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 CF7E7C433F5 for ; Wed, 13 Oct 2021 19:54:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A171D610CE for ; Wed, 13 Oct 2021 19:54:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233971AbhJMT4f (ORCPT ); Wed, 13 Oct 2021 15:56:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230312AbhJMT4d (ORCPT ); Wed, 13 Oct 2021 15:56:33 -0400 Received: from mail-lf1-x12f.google.com (mail-lf1-x12f.google.com [IPv6:2a00:1450:4864:20::12f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B1CCDC061570 for ; Wed, 13 Oct 2021 12:54:29 -0700 (PDT) Received: by mail-lf1-x12f.google.com with SMTP id x27so16567156lfa.9 for ; Wed, 13 Oct 2021 12:54:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=kv1AJJc4apgDHEZekSLA616qsDySaGD6xxGVlfrlDzs=; b=AGWEJ4iVprTucBh+QbMUdUslVJq727rx03gij5ctzZp9RXsw2bB4M1uFmoT/L3CfSV /LIsooQyWud7zXzrVaSEF4YQuyL+VOIe4N0f1bZGuV34hyoERvSU2rjyMeU5IyHSIia5 AN55Q0dRdjk9N2RHCtpC6edPOSz1+2c3p7kqr7M+J9cUwhb9fMyQXw6wklSPhbIHHOWZ ZSq5CcES/0o242QHUCLvhT0QDbKj5HUWDCaBQ6S6K1FpoDFoFwuRdOQroPsSLFFMDtQX JXxURsAaIeI0bwRJPZ4zqmNoiAuNHggNTX1B/1QLAzTMr6jnyH0m1z9bPL1YpvcGFxWC T2vA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=kv1AJJc4apgDHEZekSLA616qsDySaGD6xxGVlfrlDzs=; b=Md0XbbcFSjZQpiy5sp3xdM/+s7zIQdIwNm899PiGFfXESx+0/J3nen/IFTxypG3d4T qV0+pHMGr22f2qz+++3lVYsjEefxVvJsu37Jq66WvQ7rf74uqXt/twgQ7FHBCvsLP7OX EUvapwajSEcDMoPxC049Y3co0uWKkiKH+Rq+RpZFSK5Lag1YrEdDu11S+1O/Du2+fzbh S7dPyxLIej+78MG408BSotPmNOeOPjYm9fxRrGafM2VtHmzAo0swoIf5rQcyNsHkDPsu wB9gyp2shYb23UPL8hnX7SrS/rC3gT6KkU8pSQYnSL3g+PX8Ffa8T5nJJf1NuRBEtqba RycQ== X-Gm-Message-State: AOAM533uOCK7aCuNu6ooQ9333LVAgmp7m973PwtrXFzrcjm0+Fhgkmdv E6EccDjG1lfv4yU3/KH96fxyuHand61vDnxBXljybQ== X-Google-Smtp-Source: ABdhPJz6kQDWkM0JV4Rx++gZpdlLIYyrAycIprj6NRQujF6dKkQoPvlEk05ygnXxzKntKEB8T27Sz9TOjwga+9c562I= X-Received: by 2002:a2e:534e:: with SMTP id t14mr1432085ljd.526.1634154867806; Wed, 13 Oct 2021 12:54:27 -0700 (PDT) MIME-Version: 1.0 References: <163369609308.636038.15295764725220907794.stgit@devnote2> <163369614818.636038.5019945597127474028.stgit@devnote2> <20211012231835.522ac7ba366e5019192c1a5a@kernel.org> In-Reply-To: <20211012231835.522ac7ba366e5019192c1a5a@kernel.org> From: Nick Desaulniers Date: Wed, 13 Oct 2021 12:54:16 -0700 Message-ID: Subject: Re: [PATCH 6/8] ARM: clang: Do not relay on lr register for stacktrace To: Masami Hiramatsu Cc: Steven Rostedt , "Naveen N . Rao" , Ananth N Mavinakayanahalli , Ingo Molnar , linux-kernel@vger.kernel.org, Sven Schnelle , Catalin Marinas , Will Deacon , Russell King , Nathan Chancellor , linux-arm-kernel@lists.infradead.org, Nathan Huckleberry Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 12, 2021 at 7:18 AM Masami Hiramatsu wrote: > > Hi Nick, > > On Mon, 11 Oct 2021 11:45:22 -0700 > Nick Desaulniers wrote: > > > > > If I change from CONFIG_UNWINDER_ARM=y to > > CONFIG_UNWINDER_FRAME_POINTER=y, before: > > > > # cat /proc/self/stack > > [<0>] stack_trace_save_tsk+0x50/0x6c > > [<0>] proc_pid_stack+0xa0/0xf8 > > [<0>] proc_single_show+0x50/0xbc > > [<0>] seq_read_iter+0x178/0x4ec > > [<0>] seq_read+0x138/0x15c > > [<0>] vfs_read+0xd0/0x304 > > [<0>] ksys_read+0x78/0xd4 > > [<0>] sys_read+0xc/0x10 > > > > after: > > # cat /proc/self/stack > > [<0>] proc_pid_stack+0xa0/0xf8 > > [<0>] proc_single_show+0x50/0xbc > > [<0>] seq_read_iter+0x178/0x4ec > > [<0>] seq_read+0x138/0x15c > > [<0>] vfs_read+0xd0/0x304 > > [<0>] ksys_read+0x78/0xd4 > > [<0>] sys_read+0xc/0x10 > > [<0>] __entry_text_start+0x14/0x14 > > [<0>] 0xffffffff > > > > So I guess this helps the CONFIG_UNWINDER_FRAME_POINTER=y case? (That > > final frame address looks wrong, but is potentially yet another bug; > > perhaps for clang we need to manually store the previous frame's pc at > > a different offset before jumping to __entry_text_start). > > Ah, yes. I didn't touch the UNWINDER_ARM. As you may know the > unwind_frame()@arch/arm/kernel/stacktrace.c is compiled only > CONFIG_UNWINDER_FRAME_POINTER=y. Ah, right, thanks for pointing that out. > > so likely this fixes/improves CONFIG_UNWINDER_FRAME_POINTER=y? Is that correct? > > Yes, that is correct. In that case, additionally: Reviewed-by: Nick Desaulniers -- Thanks, ~Nick Desaulniers