Commit 43994049 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt (Google)
Browse files

kprobes: Fix build errors with CONFIG_KRETPROBES=n 

Max Filippov reported:

When building kernel with CONFIG_KRETPROBES=n kernel/kprobes.c
compilation fails with the following messages:

  kernel/kprobes.c: In function ‘recycle_rp_inst’:
  kernel/kprobes.c:1273:32: error: implicit declaration of function
                                   ‘get_kretprobe’

  kernel/kprobes.c: In function ‘kprobe_flush_task’:
  kernel/kprobes.c:1299:35: error: ‘struct task_struct’ has no member
                                   named ‘kretprobe_instances’

This came from the commit d741bf41 ("kprobes: Remove
kretprobe hash") which introduced get_kretprobe() and
kretprobe_instances member in task_struct when CONFIG_KRETPROBES=y,
but did not make recycle_rp_inst() and kprobe_flush_task()
depending on CONFIG_KRETPORBES.

Since those functions are only used for kretprobe, move those
functions into #ifdef CONFIG_KRETPROBE area.

Link: https://lkml.kernel.org/r/165163539094.74407.3838114721073251225.stgit@devnote2



Reported-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
Fixes: d741bf41 ("kprobes: Remove kretprobe hash")
Cc: "Naveen N . Rao" <naveen.n.rao@linux.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S . Miller" <davem@davemloft.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Tested-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent b27f266f

include/linux/kprobes.h

+1 −1
Original line number Diff line number Diff line
@@ -424,7 +424,7 @@ void unregister_kretprobe(struct kretprobe *rp); 
int register_kretprobes(struct kretprobe **rps, int num);

void unregister_kretprobes(struct kretprobe **rps, int num);



#ifdef CONFIG_KRETPROBE_ON_RETHOOK

#if defined(CONFIG_KRETPROBE_ON_RETHOOK) || !defined(CONFIG_KRETPROBES)

#define kprobe_flush_task(tk)	do {} while (0)

#else

void kprobe_flush_task(struct task_struct *tk);

kernel/kprobes.c

+71 −73
Original line number Diff line number Diff line
@@ -1257,79 +1257,6 @@ void kprobe_busy_end(void) 
	preempt_enable();

}



#if !defined(CONFIG_KRETPROBE_ON_RETHOOK)

static void free_rp_inst_rcu(struct rcu_head *head)

{

	struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu);



	if (refcount_dec_and_test(&ri->rph->ref))

		kfree(ri->rph);

	kfree(ri);

}

NOKPROBE_SYMBOL(free_rp_inst_rcu);



static void recycle_rp_inst(struct kretprobe_instance *ri)

{

	struct kretprobe *rp = get_kretprobe(ri);



	if (likely(rp))

		freelist_add(&ri->freelist, &rp->freelist);

	else

		call_rcu(&ri->rcu, free_rp_inst_rcu);

}

NOKPROBE_SYMBOL(recycle_rp_inst);



/*

 * This function is called from delayed_put_task_struct() when a task is

 * dead and cleaned up to recycle any kretprobe 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 llist_node *node;



	/* Early boot, not yet initialized. */

	if (unlikely(!kprobes_initialized))

		return;



	kprobe_busy_begin();



	node = __llist_del_all(&tk->kretprobe_instances);

	while (node) {

		ri = container_of(node, struct kretprobe_instance, llist);

		node = node->next;



		recycle_rp_inst(ri);

	}



	kprobe_busy_end();

}

NOKPROBE_SYMBOL(kprobe_flush_task);



static inline void free_rp_inst(struct kretprobe *rp)

{

	struct kretprobe_instance *ri;

	struct freelist_node *node;

	int count = 0;



	node = rp->freelist.head;

	while (node) {

		ri = container_of(node, struct kretprobe_instance, freelist);

		node = node->next;



		kfree(ri);

		count++;

	}



	if (refcount_sub_and_test(count, &rp->rph->ref)) {

		kfree(rp->rph);

		rp->rph = NULL;

	}

}

#endif	/* !CONFIG_KRETPROBE_ON_RETHOOK */



/* Add the new probe to 'ap->list'. */

static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)

{
@@ -1928,6 +1855,77 @@ static struct notifier_block kprobe_exceptions_nb = { 
#ifdef CONFIG_KRETPROBES



#if !defined(CONFIG_KRETPROBE_ON_RETHOOK)

static void free_rp_inst_rcu(struct rcu_head *head)

{

	struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu);



	if (refcount_dec_and_test(&ri->rph->ref))

		kfree(ri->rph);

	kfree(ri);

}

NOKPROBE_SYMBOL(free_rp_inst_rcu);



static void recycle_rp_inst(struct kretprobe_instance *ri)

{

	struct kretprobe *rp = get_kretprobe(ri);



	if (likely(rp))

		freelist_add(&ri->freelist, &rp->freelist);

	else

		call_rcu(&ri->rcu, free_rp_inst_rcu);

}

NOKPROBE_SYMBOL(recycle_rp_inst);



/*

 * This function is called from delayed_put_task_struct() when a task is

 * dead and cleaned up to recycle any kretprobe 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 llist_node *node;



	/* Early boot, not yet initialized. */

	if (unlikely(!kprobes_initialized))

		return;



	kprobe_busy_begin();



	node = __llist_del_all(&tk->kretprobe_instances);

	while (node) {

		ri = container_of(node, struct kretprobe_instance, llist);

		node = node->next;



		recycle_rp_inst(ri);

	}



	kprobe_busy_end();

}

NOKPROBE_SYMBOL(kprobe_flush_task);



static inline void free_rp_inst(struct kretprobe *rp)

{

	struct kretprobe_instance *ri;

	struct freelist_node *node;

	int count = 0;



	node = rp->freelist.head;

	while (node) {

		ri = container_of(node, struct kretprobe_instance, freelist);

		node = node->next;



		kfree(ri);

		count++;

	}



	if (refcount_sub_and_test(count, &rp->rph->ref)) {

		kfree(rp->rph);

		rp->rph = NULL;

	}

}



/* This assumes the 'tsk' is the current task or the is not running. */

static kprobe_opcode_t *__kretprobe_find_ret_addr(struct task_struct *tsk,

						  struct llist_node **cur)