diff options
Diffstat (limited to 'kernel/kprobes.c')
| -rw-r--r-- | kernel/kprobes.c | 1916 |
1 files changed, 1089 insertions, 827 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 2e97febeef77..88aeac84e4c0 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1,7 +1,6 @@ // SPDX-License-Identifier: GPL-2.0-or-later /* * Kernel Probes (KProbes) - * kernel/kprobes.c * * Copyright (C) IBM Corporation, 2002, 2004 * @@ -18,13 +17,15 @@ * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi * <prasanna@in.ibm.com> added function-return probes. */ + +#define pr_fmt(fmt) "kprobes: " fmt + #include <linux/kprobes.h> #include <linux/hash.h> #include <linux/init.h> #include <linux/slab.h> #include <linux/stddef.h> #include <linux/export.h> -#include <linux/moduleloader.h> #include <linux/kallsyms.h> #include <linux/freezer.h> #include <linux/seq_file.h> @@ -35,6 +36,10 @@ #include <linux/ftrace.h> #include <linux/cpu.h> #include <linux/jump_label.h> +#include <linux/static_call.h> +#include <linux/perf_event.h> +#include <linux/execmem.h> +#include <linux/cleanup.h> #include <asm/sections.h> #include <asm/cacheflush.h> @@ -44,25 +49,24 @@ #define KPROBE_HASH_BITS 6 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) +#if !defined(CONFIG_OPTPROBES) || !defined(CONFIG_SYSCTL) +#define kprobe_sysctls_init() do { } while (0) +#endif static int kprobes_initialized; /* kprobe_table can be accessed by - * - Normal hlist traversal and RCU add/del under kprobe_mutex is held. + * - Normal hlist traversal and RCU add/del under 'kprobe_mutex' is held. * Or * - RCU hlist traversal under disabling preempt (breakpoint handlers) */ static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; -static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; -/* NOTE: change this value only with kprobe_mutex held */ +/* NOTE: change this value only with 'kprobe_mutex' held */ static bool kprobes_all_disarmed; -/* This protects kprobe_table and optimizing_list */ +/* This protects 'kprobe_table' and 'optimizing_list' */ static DEFINE_MUTEX(kprobe_mutex); -static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL; -static struct { - raw_spinlock_t lock ____cacheline_aligned_in_smp; -} kretprobe_table_locks[KPROBE_TABLE_SIZE]; +static DEFINE_PER_CPU(struct kprobe *, kprobe_instance); kprobe_opcode_t * __weak kprobe_lookup_name(const char *name, unsigned int __unused) @@ -70,17 +74,15 @@ kprobe_opcode_t * __weak kprobe_lookup_name(const char *name, return ((kprobe_opcode_t *)(kallsyms_lookup_name(name))); } -static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash) -{ - return &(kretprobe_table_locks[hash].lock); -} - -/* Blacklist -- list of struct kprobe_blacklist_entry */ +/* + * Blacklist -- list of 'struct kprobe_blacklist_entry' to store info where + * kprobes can not probe. + */ static LIST_HEAD(kprobe_blacklist); #ifdef __ARCH_WANT_KPROBES_INSN_SLOT /* - * kprobe->ainsn.insn points to the copy of the instruction to be + * 'kprobe::ainsn.insn' points to the copy of the instruction to be * single-stepped. x86_64, POWER4 and above have no-exec support and * stepping on the instruction on a vmalloced/kmalloced/data page * is a recipe for disaster @@ -94,10 +96,6 @@ struct kprobe_insn_page { char slot_used[]; }; -#define KPROBE_INSN_PAGE_SIZE(slots) \ - (offsetof(struct kprobe_insn_page, slot_used) + \ - (sizeof(char) * (slots))) - static int slots_per_page(struct kprobe_insn_cache *c) { return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t)); @@ -111,18 +109,25 @@ enum kprobe_slot_state { void __weak *alloc_insn_page(void) { - return module_alloc(PAGE_SIZE); + /* + * Use execmem_alloc() so this page is within +/- 2GB of where the + * kernel image and loaded module images reside. This is required + * for most of the architectures. + * (e.g. x86-64 needs this to handle the %rip-relative fixups.) + */ + return execmem_alloc(EXECMEM_KPROBES, PAGE_SIZE); } -void __weak free_insn_page(void *page) +static void free_insn_page(void *page) { - module_memfree(page); + execmem_free(page); } struct kprobe_insn_cache kprobe_insn_slots = { .mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex), .alloc = alloc_insn_page, .free = free_insn_page, + .sym = KPROBE_INSN_PAGE_SYM, .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages), .insn_size = MAX_INSN_SIZE, .nr_garbage = 0, @@ -136,49 +141,39 @@ static int collect_garbage_slots(struct kprobe_insn_cache *c); kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c) { struct kprobe_insn_page *kip; - kprobe_opcode_t *slot = NULL; /* Since the slot array is not protected by rcu, we need a mutex */ - mutex_lock(&c->mutex); - retry: - rcu_read_lock(); - list_for_each_entry_rcu(kip, &c->pages, list) { - if (kip->nused < slots_per_page(c)) { - int i; - for (i = 0; i < slots_per_page(c); i++) { - if (kip->slot_used[i] == SLOT_CLEAN) { - kip->slot_used[i] = SLOT_USED; - kip->nused++; - slot = kip->insns + (i * c->insn_size); - rcu_read_unlock(); - goto out; + guard(mutex)(&c->mutex); + do { + guard(rcu)(); + list_for_each_entry_rcu(kip, &c->pages, list) { + if (kip->nused < slots_per_page(c)) { + int i; + + for (i = 0; i < slots_per_page(c); i++) { + if (kip->slot_used[i] == SLOT_CLEAN) { + kip->slot_used[i] = SLOT_USED; + kip->nused++; + return kip->insns + (i * c->insn_size); + } } + /* kip->nused is broken. Fix it. */ + kip->nused = slots_per_page(c); + WARN_ON(1); } - /* kip->nused is broken. Fix it. */ - kip->nused = slots_per_page(c); - WARN_ON(1); } - } - rcu_read_unlock(); - /* If there are any garbage slots, collect it and try again. */ - if (c->nr_garbage && collect_garbage_slots(c) == 0) - goto retry; + } while (c->nr_garbage && collect_garbage_slots(c) == 0); /* All out of space. Need to allocate a new page. */ - kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL); + kip = kmalloc(struct_size(kip, slot_used, slots_per_page(c)), GFP_KERNEL); if (!kip) - goto out; + return NULL; - /* - * Use module_alloc so this page is within +/- 2GB of where the - * kernel image and loaded module images reside. This is required - * so x86_64 can correctly handle the %rip-relative fixups. - */ kip->insns = c->alloc(); if (!kip->insns) { kfree(kip); - goto out; + return NULL; } INIT_LIST_HEAD(&kip->list); memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c)); @@ -187,33 +182,42 @@ kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c) kip->ngarbage = 0; kip->cache = c; list_add_rcu(&kip->list, &c->pages); - slot = kip->insns; -out: - mutex_unlock(&c->mutex); - return slot; + + /* Record the perf ksymbol register event after adding the page */ + perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL, (unsigned long)kip->insns, + PAGE_SIZE, false, c->sym); + + return kip->insns; } -/* Return 1 if all garbages are collected, otherwise 0. */ -static int collect_one_slot(struct kprobe_insn_page *kip, int idx) +/* Return true if all garbages are collected, otherwise false. */ +static bool collect_one_slot(struct kprobe_insn_page *kip, int idx) { kip->slot_used[idx] = SLOT_CLEAN; kip->nused--; - if (kip->nused == 0) { + if (kip->nused != 0) + return false; + + /* + * Page is no longer in use. Free it unless + * it's the last one. We keep the last one + * so as not to have to set it up again the + * next time somebody inserts a probe. + */ + if (!list_is_singular(&kip->list)) { /* - * Page is no longer in use. Free it unless - * it's the last one. We keep the last one - * so as not to have to set it up again the - * next time somebody inserts a probe. + * Record perf ksymbol unregister event before removing + * the page. */ - if (!list_is_singular(&kip->list)) { - list_del_rcu(&kip->list); - synchronize_rcu(); - kip->cache->free(kip->insns); - kfree(kip); - } - return 1; + perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL, + (unsigned long)kip->insns, PAGE_SIZE, true, + kip->cache->sym); + list_del_rcu(&kip->list); + synchronize_rcu(); + kip->cache->free(kip->insns); + kfree(kip); } - return 0; + return true; } static int collect_garbage_slots(struct kprobe_insn_cache *c) @@ -225,6 +229,7 @@ static int collect_garbage_slots(struct kprobe_insn_cache *c) list_for_each_entry_safe(kip, next, &c->pages, list) { int i; + if (kip->ngarbage == 0) continue; kip->ngarbage = 0; /* we will collect all garbages */ @@ -237,25 +242,35 @@ static int collect_garbage_slots(struct kprobe_insn_cache *c) return 0; } -void __free_insn_slot(struct kprobe_insn_cache *c, - kprobe_opcode_t *slot, int dirty) +static long __find_insn_page(struct kprobe_insn_cache *c, + kprobe_opcode_t *slot, struct kprobe_insn_page **pkip) { - struct kprobe_insn_page *kip; + struct kprobe_insn_page *kip = NULL; long idx; - mutex_lock(&c->mutex); - rcu_read_lock(); + guard(rcu)(); list_for_each_entry_rcu(kip, &c->pages, list) { idx = ((long)slot - (long)kip->insns) / (c->insn_size * sizeof(kprobe_opcode_t)); - if (idx >= 0 && idx < slots_per_page(c)) - goto out; + if (idx >= 0 && idx < slots_per_page(c)) { + *pkip = kip; + return idx; + } } /* Could not find this slot. */ WARN_ON(1); - kip = NULL; -out: - rcu_read_unlock(); + *pkip = NULL; + return -1; +} + +void __free_insn_slot(struct kprobe_insn_cache *c, + kprobe_opcode_t *slot, int dirty) +{ + struct kprobe_insn_page *kip = NULL; + long idx; + + guard(mutex)(&c->mutex); + idx = __find_insn_page(c, slot, &kip); /* Mark and sweep: this may sleep */ if (kip) { /* Check double free */ @@ -269,7 +284,6 @@ out: collect_one_slot(kip, idx); } } - mutex_unlock(&c->mutex); } /* @@ -295,18 +309,50 @@ bool __is_insn_slot_addr(struct kprobe_insn_cache *c, unsigned long addr) return ret; } +int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum, + unsigned long *value, char *type, char *sym) +{ + struct kprobe_insn_page *kip; + int ret = -ERANGE; + + rcu_read_lock(); + list_for_each_entry_rcu(kip, &c->pages, list) { + if ((*symnum)--) + continue; + strscpy(sym, c->sym, KSYM_NAME_LEN); + *type = 't'; + *value = (unsigned long)kip->insns; + ret = 0; + break; + } + rcu_read_unlock(); + + return ret; +} + #ifdef CONFIG_OPTPROBES +void __weak *alloc_optinsn_page(void) +{ + return alloc_insn_page(); +} + +void __weak free_optinsn_page(void *page) +{ + free_insn_page(page); +} + /* For optimized_kprobe buffer */ struct kprobe_insn_cache kprobe_optinsn_slots = { .mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex), - .alloc = alloc_insn_page, - .free = free_insn_page, + .alloc = alloc_optinsn_page, + .free = free_optinsn_page, + .sym = KPROBE_OPTINSN_PAGE_SYM, .pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages), /* .insn_size is initialized later */ .nr_garbage = 0, }; -#endif -#endif +#endif /* CONFIG_OPTPROBES */ +#endif /* __ARCH_WANT_KPROBES_INSN_SLOT */ /* We have preemption disabled.. so it is safe to use __ versions */ static inline void set_kprobe_instance(struct kprobe *kp) @@ -321,9 +367,9 @@ static inline void reset_kprobe_instance(void) /* * This routine is called either: - * - under the kprobe_mutex - during kprobe_[un]register() - * OR - * - with preemption disabled - from arch/xxx/kernel/kprobes.c + * - under the 'kprobe_mutex' - during kprobe_[un]register(). + * OR + * - with preemption disabled - from architecture specific code. */ struct kprobe *get_kprobe(void *addr) { @@ -343,22 +389,20 @@ NOKPROBE_SYMBOL(get_kprobe); static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs); -/* Return true if the kprobe is an aggregator */ -static inline int kprobe_aggrprobe(struct kprobe *p) +/* Return true if 'p' is an aggregator */ +static inline bool kprobe_aggrprobe(struct kprobe *p) { return p->pre_handler == aggr_pre_handler; } -/* Return true(!0) if the kprobe is unused */ -static inline int kprobe_unused(struct kprobe *p) +/* Return true if 'p' is unused */ +static inline bool kprobe_unused(struct kprobe *p) { return kprobe_aggrprobe(p) && kprobe_disabled(p) && list_empty(&p->list); } -/* - * Keep all fields in the kprobe consistent - */ +/* Keep all fields in the kprobe consistent. */ static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p) { memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t)); @@ -366,11 +410,11 @@ static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p) } #ifdef CONFIG_OPTPROBES -/* NOTE: change this value only with kprobe_mutex held */ +/* NOTE: This is protected by 'kprobe_mutex'. */ static bool kprobes_allow_optimization; /* - * Call all pre_handler on the list, but ignores its return value. + * Call all 'kprobe::pre_handler' on the list, but ignores its return value. * This must be called from arch-dep optimized caller. */ void opt_pre_handler(struct kprobe *p, struct pt_regs *regs) @@ -398,7 +442,7 @@ static void free_aggr_kprobe(struct kprobe *p) kfree(op); } -/* Return true(!0) if the kprobe is ready for optimization. */ +/* Return true if the kprobe is ready for optimization. */ static inline int kprobe_optready(struct kprobe *p) { struct optimized_kprobe *op; @@ -411,8 +455,8 @@ static inline int kprobe_optready(struct kprobe *p) return 0; } -/* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */ -static inline int kprobe_disarmed(struct kprobe *p) +/* Return true if the kprobe is disarmed. Note: p must be on hash list */ +bool kprobe_disarmed(struct kprobe *p) { struct optimized_kprobe *op; @@ -425,32 +469,32 @@ static inline int kprobe_disarmed(struct kprobe *p) return kprobe_disabled(p) && list_empty(&op->list); } -/* Return true(!0) if the probe is queued on (un)optimizing lists */ -static int kprobe_queued(struct kprobe *p) +/* Return true if the probe is queued on (un)optimizing lists */ +static bool kprobe_queued(struct kprobe *p) { struct optimized_kprobe *op; if (kprobe_aggrprobe(p)) { op = container_of(p, struct optimized_kprobe, kp); if (!list_empty(&op->list)) - return 1; + return true; } - return 0; + return false; } /* * Return an optimized kprobe whose optimizing code replaces - * instructions including addr (exclude breakpoint). + * instructions including 'addr' (exclude breakpoint). */ -static struct kprobe *get_optimized_kprobe(unsigned long addr) +static struct kprobe *get_optimized_kprobe(kprobe_opcode_t *addr) { int i; struct kprobe *p = NULL; struct optimized_kprobe *op; /* Don't check i == 0, since that is a breakpoint case. */ - for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++) - p = get_kprobe((void *)(addr - i)); + for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH / sizeof(kprobe_opcode_t); i++) + p = get_kprobe(addr - i); if (p && kprobe_optready(p)) { op = container_of(p, struct optimized_kprobe, kp); @@ -461,7 +505,7 @@ static struct kprobe *get_optimized_kprobe(unsigned long addr) return NULL; } -/* Optimization staging list, protected by kprobe_mutex */ +/* Optimization staging list, protected by 'kprobe_mutex' */ static LIST_HEAD(optimizing_list); static LIST_HEAD(unoptimizing_list); static LIST_HEAD(freeing_list); @@ -472,20 +516,20 @@ static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer); /* * Optimize (replace a breakpoint with a jump) kprobes listed on - * optimizing_list. + * '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 online_cpus. - * And same time, text_mutex will be held in cpu-hotplug and here. - * This combination can cause a deadlock (cpu-hotplug try to lock - * text_mutex but stop_machine can not be done because online_cpus - * has been changed) - * To avoid this deadlock, caller must have locked cpu hotplug - * for preventing cpu-hotplug outside of text_mutex locking. + * The optimization/unoptimization refers 'online_cpus' via + * stop_machine() and cpu-hotplug modifies the 'online_cpus'. + * And same time, 'text_mutex' will be held in cpu-hotplug and here. + * This combination can cause a deadlock (cpu-hotplug tries to lock + * 'text_mutex' but stop_machine() can not be done because + * the 'online_cpus' has been changed) + * To avoid this deadlock, caller must have locked cpu-hotplug + * for preventing cpu-hotplug outside of 'text_mutex' locking. */ lockdep_assert_cpus_held(); @@ -499,7 +543,7 @@ static void do_optimize_kprobes(void) /* * Unoptimize (replace a jump with a breakpoint and remove the breakpoint - * if need) kprobes listed on unoptimizing_list. + * if need) kprobes listed on 'unoptimizing_list'. */ static void do_unoptimize_kprobes(void) { @@ -509,23 +553,21 @@ static void do_unoptimize_kprobes(void) /* See comment in do_optimize_kprobes() */ lockdep_assert_cpus_held(); - /* Unoptimization must be done anytime */ - if (list_empty(&unoptimizing_list)) - return; + if (!list_empty(&unoptimizing_list)) + arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list); - arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list); - /* Loop free_list for disarming */ + /* Loop on 'freeing_list' for disarming and removing from kprobe hash list */ list_for_each_entry_safe(op, tmp, &freeing_list, list) { /* Switching from detour code to origin */ op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED; - /* Disarm probes if marked disabled */ - if (kprobe_disabled(&op->kp)) + /* Disarm probes if marked disabled and not gone */ + if (kprobe_disabled(&op->kp) && !kprobe_gone(&op->kp)) arch_disarm_kprobe(&op->kp); if (kprobe_unused(&op->kp)) { /* * Remove unused probes from hash list. After waiting * for synchronization, these probes are reclaimed. - * (reclaiming is done by do_free_cleaned_kprobes.) + * (reclaiming is done by do_free_cleaned_kprobes().) */ hlist_del_rcu(&op->kp.hlist); } else @@ -533,7 +575,7 @@ static void do_unoptimize_kprobes(void) } } -/* Reclaim all kprobes on the free_list */ +/* Reclaim all kprobes on the 'freeing_list' */ static void do_free_cleaned_kprobes(void) { struct optimized_kprobe *op, *tmp; @@ -560,66 +602,65 @@ static void kick_kprobe_optimizer(void) /* Kprobe jump optimizer */ static void kprobe_optimizer(struct work_struct *work) { - mutex_lock(&kprobe_mutex); - cpus_read_lock(); - mutex_lock(&text_mutex); - /* Lock modules while optimizing kprobes */ - mutex_lock(&module_mutex); + guard(mutex)(&kprobe_mutex); - /* - * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed) - * kprobes before waiting for quiesence period. - */ - do_unoptimize_kprobes(); + scoped_guard(cpus_read_lock) { + guard(mutex)(&text_mutex); - /* - * 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 1: Unoptimize kprobes and collect cleaned (unused and disarmed) + * kprobes before waiting for quiesence period. + */ + do_unoptimize_kprobes(); - /* Step 3: Optimize kprobes after quiesence period */ - do_optimize_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 4: Free cleaned kprobes after quiesence period */ - do_free_cleaned_kprobes(); + /* Step 3: Optimize kprobes after quiesence period */ + do_optimize_kprobes(); - mutex_unlock(&module_mutex); - mutex_unlock(&text_mutex); - cpus_read_unlock(); + /* Step 4: Free cleaned kprobes after quiesence period */ + do_free_cleaned_kprobes(); + } /* 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) +static void wait_for_kprobe_optimizer_locked(void) { - mutex_lock(&kprobe_mutex); + lockdep_assert_held(&kprobe_mutex); while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) { mutex_unlock(&kprobe_mutex); - /* this will also make optimizing_work execute immmediately */ + /* This will also make 'optimizing_work' execute immmediately */ flush_delayed_work(&optimizing_work); - /* @optimizing_work might not have been queued yet, relax */ + /* 'optimizing_work' might not have been queued yet, relax */ cpu_relax(); mutex_lock(&kprobe_mutex); } +} - mutex_unlock(&kprobe_mutex); +/* Wait for completing optimization and unoptimization */ +void wait_for_kprobe_optimizer(void) +{ + guard(mutex)(&kprobe_mutex); + + wait_for_kprobe_optimizer_locked(); } -static bool optprobe_queued_unopt(struct optimized_kprobe *op) +bool optprobe_queued_unopt(struct optimized_kprobe *op) { struct optimized_kprobe *_op; @@ -641,7 +682,7 @@ static void optimize_kprobe(struct kprobe *p) (kprobe_disabled(p) || kprobes_all_disarmed)) return; - /* kprobes with post_handler can not be optimized */ + /* kprobes with 'post_handler' can not be optimized */ if (p->post_handler) return; @@ -661,7 +702,10 @@ static void optimize_kprobe(struct kprobe *p) } op->kp.flags |= KPROBE_FLAG_OPTIMIZED; - /* On unoptimizing/optimizing_list, op must have OPTIMIZED flag */ + /* + * On the 'unoptimizing_list' and 'optimizing_list', + * 'op' must have OPTIMIZED flag + */ if (WARN_ON_ONCE(!list_empty(&op->list))) return; @@ -731,7 +775,7 @@ static int reuse_unused_kprobe(struct kprobe *ap) WARN_ON_ONCE(list_empty(&op->list)); /* Enable the probe again */ ap->flags &= ~KPROBE_FLAG_DISABLED; - /* Optimize it again (remove from op->list) */ + /* Optimize it again. (remove from 'op->list') */ if (!kprobe_optready(ap)) return -EINVAL; @@ -751,14 +795,13 @@ static void kill_optimized_kprobe(struct kprobe *p) 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().) + * Unused kprobe is on unoptimizing or freeing list. We move it + * to freeing_list and let the kprobe_optimizer() remove it from + * the kprobe hash list and free it. */ - hlist_del_rcu(&op->kp.hlist); + if (optprobe_queued_unopt(op)) + list_move(&op->list, &freeing_list); } /* Don't touch the code, because it is already freed. */ @@ -781,7 +824,7 @@ static void prepare_optimized_kprobe(struct kprobe *p) __prepare_optimized_kprobe(op, p); } -/* Allocate new optimized_kprobe and try to prepare optimized instructions */ +/* Allocate new optimized_kprobe and try to prepare optimized instructions. */ static struct kprobe *alloc_aggr_kprobe(struct kprobe *p) { struct optimized_kprobe *op; @@ -800,55 +843,49 @@ static struct kprobe *alloc_aggr_kprobe(struct kprobe *p) 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 + * 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 */ + /* 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); + /* For preparing optimization, jump_label_text_reserved() is called. */ + guard(cpus_read_lock)(); + guard(jump_label_lock)(); + guard(mutex)(&text_mutex); ap = alloc_aggr_kprobe(p); if (!ap) - goto out; + return; op = container_of(ap, struct optimized_kprobe, kp); if (!arch_prepared_optinsn(&op->optinsn)) { - /* If failed to setup optimizing, fallback to kprobe */ + /* If failed to setup optimizing, fallback to kprobe. */ arch_remove_optimized_kprobe(op); kfree(op); - goto out; + return; } init_aggr_kprobe(ap, p); - optimize_kprobe(ap); /* This just kicks optimizer thread */ - -out: - mutex_unlock(&text_mutex); - jump_label_unlock(); - cpus_read_unlock(); + optimize_kprobe(ap); /* This just kicks optimizer thread. */ } -#ifdef CONFIG_SYSCTL 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 */ + guard(mutex)(&kprobe_mutex); + /* If optimization is already allowed, just return. */ if (kprobes_allow_optimization) - goto out; + return; cpus_read_lock(); kprobes_allow_optimization = true; @@ -859,23 +896,20 @@ static void optimize_all_kprobes(void) optimize_kprobe(p); } cpus_read_unlock(); - printk(KERN_INFO "Kprobes globally optimized\n"); -out: - mutex_unlock(&kprobe_mutex); + pr_info("kprobe jump-optimization is enabled. All kprobes are optimized if possible.\n"); } +#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); + guard(mutex)(&kprobe_mutex); + /* If optimization is already prohibited, just return. */ + if (!kprobes_allow_optimization) return; - } cpus_read_lock(); kprobes_allow_optimization = false; @@ -887,22 +921,20 @@ static void unoptimize_all_kprobes(void) } } cpus_read_unlock(); - mutex_unlock(&kprobe_mutex); - - /* Wait for unoptimizing completion */ - wait_for_kprobe_optimizer(); - printk(KERN_INFO "Kprobes globally unoptimized\n"); + /* Wait for unoptimizing completion. */ + wait_for_kprobe_optimizer_locked(); + pr_info("kprobe jump-optimization is disabled. All kprobes are based on software breakpoint.\n"); } static DEFINE_MUTEX(kprobe_sysctl_mutex); -int sysctl_kprobes_optimization; -int proc_kprobes_optimization_handler(struct ctl_table *table, int write, - void *buffer, size_t *length, - loff_t *ppos) +static int sysctl_kprobes_optimization; +static int proc_kprobes_optimization_handler(const struct ctl_table *table, + int write, void *buffer, + size_t *length, loff_t *ppos) { int ret; - mutex_lock(&kprobe_sysctl_mutex); + guard(mutex)(&kprobe_sysctl_mutex); sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0; ret = proc_dointvec_minmax(table, write, buffer, length, ppos); @@ -910,19 +942,37 @@ int proc_kprobes_optimization_handler(struct ctl_table *table, int write, optimize_all_kprobes(); else unoptimize_all_kprobes(); - mutex_unlock(&kprobe_sysctl_mutex); return ret; } + +static const 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. Must be called with text_mutex locked */ +/* Put a breakpoint for a probe. */ static void __arm_kprobe(struct kprobe *p) { struct kprobe *_p; - /* Check collision with other optimized kprobes */ - _p = get_optimized_kprobe((unsigned long)p->addr); + 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); @@ -931,22 +981,29 @@ static void __arm_kprobe(struct kprobe *p) optimize_kprobe(p); /* Try to optimize (add kprobe to a list) */ } -/* Remove the breakpoint of a probe. Must be called with text_mutex locked */ +/* 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, optimize it. */ - _p = get_optimized_kprobe((unsigned long)p->addr); + /* If another kprobe was blocked, re-optimize it. */ + _p = get_optimized_kprobe(p->addr); if (unlikely(_p) && reopt) optimize_kprobe(_p); } - /* TODO: reoptimize others after unoptimized this probe */ + /* + * 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 */ @@ -959,7 +1016,8 @@ static void __disarm_kprobe(struct kprobe *p, bool reopt) #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) +#define wait_for_kprobe_optimizer_locked() \ + lockdep_assert_held(&kprobe_mutex) static int reuse_unused_kprobe(struct kprobe *ap) { @@ -969,7 +1027,7 @@ static int reuse_unused_kprobe(struct kprobe *ap) * unregistered. * Thus there should be no chance to reuse unused kprobe. */ - printk(KERN_ERR "Error: There should be no unused kprobe here.\n"); + WARN_ON_ONCE(1); return -EINVAL; } @@ -998,47 +1056,33 @@ static struct ftrace_ops kprobe_ipmodify_ops __read_mostly = { static int kprobe_ipmodify_enabled; static int kprobe_ftrace_enabled; +bool kprobe_ftrace_disabled; -/* Must ensure p->addr is really on ftrace */ -static int prepare_kprobe(struct kprobe *p) -{ - if (!kprobe_ftrace(p)) - return arch_prepare_kprobe(p); - - return arch_prepare_kprobe_ftrace(p); -} - -/* Caller must lock kprobe_mutex */ static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops, int *cnt) { - int ret = 0; + int ret; + + lockdep_assert_held(&kprobe_mutex); ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0); - if (ret) { - pr_debug("Failed to arm kprobe-ftrace at %pS (%d)\n", - p->addr, ret); + 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 (ret) { - pr_debug("Failed to init kprobe-ftrace (%d)\n", ret); - goto err_ftrace; + if (WARN(ret < 0, "Failed to register kprobe-ftrace (error %d)\n", ret)) { + /* + * 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; } } (*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) @@ -1050,22 +1094,23 @@ static int arm_kprobe_ftrace(struct kprobe *p) ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled); } -/* Caller must lock kprobe_mutex */ static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops, int *cnt) { - int ret = 0; + int ret; + + lockdep_assert_held(&kprobe_mutex); if (*cnt == 1) { ret = unregister_ftrace_function(ops); - if (WARN(ret < 0, "Failed to unregister kprobe-ftrace (%d)\n", ret)) + 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 (%d)\n", + WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (error %d)\n", p->addr, ret); return ret; } @@ -1078,39 +1123,51 @@ static int disarm_kprobe_ftrace(struct kprobe *p) ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops, ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled); } + +void kprobe_ftrace_kill(void) +{ + kprobe_ftrace_disabled = true; +} #else /* !CONFIG_KPROBES_ON_FTRACE */ -#define prepare_kprobe(p) arch_prepare_kprobe(p) -#define arm_kprobe_ftrace(p) (-ENODEV) -#define disarm_kprobe_ftrace(p) (-ENODEV) +static inline int arm_kprobe_ftrace(struct kprobe *p) +{ + return -ENODEV; +} + +static inline int disarm_kprobe_ftrace(struct kprobe *p) +{ + return -ENODEV; +} #endif -/* Arm a kprobe with text_mutex */ +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); + guard(cpus_read_lock)(); + guard(mutex)(&text_mutex); __arm_kprobe(kp); - mutex_unlock(&text_mutex); - cpus_read_unlock(); - return 0; } -/* Disarm a kprobe with text_mutex */ 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); + guard(cpus_read_lock)(); + guard(mutex)(&text_mutex); __disarm_kprobe(kp, reopt); - mutex_unlock(&text_mutex); - cpus_read_unlock(); - return 0; } @@ -1149,99 +1206,21 @@ static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs, } NOKPROBE_SYMBOL(aggr_post_handler); -static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, - int trapnr) -{ - struct kprobe *cur = __this_cpu_read(kprobe_instance); - - /* - * if we faulted "during" the execution of a user specified - * probe handler, invoke just that probe's fault handler - */ - if (cur && cur->fault_handler) { - if (cur->fault_handler(cur, regs, trapnr)) - return 1; - } - return 0; -} -NOKPROBE_SYMBOL(aggr_fault_handler); - -/* Walks the list and increments nmissed count for multiprobe case */ +/* 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++; } - return; } NOKPROBE_SYMBOL(kprobes_inc_nmissed_count); -void recycle_rp_inst(struct kretprobe_instance *ri, - struct hlist_head *head) -{ - struct kretprobe *rp = ri->rp; - - /* remove rp inst off the rprobe_inst_table */ - hlist_del(&ri->hlist); - INIT_HLIST_NODE(&ri->hlist); - if (likely(rp)) { - raw_spin_lock(&rp->lock); - hlist_add_head(&ri->hlist, &rp->free_instances); - raw_spin_unlock(&rp->lock); - } else - /* Unregistering */ - hlist_add_head(&ri->hlist, head); -} -NOKPROBE_SYMBOL(recycle_rp_inst); - -void kretprobe_hash_lock(struct task_struct *tsk, - struct hlist_head **head, unsigned long *flags) -__acquires(hlist_lock) -{ - unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS); - raw_spinlock_t *hlist_lock; - - *head = &kretprobe_inst_table[hash]; - hlist_lock = kretprobe_table_lock_ptr(hash); - raw_spin_lock_irqsave(hlist_lock, *flags); -} -NOKPROBE_SYMBOL(kretprobe_hash_lock); - -static void kretprobe_table_lock(unsigned long hash, - unsigned long *flags) -__acquires(hlist_lock) -{ - raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash); - raw_spin_lock_irqsave(hlist_lock, *flags); -} -NOKPROBE_SYMBOL(kretprobe_table_lock); - -void kretprobe_hash_unlock(struct task_struct *tsk, - unsigned long *flags) -__releases(hlist_lock) -{ - unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS); - raw_spinlock_t *hlist_lock; - - hlist_lock = kretprobe_table_lock_ptr(hash); - raw_spin_unlock_irqrestore(hlist_lock, *flags); -} -NOKPROBE_SYMBOL(kretprobe_hash_unlock); - -static void kretprobe_table_unlock(unsigned long hash, - unsigned long *flags) -__releases(hlist_lock) -{ - raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash); - raw_spin_unlock_irqrestore(hlist_lock, *flags); -} -NOKPROBE_SYMBOL(kretprobe_table_unlock); - -struct kprobe kprobe_busy = { +static struct kprobe kprobe_busy = { .addr = (void *) get_kprobe, }; @@ -1261,76 +1240,7 @@ void kprobe_busy_end(void) preempt_enable(); } -/* - * This function is called from finish_task_switch when task tk becomes dead, - * so that we can recycle any function-return probe 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 hlist_head *head, empty_rp; - struct hlist_node *tmp; - unsigned long hash, flags = 0; - - if (unlikely(!kprobes_initialized)) - /* Early boot. kretprobe_table_locks not yet initialized. */ - return; - - kprobe_busy_begin(); - - INIT_HLIST_HEAD(&empty_rp); - hash = hash_ptr(tk, KPROBE_HASH_BITS); - head = &kretprobe_inst_table[hash]; - kretprobe_table_lock(hash, &flags); - hlist_for_each_entry_safe(ri, tmp, head, hlist) { - if (ri->task == tk) - recycle_rp_inst(ri, &empty_rp); - } - kretprobe_table_unlock(hash, &flags); - hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { - hlist_del(&ri->hlist); - kfree(ri); - } - - kprobe_busy_end(); -} -NOKPROBE_SYMBOL(kprobe_flush_task); - -static inline void free_rp_inst(struct kretprobe *rp) -{ - struct kretprobe_instance *ri; - struct hlist_node *next; - - hlist_for_each_entry_safe(ri, next, &rp->free_instances, hlist) { - hlist_del(&ri->hlist); - kfree(ri); - } -} - -static void cleanup_rp_inst(struct kretprobe *rp) -{ - unsigned long flags, hash; - struct kretprobe_instance *ri; - struct hlist_node *next; - struct hlist_head *head; - - /* No race here */ - for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) { - kretprobe_table_lock(hash, &flags); - head = &kretprobe_inst_table[hash]; - hlist_for_each_entry_safe(ri, next, head, hlist) { - if (ri->rp == rp) - ri->rp = NULL; - } - kretprobe_table_unlock(hash, &flags); - } - free_rp_inst(rp); -} -NOKPROBE_SYMBOL(cleanup_rp_inst); - -/* Add the new probe to ap->list */ +/* Add the new probe to 'ap->list'. */ static int add_new_kprobe(struct kprobe *ap, struct kprobe *p) { if (p->post_handler) @@ -1344,18 +1254,17 @@ static int add_new_kprobe(struct kprobe *ap, struct kprobe *p) } /* - * Fill in the required fields of the "manager kprobe". Replace the - * earlier kprobe in the hlist with the manager kprobe + * 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 p's insn slot to ap */ + /* 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; - ap->fault_handler = aggr_fault_handler; /* We don't care the kprobe which has gone. */ if (p->post_handler && !kprobe_gone(p)) ap->post_handler = aggr_post_handler; @@ -1368,70 +1277,62 @@ static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p) } /* - * This is the second or subsequent kprobe at the address - handle - * the intricacies + * 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 aggr_kprobe. */ - ap = alloc_aggr_kprobe(orig_p); - if (!ap) { - ret = -ENOMEM; - goto out; + scoped_guard(cpus_read_lock) { + /* For preparing optimization, jump_label_text_reserved() is called */ + guard(jump_label_lock)(); + guard(mutex)(&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) + return -ENOMEM; + 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) + return ret; } - 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) + if (kprobe_gone(ap)) { /* - * Even if fail to allocate new slot, don't need to - * free aggr_probe. It will be used next time, or - * freed by unregister_kprobe. + * 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. */ - goto out; + 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(). + */ + return ret; - /* Prepare optimized instructions if possible. */ - prepare_optimized_kprobe(ap); + /* 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 ap's insn slot to p */ - copy_kprobe(ap, p); - ret = add_new_kprobe(ap, p); + /* + * 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; + } -out: - mutex_unlock(&text_mutex); - jump_label_unlock(); - cpus_read_unlock(); + /* Copy the insn slot of 'p' to 'ap'. */ + copy_kprobe(ap, p); + ret = add_new_kprobe(ap, p); + } if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) { ap->flags &= ~KPROBE_FLAG_DISABLED; @@ -1450,7 +1351,7 @@ out: bool __weak arch_within_kprobe_blacklist(unsigned long addr) { - /* The __kprobes marked functions and entry code must not be probed */ + /* The '__kprobes' functions and entry code must not be probed. */ return addr >= (unsigned long)__kprobes_text_start && addr < (unsigned long)__kprobes_text_end; } @@ -1462,8 +1363,8 @@ static bool __within_kprobe_blacklist(unsigned long addr) if (arch_within_kprobe_blacklist(addr)) return true; /* - * If there exists a kprobe_blacklist, verify and - * fail any probe registration in the prohibited area + * 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) @@ -1493,37 +1394,85 @@ bool within_kprobe_blacklist(unsigned long addr) } /* - * If we have a symbol_name argument, look it up and add the offset field + * 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 int offset) +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; + return ERR_PTR(-EINVAL); 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); } - addr = (kprobe_opcode_t *)(((char *)addr) + offset); - if (addr) - return addr; + /* + * 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; -invalid: - return ERR_PTR(-EINVAL); + /* + * 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 ERR_PTR(-EINVAL); + + return addr; } static kprobe_opcode_t *kprobe_addr(struct kprobe *p) { - return _kprobe_addr(p->addr, p->symbol_name, p->offset); + bool on_func_entry; + + return _kprobe_addr(p->addr, p->symbol_name, p->offset, &on_func_entry); } -/* Check passed kprobe is valid and return kprobe in kprobe_table. */ +/* + * 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; @@ -1534,142 +1483,129 @@ static struct kprobe *__get_valid_kprobe(struct kprobe *p) 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; + if (p == ap) + return ap; + + list_for_each_entry(list_p, &ap->list, list) + if (list_p == p) + /* kprobe p is a valid probe */ + return ap; + + return NULL; } -/* Return error if the kprobe is being re-registered */ -static inline int check_kprobe_rereg(struct kprobe *p) +/* + * 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; + guard(mutex)(&kprobe_mutex); - mutex_lock(&kprobe_mutex); - if (__get_valid_kprobe(p)) - ret = -EINVAL; - mutex_unlock(&kprobe_mutex); + if (WARN_ON_ONCE(__get_valid_kprobe(p))) + return -EINVAL; - return ret; + return 0; } -int __weak arch_check_ftrace_location(struct kprobe *p) +static int check_ftrace_location(struct kprobe *p) { - unsigned long ftrace_addr; + unsigned long addr = (unsigned long)p->addr; - ftrace_addr = ftrace_location((unsigned long)p->addr); - if (ftrace_addr) { + if (ftrace_location(addr) == addr) { #ifdef CONFIG_KPROBES_ON_FTRACE - /* Given address is not on the instruction boundary */ - if ((unsigned long)p->addr != ftrace_addr) - return -EILSEQ; p->flags |= KPROBE_FLAG_FTRACE; -#else /* !CONFIG_KPROBES_ON_FTRACE */ +#else return -EINVAL; #endif } return 0; } +static bool is_cfi_preamble_symbol(unsigned long addr) +{ + char symbuf[KSYM_NAME_LEN]; + + if (lookup_symbol_name(addr, symbuf)) + return false; + + return str_has_prefix(symbuf, "__cfi_") || + str_has_prefix(symbuf, "__pfx_"); +} + static int check_kprobe_address_safe(struct kprobe *p, struct module **probed_mod) { int ret; - ret = arch_check_ftrace_location(p); + 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 (!kernel_text_address((unsigned long) p->addr) || - within_kprobe_blacklist((unsigned long) p->addr) || - jump_label_text_reserved(p->addr, p->addr) || - find_bug((unsigned long)p->addr)) { - ret = -EINVAL; - goto out; - } + guard(jump_label_lock)(); + + /* Ensure the address is in a text area, and find a module if exists. */ + *probed_mod = NULL; + if (!core_kernel_text((unsigned long) p->addr)) { + guard(preempt)(); + *probed_mod = __module_text_address((unsigned long) p->addr); + if (!(*probed_mod)) + return -EINVAL; - /* Check if are we 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 (unlikely(!try_module_get(*probed_mod))) + return -ENOENT; + } + /* Ensure it is not in reserved area. */ + if (in_gate_area_no_mm((unsigned long) p->addr) || + within_kprobe_blacklist((unsigned long) p->addr) || + jump_label_text_reserved(p->addr, p->addr) || + static_call_text_reserved(p->addr, p->addr) || + find_bug((unsigned long)p->addr) || + is_cfi_preamble_symbol((unsigned long)p->addr)) { + module_put(*probed_mod); + return -EINVAL; + } + /* Get module refcount and reject __init functions for loaded modules. */ + if (IS_ENABLED(CONFIG_MODULES) && *probed_mod) { /* - * If the module freed .init.text, we couldn't insert + * 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_is_coming(*probed_mod)) { module_put(*probed_mod); - *probed_mod = NULL; - ret = -ENOENT; + return -ENOENT; } } -out: - preempt_enable(); - jump_label_unlock(); - return ret; + return 0; } -int register_kprobe(struct kprobe *p) +static int __register_kprobe(struct kprobe *p) { int ret; struct kprobe *old_p; - struct module *probed_mod; - kprobe_opcode_t *addr; - - /* Adjust probe address from symbol */ - addr = kprobe_addr(p); - if (IS_ERR(addr)) - return PTR_ERR(addr); - p->addr = addr; - - ret = check_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); + guard(mutex)(&kprobe_mutex); old_p = get_kprobe(p->addr); - if (old_p) { - /* Since this may unoptimize old_p, locking text_mutex. */ - ret = register_aggr_kprobe(old_p, p); - goto out; + if (old_p) + /* Since this may unoptimize 'old_p', locking 'text_mutex'. */ + return register_aggr_kprobe(old_p, p); + + scoped_guard(cpus_read_lock) { + /* Prevent text modification */ + guard(mutex)(&text_mutex); + ret = prepare_kprobe(p); + if (ret) + return ret; } - 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)]); @@ -1679,14 +1615,43 @@ int register_kprobe(struct 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); + return 0; +} + +int register_kprobe(struct kprobe *p) +{ + int ret; + struct module *probed_mod; + kprobe_opcode_t *addr; + bool on_func_entry; + + /* Canonicalize 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; + if (on_func_entry) + p->flags |= KPROBE_FLAG_ON_FUNC_ENTRY; + p->nmissed = 0; + INIT_LIST_HEAD(&p->list); + + ret = check_kprobe_address_safe(p, &probed_mod); + if (ret) + return ret; + + ret = __register_kprobe(p); if (probed_mod) module_put(probed_mod); @@ -1695,8 +1660,8 @@ out: } EXPORT_SYMBOL_GPL(register_kprobe); -/* Check if all probes on the aggrprobe are disabled */ -static int aggr_kprobe_disabled(struct kprobe *ap) +/* Check if all probes on the 'ap' are disabled. */ +static bool aggr_kprobe_disabled(struct kprobe *ap) { struct kprobe *kp; @@ -1705,46 +1670,49 @@ static int aggr_kprobe_disabled(struct kprobe *ap) list_for_each_entry(kp, &ap->list, list) if (!kprobe_disabled(kp)) /* - * There is an active probe on the list. - * We can't disable this ap. + * Since there is an active probe on the list, + * we can't disable this 'ap'. */ - return 0; + return false; - return 1; + return true; } -/* Disable one kprobe: Make sure called under kprobe_mutex is locked */ 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; + if (kprobe_disabled(p)) + return orig_p; - /* Try to disarm and disable this/parent probe */ - if (p == orig_p || aggr_kprobe_disabled(orig_p)) { - /* - * If kprobes_all_disarmed is set, orig_p - * should have already been disarmed, so - * skip unneed disarming process. - */ - if (!kprobes_all_disarmed) { - ret = disarm_kprobe(orig_p, true); - if (ret) { - p->flags &= ~KPROBE_FLAG_DISABLED; - return ERR_PTR(ret); - } + /* 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; } + orig_p->flags |= KPROBE_FLAG_DISABLED; } return orig_p; @@ -1762,49 +1730,54 @@ static int __unregister_kprobe_top(struct 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)); + WARN_ON(ap != p && !kprobe_aggrprobe(ap)); - if (list_is_singular(&ap->list) && kprobe_disarmed(ap)) + /* + * If the probe is an independent(and non-optimized) kprobe + * (not an aggrprobe), the last kprobe on the aggrprobe, or + * kprobe is already disarmed, just remove from the hash list. + */ + if (ap == p || + (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; - } - ap->post_handler = NULL; + hlist_del_rcu(&ap->hlist); + return 0; + } + + /* 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)) + break; } -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) + /* No other probe has post_handler */ + if (list_entry_is_head(list_p, &ap->list, list)) { /* - * Try to optimize this probe again, because post - * handler may have been changed. + * For the kprobe-on-ftrace case, we keep the + * post_handler setting to identify this aggrprobe + * armed with kprobe_ipmodify_ops. */ - optimize_kprobe(ap); + if (!kprobe_ftrace(ap)) + ap->post_handler = NULL; + } } - return 0; -disarmed: - hlist_del_rcu(&ap->hlist); + /* + * 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; + } static void __unregister_kprobe_bottom(struct kprobe *p) @@ -1853,12 +1826,11 @@ void unregister_kprobes(struct kprobe **kps, int num) 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); - + scoped_guard(mutex, &kprobe_mutex) { + for (i = 0; i < num; i++) + if (__unregister_kprobe_top(kps[i]) < 0) + kps[i]->addr = NULL; + } synchronize_rcu(); for (i = 0; i < num; i++) if (kps[i]->addr) @@ -1878,12 +1850,215 @@ static struct notifier_block kprobe_exceptions_nb = { .priority = 0x7fffffff /* we need to be notified first */ }; -unsigned long __weak arch_deref_entry_point(void *entry) +#ifdef CONFIG_KRETPROBES + +#if !defined(CONFIG_KRETPROBE_ON_RETHOOK) + +/* callbacks for objpool of kretprobe instances */ +static int kretprobe_init_inst(void *nod, void *context) +{ + struct kretprobe_instance *ri = nod; + + ri->rph = context; + return 0; +} +static int kretprobe_fini_pool(struct objpool_head *head, void *context) +{ + kfree(context); + return 0; +} + +static void free_rp_inst_rcu(struct rcu_head *head) { - return (unsigned long)entry; + struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu); + struct kretprobe_holder *rph = ri->rph; + + objpool_drop(ri, &rph->pool); } +NOKPROBE_SYMBOL(free_rp_inst_rcu); + +static void recycle_rp_inst(struct kretprobe_instance *ri) +{ + struct kretprobe *rp = get_kretprobe(ri); + + if (likely(rp)) + objpool_push(ri, &rp->rph->pool); + 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_holder *rph = rp->rph; + + if (!rph) + return; + rp->rph = NULL; + objpool_fini(&rph->pool); +} + +/* 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; + kprobe_opcode_t *ret; + + if (WARN_ON_ONCE(!cur)) + return 0; + + do { + ret = __kretprobe_find_ret_addr(tsk, cur); + if (!ret) + break; + ri = container_of(*cur, struct kretprobe_instance, llist); + } while (ri->fp != fp); + + return (unsigned long)ret; +} +NOKPROBE_SYMBOL(kretprobe_find_ret_addr); + +void __weak arch_kretprobe_fixup_return(struct pt_regs *regs, + kprobe_opcode_t *correct_ret_addr) +{ + /* + * Do nothing by default. Please fill this to update the fake return + * address on the stack with the correct one on each arch if possible. + */ +} + +unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, + void *frame_pointer) +{ + struct kretprobe_instance *ri = NULL; + struct llist_node *first, *node = NULL; + kprobe_opcode_t *correct_ret_addr; + struct kretprobe *rp; + + /* Find correct address and all nodes for this frame. */ + correct_ret_addr = __kretprobe_find_ret_addr(current, &node); + if (!correct_ret_addr) { + pr_err("kretprobe: Return address not found, not execute handler. Maybe there is a bug in the kernel.\n"); + BUG_ON(1); + } + + /* + * Set the return address as the instruction pointer, because if the + * user handler calls stack_trace_save_regs() with this 'regs', + * the stack trace will start from the instruction pointer. + */ + instruction_pointer_set(regs, (unsigned long)correct_ret_addr); + + /* Run the user handler of the nodes. */ + first = current->kretprobe_instances.first; + while (first) { + ri = container_of(first, struct kretprobe_instance, llist); + + if (WARN_ON_ONCE(ri->fp != frame_pointer)) + break; + + rp = get_kretprobe(ri); + if (rp && rp->handler) { + struct kprobe *prev = kprobe_running(); + + __this_cpu_write(current_kprobe, &rp->kp); + ri->ret_addr = correct_ret_addr; + rp->handler(ri, regs); + __this_cpu_write(current_kprobe, prev); + } + if (first == node) + break; + + first = first->next; + } + + arch_kretprobe_fixup_return(regs, correct_ret_addr); + + /* Unlink all nodes for this frame. */ + first = current->kretprobe_instances.first; + current->kretprobe_instances.first = node->next; + node->next = NULL; + + /* Recycle free instances. */ + while (first) { + ri = container_of(first, struct kretprobe_instance, llist); + first = first->next; + + recycle_rp_inst(ri); + } + + return (unsigned long)correct_ret_addr; +} +NOKPROBE_SYMBOL(__kretprobe_trampoline_handler) -#ifdef CONFIG_KRETPROBES /* * This kprobe pre_handler is registered with every kretprobe. When probe * hits it will set up the return probe. @@ -1891,81 +2066,119 @@ unsigned long __weak arch_deref_entry_point(void *entry) static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) { struct kretprobe *rp = container_of(p, struct kretprobe, kp); - unsigned long hash, flags = 0; + struct kretprobe_holder *rph = rp->rph; struct kretprobe_instance *ri; - /* - * To avoid deadlocks, prohibit return probing in NMI contexts, - * just skip the probe and increase the (inexact) 'nmissed' - * statistical counter, so that the user is informed that - * something happened: - */ - if (unlikely(in_nmi())) { + ri = objpool_pop(&rph->pool); + if (!ri) { rp->nmissed++; return 0; } - /* TODO: consider to only swap the RA after the last pre_handler fired */ - hash = hash_ptr(current, KPROBE_HASH_BITS); - raw_spin_lock_irqsave(&rp->lock, flags); - if (!hlist_empty(&rp->free_instances)) { - ri = hlist_entry(rp->free_instances.first, - struct kretprobe_instance, hlist); - hlist_del(&ri->hlist); - raw_spin_unlock_irqrestore(&rp->lock, flags); + if (rp->entry_handler && rp->entry_handler(ri, regs)) { + objpool_push(ri, &rph->pool); + return 0; + } - ri->rp = rp; - ri->task = current; + arch_prepare_kretprobe(ri, regs); - if (rp->entry_handler && rp->entry_handler(ri, regs)) { - raw_spin_lock_irqsave(&rp->lock, flags); - hlist_add_head(&ri->hlist, &rp->free_instances); - raw_spin_unlock_irqrestore(&rp->lock, flags); - return 0; - } + __llist_add(&ri->llist, ¤t->kretprobe_instances); - arch_prepare_kretprobe(ri, regs); + 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; - /* XXX(hch): why is there no hlist_move_head? */ - INIT_HLIST_NODE(&ri->hlist); - kretprobe_table_lock(hash, &flags); - hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]); - kretprobe_table_unlock(hash, &flags); - } else { + rhn = rethook_try_get(rp->rh); + if (!rhn) { rp->nmissed++; - raw_spin_unlock_irqrestore(&rp->lock, flags); + 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); -bool __weak arch_kprobe_on_func_entry(unsigned long offset) +static void kretprobe_rethook_handler(struct rethook_node *rh, void *data, + unsigned long ret_addr, + struct pt_regs *regs) { - return !offset; + 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); -bool kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset) +#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) { - kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset); + bool on_func_entry; + kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset, &on_func_entry); if (IS_ERR(kp_addr)) - return false; + return PTR_ERR(kp_addr); - if (!kallsyms_lookup_size_offset((unsigned long)kp_addr, NULL, &offset) || - !arch_kprobe_on_func_entry(offset)) - return false; + if (!on_func_entry) + return -EINVAL; - return true; + return 0; } int register_kretprobe(struct kretprobe *rp) { - int ret = 0; - struct kretprobe_instance *inst; + int ret; int i; void *addr; - if (!kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset)) + 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) { @@ -1979,36 +2192,49 @@ int register_kretprobe(struct kretprobe *rp) } } + if (rp->data_size > KRETPROBE_MAX_DATA_SIZE) + return -E2BIG; + rp->kp.pre_handler = pre_handler_kretprobe; rp->kp.post_handler = NULL; - rp->kp.fault_handler = NULL; /* Pre-allocate memory for max kretprobe instances */ - if (rp->maxactive <= 0) { -#ifdef CONFIG_PREEMPTION + if (rp->maxactive <= 0) rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus()); -#else - rp->maxactive = num_possible_cpus(); -#endif - } - raw_spin_lock_init(&rp->lock); - INIT_HLIST_HEAD(&rp->free_instances); - for (i = 0; i < rp->maxactive; i++) { - inst = kmalloc(sizeof(struct kretprobe_instance) + - rp->data_size, GFP_KERNEL); - if (inst == NULL) { - free_rp_inst(rp); - return -ENOMEM; - } - INIT_HLIST_NODE(&inst->hlist); - hlist_add_head(&inst->hlist, &rp->free_instances); + +#ifdef CONFIG_KRETPROBE_ON_RETHOOK + rp->rh = rethook_alloc((void *)rp, kretprobe_rethook_handler, + sizeof(struct kretprobe_instance) + + rp->data_size, rp->maxactive); + if (IS_ERR(rp->rh)) + return PTR_ERR(rp->rh); + + 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->rph = kzalloc(sizeof(struct kretprobe_holder), GFP_KERNEL); + if (!rp->rph) + return -ENOMEM; + if (objpool_init(&rp->rph->pool, rp->maxactive, rp->data_size + + sizeof(struct kretprobe_instance), GFP_KERNEL, + rp->rph, kretprobe_init_inst, kretprobe_fini_pool)) { + kfree(rp->rph); + rp->rph = NULL; + return -ENOMEM; + } + rcu_assign_pointer(rp->rph->rp, rp); 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); @@ -2043,17 +2269,25 @@ void unregister_kretprobes(struct kretprobe **rps, int num) if (num <= 0) return; - mutex_lock(&kprobe_mutex); - for (i = 0; i < num; i++) + for (i = 0; i < num; i++) { + guard(mutex)(&kprobe_mutex); + if (__unregister_kprobe_top(&rps[i]->kp) < 0) rps[i]->kp.addr = NULL; - mutex_unlock(&kprobe_mutex); +#ifdef CONFIG_KRETPROBE_ON_RETHOOK + rethook_free(rps[i]->rh); +#else + rcu_assign_pointer(rps[i]->rph->rp, NULL); +#endif + } synchronize_rcu(); for (i = 0; i < num; i++) { if (rps[i]->kp.addr) { __unregister_kprobe_bottom(&rps[i]->kp); - cleanup_rp_inst(rps[i]); +#ifndef CONFIG_KRETPROBE_ON_RETHOOK + free_rp_inst(rps[i]); +#endif } } } @@ -2062,13 +2296,13 @@ EXPORT_SYMBOL_GPL(unregister_kretprobes); #else /* CONFIG_KRETPROBES */ int register_kretprobe(struct kretprobe *rp) { - return -ENOSYS; + return -EOPNOTSUPP; } EXPORT_SYMBOL_GPL(register_kretprobe); int register_kretprobes(struct kretprobe **rps, int num) { - return -ENOSYS; + return -EOPNOTSUPP; } EXPORT_SYMBOL_GPL(register_kretprobes); @@ -2097,6 +2331,14 @@ static void kill_kprobe(struct kprobe *p) lockdep_assert_held(&kprobe_mutex); + /* + * The module is going away. We should disarm the kprobe which + * is using ftrace, because ftrace framework is still available at + * 'MODULE_STATE_GOING' notification. + */ + if (kprobe_ftrace(p) && !kprobe_disabled(p) && !kprobes_all_disarmed) + disarm_kprobe_ftrace(p); + p->flags |= KPROBE_FLAG_GONE; if (kprobe_aggrprobe(p)) { /* @@ -2118,18 +2360,14 @@ static void kill_kprobe(struct kprobe *p) /* Disable one kprobe */ int disable_kprobe(struct kprobe *kp) { - int ret = 0; struct kprobe *p; - mutex_lock(&kprobe_mutex); + guard(mutex)(&kprobe_mutex); /* Disable this kprobe */ p = __disable_kprobe(kp); - if (IS_ERR(p)) - ret = PTR_ERR(p); - mutex_unlock(&kprobe_mutex); - return ret; + return IS_ERR(p) ? PTR_ERR(p) : 0; } EXPORT_SYMBOL_GPL(disable_kprobe); @@ -2139,20 +2377,16 @@ int enable_kprobe(struct kprobe *kp) int ret = 0; struct kprobe *p; - mutex_lock(&kprobe_mutex); + guard(mutex)(&kprobe_mutex); /* Check whether specified probe is valid. */ p = __get_valid_kprobe(kp); - if (unlikely(p == NULL)) { - ret = -EINVAL; - goto out; - } + if (unlikely(p == NULL)) + return -EINVAL; - if (kprobe_gone(kp)) { + if (kprobe_gone(kp)) /* This kprobe has gone, we couldn't enable it. */ - ret = -EINVAL; - goto out; - } + return -EINVAL; if (p != kp) kp->flags &= ~KPROBE_FLAG_DISABLED; @@ -2160,11 +2394,12 @@ int enable_kprobe(struct kprobe *kp) if (!kprobes_all_disarmed && kprobe_disabled(p)) { p->flags &= ~KPROBE_FLAG_DISABLED; ret = arm_kprobe(p); - if (ret) + 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); @@ -2172,8 +2407,7 @@ 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("Dumping kprobe:\n"); - pr_err("Name: %s\nOffset: %x\nAddress: %pS\n", + pr_err("Dump kprobe:\n.symbol_name = %s, .offset = %x, .addr = %pS\n", kp->symbol_name, kp->offset, kp->addr); } NOKPROBE_SYMBOL(dump_kprobe); @@ -2214,22 +2448,26 @@ int kprobe_add_area_blacklist(unsigned long start, unsigned long end) return 0; } -/* Remove all symbols in given area from kprobe blacklist */ -static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end) +int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, + char *type, char *sym) { - 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); - } + return -ERANGE; } -static void kprobe_remove_ksym_blacklist(unsigned long entry) +int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type, + char *sym) { - kprobe_remove_area_blacklist(entry, entry + 1); +#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) @@ -2253,7 +2491,7 @@ static int __init populate_kprobe_blacklist(unsigned long *start, int ret; for (iter = start; iter < end; iter++) { - entry = arch_deref_entry_point((void *)*iter); + entry = (unsigned long)dereference_symbol_descriptor((void *)*iter); ret = kprobe_add_ksym_blacklist(entry); if (ret == -EINVAL) continue; @@ -2261,19 +2499,38 @@ static int __init populate_kprobe_blacklist(unsigned long *start, return ret; } - /* Symbols in __kprobes_text are blacklisted */ + /* 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 */ + /* 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(); } +#ifdef CONFIG_MODULES +/* 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); +} + static void add_module_kprobe_blacklist(struct module *mod) { unsigned long start, end; @@ -2330,21 +2587,20 @@ static int kprobes_module_callback(struct notifier_block *nb, unsigned int i; int checkcore = (val == MODULE_STATE_GOING); - if (val == MODULE_STATE_COMING) { - mutex_lock(&kprobe_mutex); + guard(mutex)(&kprobe_mutex); + + if (val == MODULE_STATE_COMING) 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 + * 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) @@ -2358,16 +2614,15 @@ static int kprobes_module_callback(struct notifier_block *nb, * * Note, this will also move any optimized probes * that are pending to be removed from their - * corresponding lists to the freeing_list and + * corresponding lists to the 'freeing_list' and * will not be touched by the delayed - * kprobe_optimizer work handler. + * kprobe_optimizer() work handler. */ kill_kprobe(p); } } if (val == MODULE_STATE_GOING) remove_module_kprobe_blacklist(mod); - mutex_unlock(&kprobe_mutex); return NOTIFY_DONE; } @@ -2376,28 +2631,50 @@ static struct notifier_block kprobe_module_nb = { .priority = 0 }; -/* Markers of _kprobe_blacklist section */ -extern unsigned long __start_kprobe_blacklist[]; -extern unsigned long __stop_kprobe_blacklist[]; +static int kprobe_register_module_notifier(void) +{ + return register_module_notifier(&kprobe_module_nb); +} +#else +static int kprobe_register_module_notifier(void) +{ + return 0; +} +#endif /* CONFIG_MODULES */ + +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; + + guard(mutex)(&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); + } + } +} static int __init init_kprobes(void) { - int i, err = 0; + int i, err; /* FIXME allocate the probe table, currently defined statically */ /* initialize all list heads */ - for (i = 0; i < KPROBE_TABLE_SIZE; i++) { + for (i = 0; i < KPROBE_TABLE_SIZE; i++) INIT_HLIST_HEAD(&kprobe_table[i]); - INIT_HLIST_HEAD(&kretprobe_inst_table[i]); - raw_spin_lock_init(&(kretprobe_table_locks[i].lock)); - } err = populate_kprobe_blacklist(__start_kprobe_blacklist, __stop_kprobe_blacklist); - if (err) { - pr_err("kprobes: failed to populate blacklist: %d\n", err); - pr_err("Please take care of using kprobes.\n"); - } + 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 */ @@ -2405,36 +2682,45 @@ static int __init init_kprobes(void) kretprobe_blacklist[i].addr = kprobe_lookup_name(kretprobe_blacklist[i].name, 0); if (!kretprobe_blacklist[i].addr) - printk("kretprobe: lookup failed: %s\n", + pr_err("Failed to lookup symbol '%s' for kretprobe blacklist. Maybe the target function is removed or renamed.\n", kretprobe_blacklist[i].name); } } -#if defined(CONFIG_OPTPROBES) -#if defined(__ARCH_WANT_KPROBES_INSN_SLOT) - /* Init kprobe_optinsn_slots */ - kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE; -#endif - /* By default, kprobes can be optimized */ - kprobes_allow_optimization = true; -#endif - /* By default, kprobes are armed */ kprobes_all_disarmed = false; +#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); + err = kprobe_register_module_notifier(); kprobes_initialized = (err == 0); - - if (!err) - init_test_probes(); + kprobe_sysctls_init(); return err; } -subsys_initcall(init_kprobes); +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, @@ -2490,7 +2776,7 @@ static int show_kprobe_addr(struct seq_file *pi, void *v) { struct hlist_head *head; struct kprobe *p, *kp; - const char *sym = NULL; + const char *sym; unsigned int i = *(loff_t *) v; unsigned long offset = 0; char *modname, namebuf[KSYM_NAME_LEN]; @@ -2537,7 +2823,7 @@ static int kprobe_blacklist_seq_show(struct seq_file *m, void *v) list_entry(v, struct kprobe_blacklist_entry, list); /* - * If /proc/kallsyms is not showing kernel address, we won't + * If '/proc/kallsyms' is not showing kernel address, we won't * show them here either. */ if (!kallsyms_show_value(m->file->f_cred)) @@ -2569,11 +2855,11 @@ static int arm_all_kprobes(void) unsigned int i, total = 0, errors = 0; int err, ret = 0; - mutex_lock(&kprobe_mutex); + guard(mutex)(&kprobe_mutex); /* If kprobes are armed, just return */ if (!kprobes_all_disarmed) - goto already_enabled; + return 0; /* * optimize_kprobe() called by arm_kprobe() checks @@ -2598,13 +2884,11 @@ static int arm_all_kprobes(void) } if (errors) - pr_warn("Kprobes globally enabled, but failed to arm %d out of %d probes\n", + 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; } @@ -2615,13 +2899,11 @@ static int disarm_all_kprobes(void) unsigned int i, total = 0, errors = 0; int err, ret = 0; - mutex_lock(&kprobe_mutex); + guard(mutex)(&kprobe_mutex); /* If kprobes are already disarmed, just return */ - if (kprobes_all_disarmed) { - mutex_unlock(&kprobe_mutex); + if (kprobes_all_disarmed) return 0; - } kprobes_all_disarmed = true; @@ -2641,16 +2923,13 @@ static int disarm_all_kprobes(void) } if (errors) - pr_warn("Kprobes globally disabled, but failed to disarm %d out of %d probes\n", + 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(); - + wait_for_kprobe_optimizer_locked(); return ret; } @@ -2676,30 +2955,14 @@ static ssize_t read_enabled_file_bool(struct file *file, static ssize_t write_enabled_file_bool(struct file *file, const char __user *user_buf, size_t count, loff_t *ppos) { - char buf[32]; - size_t buf_size; - int ret = 0; - - buf_size = min(count, (sizeof(buf)-1)); - if (copy_from_user(buf, user_buf, buf_size)) - return -EFAULT; + bool enable; + int ret; - buf[buf_size] = '\0'; - switch (buf[0]) { - case 'y': - case 'Y': - case '1': - ret = arm_all_kprobes(); - break; - case 'n': - case 'N': - case '0': - ret = disarm_all_kprobes(); - break; - default: - return -EINVAL; - } + ret = kstrtobool_from_user(user_buf, count, &enable); + if (ret) + return ret; + ret = enable ? arm_all_kprobes() : disarm_all_kprobes(); if (ret) return ret; @@ -2715,13 +2978,12 @@ static const struct file_operations fops_kp = { static int __init debugfs_kprobe_init(void) { struct dentry *dir; - unsigned int value = 1; dir = debugfs_create_dir("kprobes", NULL); debugfs_create_file("list", 0400, dir, NULL, &kprobes_fops); - debugfs_create_file("enabled", 0600, dir, &value, &fops_kp); + debugfs_create_file("enabled", 0600, dir, NULL, &fops_kp); debugfs_create_file("blacklist", 0400, dir, NULL, &kprobe_blacklist_fops); |