diff options
Diffstat (limited to 'kernel/kprobes.c')
| -rw-r--r-- | kernel/kprobes.c | 137 |
1 files changed, 79 insertions, 58 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 3bb71e63a37e0..3ea6325228daf 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -48,10 +48,11 @@ static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; -static DEFINE_SPINLOCK(kprobe_lock); /* Protects kprobe_table */ +DECLARE_MUTEX(kprobe_mutex); /* Protects kprobe_table */ DEFINE_SPINLOCK(kretprobe_lock); /* Protects kretprobe_inst_table */ static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL; +#ifdef __ARCH_WANT_KPROBES_INSN_SLOT /* * kprobe->ainsn.insn points to the copy of the instruction to be * single-stepped. x86_64, POWER4 and above have no-exec support and @@ -151,6 +152,7 @@ void __kprobes free_insn_slot(kprobe_opcode_t *slot) } } } +#endif /* We have preemption disabled.. so it is safe to use __ versions */ static inline void set_kprobe_instance(struct kprobe *kp) @@ -165,7 +167,7 @@ static inline void reset_kprobe_instance(void) /* * This routine is called either: - * - under the kprobe_lock spinlock - during kprobe_[un]register() + * - under the kprobe_mutex - during kprobe_[un]register() * OR * - with preemption disabled - from arch/xxx/kernel/kprobes.c */ @@ -418,7 +420,6 @@ static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p) /* * This is the second or subsequent kprobe at the address - handle * the intricacies - * TODO: Move kcalloc outside the spin_lock */ static int __kprobes register_aggr_kprobe(struct kprobe *old_p, struct kprobe *p) @@ -430,7 +431,7 @@ static int __kprobes register_aggr_kprobe(struct kprobe *old_p, copy_kprobe(old_p, p); ret = add_new_kprobe(old_p, p); } else { - ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC); + ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL); if (!ap) return -ENOMEM; add_aggr_kprobe(ap, old_p); @@ -440,25 +441,6 @@ static int __kprobes register_aggr_kprobe(struct kprobe *old_p, return ret; } -/* kprobe removal house-keeping routines */ -static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags) -{ - arch_disarm_kprobe(p); - hlist_del_rcu(&p->hlist); - spin_unlock_irqrestore(&kprobe_lock, flags); - arch_remove_kprobe(p); -} - -static inline void cleanup_aggr_kprobe(struct kprobe *old_p, - struct kprobe *p, unsigned long flags) -{ - list_del_rcu(&p->list); - if (list_empty(&old_p->list)) - cleanup_kprobe(old_p, flags); - else - spin_unlock_irqrestore(&kprobe_lock, flags); -} - static int __kprobes in_kprobes_functions(unsigned long addr) { if (addr >= (unsigned long)__kprobes_text_start @@ -467,33 +449,44 @@ static int __kprobes in_kprobes_functions(unsigned long addr) return 0; } -int __kprobes register_kprobe(struct kprobe *p) +static int __kprobes __register_kprobe(struct kprobe *p, + unsigned long called_from) { int ret = 0; - unsigned long flags = 0; struct kprobe *old_p; - struct module *mod; + struct module *probed_mod; if ((!kernel_text_address((unsigned long) p->addr)) || in_kprobes_functions((unsigned long) p->addr)) return -EINVAL; - if ((mod = module_text_address((unsigned long) p->addr)) && - (unlikely(!try_module_get(mod)))) - return -EINVAL; - - if ((ret = arch_prepare_kprobe(p)) != 0) - goto rm_kprobe; + p->mod_refcounted = 0; + /* Check are we probing a module */ + if ((probed_mod = module_text_address((unsigned long) p->addr))) { + struct module *calling_mod = module_text_address(called_from); + /* We must allow modules to probe themself and + * in this case avoid incrementing the module refcount, + * so as to allow unloading of self probing modules. + */ + if (calling_mod && (calling_mod != probed_mod)) { + if (unlikely(!try_module_get(probed_mod))) + return -EINVAL; + p->mod_refcounted = 1; + } else + probed_mod = NULL; + } p->nmissed = 0; - spin_lock_irqsave(&kprobe_lock, flags); + down(&kprobe_mutex); old_p = get_kprobe(p->addr); if (old_p) { ret = register_aggr_kprobe(old_p, p); goto out; } - arch_copy_kprobe(p); + if ((ret = arch_prepare_kprobe(p)) != 0) + goto out; + INIT_HLIST_NODE(&p->hlist); hlist_add_head_rcu(&p->hlist, &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); @@ -501,40 +494,66 @@ int __kprobes register_kprobe(struct kprobe *p) arch_arm_kprobe(p); out: - spin_unlock_irqrestore(&kprobe_lock, flags); -rm_kprobe: - if (ret == -EEXIST) - arch_remove_kprobe(p); - if (ret && mod) - module_put(mod); + up(&kprobe_mutex); + + if (ret && probed_mod) + module_put(probed_mod); return ret; } +int __kprobes register_kprobe(struct kprobe *p) +{ + return __register_kprobe(p, + (unsigned long)__builtin_return_address(0)); +} + void __kprobes unregister_kprobe(struct kprobe *p) { - unsigned long flags; - struct kprobe *old_p; struct module *mod; + struct kprobe *old_p, *list_p; + int cleanup_p; - spin_lock_irqsave(&kprobe_lock, flags); + down(&kprobe_mutex); old_p = get_kprobe(p->addr); - if (old_p) { - /* cleanup_*_kprobe() does the spin_unlock_irqrestore */ - if (old_p->pre_handler == aggr_pre_handler) - cleanup_aggr_kprobe(old_p, p, flags); - else - cleanup_kprobe(p, flags); + if (unlikely(!old_p)) { + up(&kprobe_mutex); + return; + } + if (p != old_p) { + list_for_each_entry_rcu(list_p, &old_p->list, list) + if (list_p == p) + /* kprobe p is a valid probe */ + goto valid_p; + up(&kprobe_mutex); + return; + } +valid_p: + if ((old_p == p) || ((old_p->pre_handler == aggr_pre_handler) && + (p->list.next == &old_p->list) && + (p->list.prev == &old_p->list))) { + /* Only probe on the hash list */ + arch_disarm_kprobe(p); + hlist_del_rcu(&old_p->hlist); + cleanup_p = 1; + } else { + list_del_rcu(&p->list); + cleanup_p = 0; + } - synchronize_sched(); + up(&kprobe_mutex); - if ((mod = module_text_address((unsigned long)p->addr))) - module_put(mod); + synchronize_sched(); + if (p->mod_refcounted && + (mod = module_text_address((unsigned long)p->addr))) + module_put(mod); - if (old_p->pre_handler == aggr_pre_handler && - list_empty(&old_p->list)) + if (cleanup_p) { + if (p != old_p) { + list_del_rcu(&p->list); kfree(old_p); - } else - spin_unlock_irqrestore(&kprobe_lock, flags); + } + arch_remove_kprobe(p); + } } static struct notifier_block kprobe_exceptions_nb = { @@ -548,7 +567,8 @@ int __kprobes register_jprobe(struct jprobe *jp) jp->kp.pre_handler = setjmp_pre_handler; jp->kp.break_handler = longjmp_break_handler; - return register_kprobe(&jp->kp); + return __register_kprobe(&jp->kp, + (unsigned long)__builtin_return_address(0)); } void __kprobes unregister_jprobe(struct jprobe *jp) @@ -588,7 +608,8 @@ int __kprobes register_kretprobe(struct kretprobe *rp) rp->nmissed = 0; /* Establish function entry probe point */ - if ((ret = register_kprobe(&rp->kp)) != 0) + if ((ret = __register_kprobe(&rp->kp, + (unsigned long)__builtin_return_address(0))) != 0) free_rp_inst(rp); return ret; } |