diff options
| -rw-r--r-- | include/linux/kprobes.h | 3 | ||||
| -rw-r--r-- | kernel/kprobes.c | 144 |
2 files changed, 134 insertions, 13 deletions
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index f20c163..99ddba5 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -43,6 +43,9 @@ typedef int (*kprobe_fault_handler_t) (struct kprobe *, struct pt_regs *, struct kprobe { struct hlist_node hlist; + /* list of kprobes for multi-handler support */ + struct list_head list; + /* location of the probe point */ kprobe_opcode_t *addr; diff --git a/kernel/kprobes.c b/kernel/kprobes.c index d8903e6..037142b7 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -44,6 +44,7 @@ static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; unsigned int kprobe_cpu = NR_CPUS; static DEFINE_SPINLOCK(kprobe_lock); +static struct kprobe *curr_kprobe; /* Locks kprobe: irqs must be disabled */ void lock_kprobes(void) @@ -73,22 +74,139 @@ struct kprobe *get_kprobe(void *addr) return NULL; } +/* + * Aggregate handlers for multiple kprobes support - these handlers + * take care of invoking the individual kprobe handlers on p->list + */ +int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs) +{ + struct kprobe *kp; + + list_for_each_entry(kp, &p->list, list) { + if (kp->pre_handler) { + curr_kprobe = kp; + kp->pre_handler(kp, regs); + curr_kprobe = NULL; + } + } + return 0; +} + +void aggr_post_handler(struct kprobe *p, struct pt_regs *regs, + unsigned long flags) +{ + struct kprobe *kp; + + list_for_each_entry(kp, &p->list, list) { + if (kp->post_handler) { + curr_kprobe = kp; + kp->post_handler(kp, regs, flags); + curr_kprobe = NULL; + } + } + return; +} + +int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, int trapnr) +{ + /* + * if we faulted "during" the execution of a user specified + * probe handler, invoke just that probe's fault handler + */ + if (curr_kprobe && curr_kprobe->fault_handler) { + if (curr_kprobe->fault_handler(curr_kprobe, regs, trapnr)) + return 1; + } + return 0; +} + +/* + * Fill in the required fields of the "manager kprobe". Replace the + * earlier kprobe in the hlist with the manager kprobe + */ +static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p) +{ + ap->addr = p->addr; + ap->opcode = p->opcode; + memcpy(&ap->ainsn, &p->ainsn, sizeof(struct arch_specific_insn)); + + ap->pre_handler = aggr_pre_handler; + ap->post_handler = aggr_post_handler; + ap->fault_handler = aggr_fault_handler; + + INIT_LIST_HEAD(&ap->list); + list_add(&p->list, &ap->list); + + INIT_HLIST_NODE(&ap->hlist); + hlist_del(&p->hlist); + hlist_add_head(&ap->hlist, + &kprobe_table[hash_ptr(ap->addr, KPROBE_HASH_BITS)]); +} + +/* + * This is the second or subsequent kprobe at the address - handle + * the intricacies + * TODO: Move kcalloc outside the spinlock + */ +static int register_aggr_kprobe(struct kprobe *old_p, struct kprobe *p) +{ + int ret = 0; + struct kprobe *ap; + + if (old_p->break_handler || p->break_handler) { + ret = -EEXIST; /* kprobe and jprobe can't (yet) coexist */ + } else if (old_p->pre_handler == aggr_pre_handler) { + list_add(&p->list, &old_p->list); + } else { + ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC); + if (!ap) + return -ENOMEM; + add_aggr_kprobe(ap, old_p); + list_add(&p->list, &ap->list); + } + return ret; +} + +/* kprobe removal house-keeping routines */ +static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags) +{ + *p->addr = p->opcode; + hlist_del(&p->hlist); + flush_icache_range((unsigned long) p->addr, + (unsigned long) p->addr + sizeof(kprobe_opcode_t)); + 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(&p->list); + if (list_empty(&old_p->list)) { + cleanup_kprobe(old_p, flags); + kfree(old_p); + } else + spin_unlock_irqrestore(&kprobe_lock, flags); +} + int register_kprobe(struct kprobe *p) { int ret = 0; unsigned long flags = 0; + struct kprobe *old_p; if ((ret = arch_prepare_kprobe(p)) != 0) { goto rm_kprobe; } spin_lock_irqsave(&kprobe_lock, flags); - INIT_HLIST_NODE(&p->hlist); - if (get_kprobe(p->addr)) { - ret = -EEXIST; + old_p = get_kprobe(p->addr); + if (old_p) { + ret = register_aggr_kprobe(old_p, p); goto out; } - arch_copy_kprobe(p); + arch_copy_kprobe(p); + INIT_HLIST_NODE(&p->hlist); hlist_add_head(&p->hlist, &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); @@ -107,17 +225,17 @@ rm_kprobe: void unregister_kprobe(struct kprobe *p) { unsigned long flags; + struct kprobe *old_p; + spin_lock_irqsave(&kprobe_lock, flags); - if (!get_kprobe(p->addr)) { + old_p = get_kprobe(p->addr); + if (old_p) { + if (old_p->pre_handler == aggr_pre_handler) + cleanup_aggr_kprobe(old_p, p, flags); + else + cleanup_kprobe(p, flags); + } else spin_unlock_irqrestore(&kprobe_lock, flags); - return; - } - *p->addr = p->opcode; - hlist_del(&p->hlist); - flush_icache_range((unsigned long) p->addr, - (unsigned long) p->addr + sizeof(kprobe_opcode_t)); - spin_unlock_irqrestore(&kprobe_lock, flags); - arch_remove_kprobe(p); } static struct notifier_block kprobe_exceptions_nb = { |
