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