From patchwork Fri Jan 14 10:19:59 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu \(Google\)" X-Patchwork-Id: 532574 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 95A46C433F5 for ; Fri, 14 Jan 2022 10:20:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237487AbiANKUF (ORCPT ); Fri, 14 Jan 2022 05:20:05 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:34056 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233263AbiANKUF (ORCPT ); Fri, 14 Jan 2022 05:20:05 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 342F9B82593; Fri, 14 Jan 2022 10:20:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A4D04C36AE5; Fri, 14 Jan 2022 10:20:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1642155603; bh=H2cwqX6hP/TTryeKSioq1szTFJyrpgVKfMYJ0fjXn34=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UGGhrqVldk+09VVLl6OIP2pxUDg7sugmpHJA8Ski2ERPSJbT7Mh4btQfkgkaOMpze yLfnsXM5v++g1rSF50zz+1DKtvlaKg+oMn0D3uJptBZb8oWM5a/lgknSIyNy82IGTt mkpbAkSc+2tI4A3dxr1075z5Gfv3ssfWNtpeiU37xhXSpqfgnAh1BmzTI8F9Opd8a4 QzNDZ06INZCbtk0fUZJuS7SjNiMDndPFxZfEn8GOHVeE8OCigRu4+ENNsP3vkPbyiG oQ61NjvLQ7vexK9/OyGQS1v8mX8RnHOjw4h192Rm0KaU4o0y13oNOymOVMOZ8KvVGG j9O8xzHA5t23Q== From: Masami Hiramatsu To: stable@vger.kernel.org, Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Sasha Levin Subject: [PATCH 5.4.y] Revert "ia64: kprobes: Use generic kretprobe trampoline handler" Date: Fri, 14 Jan 2022 19:19:59 +0900 Message-Id: <164215559880.1662358.1475310445318313122.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: User-Agent: StGit/0.19 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This reverts commit 77fa5e15c933a1ec812de61ad709c00aa51e96ae. Since the upstream commit e792ff804f49720ce003b3e4c618b5d996256a18 depends on the generic kretprobe trampoline handler, which was introduced by commit 66ada2ccae4e ("kprobes: Add generic kretprobe trampoline handler") but that is not ported to the stable kernel because it is not a bugfix series. So revert this commit to fix a build error. NOTE: I keep commit a7fe2378454c ("ia64: kprobes: Fix to pass correct trampoline address to the handler") on the tree, that seems just a cleanup without the original reverted commit, but it would be better to use dereference_function_descriptor() macro instead of accessing descriptor's field directly. Fixes: 77fa5e15c933 ("ia64: kprobes: Use generic kretprobe trampoline handler") Reported-by: kernel test robot Signed-off-by: Masami Hiramatsu --- arch/ia64/kernel/kprobes.c | 78 ++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 75 insertions(+), 3 deletions(-) diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c index 8a223d0e4918..5d2d58644378 100644 --- a/arch/ia64/kernel/kprobes.c +++ b/arch/ia64/kernel/kprobes.c @@ -396,10 +396,83 @@ 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) { - regs->cr_iip = __kretprobe_trampoline_handler(regs, - dereference_function_descriptor(kretprobe_trampoline), NULL); + 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 = + dereference_function_descriptor(kretprobe_trampoline); + + 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); + } /* * By returning a non-zero value, we are telling * kprobe_handler() that we don't want the post_handler @@ -412,7 +485,6 @@ 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 = (unsigned long)dereference_function_descriptor(kretprobe_trampoline);