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-rw-r--r--kernel/kprobes.c213
1 files changed, 208 insertions, 5 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 037142b72a4..692fbf75ab4 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -27,6 +27,9 @@
* interface to access function arguments.
* 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
* exceptions notifier to be first on the priority list.
+ * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
+ * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
+ * <prasanna@in.ibm.com> added function-return probes.
*/
#include <linux/kprobes.h>
#include <linux/spinlock.h>
@@ -41,6 +44,7 @@
#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
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);
@@ -78,7 +82,7 @@ struct kprobe *get_kprobe(void *addr)
* 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)
+static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
struct kprobe *kp;
@@ -92,8 +96,8 @@ int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
return 0;
}
-void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
- unsigned long flags)
+static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
+ unsigned long flags)
{
struct kprobe *kp;
@@ -107,7 +111,8 @@ void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
return;
}
-int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, int trapnr)
+static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
+ int trapnr)
{
/*
* if we faulted "during" the execution of a user specified
@@ -120,6 +125,135 @@ int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, int trapnr)
return 0;
}
+struct kprobe trampoline_p = {
+ .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
+ .pre_handler = trampoline_probe_handler,
+ .post_handler = trampoline_post_handler
+};
+
+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;
+}
+
+struct kretprobe_instance *get_rp_inst(void *sara)
+{
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct task_struct *tsk;
+ struct kretprobe_instance *ri;
+
+ tsk = arch_get_kprobe_task(sara);
+ head = &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
+ hlist_for_each_entry(ri, node, head, hlist) {
+ if (ri->stack_addr == sara)
+ return ri;
+ }
+ return NULL;
+}
+
+void add_rp_inst(struct kretprobe_instance *ri)
+{
+ struct task_struct *tsk;
+ /*
+ * Remove rp inst off the free list -
+ * Add it back when probed function returns
+ */
+ hlist_del(&ri->uflist);
+ tsk = arch_get_kprobe_task(ri->stack_addr);
+ /* Add rp inst onto table */
+ INIT_HLIST_NODE(&ri->hlist);
+ hlist_add_head(&ri->hlist,
+ &kretprobe_inst_table[hash_ptr(tsk, 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)];
+}
+
+struct kretprobe_instance *get_rp_inst_tsk(struct task_struct *tk)
+{
+ struct task_struct *tsk;
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct kretprobe_instance *ri;
+
+ head = &kretprobe_inst_table[hash_ptr(tk, KPROBE_HASH_BITS)];
+
+ hlist_for_each_entry(ri, node, head, hlist) {
+ tsk = arch_get_kprobe_task(ri->stack_addr);
+ if (tsk == tk)
+ return ri;
+ }
+ return NULL;
+}
+
+/*
+ * This function is called from do_exit or do_execv when task tk's stack is
+ * about to be recycled. Recycle any function-return probe instances
+ * associated with this task. These represent probed functions that have
+ * been called but may never return.
+ */
+void kprobe_flush_task(struct task_struct *tk)
+{
+ arch_kprobe_flush_task(tk, &kprobe_lock);
+}
+
+/*
+ * 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);
+ }
+}
+
/*
* Fill in the required fields of the "manager kprobe". Replace the
* earlier kprobe in the hlist with the manager kprobe
@@ -257,16 +391,82 @@ void unregister_jprobe(struct jprobe *jp)
unregister_kprobe(&jp->kp);
}
+#ifdef ARCH_SUPPORTS_KRETPROBES
+
+int register_kretprobe(struct kretprobe *rp)
+{
+ int ret = 0;
+ struct kretprobe_instance *inst;
+ int i;
+
+ rp->kp.pre_handler = pre_handler_kretprobe;
+
+ /* Pre-allocate memory for max kretprobe instances */
+ if (rp->maxactive <= 0) {
+#ifdef CONFIG_PREEMPT
+ rp->maxactive = max(10, 2 * NR_CPUS);
+#else
+ rp->maxactive = NR_CPUS;
+#endif
+ }
+ INIT_HLIST_HEAD(&rp->used_instances);
+ INIT_HLIST_HEAD(&rp->free_instances);
+ for (i = 0; i < rp->maxactive; i++) {
+ inst = kmalloc(sizeof(struct kretprobe_instance), GFP_KERNEL);
+ if (inst == NULL) {
+ free_rp_inst(rp);
+ return -ENOMEM;
+ }
+ INIT_HLIST_NODE(&inst->uflist);
+ hlist_add_head(&inst->uflist, &rp->free_instances);
+ }
+
+ rp->nmissed = 0;
+ /* Establish function entry probe point */
+ if ((ret = register_kprobe(&rp->kp)) != 0)
+ free_rp_inst(rp);
+ return ret;
+}
+
+#else /* ARCH_SUPPORTS_KRETPROBES */
+
+int register_kretprobe(struct kretprobe *rp)
+{
+ return -ENOSYS;
+}
+
+#endif /* ARCH_SUPPORTS_KRETPROBES */
+
+void unregister_kretprobe(struct kretprobe *rp)
+{
+ unsigned long flags;
+ struct kretprobe_instance *ri;
+
+ unregister_kprobe(&rp->kp);
+ /* No race here */
+ spin_lock_irqsave(&kprobe_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);
+}
+
static int __init init_kprobes(void)
{
int i, err = 0;
/* FIXME allocate the probe table, currently defined statically */
/* initialize all list heads */
- for (i = 0; i < KPROBE_TABLE_SIZE; i++)
+ for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
INIT_HLIST_HEAD(&kprobe_table[i]);
+ INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
+ }
err = register_die_notifier(&kprobe_exceptions_nb);
+ /* Register the trampoline probe for return probe */
+ register_kprobe(&trampoline_p);
return err;
}
@@ -277,3 +477,6 @@ EXPORT_SYMBOL_GPL(unregister_kprobe);
EXPORT_SYMBOL_GPL(register_jprobe);
EXPORT_SYMBOL_GPL(unregister_jprobe);
EXPORT_SYMBOL_GPL(jprobe_return);
+EXPORT_SYMBOL_GPL(register_kretprobe);
+EXPORT_SYMBOL_GPL(unregister_kretprobe);
+