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3037 lines
74 KiB
3037 lines
74 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Kernel Probes (KProbes) |
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* |
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* Copyright (C) IBM Corporation, 2002, 2004 |
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* |
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* 2002-Oct Created by Vamsi Krishna S <[email protected]> Kernel |
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* Probes initial implementation (includes suggestions from |
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* Rusty Russell). |
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* 2004-Aug Updated by Prasanna S Panchamukhi <[email protected]> with |
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* hlists and exceptions notifier as suggested by Andi Kleen. |
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* 2004-July Suparna Bhattacharya <[email protected]> added jumper probes |
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* interface to access function arguments. |
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* 2004-Sep Prasanna S Panchamukhi <[email protected]> Changed Kprobes |
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* exceptions notifier to be first on the priority list. |
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* 2005-May Hien Nguyen <[email protected]>, Jim Keniston |
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* <[email protected]> and Prasanna S Panchamukhi |
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* <[email protected]> added function-return probes. |
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*/ |
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|
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#define pr_fmt(fmt) "kprobes: " fmt |
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|
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#include <linux/kprobes.h> |
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#include <linux/hash.h> |
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#include <linux/init.h> |
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#include <linux/slab.h> |
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#include <linux/stddef.h> |
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#include <linux/export.h> |
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#include <linux/moduleloader.h> |
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#include <linux/kallsyms.h> |
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#include <linux/freezer.h> |
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#include <linux/seq_file.h> |
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#include <linux/debugfs.h> |
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#include <linux/sysctl.h> |
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#include <linux/kdebug.h> |
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#include <linux/memory.h> |
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#include <linux/ftrace.h> |
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#include <linux/cpu.h> |
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#include <linux/jump_label.h> |
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#include <linux/static_call.h> |
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#include <linux/perf_event.h> |
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|
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#include <asm/sections.h> |
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#include <asm/cacheflush.h> |
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#include <asm/errno.h> |
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#include <linux/uaccess.h> |
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|
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#define KPROBE_HASH_BITS 6 |
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#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) |
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|
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#if !defined(CONFIG_OPTPROBES) || !defined(CONFIG_SYSCTL) |
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#define kprobe_sysctls_init() do { } while (0) |
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#endif |
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|
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static int kprobes_initialized; |
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/* kprobe_table can be accessed by |
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* - Normal hlist traversal and RCU add/del under 'kprobe_mutex' is held. |
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* Or |
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* - RCU hlist traversal under disabling preempt (breakpoint handlers) |
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*/ |
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static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; |
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|
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/* NOTE: change this value only with 'kprobe_mutex' held */ |
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static bool kprobes_all_disarmed; |
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|
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/* This protects 'kprobe_table' and 'optimizing_list' */ |
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static DEFINE_MUTEX(kprobe_mutex); |
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static DEFINE_PER_CPU(struct kprobe *, kprobe_instance); |
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|
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kprobe_opcode_t * __weak kprobe_lookup_name(const char *name, |
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unsigned int __unused) |
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{ |
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return ((kprobe_opcode_t *)(kallsyms_lookup_name(name))); |
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} |
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|
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/* |
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* Blacklist -- list of 'struct kprobe_blacklist_entry' to store info where |
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* kprobes can not probe. |
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*/ |
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static LIST_HEAD(kprobe_blacklist); |
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|
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#ifdef __ARCH_WANT_KPROBES_INSN_SLOT |
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/* |
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* 'kprobe::ainsn.insn' points to the copy of the instruction to be |
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* single-stepped. x86_64, POWER4 and above have no-exec support and |
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* stepping on the instruction on a vmalloced/kmalloced/data page |
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* is a recipe for disaster |
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*/ |
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struct kprobe_insn_page { |
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struct list_head list; |
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kprobe_opcode_t *insns; /* Page of instruction slots */ |
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struct kprobe_insn_cache *cache; |
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int nused; |
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int ngarbage; |
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char slot_used[]; |
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}; |
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|
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#define KPROBE_INSN_PAGE_SIZE(slots) \ |
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(offsetof(struct kprobe_insn_page, slot_used) + \ |
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(sizeof(char) * (slots))) |
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|
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static int slots_per_page(struct kprobe_insn_cache *c) |
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{ |
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return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t)); |
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} |
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|
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enum kprobe_slot_state { |
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SLOT_CLEAN = 0, |
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SLOT_DIRTY = 1, |
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SLOT_USED = 2, |
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}; |
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|
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void __weak *alloc_insn_page(void) |
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{ |
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/* |
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* Use module_alloc() so this page is within +/- 2GB of where the |
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* kernel image and loaded module images reside. This is required |
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* for most of the architectures. |
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* (e.g. x86-64 needs this to handle the %rip-relative fixups.) |
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*/ |
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return module_alloc(PAGE_SIZE); |
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} |
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|
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static void free_insn_page(void *page) |
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{ |
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module_memfree(page); |
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} |
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|
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struct kprobe_insn_cache kprobe_insn_slots = { |
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.mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex), |
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.alloc = alloc_insn_page, |
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.free = free_insn_page, |
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.sym = KPROBE_INSN_PAGE_SYM, |
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.pages = LIST_HEAD_INIT(kprobe_insn_slots.pages), |
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.insn_size = MAX_INSN_SIZE, |
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.nr_garbage = 0, |
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}; |
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static int collect_garbage_slots(struct kprobe_insn_cache *c); |
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|
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/** |
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* __get_insn_slot() - Find a slot on an executable page for an instruction. |
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* We allocate an executable page if there's no room on existing ones. |
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*/ |
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kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c) |
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{ |
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struct kprobe_insn_page *kip; |
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kprobe_opcode_t *slot = NULL; |
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|
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/* Since the slot array is not protected by rcu, we need a mutex */ |
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mutex_lock(&c->mutex); |
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retry: |
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rcu_read_lock(); |
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list_for_each_entry_rcu(kip, &c->pages, list) { |
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if (kip->nused < slots_per_page(c)) { |
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int i; |
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|
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for (i = 0; i < slots_per_page(c); i++) { |
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if (kip->slot_used[i] == SLOT_CLEAN) { |
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kip->slot_used[i] = SLOT_USED; |
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kip->nused++; |
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slot = kip->insns + (i * c->insn_size); |
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rcu_read_unlock(); |
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goto out; |
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} |
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} |
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/* kip->nused is broken. Fix it. */ |
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kip->nused = slots_per_page(c); |
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WARN_ON(1); |
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} |
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} |
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rcu_read_unlock(); |
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|
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/* If there are any garbage slots, collect it and try again. */ |
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if (c->nr_garbage && collect_garbage_slots(c) == 0) |
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goto retry; |
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|
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/* All out of space. Need to allocate a new page. */ |
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kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL); |
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if (!kip) |
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goto out; |
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|
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kip->insns = c->alloc(); |
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if (!kip->insns) { |
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kfree(kip); |
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goto out; |
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} |
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INIT_LIST_HEAD(&kip->list); |
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memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c)); |
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kip->slot_used[0] = SLOT_USED; |
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kip->nused = 1; |
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kip->ngarbage = 0; |
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kip->cache = c; |
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list_add_rcu(&kip->list, &c->pages); |
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slot = kip->insns; |
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|
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/* Record the perf ksymbol register event after adding the page */ |
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perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL, (unsigned long)kip->insns, |
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PAGE_SIZE, false, c->sym); |
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out: |
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mutex_unlock(&c->mutex); |
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return slot; |
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} |
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|
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/* Return true if all garbages are collected, otherwise false. */ |
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static bool collect_one_slot(struct kprobe_insn_page *kip, int idx) |
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{ |
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kip->slot_used[idx] = SLOT_CLEAN; |
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kip->nused--; |
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if (kip->nused == 0) { |
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/* |
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* Page is no longer in use. Free it unless |
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* it's the last one. We keep the last one |
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* so as not to have to set it up again the |
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* next time somebody inserts a probe. |
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*/ |
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if (!list_is_singular(&kip->list)) { |
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/* |
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* Record perf ksymbol unregister event before removing |
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* the page. |
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*/ |
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perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL, |
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(unsigned long)kip->insns, PAGE_SIZE, true, |
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kip->cache->sym); |
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list_del_rcu(&kip->list); |
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synchronize_rcu(); |
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kip->cache->free(kip->insns); |
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kfree(kip); |
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} |
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return true; |
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} |
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return false; |
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} |
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|
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static int collect_garbage_slots(struct kprobe_insn_cache *c) |
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{ |
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struct kprobe_insn_page *kip, *next; |
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|
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/* Ensure no-one is interrupted on the garbages */ |
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synchronize_rcu(); |
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|
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list_for_each_entry_safe(kip, next, &c->pages, list) { |
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int i; |
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|
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if (kip->ngarbage == 0) |
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continue; |
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kip->ngarbage = 0; /* we will collect all garbages */ |
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for (i = 0; i < slots_per_page(c); i++) { |
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if (kip->slot_used[i] == SLOT_DIRTY && collect_one_slot(kip, i)) |
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break; |
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} |
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} |
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c->nr_garbage = 0; |
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return 0; |
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} |
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|
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void __free_insn_slot(struct kprobe_insn_cache *c, |
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kprobe_opcode_t *slot, int dirty) |
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{ |
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struct kprobe_insn_page *kip; |
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long idx; |
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|
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mutex_lock(&c->mutex); |
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rcu_read_lock(); |
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list_for_each_entry_rcu(kip, &c->pages, list) { |
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idx = ((long)slot - (long)kip->insns) / |
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(c->insn_size * sizeof(kprobe_opcode_t)); |
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if (idx >= 0 && idx < slots_per_page(c)) |
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goto out; |
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} |
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/* Could not find this slot. */ |
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WARN_ON(1); |
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kip = NULL; |
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out: |
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rcu_read_unlock(); |
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/* Mark and sweep: this may sleep */ |
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if (kip) { |
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/* Check double free */ |
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WARN_ON(kip->slot_used[idx] != SLOT_USED); |
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if (dirty) { |
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kip->slot_used[idx] = SLOT_DIRTY; |
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kip->ngarbage++; |
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if (++c->nr_garbage > slots_per_page(c)) |
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collect_garbage_slots(c); |
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} else { |
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collect_one_slot(kip, idx); |
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} |
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} |
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mutex_unlock(&c->mutex); |
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} |
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|
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/* |
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* Check given address is on the page of kprobe instruction slots. |
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* This will be used for checking whether the address on a stack |
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* is on a text area or not. |
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*/ |
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bool __is_insn_slot_addr(struct kprobe_insn_cache *c, unsigned long addr) |
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{ |
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struct kprobe_insn_page *kip; |
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bool ret = false; |
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|
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rcu_read_lock(); |
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list_for_each_entry_rcu(kip, &c->pages, list) { |
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if (addr >= (unsigned long)kip->insns && |
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addr < (unsigned long)kip->insns + PAGE_SIZE) { |
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ret = true; |
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break; |
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} |
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} |
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rcu_read_unlock(); |
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|
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return ret; |
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} |
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int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum, |
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unsigned long *value, char *type, char *sym) |
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{ |
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struct kprobe_insn_page *kip; |
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int ret = -ERANGE; |
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|
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rcu_read_lock(); |
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list_for_each_entry_rcu(kip, &c->pages, list) { |
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if ((*symnum)--) |
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continue; |
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strscpy(sym, c->sym, KSYM_NAME_LEN); |
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*type = 't'; |
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*value = (unsigned long)kip->insns; |
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ret = 0; |
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break; |
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} |
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rcu_read_unlock(); |
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|
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return ret; |
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} |
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#ifdef CONFIG_OPTPROBES |
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void __weak *alloc_optinsn_page(void) |
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{ |
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return alloc_insn_page(); |
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} |
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|
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void __weak free_optinsn_page(void *page) |
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{ |
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free_insn_page(page); |
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} |
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|
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/* For optimized_kprobe buffer */ |
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struct kprobe_insn_cache kprobe_optinsn_slots = { |
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.mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex), |
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.alloc = alloc_optinsn_page, |
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.free = free_optinsn_page, |
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.sym = KPROBE_OPTINSN_PAGE_SYM, |
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.pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages), |
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/* .insn_size is initialized later */ |
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.nr_garbage = 0, |
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}; |
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#endif |
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#endif |
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|
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/* We have preemption disabled.. so it is safe to use __ versions */ |
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static inline void set_kprobe_instance(struct kprobe *kp) |
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{ |
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__this_cpu_write(kprobe_instance, kp); |
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} |
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|
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static inline void reset_kprobe_instance(void) |
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{ |
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__this_cpu_write(kprobe_instance, NULL); |
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} |
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|
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/* |
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* This routine is called either: |
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* - under the 'kprobe_mutex' - during kprobe_[un]register(). |
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* OR |
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* - with preemption disabled - from architecture specific code. |
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*/ |
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struct kprobe *get_kprobe(void *addr) |
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{ |
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struct hlist_head *head; |
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struct kprobe *p; |
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|
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head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; |
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hlist_for_each_entry_rcu(p, head, hlist, |
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lockdep_is_held(&kprobe_mutex)) { |
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if (p->addr == addr) |
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return p; |
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} |
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|
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return NULL; |
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} |
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NOKPROBE_SYMBOL(get_kprobe); |
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|
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static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs); |
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|
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/* Return true if 'p' is an aggregator */ |
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static inline bool kprobe_aggrprobe(struct kprobe *p) |
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{ |
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return p->pre_handler == aggr_pre_handler; |
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} |
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|
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/* Return true if 'p' is unused */ |
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static inline bool kprobe_unused(struct kprobe *p) |
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{ |
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return kprobe_aggrprobe(p) && kprobe_disabled(p) && |
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list_empty(&p->list); |
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} |
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|
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/* Keep all fields in the kprobe consistent. */ |
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static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p) |
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{ |
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memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t)); |
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memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn)); |
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} |
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|
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#ifdef CONFIG_OPTPROBES |
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/* NOTE: This is protected by 'kprobe_mutex'. */ |
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static bool kprobes_allow_optimization; |
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|
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/* |
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* Call all 'kprobe::pre_handler' on the list, but ignores its return value. |
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* This must be called from arch-dep optimized caller. |
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*/ |
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void opt_pre_handler(struct kprobe *p, struct pt_regs *regs) |
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{ |
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struct kprobe *kp; |
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|
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list_for_each_entry_rcu(kp, &p->list, list) { |
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if (kp->pre_handler && likely(!kprobe_disabled(kp))) { |
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set_kprobe_instance(kp); |
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kp->pre_handler(kp, regs); |
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} |
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reset_kprobe_instance(); |
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} |
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} |
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NOKPROBE_SYMBOL(opt_pre_handler); |
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|
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/* Free optimized instructions and optimized_kprobe */ |
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static void free_aggr_kprobe(struct kprobe *p) |
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{ |
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struct optimized_kprobe *op; |
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|
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op = container_of(p, struct optimized_kprobe, kp); |
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arch_remove_optimized_kprobe(op); |
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arch_remove_kprobe(p); |
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kfree(op); |
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} |
|
|
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/* Return true if the kprobe is ready for optimization. */ |
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static inline int kprobe_optready(struct kprobe *p) |
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{ |
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struct optimized_kprobe *op; |
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|
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if (kprobe_aggrprobe(p)) { |
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op = container_of(p, struct optimized_kprobe, kp); |
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return arch_prepared_optinsn(&op->optinsn); |
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} |
|
|
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return 0; |
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} |
|
|
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/* Return true if the kprobe is disarmed. Note: p must be on hash list */ |
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static inline bool kprobe_disarmed(struct kprobe *p) |
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{ |
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struct optimized_kprobe *op; |
|
|
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/* If kprobe is not aggr/opt probe, just return kprobe is disabled */ |
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if (!kprobe_aggrprobe(p)) |
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return kprobe_disabled(p); |
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|
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op = container_of(p, struct optimized_kprobe, kp); |
|
|
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return kprobe_disabled(p) && list_empty(&op->list); |
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} |
|
|
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/* Return true if the probe is queued on (un)optimizing lists */ |
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static bool kprobe_queued(struct kprobe *p) |
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{ |
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struct optimized_kprobe *op; |
|
|
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if (kprobe_aggrprobe(p)) { |
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op = container_of(p, struct optimized_kprobe, kp); |
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if (!list_empty(&op->list)) |
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return true; |
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} |
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return false; |
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} |
|
|
|
/* |
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* Return an optimized kprobe whose optimizing code replaces |
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* instructions including 'addr' (exclude breakpoint). |
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*/ |
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static struct kprobe *get_optimized_kprobe(kprobe_opcode_t *addr) |
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{ |
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int i; |
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struct kprobe *p = NULL; |
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struct optimized_kprobe *op; |
|
|
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/* Don't check i == 0, since that is a breakpoint case. */ |
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for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH / sizeof(kprobe_opcode_t); i++) |
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p = get_kprobe(addr - i); |
|
|
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if (p && kprobe_optready(p)) { |
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op = container_of(p, struct optimized_kprobe, kp); |
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if (arch_within_optimized_kprobe(op, addr)) |
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return p; |
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} |
|
|
|
return NULL; |
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} |
|
|
|
/* Optimization staging list, protected by 'kprobe_mutex' */ |
|
static LIST_HEAD(optimizing_list); |
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static LIST_HEAD(unoptimizing_list); |
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static LIST_HEAD(freeing_list); |
|
|
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static void kprobe_optimizer(struct work_struct *work); |
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static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer); |
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#define OPTIMIZE_DELAY 5 |
|
|
|
/* |
|
* Optimize (replace a breakpoint with a jump) kprobes listed on |
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* '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. |
|
*/ |
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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(); |
|
|
|
/* Unoptimization must be done anytime */ |
|
if (list_empty(&unoptimizing_list)) |
|
return; |
|
|
|
arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list); |
|
/* Loop on 'freeing_list' for disarming */ |
|
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 */ |
|
if (kprobe_disabled(&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); |
|
} |
|
|
|
static 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)) { |
|
/* Enqueue if it is unused */ |
|
list_add(&op->list, &freeing_list); |
|
/* |
|
* Remove unused probes from the hash list. After waiting |
|
* for synchronization, this probe is reclaimed. |
|
* (reclaiming is done by do_free_cleaned_kprobes().) |
|
*/ |
|
hlist_del_rcu(&op->kp.hlist); |
|
} |
|
|
|
/* 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 = 0; |
|
|
|
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 = 0; |
|
|
|
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 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)) { |
|
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) |
|
{ |
|
kprobe_opcode_t *correct_ret_addr = NULL; |
|
struct kretprobe_instance *ri = NULL; |
|
struct llist_node *first, *node = NULL; |
|
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, ¤t->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, |
|
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) { |
|
#ifdef CONFIG_PREEMPTION |
|
rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus()); |
|
#else |
|
rp->maxactive = num_possible_cpus(); |
|
#endif |
|
} |
|
#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(sizeof(struct kretprobe_instance) + |
|
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; |
|
|
|
rp->rph->rp = rp; |
|
for (i = 0; i < rp->maxactive; i++) { |
|
inst = kzalloc(sizeof(struct kretprobe_instance) + |
|
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 |
|
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); |
|
|
|
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); |
|
|
|
/* |
|
* 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); |
|
} |
|
|
|
/* 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 = 0; |
|
|
|
/* 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 */
|
|
|