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 X-Spam-Level: X-Spam-Status: No, score=-5.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 63D85C2B9F4 for ; Thu, 17 Jun 2021 19:26:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 467066113C for ; Thu, 17 Jun 2021 19:26:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230361AbhFQT2Z (ORCPT ); Thu, 17 Jun 2021 15:28:25 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:41256 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229784AbhFQT2X (ORCPT ); Thu, 17 Jun 2021 15:28:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623957973; 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=shbYLoohryqH6/R4MBpUAe6sg2YajDW8HCMUBWA860I=; b=XznvKXLoqXNwex5Dg7kSKwHyHiN8e+nBphLzKHDV8mmgB8zus5Xz4AGAgfyUFgnieVF98Q pUWld6idAI/n7tbgydXegRXbcLEGbKZjLZKZErJoLKvX2QuotGXrPAHz412Tw9wl1ieBaZ HD3eQ1y6kHII3CCwE2jdev9EOuHGXSE= 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-588-NoP7XK5eNHOSTzKB4kgmAQ-1; Thu, 17 Jun 2021 15:26:12 -0400 X-MC-Unique: NoP7XK5eNHOSTzKB4kgmAQ-1 Received: by mail-qt1-f200.google.com with SMTP id f13-20020ac85d0d0000b029024ba963cb08so4873013qtx.4 for ; Thu, 17 Jun 2021 12:26:12 -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=shbYLoohryqH6/R4MBpUAe6sg2YajDW8HCMUBWA860I=; b=luHCrvkiM1S9q8w/8nw7f7k5DjMUSGJYdF1Q9zELqRmk8P/6S7R/XUBSEebdzdgnu4 DeAbTSBKvW9/L9NQUBZjKiCsbz8vdSLDsVAxskn3M9W4y8OW7m+0nFa/GzyA8AcsV0Ct QBjE8y2BASVNrzMAsgORQ6OKpmIAVSID9hS2k0+6hQIU4gQKLPOVyUMFEN/coE4AW4PL YvnXqjEWNApnu+LcNtaHTEHAcz23zBlP3Mpqi+nweI3DnU8dbCM+HDTnOijS1GjWLxXz pSnZC/d6Ft27nVdb99KHvmLdatXX91fgs09/vqDkMVIFGL28uf7yjP+P4R1xLOa8aeo0 w1YQ== X-Gm-Message-State: AOAM532qyXA7v/sXpphUmmmWDcIa0OtRskX+k1pM4pHM+7qw5DoyVQIt SHWO5YAg1gvz74cy8qBVfVqvrZAagJ6HQ0a8DaDJUmF8CntcijlxUFH2wK8ZShpzZ7hxsz+xCvK /YES7pqiyH5HFCGQH7LTYrRKC X-Received: by 2002:a05:620a:5b5:: with SMTP id q21mr5405618qkq.58.1623957971790; Thu, 17 Jun 2021 12:26:11 -0700 (PDT) X-Google-Smtp-Source: ABdhPJw6eeI4g6lsrMZ8thV4evhhAYVuOqxHtre6BqUjNgVh3smQXBZnMjvBrTJlvStH1PgD5Oskyg== X-Received: by 2002:a05:620a:5b5:: with SMTP id q21mr5405600qkq.58.1623957971566; Thu, 17 Jun 2021 12:26:11 -0700 (PDT) Received: from treble ([68.52.236.68]) by smtp.gmail.com with ESMTPSA id s69sm2242882qke.115.2021.06.17.12.26.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Jun 2021 12:26:11 -0700 (PDT) Date: Thu, 17 Jun 2021 14:26:08 -0500 From: Josh Poimboeuf To: Andrii Nakryiko Cc: Masami Hiramatsu , Steven Rostedt , Ingo Molnar , X86 ML , Daniel Xu , open list , bpf , Jakub Kicinski , Ingo Molnar , Alexei Starovoitov , Thomas Gleixner , Kernel Team , Yonghong Song , linux-ia64@vger.kernel.org, Abhishek Sagar Subject: Re: [PATCH -tip v7 09/13] kprobes: Setup instruction pointer in __kretprobe_trampoline_handler Message-ID: <20210617192608.4nt6sdass6gw5ehl@treble> References: <162209754288.436794.3904335049560916855.stgit@devnote2> <162209762943.436794.874947392889792501.stgit@devnote2> <20210617043909.fgu2lhnkxflmy5mk@treble> <20210617044032.txng4enhiduacvt6@treble> <20210617234001.54cd2ff60410ff82a39a2020@kernel.org> <20210618000239.f95de17418beae6d84ce783d@kernel.org> <20210617182159.ka227nkmhe4yu2de@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 17, 2021 at 11:31:03AM -0700, Andrii Nakryiko wrote: > On Thu, Jun 17, 2021 at 11:22 AM Josh Poimboeuf wrote: > > > > On Thu, Jun 17, 2021 at 10:45:41AM -0700, Andrii Nakryiko wrote: > > > > > > > I know I suggested this patch, but I believe it would only be useful in > > > > > > > combination with the use of UNWIND_HINT_REGS in SAVE_REGS_STRING. But I > > > > > > > think that would be tricky to pull off correctly. Instead, we have > > > > > > > UNWIND_HINT_FUNC, which is working fine. > > > > > > > > > > > > > > So I'd suggest dropping this patch, as the unwinder isn't actually > > > > > > > reading regs->ip after all. > > > > > > > > > > > > ... and I guess this means patches 6-8 are no longer necessary. > > > > > > > > > > OK, I also confirmed that dropping those patche does not make any change > > > > > on the stacktrace. > > > > > Let me update the series without those. > > > > > > > > Oops, Andrii, can you also test the kernel without this patch? > > > > (you don't need to drop patch 6-8) > > > > > > Hi Masami, > > > > > > Dropping this patch and leaving all the other in place breaks stack > > > traces from kretprobes for BPF. I double checked with and without this > > > patch. Without this patch we are back to having broken stack traces. I > > > see either > > > > > > kretprobe_trampoline+0x0 > > > > > > or > > > > > > ftrace_trampoline+0xc8 > > > kretprobe_trampoline+0x0 Do the stack traces end there? Or do they continue normally after that? -- Josh