+/*
+ * Aggregate handlers for multiple kprobes support - these handlers
+ * take care of invoking the individual kprobe handlers on p->list
+ */
+static 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;
+ if (kp->pre_handler(kp, regs))
+ return 1;
+ }
+ curr_kprobe = NULL;
+ }
+ return 0;
+}
+
+static 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;
+}
+
+static 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;
+}
+
+static int 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;
+ }
+ }
+ curr_kprobe = NULL;
+ return 0;
+}
+
+struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp)
+{
+ struct hlist_node *node;
+ struct kretprobe_instance *ri;
+ hlist_for_each_entry(ri, node, &rp->free_instances, uflist)
+ return ri;
+ return NULL;
+}
+
+static struct kretprobe_instance *get_used_rp_inst(struct kretprobe *rp)
+{
+ struct hlist_node *node;
+ struct kretprobe_instance *ri;
+ hlist_for_each_entry(ri, node, &rp->used_instances, uflist)
+ return ri;
+ return NULL;
+}
+
+void add_rp_inst(struct kretprobe_instance *ri)
+{
+ /*
+ * Remove rp inst off the free list -
+ * Add it back when probed function returns
+ */
+ hlist_del(&ri->uflist);
+
+ /* Add rp inst onto table */
+ INIT_HLIST_NODE(&ri->hlist);
+ hlist_add_head(&ri->hlist,
+ &kretprobe_inst_table[hash_ptr(ri->task, KPROBE_HASH_BITS)]);
+
+ /* Also add this rp inst to the used list. */
+ INIT_HLIST_NODE(&ri->uflist);
+ hlist_add_head(&ri->uflist, &ri->rp->used_instances);
+}
+
+void recycle_rp_inst(struct kretprobe_instance *ri)
+{
+ /* remove rp inst off the rprobe_inst_table */
+ hlist_del(&ri->hlist);
+ if (ri->rp) {
+ /* remove rp inst off the used list */
+ hlist_del(&ri->uflist);
+ /* put rp inst back onto the free list */
+ INIT_HLIST_NODE(&ri->uflist);
+ hlist_add_head(&ri->uflist, &ri->rp->free_instances);
+ } else
+ /* Unregistering */
+ kfree(ri);
+}
+
+struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk)
+{
+ return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
+}
+
+/*
+ * This function is called from exit_thread or flush_thread when task tk's
+ * stack is being recycled 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;
+ struct hlist_node *node, *tmp;
+ unsigned long flags = 0;
+
+ spin_lock_irqsave(&kprobe_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);
+}
+
+/*
+ * 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);
+
+ /*TODO: consider to only swap the RA after the last pre_handler fired */
+ arch_prepare_kretprobe(rp, regs);
+ return 0;
+}
+
+static inline void free_rp_inst(struct kretprobe *rp)
+{
+ struct kretprobe_instance *ri;
+ while ((ri = get_free_rp_inst(rp)) != NULL) {
+ hlist_del(&ri->uflist);
+ kfree(ri);
+ }
+}
+
+/*
+ * Keep all fields in the kprobe consistent
+ */
+static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
+{
+ memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
+ memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
+}
+
+/*
+* Add the new probe to old_p->list. Fail if this is the
+* second jprobe at the address - two jprobes can't coexist
+*/
+static int 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) {
+ if (kp->break_handler)
+ return -EEXIST;
+ }
+ list_add_tail(&p->list, &old_p->list);
+ } else
+ list_add(&p->list, &old_p->list);
+ 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)
+{
+ copy_kprobe(p, ap);
+ ap->addr = p->addr;
+ ap->pre_handler = aggr_pre_handler;
+ ap->post_handler = aggr_post_handler;
+ ap->fault_handler = aggr_fault_handler;
+ ap->break_handler = aggr_break_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->pre_handler == aggr_pre_handler) {
+ copy_kprobe(old_p, p);
+ ret = add_new_kprobe(old_p, p);
+ } else {
+ ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC);
+ if (!ap)
+ return -ENOMEM;
+ add_aggr_kprobe(ap, old_p);
+ copy_kprobe(ap, p);
+ ret = add_new_kprobe(ap, 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(&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(&p->list);
+ if (list_empty(&old_p->list)) {
+ cleanup_kprobe(old_p, flags);
+ kfree(old_p);
+ } else
+ spin_unlock_irqrestore(&kprobe_lock, flags);
+}
+