn_slots = {
+	.mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
+	.alloc = alloc_optinsn_page,
+	.free = free_optinsn_page,
+	.sym = KPROBE_OPTINSN_PAGE_SYM,
+	.pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
+	/* .insn_size is initialized later */
+	.nr_garbage = 0,
+};
+#endif
+#endif
+
+/* We have preemption disabled.. so it is safe to use __ versions */
+static inline void set_kprobe_instance(struct kprobe *kp)
+{
+	__this_cpu_write(kprobe_instance, kp);
+}
+
+static inline void reset_kprobe_instance(void)
+{
+	__this_cpu_write(kprobe_instance, NULL);
+}
+
+/*
+ * This routine is called either:
+ *	- under the 'kprobe_mutex' - during kprobe_[un]register().
+ *				OR
+ *	- with preemption disabled - from architecture specific code.
+ */
+struct kprobe *get_kprobe(void *addr)
+{
+	struct hlist_head *head;
+	struct kprobe *p;
+
+	head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
+	hlist_for_each_entry_rcu(p, head, hlist,
+				 lockdep_is_held(&kprobe_mutex)) {
+		if (p->addr == addr)
+			return p;
+	}
+
+	return NULL;
+}
+NOKPROBE_SYMBOL(get_kprobe);
+
+static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
+
+/* Return true if 'p' is an aggregator */
+static inline bool kprobe_aggrprobe(struct kprobe *p)
+{
+	return p->pre_handler == aggr_pre_handler;
+}
+
+/* Return true if 'p' is unused */
+static inline bool kprobe_unused(struct kprobe *p)
+{
+	return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
+	       list_empty(&p->list);
+}
+
+/* Keep all fields in the kprobe consistent. */
+static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
+{
+	memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
+	memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
+}
+
+#ifdef CONFIG_OPTPROBES
+/* NOTE: This is protected by 'kprobe_mutex'. */
+static bool kprobes_allow_optimization;
+
+/*
+ * Call all 'kprobe::pre_handler' on the list, but ignores its return value.
+ * This must be called from arch-dep optimized caller.
+ */
+void 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();
+	}
+}
+NOKPROBE_SYMBOL(opt_pre_handler);
+
+/* Free optimized instructions and optimized_kprobe */
+static void free_aggr_kprobe(struct kprobe *p)
+{
+	struct optimized_kprobe *op;
+
+	op = container_of(p, struct optimized_kprobe, kp);
+	arch_remove_optimized_kprobe(op);
+	arch_remove_kprobe(p);
+	kfree(op);
+}
+
+/* Return true 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 true if the kprobe is disarmed. Note: p must be on hash list */
+bool kprobe_disarmed(struct kprobe *p)
+{
+	struct optimized_kprobe *op;
+
+	/* If kprobe is not aggr/opt probe, just return kprobe is disabled */
+	if (!kprobe_aggrprobe(p))
+		return kprobe_disabled(p);
+
+	op = container_of(p, struct optimized_kprobe, kp);
+
+	return kprobe_disabled(p) && list_empty(&op->list);
+}
+
+/* Return true if the probe is queued on (un)optimizing lists */
+static bool kprobe_queued(struct kprobe *p)
+{
+	struct optimized_kprobe *op;
+
+	if (kprobe_aggrprobe(p)) {
+		op = container_of(p, struct optimized_kprobe, kp);
+		if (!list_empty(&op->list))
+			return true;
+	}
+	return false;
+}
+
+/*
+ * Return an optimized kprobe whose optimizing code replaces
+ * instructions including 'addr' (exclude breakpoint).
+ */
+static struct kprobe *get_optimized_kprobe(kprobe_opcode_t *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 / sizeof(kprobe_opcode_t); i++)
+		p = get_kprobe(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 LIST_HEAD(unoptimizing_list);
+static LIST_HEAD(freeing_list);
+
+static void kprobe_optimizer(struct work_struct *work);
+static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
+#define OPTIMIZE_DELAY 5
+
+/*
+ * Optimize (replace a breakpoint with a jump) kprobes listed on
+ * 'optimizing_list'.
+ */
+static void do_optimize_kprobes(void)
+{
+	lockdep_assert_held(&text_mutex);
+	/*
+	 * The optimization/unoptimization refers 'online_cpus' via
+	 * stop_machine() and cpu-hotplug modifies the 'online_cpus'.
+	 * And same time, 'text_mutex' will be held in cpu-hotplug and here.
+	 * This combination can cause a deadlock (cpu-hotplug tries to lock
+	 * 'text_mutex' but stop_machine() can not be done because
+	 * the 'online_cpus' has been changed)
+	 * To avoid this deadlock, caller must have locked cpu-hotplug
+	 * for preventing cpu-hotplug outside of 'text_mutex' locking.
+	 */
+	lockdep_assert_cpus_held();
+
+	/* Optimization never be done when disarmed */
+	if (kprobes_all_disarmed || !kprobes_allow_optimization ||
+	    list_empty(&optimizing_list))
+		return;
+
+	arch_optimize_kprobes(&optimizing_list);
+}
+
+/*
+ * Unoptimize (replace a jump with a breakpoint and remove the breakpoint
+ * if need) kprobes listed on 'unoptimizing_list'.
+ */
+static void do_unoptimize_kprobes(void)
+{
+	struct optimized_kprobe *op, *tmp;
+
+	lockdep_assert_held(&text_mutex);
+	/* See comment in do_optimize_kprobes() */
+	lockdep_assert_cpus_held();
+
+	if (!list_empty(&unoptimizing_list))
+		arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
+
+	/* Loop on 'freeing_list' for disarming and removing from kprobe hash list */
+	list_for_each_entry_safe(op, tmp, &freeing_list, list) {
+		/* Switching from detour code to origin */
+		op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
+		/* Disarm probes if marked disabled and not gone */
+		if (kprobe_disabled(&op->kp) && !kprobe_gone(&op->kp))
+			arch_disarm_kprobe(&op->kp);
+		if (kprobe_unused(&op->kp)) {
+			/*
+			 * Remove unused probes from hash list. After waiting
+			 * for synchronization, these probes are reclaimed.
+			 * (reclaiming is done by do_free_cleaned_kprobes().)
+			 */
+			hlist_del_rcu(&op->kp.hlist);
+		} else
+			list_del_init(&op->list);
+	}
+}
+
+/* Reclaim all kprobes on the 'freeing_list' */
+static void do_free_cleaned_kprobes(void)
+{
+	struct optimized_kprobe *op, *tmp;
+
+	list_for_each_entry_safe(op, tmp, &freeing_list, list) {
+		list_del_init(&op->list);
+		if (WARN_ON_ONCE(!kprobe_unused(&op->kp))) {
+			/*
+			 * This must not happen, but if there is a kprobe
+			 * still in use, keep it on kprobes hash list.
+			 */
+			continue;
+		}
+		free_aggr_kprobe(&op->kp);
+	}
+}
+
+/* Start optimizer after OPTIMIZE_DELAY passed */
+static void kick_kprobe_optimizer(void)
+{
+	schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
+}
+
+/* Kprobe jump optimizer */
+static void kprobe_optimizer(struct work_struct *work)
+{
+	mutex_lock(&kprobe_mutex);
+	cpus_read_lock();
+	mutex_lock(&text_mutex);
+
+	/*
+	 * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
+	 * kprobes before waiting for quiesence period.
+	 */
+	do_unoptimize_kprobes();
+
+	/*
+	 * Step 2: Wait for quiesence period to ensure all potentially
+	 * preempted tasks to have normally scheduled. Because optprobe
+	 * may modify multiple instructions, there is a chance that Nth
+	 * instruction is preempted. In that case, such tasks can return
+	 * to 2nd-Nth byte of jump instruction. This wait is for avoiding it.
+	 * Note that on non-preemptive kernel, this is transparently converted
+	 * to synchronoze_sched() to wait for all interrupts to have completed.
+	 */
+	synchronize_rcu_tasks();
+
+	/* Step 3: Optimize kprobes after quiesence period */
+	do_optimize_kprobes();
+
+	/* Step 4: Free cleaned kprobes after quiesence period */
+	do_free_cleaned_kprobes();
+
+	mutex_unlock(&text_mutex);
+	cpus_read_unlock();
+
+	/* Step 5: Kick optimizer again if needed */
+	if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
+		kick_kprobe_optimizer();
+
+	mutex_unlock(&kprobe_mutex);
+}
+
+/* Wait for completing optimization and unoptimization */
+void wait_for_kprobe_optimizer(void)
+{
+	mutex_lock(&kprobe_mutex);
+
+	while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
+		mutex_unlock(&kprobe_mutex);
+
+		/* This will also make 'optimizing_work' execute immmediately */
+		flush_delayed_work(&optimizing_work);
+		/* 'optimizing_work' might not have been queued yet, relax */
+		cpu_relax();
+
+		mutex_lock(&kprobe_mutex);
+	}
+
+	mutex_unlock(&kprobe_mutex);
+}
+
+bool optprobe_queued_unopt(struct optimized_kprobe *op)
+{
+	struct optimized_kprobe *_op;
+
+	list_for_each_entry(_op, &unoptimizing_list, list) {
+		if (op == _op)
+			return true;
+	}
+
+	return false;
+}
+
+/* Optimize kprobe if p is ready to be optimized */
+static 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;
+
+	/* kprobes with 'post_handler' can not be optimized */
+	if (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) {
+		if (optprobe_queued_unopt(op)) {
+			/* This is under unoptimizing. Just dequeue the probe */
+			list_del_init(&op->list);
+		}
+		return;
+	}
+	op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
+
+	/*
+	 * On the 'unoptimizing_list' and 'optimizing_list',
+	 * 'op' must have OPTIMIZED flag
+	 */
+	if (WARN_ON_ONCE(!list_empty(&op->list)))
+		return;
+
+	list_add(&op->list, &optimizing_list);
+	kick_kprobe_optimizer();
+}
+
+/* Short cut to direct unoptimizing */
+static void force_unoptimize_kprobe(struct optimized_kprobe *op)
+{
+	lockdep_assert_cpus_held();
+	arch_unoptimize_kprobe(op);
+	op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
+}
+
+/* Unoptimize a kprobe if p is optimized */
+static void unoptimize_kprobe(struct kprobe *p, bool force)
+{
+	struct optimized_kprobe *op;
+
+	if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
+		return; /* This is not an optprobe nor optimized */
+
+	op = container_of(p, struct optimized_kprobe, kp);
+	if (!kprobe_optimized(p))
+		return;
+
+	if (!list_empty(&op->list)) {
+		if (optprobe_queued_unopt(op)) {
+			/* Queued in unoptimizing queue */
+			if (force) {
+				/*
+				 * Forcibly unoptimize the kprobe here, and queue it
+				 * in the freeing list for release afterwards.
+				 */
+				force_unoptimize_kprobe(op);
+				list_move(&op->list, &freeing_list);
+			}
+		} else {
+			/* Dequeue from the optimizing queue */
+			list_del_init(&op->list);
+			op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
+		}
+		return;
+	}
+
+	/* Optimized kprobe case */
+	if (force) {
+		/* Forcibly update the code: this is a special case */
+		force_unoptimize_kprobe(op);
+	} else {
+		list_add(&op->list, &unoptimizing_list);
+		kick_kprobe_optimizer();
+	}
+}
+
+/* Cancel unoptimizing for reusing */
+static int reuse_unused_kprobe(struct kprobe *ap)
+{
+	struct optimized_kprobe *op;
+
+	/*
+	 * Unused kprobe MUST be on the way of delayed unoptimizing (means
+	 * there is still a relative jump) and disabled.
+	 */
+	op = container_of(ap, struct optimized_kprobe, kp);
+	WARN_ON_ONCE(list_empty(&op->list));
+	/* Enable the probe again */
+	ap->flags &= ~KPROBE_FLAG_DISABLED;
+	/* Optimize it again. (remove from 'op->list') */
+	if (!kprobe_optready(ap))
+		return -EINVAL;
+
+	optimize_kprobe(ap);
+	return 0;
+}
+
+/* Remove optimized instructions */
+static void 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 (un)optimization queue */
+		list_del_init(&op->list);
+	op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
+
+	if (kprobe_unused(p)) {
+		/*
+		 * Unused kprobe is on unoptimizing or freeing list. We move it
+		 * to freeing_list and let the kprobe_optimizer() remove it from
+		 * the kprobe hash list and free it.
+		 */
+		if (optprobe_queued_unopt(op))
+			list_move(&op->list, &freeing_list);
+	}
+
+	/* Don't touch the code, because it is already freed. */
+	arch_remove_optimized_kprobe(op);
+}
+
+static inline
+void __prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
+{
+	if (!kprobe_ftrace(p))
+		arch_prepare_optimized_kprobe(op, p);
+}
+
+/* Try to prepare optimized instructions */
+static void prepare_optimized_kprobe(struct kprobe *p)
+{
+	struct optimized_kprobe *op;
+
+	op = container_of(p, struct optimized_kprobe, kp);
+	__prepare_optimized_kprobe(op, p);
+}
+
+/* Allocate new optimized_kprobe and try to prepare optimized instructions. */
+static 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;
+	__prepare_optimized_kprobe(op, p);
+
+	return &op->kp;
+}
+
+static void 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 void try_to_optimize_kprobe(struct kprobe *p)
+{
+	struct kprobe *ap;
+	struct optimized_kprobe *op;
+
+	/* Impossible to optimize ftrace-based kprobe. */
+	if (kprobe_ftrace(p))
+		return;
+
+	/* For preparing optimization, jump_label_text_reserved() is called. */
+	cpus_read_lock();
+	jump_label_lock();
+	mutex_lock(&text_mutex);
+
+	ap = alloc_aggr_kprobe(p);
+	if (!ap)
+		goto out;
+
+	op = container_of(ap, struct optimized_kprobe, kp);
+	if (!arch_prepared_optinsn(&op->optinsn)) {
+		/* If failed to setup optimizing, fallback to kprobe. */
+		arch_remove_optimized_kprobe(op);
+		kfree(op);
+		goto out;
+	}
+
+	init_aggr_kprobe(ap, p);
+	optimize_kprobe(ap);	/* This just kicks optimizer thread. */
+
+out:
+	mutex_unlock(&text_mutex);
+	jump_label_unlock();
+	cpus_read_unlock();
+}
+
+static void optimize_all_kprobes(void)
+{
+	struct hlist_head *head;
+	struct kprobe *p;
+	unsigned int i;
+
+	mutex_lock(&kprobe_mutex);
+	/* If optimization is already allowed, just return. */
+	if (kprobes_allow_optimization)
+		goto out;
+
+	cpus_read_lock();
+	kprobes_allow_optimization = true;
+	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
+		head = &kprobe_table[i];
+		hlist_for_each_entry(p, head, hlist)
+			if (!kprobe_disabled(p))
+				optimize_kprobe(p);
+	}
+	cpus_read_unlock();
+	pr_info("kprobe jump-optimization is enabled. All kprobes are optimized if possible.\n");
+out:
+	mutex_unlock(&kprobe_mutex);
+}
+
+#ifdef CONFIG_SYSCTL
+static void unoptimize_all_kprobes(void)
+{
+	struct hlist_head *head;
+	struct kprobe *p;
+	unsigned int i;
+
+	mutex_lock(&kprobe_mutex);
+	/* If optimization is already prohibited, just return. */
+	if (!kprobes_allow_optimization) {
+		mutex_unlock(&kprobe_mutex);
+		return;
+	}
+
+	cpus_read_lock();
+	kprobes_allow_optimization = false;
+	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
+		head = &kprobe_table[i];
+		hlist_for_each_entry(p, head, hlist) {
+			if (!kprobe_disabled(p))
+				unoptimize_kprobe(p, false);
+		}
+	}
+	cpus_read_unlock();
+	mutex_unlock(&kprobe_mutex);
+
+	/* Wait for unoptimizing completion. */
+	wait_for_kprobe_optimizer();
+	pr_info("kprobe jump-optimization is disabled. All kprobes are based on software breakpoint.\n");
+}
+
+static DEFINE_MUTEX(kprobe_sysctl_mutex);
+static int sysctl_kprobes_optimization;
+static int proc_kprobes_optimization_handler(struct ctl_table *table,
+					     int write, void *buffer,
+					     size_t *length, loff_t *ppos)
+{
+	int ret;
+
+	mutex_lock(&kprobe_sysctl_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_sysctl_mutex);
+
+	return ret;
+}
+
+static struct ctl_table kprobe_sysctls[] = {
+	{
+		.procname	= "kprobes-optimization",
+		.data		= &sysctl_kprobes_optimization,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_kprobes_optimization_handler,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
+	{}
+};
+
+static void __init kprobe_sysctls_init(void)
+{
+	register_sysctl_init("debug", kprobe_sysctls);
+}
+#endif /* CONFIG_SYSCTL */
+
+/* Put a breakpoint for a probe. */
+static void __arm_kprobe(struct kprobe *p)
+{
+	struct kprobe *_p;
+
+	lockdep_assert_held(&text_mutex);
+
+	/* Find the overlapping optimized kprobes. */
+	_p = get_optimized_kprobe(p->addr);
+	if (unlikely(_p))
+		/* Fallback to unoptimized kprobe */
+		unoptimize_kprobe(_p, true);
+
+	arch_arm_kprobe(p);
+	optimize_kprobe(p);	/* Try to optimize (add kprobe to a list) */
+}
+
+/* Remove the breakpoint of a probe. */
+static void __disarm_kprobe(struct kprobe *p, bool reopt)
+{
+	struct kprobe *_p;
+
+	lockdep_assert_held(&text_mutex);
+
+	/* Try to unoptimize */
+	unoptimize_kprobe(p, kprobes_all_disarmed);
+
+	if (!kprobe_queued(p)) {
+		arch_disarm_kprobe(p);
+		/* If another kprobe was blocked, re-optimize it. */
+		_p = get_optimized_kprobe(p->addr);
+		if (unlikely(_p) && reopt)
+			optimize_kprobe(_p);
+	}
+	/*
+	 * TODO: Since unoptimization and real disarming will be done by
+	 * the worker thread, we can not check whether another probe are
+	 * unoptimized because of this probe here. It should be re-optimized
+	 * by the worker thread.
+	 */
+}
+
+#else /* !CONFIG_OPTPROBES */
+
+#define optimize_kprobe(p)			do {} while (0)
+#define unoptimize_kprobe(p, f)			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, o)			arch_disarm_kprobe(p)
+#define kprobe_disarmed(p)			kprobe_disabled(p)
+#define wait_for_kprobe_optimizer()		do {} while (0)
+
+static int reuse_unused_kprobe(struct kprobe *ap)
+{
+	/*
+	 * If the optimized kprobe is NOT supported, the aggr kprobe is
+	 * released at the same time that the last aggregated kprobe is
+	 * unregistered.
+	 * Thus there should be no chance to reuse unused kprobe.
+	 */
+	WARN_ON_ONCE(1);
+	return -EINVAL;
+}
+
+static void free_aggr_kprobe(struct kprobe *p)
+{
+	arch_remove_kprobe(p);
+	kfree(p);
+}
+
+static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
+{
+	return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
+}
+#endif /* CONFIG_OPTPROBES */
+
+#ifdef CONFIG_KPROBES_ON_FTRACE
+static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
+	.func = kprobe_ftrace_handler,
+	.flags = FTRACE_OPS_FL_SAVE_REGS,
+};
+
+static struct ftrace_ops kprobe_ipmodify_ops __read_mostly = {
+	.func = kprobe_ftrace_handler,
+	.flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY,
+};
+
+static int kprobe_ipmodify_enabled;
+static int kprobe_ftrace_enabled;
+
+static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
+			       int *cnt)
+{
+	int ret;
+
+	lockdep_assert_held(&kprobe_mutex);
+
+	ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0);
+	if (WARN_ONCE(ret < 0, "Failed to arm kprobe-ftrace at %pS (error %d)\n", p->addr, ret))
+		return ret;
+
+	if (*cnt == 0) {
+		ret = register_ftrace_function(ops);
+		if (WARN(ret < 0, "Failed to register kprobe-ftrace (error %d)\n", ret))
+			goto err_ftrace;
+	}
+
+	(*cnt)++;
+	return ret;
+
+err_ftrace:
+	/*
+	 * At this point, sinec ops is not registered, we should be sefe from
+	 * registering empty filter.
+	 */
+	ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
+	return ret;
+}
+
+static int arm_kprobe_ftrace(struct kprobe *p)
+{
+	bool ipmodify = (p->post_handler != NULL);
+
+	return __arm_kprobe_ftrace(p,
+		ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops,
+		ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
+}
+
+static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
+				  int *cnt)
+{
+	int ret;
+
+	lockdep_assert_held(&kprobe_mutex);
+
+	if (*cnt == 1) {
+		ret = unregister_ftrace_function(ops);
+		if (WARN(ret < 0, "Failed to unregister kprobe-ftrace (error %d)\n", ret))
+			return ret;
+	}
+
+	(*cnt)--;
+
+	ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
+	WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (error %d)\n",
+		  p->addr, ret);
+	return ret;
+}
+
+static int disarm_kprobe_ftrace(struct kprobe *p)
+{
+	bool ipmodify = (p->post_handler != NULL);
+
+	return __disarm_kprobe_ftrace(p,
+		ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops,
+		ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
+}
+#else	/* !CONFIG_KPROBES_ON_FTRACE */
+static inline int arm_kprobe_ftrace(struct kprobe *p)
+{
+	return -ENODEV;
+}
+
+static inline int disarm_kprobe_ftrace(struct kprobe *p)
+{
+	return -ENODEV;
+}
+#endif
+
+static int prepare_kprobe(struct kprobe *p)
+{
+	/* Must ensure p->addr is really on ftrace */
+	if (kprobe_ftrace(p))
+		return arch_prepare_kprobe_ftrace(p);
+
+	return arch_prepare_kprobe(p);
+}
+
+static int arm_kprobe(struct kprobe *kp)
+{
+	if (unlikely(kprobe_ftrace(kp)))
+		return arm_kprobe_ftrace(kp);
+
+	cpus_read_lock();
+	mutex_lock(&text_mutex);
+	__arm_kprobe(kp);
+	mutex_unlock(&text_mutex);
+	cpus_read_unlock();
+
+	return 0;
+}
+
+static int disarm_kprobe(struct kprobe *kp, bool reopt)
+{
+	if (unlikely(kprobe_ftrace(kp)))
+		return disarm_kprobe_ftrace(kp);
+
+	cpus_read_lock();
+	mutex_lock(&text_mutex);
+	__disarm_kprobe(kp, reopt);
+	mutex_unlock(&text_mutex);
+	cpus_read_unlock();
+
+	return 0;
+}
+
+/*
+ * Aggregate handlers for multiple kprobes support - these handlers
+ * take care of invoking the individual kprobe handlers on p->list
+ */
+static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	struct kprobe *kp;
+
+	list_for_each_entry_rcu(kp, &p->list, list) {
+		if (kp->pre_handler && likely(!kprobe_disabled(kp))) {
+			set_kprobe_instance(kp);
+			if (kp->pre_handler(kp, regs))
+				return 1;
+		}
+		reset_kprobe_instance();
+	}
+	return 0;
+}
+NOKPROBE_SYMBOL(aggr_pre_handler);
+
+static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
+			      unsigned long flags)
+{
+	struct kprobe *kp;
+
+	list_for_each_entry_rcu(kp, &p->list, list) {
+		if (kp->post_handler && likely(!kprobe_disabled(kp))) {
+			set_kprobe_instance(kp);
+			kp->post_handler(kp, regs, flags);
+			reset_kprobe_instance();
+		}
+	}
+}
+NOKPROBE_SYMBOL(aggr_post_handler);
+
+/* Walks the list and increments 'nmissed' if 'p' has child probes. */
+void kprobes_inc_nmissed_count(struct kprobe *p)
+{
+	struct kprobe *kp;
+
+	if (!kprobe_aggrprobe(p)) {
+		p->nmissed++;
+	} else {
+		list_for_each_entry_rcu(kp, &p->list, list)
+			kp->nmissed++;
+	}
+}
+NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
+
+static struct kprobe kprobe_busy = {
+	.addr = (void *) get_kprobe,
+};
+
+void kprobe_busy_begin(void)
+{
+	struct kprobe_ctlblk *kcb;
+
+	preempt_disable();
+	__this_cpu_write(current_kprobe, &kprobe_busy);
+	kcb = get_kprobe_ctlblk();
+	kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+}
+
+void kprobe_busy_end(void)
+{
+	__this_cpu_write(current_kprobe, NULL);
+	preempt_enable();
+}
+
+/* Add the new probe to 'ap->list'. */
+static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
+{
+	if (p->post_handler)
+		unoptimize_kprobe(ap, true);	/* Fall back to normal kprobe */
+
+	list_add_rcu(&p->list, &ap->list);
+	if (p->post_handler && !ap->post_handler)
+		ap->post_handler = aggr_post_handler;
+
+	return 0;
+}
+
+/*
+ * Fill in the required fields of the aggregator kprobe. Replace the
+ * earlier kprobe in the hlist with the aggregator kprobe.
+ */
+static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
+{
+	/* Copy the insn slot of 'p' to 'ap'. */
+	copy_kprobe(p, ap);
+	flush_insn_slot(ap);
+	ap->addr = p->addr;
+	ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
+	ap->pre_handler = aggr_pre_handler;
+	/* We don't care the kprobe which has gone. */
+	if (p->post_handler && !kprobe_gone(p))
+		ap->post_handler = aggr_post_handler;
+
+	INIT_LIST_HEAD(&ap->list);
+	INIT_HLIST_NODE(&ap->hlist);
+
+	list_add_rcu(&p->list, &ap->list);
+	hlist_replace_rcu(&p->hlist, &ap->hlist);
+}
+
+/*
+ * This registers the second or subsequent kprobe at the same address.
+ */
+static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
+{
+	int ret = 0;
+	struct kprobe *ap = orig_p;
+
+	cpus_read_lock();
+
+	/* For preparing optimization, jump_label_text_reserved() is called */
+	jump_label_lock();
+	mutex_lock(&text_mutex);
+
+	if (!kprobe_aggrprobe(orig_p)) {
+		/* If 'orig_p' is not an 'aggr_kprobe', create new one. */
+		ap = alloc_aggr_kprobe(orig_p);
+		if (!ap) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		init_aggr_kprobe(ap, orig_p);
+	} else if (kprobe_unused(ap)) {
+		/* This probe is going to die. Rescue it */
+		ret = reuse_unused_kprobe(ap);
+		if (ret)
+			goto out;
+	}
+
+	if (kprobe_gone(ap)) {
+		/*
+		 * Attempting to insert new probe at the same location that
+		 * had a probe in the module vaddr area which already
+		 * freed. So, the instruction slot has already been
+		 * released. We need a new slot for the new probe.
+		 */
+		ret = arch_prepare_kprobe(ap);
+		if (ret)
+			/*
+			 * Even if fail to allocate new slot, don't need to
+			 * free the 'ap'. It will be used next time, or
+			 * freed by unregister_kprobe().
+			 */
+			goto out;
+
+		/* 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.
+		 */
+		ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
+			    | KPROBE_FLAG_DISABLED;
+	}
+
+	/* Copy the insn slot of 'p' to 'ap'. */
+	copy_kprobe(ap, p);
+	ret = add_new_kprobe(ap, p);
+
+out:
+	mutex_unlock(&text_mutex);
+	jump_label_unlock();
+	cpus_read_unlock();
+
+	if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
+		ap->flags &= ~KPROBE_FLAG_DISABLED;
+		if (!kprobes_all_disarmed) {
+			/* Arm the breakpoint again. */
+			ret = arm_kprobe(ap);
+			if (ret) {
+				ap->flags |= KPROBE_FLAG_DISABLED;
+				list_del_rcu(&p->list);
+				synchronize_rcu();
+			}
+		}
+	}
+	return ret;
+}
+
+bool __weak arch_within_kprobe_blacklist(unsigned long addr)
+{
+	/* The '__kprobes' functions and entry code must not be probed. */
+	return addr >= (unsigned long)__kprobes_text_start &&
+	       addr < (unsigned long)__kprobes_text_end;
+}
+
+static bool __within_kprobe_blacklist(unsigned long addr)
+{
+	struct kprobe_blacklist_entry *ent;
+
+	if (arch_within_kprobe_blacklist(addr))
+		return true;
+	/*
+	 * If 'kprobe_blacklist' is defined, check the address and
+	 * reject any probe registration in the prohibited area.
+	 */
+	list_for_each_entry(ent, &kprobe_blacklist, list) {
+		if (addr >= ent->start_addr && addr < ent->end_addr)
+			return true;
+	}
+	return false;
+}
+
+bool within_kprobe_blacklist(unsigned long addr)
+{
+	char symname[KSYM_NAME_LEN], *p;
+
+	if (__within_kprobe_blacklist(addr))
+		return true;
+
+	/* Check if the address is on a suffixed-symbol */
+	if (!lookup_symbol_name(addr, symname)) {
+		p = strchr(symname, '.');
+		if (!p)
+			return false;
+		*p = '\0';
+		addr = (unsigned long)kprobe_lookup_name(symname, 0);
+		if (addr)
+			return __within_kprobe_blacklist(addr);
+	}
+	return false;
+}
+
+/*
+ * arch_adjust_kprobe_addr - adjust the address
+ * @addr: symbol base address
+ * @offset: offset within the symbol
+ * @on_func_entry: was this @addr+@offset on the function entry
+ *
+ * Typically returns @addr + @offset, except for special cases where the
+ * function might be prefixed by a CFI landing pad, in that case any offset
+ * inside the landing pad is mapped to the first 'real' instruction of the
+ * symbol.
+ *
+ * Specifically, for things like IBT/BTI, skip the resp. ENDBR/BTI.C
+ * instruction at +0.
+ */
+kprobe_opcode_t *__weak arch_adjust_kprobe_addr(unsigned long addr,
+						unsigned long offset,
+						bool *on_func_entry)
+{
+	*on_func_entry = !offset;
+	return (kprobe_opcode_t *)(addr + offset);
+}
+
+/*
+ * If 'symbol_name' is specified, look it up and add the 'offset'
+ * to it. This way, we can specify a relative address to a symbol.
+ * This returns encoded errors if it fails to look up symbol or invalid
+ * combination of parameters.
+ */
+static kprobe_opcode_t *
+_kprobe_addr(kprobe_opcode_t *addr, const char *symbol_name,
+	     unsigned long offset, bool *on_func_entry)
+{
+	if ((symbol_name && addr) || (!symbol_name && !addr))
+		goto invalid;
+
+	if (symbol_name) {
+		/*
+		 * Input: @sym + @offset
+		 * Output: @addr + @offset
+		 *
+		 * NOTE: kprobe_lookup_name() does *NOT* fold the offset
+		 *       argument into it's output!
+		 */
+		addr = kprobe_lookup_name(symbol_name, offset);
+		if (!addr)
+			return ERR_PTR(-ENOENT);
+	}
+
+	/*
+	 * So here we have @addr + @offset, displace it into a new
+	 * @addr' + @offset' where @addr' is the symbol start address.
+	 */
+	addr = (void *)addr + offset;
+	if (!kallsyms_lookup_size_offset((unsigned long)addr, NULL, &offset))
+		return ERR_PTR(-ENOENT);
+	addr = (void *)addr - offset;
+
+	/*
+	 * Then ask the architecture to re-combine them, taking care of
+	 * magical function entry details while telling us if this was indeed
+	 * at the start of the function.
+	 */
+	addr = arch_adjust_kprobe_addr((unsigned long)addr, offset, on_func_entry);
+	if (addr)
+		return addr;
+
+invalid:
+	return ERR_PTR(-EINVAL);
+}
+
+static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
+{
+	bool on_func_entry;
+	return _kprobe_addr(p->addr, p->symbol_name, p->offset, &on_func_entry);
+}
+
+/*
+ * Check the 'p' is valid and return the aggregator kprobe
+ * at the same address.
+ */
+static struct kprobe *__get_valid_kprobe(struct kprobe *p)
+{
+	struct kprobe *ap, *list_p;
+
+	lockdep_assert_held(&kprobe_mutex);
+
+	ap = get_kprobe(p->addr);
+	if (unlikely(!ap))
+		return NULL;
+
+	if (p != ap) {
+		list_for_each_entry(list_p, &ap->list, list)
+			if (list_p == p)
+			/* kprobe p is a valid probe */
+				goto valid;
+		return NULL;
+	}
+valid:
+	return ap;
+}
+
+/*
+ * Warn and return error if the kprobe is being re-registered since
+ * there must be a software bug.
+ */
+static inline int warn_kprobe_rereg(struct kprobe *p)
+{
+	int ret = 0;
+
+	mutex_lock(&kprobe_mutex);
+	if (WARN_ON_ONCE(__get_valid_kprobe(p)))
+		ret = -EINVAL;
+	mutex_unlock(&kprobe_mutex);
+
+	return ret;
+}
+
+static int check_ftrace_location(struct kprobe *p)
+{
+	unsigned long addr = (unsigned long)p->addr;
+
+	if (ftrace_location(addr) == addr) {
+#ifdef CONFIG_KPROBES_ON_FTRACE
+		p->flags |= KPROBE_FLAG_FTRACE;
+#else	/* !CONFIG_KPROBES_ON_FTRACE */
+		return -EINVAL;
+#endif
+	}
+	return 0;
+}
+
+static bool is_cfi_preamble_symbol(unsigned long addr)
+{
+	char symbuf[KSYM_NAME_LEN];
+
+	if (lookup_symbol_name(addr, symbuf))
+		return false;
+
+	return str_has_prefix("__cfi_", symbuf) ||
+		str_has_prefix("__pfx_", symbuf);
+}
+
+static int check_kprobe_address_safe(struct kprobe *p,
+				     struct module **probed_mod)
+{
+	int ret;
+
+	ret = check_ftrace_location(p);
+	if (ret)
+		return ret;
+	jump_label_lock();
+	preempt_disable();
+
+	/* Ensure it is not in reserved area nor out of text */
+	if (!(core_kernel_text((unsigned long) p->addr) ||
+	    is_module_text_address((unsigned long) p->addr)) ||
+	    in_gate_area_no_mm((unsigned long) p->addr) ||
+	    within_kprobe_blacklist((unsigned long) p->addr) ||
+	    jump_label_text_reserved(p->addr, p->addr) ||
+	    static_call_text_reserved(p->addr, p->addr) ||
+	    find_bug((unsigned long)p->addr) ||
+	    is_cfi_preamble_symbol((unsigned long)p->addr)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* Check if 'p' is probing a module. */
+	*probed_mod = __module_text_address((unsigned long) p->addr);
+	if (*probed_mod) {
+		/*
+		 * We must hold a refcount of the probed module while updating
+		 * its code to prohibit unexpected unloading.
+		 */
+		if (unlikely(!try_module_get(*probed_mod))) {
+			ret = -ENOENT;
+			goto out;
+		}
+
+		/*
+		 * If the module freed '.init.text', we couldn't insert
+		 * kprobes in there.
+		 */
+		if (within_module_init((unsigned long)p->addr, *probed_mod) &&
+		    (*probed_mod)->state != MODULE_STATE_COMING) {
+			module_put(*probed_mod);
+			*probed_mod = NULL;
+			ret = -ENOENT;
+		}
+	}
+out:
+	preempt_enable();
+	jump_label_unlock();
+
+	return ret;
+}
+
+int register_kprobe(struct kprobe *p)
+{
+	int ret;
+	struct kprobe *old_p;
+	struct module *probed_mod;
+	kprobe_opcode_t *addr;
+	bool on_func_entry;
+
+	/* Adjust probe address from symbol */
+	addr = _kprobe_addr(p->addr, p->symbol_name, p->offset, &on_func_entry);
+	if (IS_ERR(addr))
+		return PTR_ERR(addr);
+	p->addr = addr;
+
+	ret = warn_kprobe_rereg(p);
+	if (ret)
+		return ret;
+
+	/* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
+	p->flags &= KPROBE_FLAG_DISABLED;
+	p->nmissed = 0;
+	INIT_LIST_HEAD(&p->list);
+
+	ret = check_kprobe_address_safe(p, &probed_mod);
+	if (ret)
+		return ret;
+
+	mutex_lock(&kprobe_mutex);
+
+	if (on_func_entry)
+		p->flags |= KPROBE_FLAG_ON_FUNC_ENTRY;
+
+	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;
+	}
+
+	cpus_read_lock();
+	/* Prevent text modification */
+	mutex_lock(&text_mutex);
+	ret = prepare_kprobe(p);
+	mutex_unlock(&text_mutex);
+	cpus_read_unlock();
+	if (ret)
+		goto out;
+
+	INIT_HLIST_NODE(&p->hlist);
+	hlist_add_head_rcu(&p->hlist,
+		       &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
+
+	if (!kprobes_all_disarmed && !kprobe_disabled(p)) {
+		ret = arm_kprobe(p);
+		if (ret) {
+			hlist_del_rcu(&p->hlist);
+			synchronize_rcu();
+			goto out;
+		}
+	}
+
+	/* Try to optimize kprobe */
+	try_to_optimize_kprobe(p);
+out:
+	mutex_unlock(&kprobe_mutex);
+
+	if (probed_mod)
+		module_put(probed_mod);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(register_kprobe);
+
+/* Check if all probes on the 'ap' are disabled. */
+static bool aggr_kprobe_disabled(struct kprobe *ap)
+{
+	struct kprobe *kp;
+
+	lockdep_assert_held(&kprobe_mutex);
+
+	list_for_each_entry(kp, &ap->list, list)
+		if (!kprobe_disabled(kp))
+			/*
+			 * Since there is an active probe on the list,
+			 * we can't disable this 'ap'.
+			 */
+			return false;
+
+	return true;
+}
+
+static struct kprobe *__disable_kprobe(struct kprobe *p)
+{
+	struct kprobe *orig_p;
+	int ret;
+
+	lockdep_assert_held(&kprobe_mutex);
+
+	/* Get an original kprobe for return */
+	orig_p = __get_valid_kprobe(p);
+	if (unlikely(orig_p == NULL))
+		return ERR_PTR(-EINVAL);
+
+	if (!kprobe_disabled(p)) {
+		/* Disable probe if it is a child probe */
+		if (p != orig_p)
+			p->flags |= KPROBE_FLAG_DISABLED;
+
+		/* Try to disarm and disable this/parent probe */
+		if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
+			/*
+			 * Don't be lazy here.  Even if 'kprobes_all_disarmed'
+			 * is false, 'orig_p' might not have been armed yet.
+			 * Note arm_all_kprobes() __tries__ to arm all kprobes
+			 * on the best effort basis.
+			 */
+			if (!kprobes_all_disarmed && !kprobe_disabled(orig_p)) {
+				ret = disarm_kprobe(orig_p, true);
+				if (ret) {
+					p->flags &= ~KPROBE_FLAG_DISABLED;
+					return ERR_PTR(ret);
+				}
+			}
+			orig_p->flags |= KPROBE_FLAG_DISABLED;
+		}
+	}
+
+	return orig_p;
+}
+
+/*
+ * Unregister a kprobe without a scheduler synchronization.
+ */
+static int __unregister_kprobe_top(struct kprobe *p)
+{
+	struct kprobe *ap, *list_p;
+
+	/* Disable kprobe. This will disarm it if needed. */
+	ap = __disable_kprobe(p);
+	if (IS_ERR(ap))
+		return PTR_ERR(ap);
+
+	if (ap == p)
+		/*
+		 * This probe is an independent(and non-optimized) kprobe
+		 * (not an aggrprobe). Remove from the hash list.
+		 */
+		goto disarmed;
+
+	/* Following process expects this probe is an aggrprobe */
+	WARN_ON(!kprobe_aggrprobe(ap));
+
+	if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
+		/*
+		 * !disarmed could be happen if the probe is under delayed
+		 * unoptimizing.
+		 */
+		goto disarmed;
+	else {
+		/* If disabling probe has special handlers, update aggrprobe */
+		if (p->post_handler && !kprobe_gone(p)) {
+			list_for_each_entry(list_p, &ap->list, list) {
+				if ((list_p != p) && (list_p->post_handler))
+					goto noclean;
+			}
+			/*
+			 * For the kprobe-on-ftrace case, we keep the
+			 * post_handler setting to identify this aggrprobe
+			 * armed with kprobe_ipmodify_ops.
+			 */
+			if (!kprobe_ftrace(ap))
+				ap->post_handler = NULL;
+		}
+noclean:
+		/*
+		 * Remove from the aggrprobe: this path will do nothing in
+		 * __unregister_kprobe_bottom().
+		 */
+		list_del_rcu(&p->list);
+		if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
+			/*
+			 * Try to optimize this probe again, because post
+			 * handler may have been changed.
+			 */
+			optimize_kprobe(ap);
+	}
+	return 0;
+
+disarmed:
+	hlist_del_rcu(&ap->hlist);
+	return 0;
+}
+
+static void __unregister_kprobe_bottom(struct kprobe *p)
+{
+	struct kprobe *ap;
+
+	if (list_empty(&p->list))
+		/* This is an independent kprobe */
+		arch_remove_kprobe(p);
+	else if (list_is_singular(&p->list)) {
+		/* This is the last child of an aggrprobe */
+		ap = list_entry(p->list.next, struct kprobe, list);
+		list_del(&p->list);
+		free_aggr_kprobe(ap);
+	}
+	/* Otherwise, do nothing. */
+}
+
+int register_kprobes(struct kprobe **kps, int num)
+{
+	int i, ret = 0;
+
+	if (num <= 0)
+		return -EINVAL;
+	for (i = 0; i < num; i++) {
+		ret = register_kprobe(kps[i]);
+		if (ret < 0) {
+			if (i > 0)
+				unregister_kprobes(kps, i);
+			break;
+		}
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(register_kprobes);
+
+void unregister_kprobe(struct kprobe *p)
+{
+	unregister_kprobes(&p, 1);
+}
+EXPORT_SYMBOL_GPL(unregister_kprobe);
+
+void unregister_kprobes(struct kprobe **kps, int num)
+{
+	int i;
+
+	if (num <= 0)
+		return;
+	mutex_lock(&kprobe_mutex);
+	for (i = 0; i < num; i++)
+		if (__unregister_kprobe_top(kps[i]) < 0)
+			kps[i]->addr = NULL;
+	mutex_unlock(&kprobe_mutex);
+
+	synchronize_rcu();
+	for (i = 0; i < num; i++)
+		if (kps[i]->addr)
+			__unregister_kprobe_bottom(kps[i]);
+}
+EXPORT_SYMBOL_GPL(unregister_kprobes);
+
+int __weak kprobe_exceptions_notify(struct notifier_block *self,
+					unsigned long val, void *data)
+{
+	return NOTIFY_DONE;
+}
+NOKPROBE_SYMBOL(kprobe_exceptions_notify);
+
+static struct notifier_block kprobe_exceptions_nb = {
+	.notifier_call = kprobe_exceptions_notify,
+	.priority = 0x7fffffff /* we need to be notified first */
+};
+
+#ifdef CONFIG_KRETPROBES
+
+#if !defined(CONFIG_KRETPROBE_ON_RETHOOK)
+static void free_rp_inst_rcu(struct rcu_head *head)
+{
+	struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu);
+
+	if (refcount_dec_and_test(&ri->rph->ref))
+		kfree(ri->rph);
+	kfree(ri);
+}
+NOKPROBE_SYMBOL(free_rp_inst_rcu);
+
+static void recycle_rp_inst(struct kretprobe_instance *ri)
+{
+	struct kretprobe *rp = get_kretprobe(ri);
+
+	if (likely(rp))
+		freelist_add(&ri->freelist, &rp->freelist);
+	else
+		call_rcu(&ri->rcu, free_rp_inst_rcu);
+}
+NOKPROBE_SYMBOL(recycle_rp_inst);
+
+/*
+ * This function is called from delayed_put_task_struct() when a task is
+ * dead and cleaned up to recycle any kretprobe instances associated with
+ * this task. These left over instances represent probed functions that
+ * have been called but will never return.
+ */
+void kprobe_flush_task(struct task_struct *tk)
+{
+	struct kretprobe_instance *ri;
+	struct llist_node *node;
+
+	/* Early boot, not yet initialized. */
+	if (unlikely(!kprobes_initialized))
+		return;
+
+	kprobe_busy_begin();
+
+	node = __llist_del_all(&tk->kretprobe_instances);
+	while (node) {
+		ri = container_of(node, struct kretprobe_instance, llist);
+		node = node->next;
+
+		recycle_rp_inst(ri);
+	}
+
+	kprobe_busy_end();
+}
+NOKPROBE_SYMBOL(kprobe_flush_task);
+
+static inline void free_rp_inst(struct kretprobe *rp)
+{
+	struct kretprobe_instance *ri;
+	struct freelist_node *node;
+	int count = 0;
+
+	node = rp->freelist.head;
+	while (node) {
+		ri = container_of(node, struct kretprobe_instance, freelist);
+		node = node->next;
+
+		kfree(ri);
+		count++;
+	}
+
+	if (refcount_sub_and_test(count, &rp->rph->ref)) {
+		kfree(rp->rph);
+		rp->rph = NULL;
+	}
+}
+
+/* This assumes the 'tsk' is the current task or the is not running. */
+static kprobe_opcode_t *__kretprobe_find_ret_addr(struct task_struct *tsk,
+						  struct llist_node **cur)
+{
+	struct kretprobe_instance *ri = NULL;
+	struct llist_node *node = *cur;
+
+	if (!node)
+		node = tsk->kretprobe_instances.first;
+	else
+		node = node->next;
+
+	while (node) {
+		ri = container_of(node, struct kretprobe_instance, llist);
+		if (ri->ret_addr != kretprobe_trampoline_addr()) {
+			*cur = node;
+			return ri->ret_addr;
+		}
+		node = node->next;
+	}
+	return NULL;
+}
+NOKPROBE_SYMBOL(__kretprobe_find_ret_addr);
+
+/**
+ * kretprobe_find_ret_addr -- Find correct return address modified by kretprobe
+ * @tsk: Target task
+ * @fp: A frame pointer
+ * @cur: a storage of the loop cursor llist_node pointer for next call
+ *
+ * Find the correct return address modified by a kretprobe on @tsk in unsigned
+ * long type. If it finds the return address, this returns that address value,
+ * or this returns 0.
+ * The @tsk must be 'current' or a task which is not running. @fp is a hint
+ * to get the currect return address - which is compared with the
+ * kretprobe_instance::fp field. The @cur is a loop cursor for searching the
+ * kretprobe return addresses on the @tsk. The '*@cur' should be NULL at the
+ * first call, but '@cur' itself must NOT NULL.
+ */
+unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
+				      struct llist_node **cur)
+{
+	struct kretprobe_instance *ri = NULL;
+	kprobe_opcode_t *ret;
+
+	if (WARN_ON_ONCE(!cur))
+		return 0;
+
+	do {
+		ret = __kretprobe_find_ret_addr(tsk, cur);
+		if (!ret)
+			break;
+		ri = container_of(*cur, struct kretprobe_instance, llist);
+	} while (ri->fp != fp);
+
+	return (unsigned long)ret;
+}
+NOKPROBE_SYMBOL(kretprobe_find_ret_addr);
+
+void __weak arch_kretprobe_fixup_return(struct pt_regs *regs,
+					kprobe_opcode_t *correct_ret_addr)
+{
+	/*
+	 * Do nothing by default. Please fill this to update the fake return
+	 * address on the stack with the correct one on each arch if possible.
+	 */
+}
+
+unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
+					     void *frame_pointer)
+{
+	struct kretprobe_instance *ri = NULL;
+	struct llist_node *first, *node = NULL;
+	kprobe_opcode_t *correct_ret_addr;
+	struct kretprobe *rp;
+
+	/* Find correct address and all nodes for this frame. */
+	correct_ret_addr = __kretprobe_find_ret_addr(current, &node);
+	if (!correct_ret_addr) {
+		pr_err("kretprobe: Return address not found, not execute handler. Maybe there is a bug in the kernel.\n");
+		BUG_ON(1);
+	}
+
+	/*
+	 * Set the return address as the instruction pointer, because if the
+	 * user handler calls stack_trace_save_regs() with this 'regs',
+	 * the stack trace will start from the instruction pointer.
+	 */
+	instruction_pointer_set(regs, (unsigned long)correct_ret_addr);
+
+	/* Run the user handler of the nodes. */
+	first = current->kretprobe_instances.first;
+	while (first) {
+		ri = container_of(first, struct kretprobe_instance, llist);
+
+		if (WARN_ON_ONCE(ri->fp != frame_pointer))
+			break;
+
+		rp = get_kretprobe(ri);
+		if (rp && rp->handler) {
+			struct kprobe *prev = kprobe_running();
+
+			__this_cpu_write(current_kprobe, &rp->kp);
+			ri->ret_addr = correct_ret_addr;
+			rp->handler(ri, regs);
+			__this_cpu_write(current_kprobe, prev);
+		}
+		if (first == node)
+			break;
+
+		first = first->next;
+	}
+
+	arch_kretprobe_fixup_return(regs, correct_ret_addr);
+
+	/* Unlink all nodes for this frame. */
+	first = current->kretprobe_instances.first;
+	current->kretprobe_instances.first = node->next;
+	node->next = NULL;
+
+	/* Recycle free instances. */
+	while (first) {
+		ri = container_of(first, struct kretprobe_instance, llist);
+		first = first->next;
+
+		recycle_rp_inst(ri);
+	}
+
+	return (unsigned long)correct_ret_addr;
+}
+NOKPROBE_SYMBOL(__kretprobe_trampoline_handler)
+
+/*
+ * This kprobe pre_handler is registered with every kretprobe. When probe
+ * hits it will set up the return probe.
+ */
+static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
+{
+	struct kretprobe *rp = container_of(p, struct kretprobe, kp);
+	struct kretprobe_instance *ri;
+	struct freelist_node *fn;
+
+	fn = freelist_try_get(&rp->freelist);
+	if (!fn) {
+		rp->nmissed++;
+		return 0;
+	}
+
+	ri = container_of(fn, struct kretprobe_instance, freelist);
+
+	if (rp->entry_handler && rp->entry_handler(ri, regs)) {
+		freelist_add(&ri->freelist, &rp->freelist);
+		return 0;
+	}
+
+	arch_prepare_kretprobe(ri, regs);
+
+	__llist_add(&ri->llist, &current->kretprobe_instances);
+
+	return 0;
+}
+NOKPROBE_SYMBOL(pre_handler_kretprobe);
+#else /* CONFIG_KRETPROBE_ON_RETHOOK */
+/*
+ * This kprobe pre_handler is registered with every kretprobe. When probe
+ * hits it will set up the return probe.
+ */
+static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
+{
+	struct kretprobe *rp = container_of(p, struct kretprobe, kp);
+	struct kretprobe_instance *ri;
+	struct rethook_node *rhn;
+
+	rhn = rethook_try_get(rp->rh);
+	if (!rhn) {
+		rp->nmissed++;
+		return 0;
+	}
+
+	ri = container_of(rhn, struct kretprobe_instance, node);
+
+	if (rp->entry_handler && rp->entry_handler(ri, regs))
+		rethook_recycle(rhn);
+	else
+		rethook_hook(rhn, regs, kprobe_ftrace(p));
+
+	return 0;
+}
+NOKPROBE_SYMBOL(pre_handler_kretprobe);
+
+static void kretprobe_rethook_handler(struct rethook_node *rh, void *data,
+				      unsigned long ret_addr,
+				      struct pt_regs *regs)
+{
+	struct kretprobe *rp = (struct kretprobe *)data;
+	struct kretprobe_instance *ri;
+	struct kprobe_ctlblk *kcb;
+
+	/* The data must NOT be null. This means rethook data structure is broken. */
+	if (WARN_ON_ONCE(!data) || !rp->handler)
+		return;
+
+	__this_cpu_write(current_kprobe, &rp->kp);
+	kcb = get_kprobe_ctlblk();
+	kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+
+	ri = container_of(rh, struct kretprobe_instance, node);
+	rp->handler(ri, regs);
+
+	__this_cpu_write(current_kprobe, NULL);
+}
+NOKPROBE_SYMBOL(kretprobe_rethook_handler);
+
+#endif /* !CONFIG_KRETPROBE_ON_RETHOOK */
+
+/**
+ * kprobe_on_func_entry() -- check whether given address is function entry
+ * @addr: Target address
+ * @sym:  Target symbol name
+ * @offset: The offset from the symbol or the address
+ *
+ * This checks whether the given @addr+@offset or @sym+@offset is on the
+ * function entry address or not.
+ * This returns 0 if it is the function entry, or -EINVAL if it is not.
+ * And also it returns -ENOENT if it fails the symbol or address lookup.
+ * Caller must pass @addr or @sym (either one must be NULL), or this
+ * returns -EINVAL.
+ */
+int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset)
+{
+	bool on_func_entry;
+	kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset, &on_func_entry);
+
+	if (IS_ERR(kp_addr))
+		return PTR_ERR(kp_addr);
+
+	if (!on_func_entry)
+		return -EINVAL;
+
+	return 0;
+}
+
+int register_kretprobe(struct kretprobe *rp)
+{
+	int ret;
+	struct kretprobe_instance *inst;
+	int i;
+	void *addr;
+
+	ret = kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset);
+	if (ret)
+		return ret;
+
+	/* If only 'rp->kp.addr' is specified, check reregistering kprobes */
+	if (rp->kp.addr && warn_kprobe_rereg(&rp->kp))
+		return -EINVAL;
+
+	if (kretprobe_blacklist_size) {
+		addr = kprobe_addr(&rp->kp);
+		if (IS_ERR(addr))
+			return PTR_ERR(addr);
+
+		for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
+			if (kretprobe_blacklist[i].addr == addr)
+				return -EINVAL;
+		}
+	}
+
+	if (rp->data_size > KRETPROBE_MAX_DATA_SIZE)
+		return -E2BIG;
+
+	rp->kp.pre_handler = pre_handler_kretprobe;
+	rp->kp.post_handler = NULL;
+
+	/* Pre-allocate memory for max kretprobe instances */
+	if (rp->maxactive <= 0)
+		rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
+
+#ifdef CONFIG_KRETPROBE_ON_RETHOOK
+	rp->rh = rethook_alloc((void *)rp, kretprobe_rethook_handler);
+	if (!rp->rh)
+		return -ENOMEM;
+
+	for (i = 0; i < rp->maxactive; i++) {
+		inst = kzalloc(struct_size(inst, data, rp->data_size), GFP_KERNEL);
+		if (inst == NULL) {
+			rethook_free(rp->rh);
+			rp->rh = NULL;
+			return -ENOMEM;
+		}
+		rethook_add_node(rp->rh, &inst->node);
+	}
+	rp->nmissed = 0;
+	/* Establish function entry probe point */
+	ret = register_kprobe(&rp->kp);
+	if (ret != 0) {
+		rethook_free(rp->rh);
+		rp->rh = NULL;
+	}
+#else	/* !CONFIG_KRETPROBE_ON_RETHOOK */
+	rp->freelist.head = NULL;
+	rp->rph = kzalloc(sizeof(struct kretprobe_holder), GFP_KERNEL);
+	if (!rp->rph)
+		return -ENOMEM;
+
+	rcu_assign_pointer(rp->rph->rp, rp);
+	for (i = 0; i < rp->maxactive; i++) {
+		inst = kzalloc(struct_size(inst, data, rp->data_size), GFP_KERNEL);
+		if (inst == NULL) {
+			refcount_set(&rp->rph->ref, i);
+			free_rp_inst(rp);
+			return -ENOMEM;
+		}
+		inst->rph = rp->rph;
+		freelist_add(&inst->freelist, &rp->freelist);
+	}
+	refcount_set(&rp->rph->ref, i);
+
+	rp->nmissed = 0;
+	/* Establish function entry probe point */
+	ret = register_kprobe(&rp->kp);
+	if (ret != 0)
+		free_rp_inst(rp);
+#endif
+	return ret;
+}
+EXPORT_SYMBOL_GPL(register_kretprobe);
+
+int register_kretprobes(struct kretprobe **rps, int num)
+{
+	int ret = 0, i;
+
+	if (num <= 0)
+		return -EINVAL;
+	for (i = 0; i < num; i++) {
+		ret = register_kretprobe(rps[i]);
+		if (ret < 0) {
+			if (i > 0)
+				unregister_kretprobes(rps, i);
+			break;
+		}
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(register_kretprobes);
+
+void unregister_kretprobe(struct kretprobe *rp)
+{
+	unregister_kretprobes(&rp, 1);
+}
+EXPORT_SYMBOL_GPL(unregister_kretprobe);
+
+void unregister_kretprobes(struct kretprobe **rps, int num)
+{
+	int i;
+
+	if (num <= 0)
+		return;
+	mutex_lock(&kprobe_mutex);
+	for (i = 0; i < num; i++) {
+		if (__unregister_kprobe_top(&rps[i]->kp) < 0)
+			rps[i]->kp.addr = NULL;
+#ifdef CONFIG_KRETPROBE_ON_RETHOOK
+		rethook_free(rps[i]->rh);
+#else
+		rcu_assign_pointer(rps[i]->rph->rp, NULL);
+#endif
+	}
+	mutex_unlock(&kprobe_mutex);
+
+	synchronize_rcu();
+	for (i = 0; i < num; i++) {
+		if (rps[i]->kp.addr) {
+			__unregister_kprobe_bottom(&rps[i]->kp);
+#ifndef CONFIG_KRETPROBE_ON_RETHOOK
+			free_rp_inst(rps[i]);
+#endif
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(unregister_kretprobes);
+
+#else /* CONFIG_KRETPROBES */
+int register_kretprobe(struct kretprobe *rp)
+{
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(register_kretprobe);
+
+int register_kretprobes(struct kretprobe **rps, int num)
+{
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(register_kretprobes);
+
+void unregister_kretprobe(struct kretprobe *rp)
+{
+}
+EXPORT_SYMBOL_GPL(unregister_kretprobe);
+
+void unregister_kretprobes(struct kretprobe **rps, int num)
+{
+}
+EXPORT_SYMBOL_GPL(unregister_kretprobes);
+
+static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
+{
+	return 0;
+}
+NOKPROBE_SYMBOL(pre_handler_kretprobe);
+
+#endif /* CONFIG_KRETPROBES */
+
+/* Set the kprobe gone and remove its instruction buffer. */
+static void kill_kprobe(struct kprobe *p)
+{
+	struct kprobe *kp;
+
+	lockdep_assert_held(&kprobe_mutex);
+
+	/*
+	 * The module is going away. We should disarm the kprobe which
+	 * is using ftrace, because ftrace framework is still available at
+	 * 'MODULE_STATE_GOING' notification.
+	 */
+	if (kprobe_ftrace(p) && !kprobe_disabled(p) && !kprobes_all_disarmed)
+		disarm_kprobe_ftrace(p);
+
+	p->flags |= KPROBE_FLAG_GONE;
+	if (kprobe_aggrprobe(p)) {
+		/*
+		 * If this is an aggr_kprobe, we have to list all the
+		 * chained probes and mark them GONE.
+		 */
+		list_for_each_entry(kp, &p->list, list)
+			kp->flags |= KPROBE_FLAG_GONE;
+		p->post_handler = NULL;
+		kill_optimized_kprobe(p);
+	}
+	/*
+	 * Here, we can remove insn_slot safely, because no thread calls
+	 * the original probed function (which will be freed soon) any more.
+	 */
+	arch_remove_kprobe(p);
+}
+
+/* Disable one kprobe */
+int disable_kprobe(struct kprobe *kp)
+{
+	int ret = 0;
+	struct kprobe *p;
+
+	mutex_lock(&kprobe_mutex);
+
+	/* Disable this kprobe */
+	p = __disable_kprobe(kp);
+	if (IS_ERR(p))
+		ret = PTR_ERR(p);
+
+	mutex_unlock(&kprobe_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(disable_kprobe);
+
+/* Enable one kprobe */
+int enable_kprobe(struct kprobe *kp)
+{
+	int ret = 0;
+	struct kprobe *p;
+
+	mutex_lock(&kprobe_mutex);
+
+	/* Check whether specified probe is valid. */
+	p = __get_valid_kprobe(kp);
+	if (unlikely(p == NULL)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (kprobe_gone(kp)) {
+		/* This kprobe has gone, we couldn't enable it. */
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (p != kp)
+		kp->flags &= ~KPROBE_FLAG_DISABLED;
+
+	if (!kprobes_all_disarmed && kprobe_disabled(p)) {
+		p->flags &= ~KPROBE_FLAG_DISABLED;
+		ret = arm_kprobe(p);
+		if (ret) {
+			p->flags |= KPROBE_FLAG_DISABLED;
+			if (p != kp)
+				kp->flags |= KPROBE_FLAG_DISABLED;
+		}
+	}
+out:
+	mutex_unlock(&kprobe_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(enable_kprobe);
+
+/* Caller must NOT call this in usual path. This is only for critical case */
+void dump_kprobe(struct kprobe *kp)
+{
+	pr_err("Dump kprobe:\n.symbol_name = %s, .offset = %x, .addr = %pS\n",
+	       kp->symbol_name, kp->offset, kp->addr);
+}
+NOKPROBE_SYMBOL(dump_kprobe);
+
+int kprobe_add_ksym_blacklist(unsigned long entry)
+{
+	struct kprobe_blacklist_entry *ent;
+	unsigned long offset = 0, size = 0;
+
+	if (!kernel_text_address(entry) ||
+	    !kallsyms_lookup_size_offset(entry, &size, &offset))
+		return -EINVAL;
+
+	ent = kmalloc(sizeof(*ent), GFP_KERNEL);
+	if (!ent)
+		return -ENOMEM;
+	ent->start_addr = entry;
+	ent->end_addr = entry + size;
+	INIT_LIST_HEAD(&ent->list);
+	list_add_tail(&ent->list, &kprobe_blacklist);
+
+	return (int)size;
+}
+
+/* Add all symbols in given area into kprobe blacklist */
+int kprobe_add_area_blacklist(unsigned long start, unsigned long end)
+{
+	unsigned long entry;
+	int ret = 0;
+
+	for (entry = start; entry < end; entry += ret) {
+		ret = kprobe_add_ksym_blacklist(entry);
+		if (ret < 0)
+			return ret;
+		if (ret == 0)	/* In case of alias symbol */
+			ret = 1;
+	}
+	return 0;
+}
+
+/* Remove all symbols in given area from kprobe blacklist */
+static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
+{
+	struct kprobe_blacklist_entry *ent, *n;
+
+	list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) {
+		if (ent->start_addr < start || ent->start_addr >= end)
+			continue;
+		list_del(&ent->list);
+		kfree(ent);
+	}
+}
+
+static void kprobe_remove_ksym_blacklist(unsigned long entry)
+{
+	kprobe_remove_area_blacklist(entry, entry + 1);
+}
+
+int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
+				   char *type, char *sym)
+{
+	return -ERANGE;
+}
+
+int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
+		       char *sym)
+{
+#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
+	if (!kprobe_cache_get_kallsym(&kprobe_insn_slots, &symnum, value, type, sym))
+		return 0;
+#ifdef CONFIG_OPTPROBES
+	if (!kprobe_cache_get_kallsym(&kprobe_optinsn_slots, &symnum, value, type, sym))
+		return 0;
+#endif
+#endif
+	if (!arch_kprobe_get_kallsym(&symnum, value, type, sym))
+		return 0;
+	return -ERANGE;
+}
+
+int __init __weak arch_populate_kprobe_blacklist(void)
+{
+	return 0;
+}
+
+/*
+ * Lookup and populate the kprobe_blacklist.
+ *
+ * Unlike the kretprobe blacklist, we'll need to determine
+ * the range of addresses that belong to the said functions,
+ * since a kprobe need not necessarily be at the beginning
+ * of a function.
+ */
+static int __init populate_kprobe_blacklist(unsigned long *start,
+					     unsigned long *end)
+{
+	unsigned long entry;
+	unsigned long *iter;
+	int ret;
+
+	for (iter = start; iter < end; iter++) {
+		entry = (unsigned long)dereference_symbol_descriptor((void *)*iter);
+		ret = kprobe_add_ksym_blacklist(entry);
+		if (ret == -EINVAL)
+			continue;
+		if (ret < 0)
+			return ret;
+	}
+
+	/* Symbols in '__kprobes_text' are blacklisted */
+	ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start,
+					(unsigned long)__kprobes_text_end);
+	if (ret)
+		return ret;
+
+	/* Symbols in 'noinstr' section are blacklisted */
+	ret = kprobe_add_area_blacklist((unsigned long)__noinstr_text_start,
+					(unsigned long)__noinstr_text_end);
+
+	return ret ? : arch_populate_kprobe_blacklist();
+}
+
+static void add_module_kprobe_blacklist(struct module *mod)
+{
+	unsigned long start, end;
+	int i;
+
+	if (mod->kprobe_blacklist) {
+		for (i = 0; i < mod->num_kprobe_blacklist; i++)
+			kprobe_add_ksym_blacklist(mod->kprobe_blacklist[i]);
+	}
+
+	start = (unsigned long)mod->kprobes_text_start;
+	if (start) {
+		end = start + mod->kprobes_text_size;
+		kprobe_add_area_blacklist(start, end);
+	}
+
+	start = (unsigned long)mod->noinstr_text_start;
+	if (start) {
+		end = start + mod->noinstr_text_size;
+		kprobe_add_area_blacklist(start, end);
+	}
+}
+
+static void remove_module_kprobe_blacklist(struct module *mod)
+{
+	unsigned long start, end;
+	int i;
+
+	if (mod->kprobe_blacklist) {
+		for (i = 0; i < mod->num_kprobe_blacklist; i++)
+			kprobe_remove_ksym_blacklist(mod->kprobe_blacklist[i]);
+	}
+
+	start = (unsigned long)mod->kprobes_text_start;
+	if (start) {
+		end = start + mod->kprobes_text_size;
+		kprobe_remove_area_blacklist(start, end);
+	}
+
+	start = (unsigned long)mod->noinstr_text_start;
+	if (start) {
+		end = start + mod->noinstr_text_size;
+		kprobe_remove_area_blacklist(start, end);
+	}
+}
+
+/* Module notifier call back, checking kprobes on the module */
+static int kprobes_module_callback(struct notifier_block *nb,
+				   unsigned long val, void *data)
+{
+	struct module *mod = data;
+	struct hlist_head *head;
+	struct kprobe *p;
+	unsigned int i;
+	int checkcore = (val == MODULE_STATE_GOING);
+
+	if (val == MODULE_STATE_COMING) {
+		mutex_lock(&kprobe_mutex);
+		add_module_kprobe_blacklist(mod);
+		mutex_unlock(&kprobe_mutex);
+	}
+	if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
+		return NOTIFY_DONE;
+
+	/*
+	 * When 'MODULE_STATE_GOING' was notified, both of module '.text' and
+	 * '.init.text' sections would be freed. When 'MODULE_STATE_LIVE' was
+	 * notified, only '.init.text' section would be freed. We need to
+	 * disable kprobes which have been inserted in the sections.
+	 */
+	mutex_lock(&kprobe_mutex);
+	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
+		head = &kprobe_table[i];
+		hlist_for_each_entry(p, head, hlist)
+			if (within_module_init((unsigned long)p->addr, mod) ||
+			    (checkcore &&
+			     within_module_core((unsigned long)p->addr, mod))) {
+				/*
+				 * The vaddr this probe is installed will soon
+				 * be vfreed buy not synced to disk. Hence,
+				 * disarming the breakpoint isn't needed.
+				 *
+				 * Note, this will also move any optimized probes
+				 * that are pending to be removed from their
+				 * corresponding lists to the 'freeing_list' and
+				 * will not be touched by the delayed
+				 * kprobe_optimizer() work handler.
+				 */
+				kill_kprobe(p);
+			}
+	}
+	if (val == MODULE_STATE_GOING)
+		remove_module_kprobe_blacklist(mod);
+	mutex_unlock(&kprobe_mutex);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block kprobe_module_nb = {
+	.notifier_call = kprobes_module_callback,
+	.priority = 0
+};
+
+void kprobe_free_init_mem(void)
+{
+	void *start = (void *)(&__init_begin);
+	void *end = (void *)(&__init_end);
+	struct hlist_head *head;
+	struct kprobe *p;
+	int i;
+
+	mutex_lock(&kprobe_mutex);
+
+	/* Kill all kprobes on initmem because the target code has been freed. */
+	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
+		head = &kprobe_table[i];
+		hlist_for_each_entry(p, head, hlist) {
+			if (start <= (void *)p->addr && (void *)p->addr < end)
+				kill_kprobe(p);
+		}
+	}
+
+	mutex_unlock(&kprobe_mutex);
+}
+
+static int __init init_kprobes(void)
+{
+	int i, err;
+
+	/* FIXME allocate the probe table, currently defined statically */
+	/* initialize all list heads */
+	for (i = 0; i < KPROBE_TABLE_SIZE; i++)
+		INIT_HLIST_HEAD(&kprobe_table[i]);
+
+	err = populate_kprobe_blacklist(__start_kprobe_blacklist,
+					__stop_kprobe_blacklist);
+	if (err)
+		pr_err("Failed to populate blacklist (error %d), kprobes not restricted, be careful using them!\n", err);
+
+	if (kretprobe_blacklist_size) {
+		/* lookup the function address from its name */
+		for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
+			kretprobe_blacklist[i].addr =
+				kprobe_lookup_name(kretprobe_blacklist[i].name, 0);
+			if (!kretprobe_blacklist[i].addr)
+				pr_err("Failed to lookup symbol '%s' for kretprobe blacklist. Maybe the target function is removed or renamed.\n",
+				       kretprobe_blacklist[i].name);
+		}
+	}
+
+	/* By default, kprobes are armed */
+	kprobes_all_disarmed = false;
+
+#if defined(CONFIG_OPTPROBES) && defined(__ARCH_WANT_KPROBES_INSN_SLOT)
+	/* Init 'kprobe_optinsn_slots' for allocation */
+	kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
+#endif
+
+	err = arch_init_kprobes();
+	if (!err)
+		err = register_die_notifier(&kprobe_exceptions_nb);
+	if (!err)
+		err = register_module_notifier(&kprobe_module_nb);
+
+	kprobes_initialized = (err == 0);
+	kprobe_sysctls_init();
+	return err;
+}
+early_initcall(init_kprobes);
+
+#if defined(CONFIG_OPTPROBES)
+static int __init init_optprobes(void)
+{
+	/*
+	 * Enable kprobe optimization - this kicks the optimizer which
+	 * depends on synchronize_rcu_tasks() and ksoftirqd, that is
+	 * not spawned in early initcall. So delay the optimization.
+	 */
+	optimize_all_kprobes();
+
+	return 0;
+}
+subsys_initcall(init_optprobes);
+#endif
+
+#ifdef CONFIG_DEBUG_FS
+static void report_probe(struct seq_file *pi, struct kprobe *p,
+		const char *sym, int offset, char *modname, struct kprobe *pp)
+{
+	char *kprobe_type;
+	void *addr = p->addr;
+
+	if (p->pre_handler == pre_handler_kretprobe)
+		kprobe_type = "r";
+	else
+		kprobe_type = "k";
+
+	if (!kallsyms_show_value(pi->file->f_cred))
+		addr = NULL;
+
+	if (sym)
+		seq_printf(pi, "%px  %s  %s+0x%x  %s ",
+			addr, kprobe_type, sym, offset,
+			(modname ? modname : " "));
+	else	/* try to use %pS */
+		seq_printf(pi, "%px  %s  %pS ",
+			addr, kprobe_type, p->addr);
+
+	if (!pp)
+		pp = p;
+	seq_printf(pi, "%s%s%s%s\n",
+		(kprobe_gone(p) ? "[GONE]" : ""),
+		((kprobe_disabled(p) && !kprobe_gone(p)) ?  "[DISABLED]" : ""),
+		(kprobe_optimized(pp) ? "[OPTIMIZED]" : ""),
+		(kprobe_ftrace(pp) ? "[FTRACE]" : ""));
+}
+
+static void *kprobe_seq_start(struct seq_file *f, loff_t *pos)
+{
+	return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
+}
+
+static void *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
+{
+	(*pos)++;
+	if (*pos >= KPROBE_TABLE_SIZE)
+		return NULL;
+	return pos;
+}
+
+static void kprobe_seq_stop(struct seq_file *f, void *v)
+{
+	/* Nothing to do */
+}
+
+static int show_kprobe_addr(struct seq_file *pi, void *v)
+{
+	struct hlist_head *head;
+	struct kprobe *p, *kp;
+	const char *sym = NULL;
+	unsigned int i = *(loff_t *) v;
+	unsigned long offset = 0;
+	char *modname, namebuf[KSYM_NAME_LEN];
+
+	head = &kprobe_table[i];
+	preempt_disable();
+	hlist_for_each_entry_rcu(p, head, hlist) {
+		sym = kallsyms_lookup((unsigned long)p->addr, NULL,
+					&offset, &modname, namebuf);
+		if (kprobe_aggrprobe(p)) {
+			list_for_each_entry_rcu(kp, &p->list, list)
+				report_probe(pi, kp, sym, offset, modname, p);
+		} else
+			report_probe(pi, p, sym, offset, modname, NULL);
+	}
+	preempt_enable();
+	return 0;
+}
+
+static const struct seq_operations kprobes_sops = {
+	.start = kprobe_seq_start,
+	.next  = kprobe_seq_next,
+	.stop  = kprobe_seq_stop,
+	.show  = show_kprobe_addr
+};
+
+DEFINE_SEQ_ATTRIBUTE(kprobes);
+
+/* kprobes/blacklist -- shows which functions can not be probed */
+static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
+{
+	mutex_lock(&kprobe_mutex);
+	return seq_list_start(&kprobe_blacklist, *pos);
+}
+
+static void *kprobe_blacklist_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	return seq_list_next(v, &kprobe_blacklist, pos);
+}
+
+static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
+{
+	struct kprobe_blacklist_entry *ent =
+		list_entry(v, struct kprobe_blacklist_entry, list);
+
+	/*
+	 * If '/proc/kallsyms' is not showing kernel address, we won't
+	 * show them here either.
+	 */
+	if (!kallsyms_show_value(m->file->f_cred))
+		seq_printf(m, "0x%px-0x%px\t%ps\n", NULL, NULL,
+			   (void *)ent->start_addr);
+	else
+		seq_printf(m, "0x%px-0x%px\t%ps\n", (void *)ent->start_addr,
+			   (void *)ent->end_addr, (void *)ent->start_addr);
+	return 0;
+}
+
+static void kprobe_blacklist_seq_stop(struct seq_file *f, void *v)
+{
+	mutex_unlock(&kprobe_mutex);
+}
+
+static const struct seq_operations kprobe_blacklist_sops = {
+	.start = kprobe_blacklist_seq_start,
+	.next  = kprobe_blacklist_seq_next,
+	.stop  = kprobe_blacklist_seq_stop,
+	.show  = kprobe_blacklist_seq_show,
+};
+DEFINE_SEQ_ATTRIBUTE(kprobe_blacklist);
+
+static int arm_all_kprobes(void)
+{
+	struct hlist_head *head;
+	struct kprobe *p;
+	unsigned int i, total = 0, errors = 0;
+	int err, ret = 0;
+
+	mutex_lock(&kprobe_mutex);
+
+	/* If kprobes are armed, just return */
+	if (!kprobes_all_disarmed)
+		goto already_enabled;
+
+	/*
+	 * optimize_kprobe() called by arm_kprobe() checks
+	 * kprobes_all_disarmed, so set kprobes_all_disarmed before
+	 * arm_kprobe.
+	 */
+	kprobes_all_disarmed = false;
+	/* Arming kprobes doesn't optimize kprobe itself */
+	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
+		head = &kprobe_table[i];
+		/* Arm all kprobes on a best-effort basis */
+		hlist_for_each_entry(p, head, hlist) {
+			if (!kprobe_disabled(p)) {
+				err = arm_kprobe(p);
+				if (err)  {
+					errors++;
+					ret = err;
+				}
+				total++;
+			}
+		}
+	}
+
+	if (errors)
+		pr_warn("Kprobes globally enabled, but failed to enable %d out of %d probes. Please check which kprobes are kept disabled via debugfs.\n",
+			errors, total);
+	else
+		pr_info("Kprobes globally enabled\n");
+
+already_enabled:
+	mutex_unlock(&kprobe_mutex);
+	return ret;
+}
+
+static int disarm_all_kprobes(void)
+{
+	struct hlist_head *head;
+	struct kprobe *p;
+	unsigned int i, total = 0, errors = 0;
+	int err, ret = 0;
+
+	mutex_lock(&kprobe_mutex);
+
+	/* If kprobes are already disarmed, just return */
+	if (kprobes_all_disarmed) {
+		mutex_unlock(&kprobe_mutex);
+		return 0;
+	}
+
+	kprobes_all_disarmed = true;
+
+	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
+		head = &kprobe_table[i];
+		/* Disarm all kprobes on a best-effort basis */
+		hlist_for_each_entry(p, head, hlist) {
+			if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p)) {
+				err = disarm_kprobe(p, false);
+				if (err) {
+					errors++;
+					ret = err;
+				}
+				total++;
+			}
+		}
+	}
+
+	if (errors)
+		pr_warn("Kprobes globally disabled, but failed to disable %d out of %d probes. Please check which kprobes are kept enabled via debugfs.\n",
+			errors, total);
+	else
+		pr_info("Kprobes globally disabled\n");
+
+	mutex_unlock(&kprobe_mutex);
+
+	/* Wait for disarming all kprobes by optimizer */
+	wait_for_kprobe_optimizer();
+
+	return ret;
+}
+
+/*
+ * XXX: The debugfs bool file interface doesn't allow for callbacks
+ * when the bool state is switched. We can reuse that facility when
+ * available
+ */
+static ssize_t read_enabled_file_bool(struct file *file,
+	       char __user *user_buf, size_t count, loff_t *ppos)
+{
+	char buf[3];
+
+	if (!kprobes_all_disarmed)
+		buf[0] = '1';
+	else
+		buf[0] = '0';
+	buf[1] = '\n';
+	buf[2] = 0x00;
+	return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
+}
+
+static ssize_t write_enabled_file_bool(struct file *file,
+	       const char __user *user_buf, size_t count, loff_t *ppos)
+{
+	bool enable;
+	int ret;
+
+	ret = kstrtobool_from_user(user_buf, count, &enable);
+	if (ret)
+		return ret;
+
+	ret = enable ? arm_all_kprobes() : disarm_all_kprobes();
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static const struct file_operations fops_kp = {
+	.read =         read_enabled_file_bool,
+	.write =        write_enabled_file_bool,
+	.llseek =	default_llseek,
+};
+
+static int __init debugfs_kprobe_init(void)
+{
+	struct dentry *dir;
+
+	dir = debugfs_create_dir("kprobes", NULL);
+
+	debugfs_create_file("list", 0400, dir, NULL, &kprobes_fops);
+
+	debugfs_create_file("enabled", 0600, dir, NULL, &fops_kp);
+
+	debugfs_create_file("blacklist", 0400, dir, NULL,
+			    &kprobe_blacklist_fops);
+
+	return 0;
+}
+
+late_initcall(debugfs_kprobe_init);
+#endif /* CONFIG_DEBUG_FS */