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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B8294C433EF for ; Tue, 5 Oct 2021 14:02:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 997CB614C8 for ; Tue, 5 Oct 2021 14:02:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235753AbhJEOES (ORCPT ); Tue, 5 Oct 2021 10:04:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:41278 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235504AbhJEOCi (ORCPT ); Tue, 5 Oct 2021 10:02:38 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E762861A08; Tue, 5 Oct 2021 13:58:30 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.94.2) (envelope-from ) id 1mXkxh-0055pv-VG; Tue, 05 Oct 2021 09:58:29 -0400 Message-ID: <20211005135829.811738907@goodmis.org> User-Agent: quilt/0.66 Date: Tue, 05 Oct 2021 09:57:56 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Josh Poimboeuf , Masami Hiramatsu , Andrii Nakryiko Subject: [for-linus][PATCH 23/27] kprobes: Enable stacktrace from pt_regs in kretprobe handler References: <20211005135733.485175654@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masami Hiramatsu Since the ORC unwinder from pt_regs requires setting up regs->ip correctly, set the correct return address to the regs->ip before calling user kretprobe handler. This allows the kretrprobe handler to trace stack from the kretprobe's pt_regs by stack_trace_save_regs() (eBPF will do this), instead of stack tracing from the handler context by stack_trace_save() (ftrace will do this). Link: https://lkml.kernel.org/r/163163053237.489837.4272653874525136832.stgit@devnote2 Suggested-by: Josh Poimboeuf Signed-off-by: Masami Hiramatsu Tested-by: Andrii Nakryiko Acked-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (VMware) --- kernel/kprobes.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 833f07f33115..ebc587b9a346 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1937,6 +1937,13 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, BUG_ON(1); } + /* + * Set the return address as the instruction pointer, because if the + * user handler calls stack_trace_save_regs() with this 'regs', + * the stack trace will start from the instruction pointer. + */ + instruction_pointer_set(regs, (unsigned long)correct_ret_addr); + /* Run the user handler of the nodes. */ first = current->kretprobe_instances.first; while (first) { -- 2.32.0