Received: by 2002:a05:6a10:206:0:0:0:0 with SMTP id 6csp1605912pxj; Fri, 18 Jun 2021 10:38:18 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzjsZ8cnR6Td3YhohM7sCr9GkRLxCoXsjDN9dS7kQmv+75TeIFzfjKV5q/nQ1rmSojWQrJm X-Received: by 2002:a17:906:8a55:: with SMTP id gx21mr12360099ejc.179.1624037898593; Fri, 18 Jun 2021 10:38:18 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1624037898; cv=none; d=google.com; s=arc-20160816; b=n3UvJw/fz6HOVpxi2btCA8Sc/wtCFSYnbpbaJUWIybkE2M30ufy5vWHr6noNTjCISQ 3TjCY0T5n4mclirg8ZLkGlGOrpdM6wWDaEY74vyCuVViUDPnNBiVaMWmFrzmeu9mJXn2 tOEQ+p/JuRDBVTZQCAbL7jB5CnFCDz3GplgfSCxLZVv3FkDvArkRd9cB2CMlh1NzlltP n44yO5w96CdH/KBjJ+ZDZuHmkrP3UgWQoQc/i8SYLzTJkiHKrGD/CLC5VhArN4TzKZyK 4u4pEswOvi/42jQ50P5fywKiTcUQmg2pct078bS4PStyiqmPSyU7Y0N+cY4Bibek/th2 aZSg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:in-reply-to:content-disposition:mime-version :references:message-id:subject:cc:to:from:date:dkim-signature; bh=o4/MAAO2RBJYfBGbAHmWoKr3dKd/cHorzGFyg6HuH7A=; b=UwGD54LoIAHlM/NKiph6X/+RbWPbRJAnJfo3TALN9yPvTIp393LJqYxFHpg5mEAhgZ yaV0JkOSj3+xM+jBvm7Espsou5jc909Dg/DZgpA4BmL/ChuwcEd1FnDDxU8r8f4c0+sQ GmV7j0grCYPX/oGmQq4pUp2wX+BK5CCTgXf82za/MkBcsuCBd8twbGVE2bAQo+GA8QR1 1F5IBSoW46SZtbTmQfEAG3ztR83oiEO0g0Ia7Yf8kMsIO+nvBlXrhsEDCOYBI6BjuPns XVnSlcwbs3YkT/G3nnhC+blAdhIF3DNmJKSNUzrk4LVffinYjxzIwsGZLulFok7OufrL UQcw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=KHWY4ouL; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id l7si3598727ejk.475.2021.06.18.10.37.54; Fri, 18 Jun 2021 10:38:18 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=KHWY4ouL; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231685AbhFROGs (ORCPT + 99 others); Fri, 18 Jun 2021 10:06:48 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:26346 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230387AbhFROGq (ORCPT ); Fri, 18 Jun 2021 10:06:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624025077; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=o4/MAAO2RBJYfBGbAHmWoKr3dKd/cHorzGFyg6HuH7A=; b=KHWY4ouLAtx0e1a8WmKU2JpFBBl1HJGxfKf2CaT54X1MzQ2XZe7MYzMdF9CH/QrTztmExG IMbzlDweS5HbwGEnbUvFEpjOG2gJ6tooTBJly1Ivph/zqebtVgmu2BUwEQPYBhccWBspdM onBt32cqOKBfLUrMa/+M45/MGMxhx6Q= Received: from mail-qt1-f200.google.com (mail-qt1-f200.google.com [209.85.160.200]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-156-jFo8WjQBOjGy7iMq-SZ3fg-1; Fri, 18 Jun 2021 10:04:36 -0400 X-MC-Unique: jFo8WjQBOjGy7iMq-SZ3fg-1 Received: by mail-qt1-f200.google.com with SMTP id 61-20020aed21430000b029024e7e455d67so7393968qtc.16 for ; Fri, 18 Jun 2021 07:04:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=o4/MAAO2RBJYfBGbAHmWoKr3dKd/cHorzGFyg6HuH7A=; b=j/g0bnZr7NfKlCQg6MSR5yXk6sb6rgJCbe7RAWtDs3cpMglL/MdDptVU5OkWZsrKUM 7FYg5rTb9Sl0b9fhOpYv1AFYoDr2C2mCqW28YBr6k+hcKJGH1Z3HGaRgsd5uknFDBMCb ESzbDvXF0DqeaNOw0FjDR8OWW8Zs408wXZQG/4ydhD0IezQ1NRai6dCSK2h9Cs56oGD3 biUIY//So+9WZpjhudxdNjCZ5rKhSmxYdxqp8CRdOBS9fOnUeAk0CWNcnXow4K+BB2SN dZUDybpe6MM7LqL5BZLjNOCoVvhfgE6hD90GaWob2J+LMgPPQYrmmaqhT0Zn/MszT5Jn 5IgQ== X-Gm-Message-State: AOAM530oq1mA5kPzCwzZXhzyEJmaQ/y3jyqo+WbaoZbgXwEy2NqA/FXH 5Yxur2AR8jcE6/a08GT3E2MI29LM7LDXz0m+vY6VEWLXrTKFBqQAsurRiVaLp/CP4f7H2guEWYY Y6zhBauIKm8pgZoFhAFSu2BBq X-Received: by 2002:a05:6214:17d2:: with SMTP id cu18mr1856571qvb.48.1624025075808; Fri, 18 Jun 2021 07:04:35 -0700 (PDT) X-Received: by 2002:a05:6214:17d2:: with SMTP id cu18mr1856524qvb.48.1624025075512; Fri, 18 Jun 2021 07:04:35 -0700 (PDT) Received: from treble ([68.52.236.68]) by smtp.gmail.com with ESMTPSA id 7sm5415837qtx.33.2021.06.18.07.04.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Jun 2021 07:04:35 -0700 (PDT) Date: Fri, 18 Jun 2021 09:04:32 -0500 From: Josh Poimboeuf To: Masami Hiramatsu Cc: Steven Rostedt , Ingo Molnar , X86 ML , Daniel Xu , linux-kernel@vger.kernel.org, bpf@vger.kernel.org, kuba@kernel.org, mingo@redhat.com, ast@kernel.org, Thomas Gleixner , Borislav Petkov , Peter Zijlstra , kernel-team@fb.com, yhs@fb.com, linux-ia64@vger.kernel.org, Abhishek Sagar , Andrii Nakryiko Subject: Re: [PATCH -tip v8 09/13] kprobes: Enable stacktrace from pt_regs in kretprobe handler Message-ID: <20210618140432.icuopdgxt2urngmy@treble> References: <162399992186.506599.8457763707951687195.stgit@devnote2> <162400000592.506599.4695807810528866713.stgit@devnote2> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <162400000592.506599.4695807810528866713.stgit@devnote2> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 18, 2021 at 04:06:46PM +0900, Masami Hiramatsu wrote: > 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). > > Suggested-by: Josh Poimboeuf > Signed-off-by: Masami Hiramatsu > Tested-by: Andrii Nakryik Acked-by: Josh Poimboeuf > --- > Changes in v8: > - Update comment to clarify why this is needed. > Changes in v3: > - Cast the correct_ret_addr to unsigned long. > --- > kernel/kprobes.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 650cbe738666..ba729ed05cb3 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -1896,6 +1896,9 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, > BUG_ON(1); > } > > + /* Set the instruction pointer to the correct address */ > + instruction_pointer_set(regs, (unsigned long)correct_ret_addr); > + > /* Run them. */ > first = current->kretprobe_instances.first; > while (first) { > -- Josh