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Commit d3380de4 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Greg Kroah-Hartman
Browse files

ia64: kprobes: Use generic kretprobe trampoline handler 



[ Upstream commit e792ff804f49720ce003b3e4c618b5d996256a18 ]

Use the generic kretprobe trampoline handler. Don't use
framepointer verification.

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/159870606883.1229682.12331813108378725668.stgit@devnote2


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 040b5319

arch/ia64/kernel/kprobes.c

+2 −75
Original line number Diff line number Diff line
@@ -409,83 +409,9 @@ static void kretprobe_trampoline(void) 
{

}



/*

 * At this point the target function has been tricked into

 * returning into our trampoline.  Lookup the associated instance

 * and then:

 *    - call the handler function

 *    - cleanup by marking the instance as unused

 *    - long jump back to the original return address

 */

int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)

{

	struct kretprobe_instance *ri = NULL;

	struct hlist_head *head, empty_rp;

	struct hlist_node *tmp;

	unsigned long flags, orig_ret_address = 0;

	unsigned long trampoline_address =

		((struct fnptr *)kretprobe_trampoline)->ip;



	INIT_HLIST_HEAD(&empty_rp);

	kretprobe_hash_lock(current, &head, &flags);



	/*

	 * It is possible to have multiple instances associated with a given

	 * task either because an multiple functions in the call path

	 * have a return probe installed on them, and/or more than one return

	 * return probe was registered for a target function.

	 *

	 * We can handle this because:

	 *     - instances are always inserted at the head of the list

	 *     - when multiple return probes are registered for the same

	 *       function, the first instance's ret_addr will point to the

	 *       real return address, and all the rest will point to

	 *       kretprobe_trampoline

	 */

	hlist_for_each_entry_safe(ri, tmp, head, hlist) {

		if (ri->task != current)

			/* another task is sharing our hash bucket */

			continue;



		orig_ret_address = (unsigned long)ri->ret_addr;

		if (orig_ret_address != trampoline_address)

			/*

			 * This is the real return address. Any other

			 * instances associated with this task are for

			 * other calls deeper on the call stack

			 */

			break;

	}



	regs->cr_iip = orig_ret_address;



	hlist_for_each_entry_safe(ri, tmp, head, hlist) {

		if (ri->task != current)

			/* another task is sharing our hash bucket */

			continue;



		if (ri->rp && ri->rp->handler)

			ri->rp->handler(ri, regs);



		orig_ret_address = (unsigned long)ri->ret_addr;

		recycle_rp_inst(ri, &empty_rp);



		if (orig_ret_address != trampoline_address)

			/*

			 * This is the real return address. Any other

			 * instances associated with this task are for

			 * other calls deeper on the call stack

			 */

			break;

	}

	kretprobe_assert(ri, orig_ret_address, trampoline_address);



	kretprobe_hash_unlock(current, &flags);



	hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {

		hlist_del(&ri->hlist);

		kfree(ri);

	}

	regs->cr_iip = __kretprobe_trampoline_handler(regs, kretprobe_trampoline, NULL);

	/*

	 * By returning a non-zero value, we are telling

	 * kprobe_handler() that we don't want the post_handler
@@ -498,6 +424,7 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, 
				      struct pt_regs *regs)

{

	ri->ret_addr = (kprobe_opcode_t *)regs->b0;

	ri->fp = NULL;



	/* Replace the return addr with trampoline addr */

	regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;