diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/kprobes.c | 103 |
1 files changed, 42 insertions, 61 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 6da8f9b33d1..cfef426e4cd 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -32,7 +32,6 @@ * <prasanna@in.ibm.com> added function-return probes. */ #include <linux/kprobes.h> -#include <linux/spinlock.h> #include <linux/hash.h> #include <linux/init.h> #include <linux/slab.h> @@ -49,8 +48,8 @@ static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; -unsigned int kprobe_cpu = NR_CPUS; -static DEFINE_SPINLOCK(kprobe_lock); +static DEFINE_SPINLOCK(kprobe_lock); /* Protects kprobe_table */ +DEFINE_SPINLOCK(kretprobe_lock); /* Protects kretprobe_inst_table */ static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL; /* @@ -153,41 +152,6 @@ void __kprobes free_insn_slot(kprobe_opcode_t *slot) } } -/* Locks kprobe: irqs must be disabled */ -void __kprobes lock_kprobes(void) -{ - unsigned long flags = 0; - - /* Avoiding local interrupts to happen right after we take the kprobe_lock - * and before we get a chance to update kprobe_cpu, this to prevent - * deadlock when we have a kprobe on ISR routine and a kprobe on task - * routine - */ - local_irq_save(flags); - - spin_lock(&kprobe_lock); - kprobe_cpu = smp_processor_id(); - - local_irq_restore(flags); -} - -void __kprobes unlock_kprobes(void) -{ - unsigned long flags = 0; - - /* Avoiding local interrupts to happen right after we update - * kprobe_cpu and before we get a a chance to release kprobe_lock, - * this to prevent deadlock when we have a kprobe on ISR routine and - * a kprobe on task routine - */ - local_irq_save(flags); - - kprobe_cpu = NR_CPUS; - spin_unlock(&kprobe_lock); - - local_irq_restore(flags); -} - /* We have preemption disabled.. so it is safe to use __ versions */ static inline void set_kprobe_instance(struct kprobe *kp) { @@ -199,15 +163,20 @@ static inline void reset_kprobe_instance(void) __get_cpu_var(kprobe_instance) = NULL; } -/* You have to be holding the kprobe_lock */ +/* + * This routine is called either: + * - under the kprobe_lock spinlock - during kprobe_[un]register() + * OR + * - under an rcu_read_lock() - from arch/xxx/kernel/kprobes.c + */ struct kprobe __kprobes *get_kprobe(void *addr) { struct hlist_head *head; struct hlist_node *node; + struct kprobe *p; head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; - hlist_for_each(node, head) { - struct kprobe *p = hlist_entry(node, struct kprobe, hlist); + hlist_for_each_entry_rcu(p, node, head, hlist) { if (p->addr == addr) return p; } @@ -222,7 +191,7 @@ static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs) { struct kprobe *kp; - list_for_each_entry(kp, &p->list, list) { + list_for_each_entry_rcu(kp, &p->list, list) { if (kp->pre_handler) { set_kprobe_instance(kp); if (kp->pre_handler(kp, regs)) @@ -238,7 +207,7 @@ static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs, { struct kprobe *kp; - list_for_each_entry(kp, &p->list, list) { + list_for_each_entry_rcu(kp, &p->list, list) { if (kp->post_handler) { set_kprobe_instance(kp); kp->post_handler(kp, regs, flags); @@ -277,6 +246,7 @@ static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs) return ret; } +/* Called with kretprobe_lock held */ struct kretprobe_instance __kprobes *get_free_rp_inst(struct kretprobe *rp) { struct hlist_node *node; @@ -286,6 +256,7 @@ struct kretprobe_instance __kprobes *get_free_rp_inst(struct kretprobe *rp) return NULL; } +/* Called with kretprobe_lock held */ static struct kretprobe_instance __kprobes *get_used_rp_inst(struct kretprobe *rp) { @@ -296,6 +267,7 @@ static struct kretprobe_instance __kprobes *get_used_rp_inst(struct kretprobe return NULL; } +/* Called with kretprobe_lock held */ void __kprobes add_rp_inst(struct kretprobe_instance *ri) { /* @@ -314,6 +286,7 @@ void __kprobes add_rp_inst(struct kretprobe_instance *ri) hlist_add_head(&ri->uflist, &ri->rp->used_instances); } +/* Called with kretprobe_lock held */ void __kprobes recycle_rp_inst(struct kretprobe_instance *ri) { /* remove rp inst off the rprobe_inst_table */ @@ -347,13 +320,13 @@ void __kprobes kprobe_flush_task(struct task_struct *tk) struct hlist_node *node, *tmp; unsigned long flags = 0; - spin_lock_irqsave(&kprobe_lock, flags); + spin_lock_irqsave(&kretprobe_lock, flags); head = kretprobe_inst_table_head(current); hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { if (ri->task == tk) recycle_rp_inst(ri); } - spin_unlock_irqrestore(&kprobe_lock, flags); + spin_unlock_irqrestore(&kretprobe_lock, flags); } /* @@ -364,9 +337,12 @@ static int __kprobes pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) { struct kretprobe *rp = container_of(p, struct kretprobe, kp); + unsigned long flags = 0; /*TODO: consider to only swap the RA after the last pre_handler fired */ + spin_lock_irqsave(&kretprobe_lock, flags); arch_prepare_kretprobe(rp, regs); + spin_unlock_irqrestore(&kretprobe_lock, flags); return 0; } @@ -397,13 +373,13 @@ static int __kprobes add_new_kprobe(struct kprobe *old_p, struct kprobe *p) struct kprobe *kp; if (p->break_handler) { - list_for_each_entry(kp, &old_p->list, list) { + list_for_each_entry_rcu(kp, &old_p->list, list) { if (kp->break_handler) return -EEXIST; } - list_add_tail(&p->list, &old_p->list); + list_add_tail_rcu(&p->list, &old_p->list); } else - list_add(&p->list, &old_p->list); + list_add_rcu(&p->list, &old_p->list); return 0; } @@ -421,18 +397,18 @@ static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p) ap->break_handler = aggr_break_handler; INIT_LIST_HEAD(&ap->list); - list_add(&p->list, &ap->list); + list_add_rcu(&p->list, &ap->list); INIT_HLIST_NODE(&ap->hlist); - hlist_del(&p->hlist); - hlist_add_head(&ap->hlist, + hlist_del_rcu(&p->hlist); + hlist_add_head_rcu(&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 + * TODO: Move kcalloc outside the spin_lock */ static int __kprobes register_aggr_kprobe(struct kprobe *old_p, struct kprobe *p) @@ -458,7 +434,7 @@ static int __kprobes register_aggr_kprobe(struct kprobe *old_p, static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags) { arch_disarm_kprobe(p); - hlist_del(&p->hlist); + hlist_del_rcu(&p->hlist); spin_unlock_irqrestore(&kprobe_lock, flags); arch_remove_kprobe(p); } @@ -466,11 +442,10 @@ static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags) 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)) { + list_del_rcu(&p->list); + if (list_empty(&old_p->list)) cleanup_kprobe(old_p, flags); - kfree(old_p); - } else + else spin_unlock_irqrestore(&kprobe_lock, flags); } @@ -493,9 +468,9 @@ int __kprobes register_kprobe(struct kprobe *p) if ((ret = arch_prepare_kprobe(p)) != 0) goto rm_kprobe; + p->nmissed = 0; spin_lock_irqsave(&kprobe_lock, flags); old_p = get_kprobe(p->addr); - p->nmissed = 0; if (old_p) { ret = register_aggr_kprobe(old_p, p); goto out; @@ -503,7 +478,7 @@ int __kprobes register_kprobe(struct kprobe *p) arch_copy_kprobe(p); INIT_HLIST_NODE(&p->hlist); - hlist_add_head(&p->hlist, + hlist_add_head_rcu(&p->hlist, &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); arch_arm_kprobe(p); @@ -524,10 +499,16 @@ void __kprobes unregister_kprobe(struct kprobe *p) spin_lock_irqsave(&kprobe_lock, flags); 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); + + synchronize_sched(); + if (old_p->pre_handler == aggr_pre_handler && + list_empty(&old_p->list)) + kfree(old_p); } else spin_unlock_irqrestore(&kprobe_lock, flags); } @@ -604,13 +585,13 @@ void __kprobes unregister_kretprobe(struct kretprobe *rp) unregister_kprobe(&rp->kp); /* No race here */ - spin_lock_irqsave(&kprobe_lock, flags); + spin_lock_irqsave(&kretprobe_lock, flags); free_rp_inst(rp); while ((ri = get_used_rp_inst(rp)) != NULL) { ri->rp = NULL; hlist_del(&ri->uflist); } - spin_unlock_irqrestore(&kprobe_lock, flags); + spin_unlock_irqrestore(&kretprobe_lock, flags); } static int __init init_kprobes(void) |