diff options
Diffstat (limited to 'kernel/kprobes.c')
-rw-r--r-- | kernel/kprobes.c | 135 |
1 files changed, 65 insertions, 70 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index f3ea492ab44..5beda378cc7 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -32,9 +32,9 @@ * <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> #include <linux/module.h> #include <linux/moduleloader.h> #include <asm-generic/sections.h> @@ -48,9 +48,9 @@ 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 struct kprobe *curr_kprobe; +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; /* * kprobe->ainsn.insn points to the copy of the instruction to be @@ -152,50 +152,31 @@ void __kprobes free_insn_slot(kprobe_opcode_t *slot) } } -/* Locks kprobe: irqs must be disabled */ -void __kprobes lock_kprobes(void) +/* We have preemption disabled.. so it is safe to use __ versions */ +static inline void set_kprobe_instance(struct kprobe *kp) { - 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); + __get_cpu_var(kprobe_instance) = kp; } -void __kprobes unlock_kprobes(void) +static inline void reset_kprobe_instance(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); + __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 + * - with preemption disabled - 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; } @@ -210,13 +191,13 @@ 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) { - curr_kprobe = kp; + set_kprobe_instance(kp); if (kp->pre_handler(kp, regs)) return 1; } - curr_kprobe = NULL; + reset_kprobe_instance(); } return 0; } @@ -226,11 +207,11 @@ 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) { - curr_kprobe = kp; + set_kprobe_instance(kp); kp->post_handler(kp, regs, flags); - curr_kprobe = NULL; + reset_kprobe_instance(); } } return; @@ -239,12 +220,14 @@ static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs, static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, int trapnr) { + struct kprobe *cur = __get_cpu_var(kprobe_instance); + /* * 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)) + if (cur && cur->fault_handler) { + if (cur->fault_handler(cur, regs, trapnr)) return 1; } return 0; @@ -252,17 +235,18 @@ static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs) { - struct kprobe *kp = curr_kprobe; - if (curr_kprobe && kp->break_handler) { - if (kp->break_handler(kp, regs)) { - curr_kprobe = NULL; - return 1; - } + struct kprobe *cur = __get_cpu_var(kprobe_instance); + int ret = 0; + + if (cur && cur->break_handler) { + if (cur->break_handler(cur, regs)) + ret = 1; } - curr_kprobe = NULL; - return 0; + reset_kprobe_instance(); + return ret; } +/* Called with kretprobe_lock held */ struct kretprobe_instance __kprobes *get_free_rp_inst(struct kretprobe *rp) { struct hlist_node *node; @@ -272,6 +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) { @@ -282,6 +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) { /* @@ -300,6 +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 */ @@ -333,13 +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); } /* @@ -350,9 +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; } @@ -383,13 +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; } @@ -407,18 +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) @@ -444,7 +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); } @@ -452,11 +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); } @@ -479,9 +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; @@ -489,7 +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); @@ -510,10 +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); } @@ -590,13 +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) |