From mboxrd@z Thu Jan 1 00:00:00 1970 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 8AD8DC433EF for ; Mon, 24 Jan 2022 15:09:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239183AbiAXPJT (ORCPT ); Mon, 24 Jan 2022 10:09:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46406 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240188AbiAXPJR (ORCPT ); Mon, 24 Jan 2022 10:09:17 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 094F0C06173B; Mon, 24 Jan 2022 07:09:17 -0800 (PST) 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 dfw.source.kernel.org (Postfix) with ESMTPS id 9A85A613C5; Mon, 24 Jan 2022 15:09:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E6DAC340E1; Mon, 24 Jan 2022 15:09:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643036956; bh=vsFL6HOQwkNugp0rbGxl+Vo5U1vQl5c5pRrmbvYpdJg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=v2EEwgMc8oWDl46QXm0Px3et0xbFoOUWFdKwlUCK/EQ8Yg9BMkD1FA9L9R/rASDiW WQEnpvf0bYPDa9uFWJ929tlMVIbqtDkGYyPzmBRIvlNWUyE8fg1Pp5nxvOVvZZBEMy vP1O7TCl8bhHtsyhl1EF97aTO/wjS/SziQUA7HzA= Date: Mon, 24 Jan 2022 16:09:13 +0100 From: Greg Kroah-Hartman To: Masami Hiramatsu Cc: stable@vger.kernel.org, linux-kernel@vger.kernel.org, Ingo Molnar , Sasha Levin Subject: Re: [PATCH v2 5.4.y] Revert "ia64: kprobes: Use generic kretprobe trampoline handler" Message-ID: References: <164225155571.1964629.11131335649262508943.stgit@devnote2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <164225155571.1964629.11131335649262508943.stgit@devnote2> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jan 15, 2022 at 09:59:16PM +0900, Masami Hiramatsu wrote: > 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 > --- > Changes in v2: > - fix the lack of type casting for dereference_function_descriptor(). > --- > 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..fa10d51f6217 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 = > + (unsigned long)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); > Now queued up, thanks. greg k-h