From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id C8E98256D; Tue, 6 Jan 2026 12:21:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767702118; cv=none; b=gvpcR6IEJRGS8fYB2x5HdboEcJERgbQWpxbg/fdLYL4Hl2eteOOF3dCa8iy0qb2BqJdht6nj7A1QaX0qhoVqOE32pQfX/LAjmiCJ8Cqnu9iA1Cma5Bcv8Yc1gLxUOv69mTt24HhfqLMhJvB9JbXhJUrcytcKeAK30K3XIkBsNes= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767702118; c=relaxed/simple; bh=fZ3Cgw90ck/IzpfwCFpJA4Z/WCoX9MwTjBm8U4VL+kA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QV6AHzRJEKR00KCQEkY1xPO5w5r7RAk2C7jB+HA1coqTkZ3gABL/VaGJ8SYD0Ch1URqWoBXHjLFOYW73fHfLkOSbyDdYcvW/2h0ZvaiGrWP2F4Y6BguIST6E41Aqsen2D26OngoAgM/xDsH2ywp7UeOZSW8uTJwNbKW+7vBcgK8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 55397497; Tue, 6 Jan 2026 04:21:49 -0800 (PST) Received: from J2N7QTR9R3 (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EC46D3F5A1; Tue, 6 Jan 2026 04:21:53 -0800 (PST) Date: Tue, 6 Jan 2026 12:21:47 +0000 From: Mark Rutland To: Breno Leitao Cc: Catalin Marinas , Will Deacon , Laura Abbott , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Steven Rostedt , Masami Hiramatsu , kernel-team@meta.com, puranjay@kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2] arm64: Disable branch profiling for all arm64 code Message-ID: References: <20260106-annotated-v2-1-fb7600ebd47f@debian.org> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260106-annotated-v2-1-fb7600ebd47f@debian.org> On Tue, Jan 06, 2026 at 02:16:35AM -0800, Breno Leitao wrote: > The arm64 kernel doesn't boot with annotated branches > (PROFILE_ANNOTATED_BRANCHES) enabled and CONFIG_DEBUG_VIRTUAL together. > > Bisecting it, I found that disabling branch profiling in arch/arm64/mm > solved the problem. Narrowing down a bit further, I found that > physaddr.c is the file that needs to have branch profiling disabled to > get the machine to boot. > > I suspect that it might invoke some ftrace helper very early in the boot > process and ftrace is still not enabled(!?). > > Rather than playing whack-a-mole with individual files, disable branch > profiling for the entire arch/arm64 tree, similar to what x86 already > does in arch/x86/Kbuild. > > Cc: stable@vger.kernel.org > Fixes: ec6d06efb0bac ("arm64: Add support for CONFIG_DEBUG_VIRTUAL") > Signed-off-by: Breno Leitao I don't think ec6d06efb0bac is to blame here, and CONFIG_DEBUG_VIRTUAL is unsound in a number of places, so I'd prefer to remove that Fixes tag and backport this for all stable trees. Regardless, I'm in favour of disabling CONFIG_DEBUG_VIRTUAL widely, so: Acked-by: Mark Rutland Mark. > --- > Changes in v2: > - Expand the scope to arch/arm64 instead of just physaddr.c > - Link to v1: https://lore.kernel.org/all/20251231-annotated-v1-1-9db1c0d03062@debian.org/ > --- > arch/arm64/Kbuild | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/arch/arm64/Kbuild b/arch/arm64/Kbuild > index 5bfbf7d79c99..d876bc0e5421 100644 > --- a/arch/arm64/Kbuild > +++ b/arch/arm64/Kbuild > @@ -1,4 +1,8 @@ > # SPDX-License-Identifier: GPL-2.0-only > + > +# Branch profiling isn't noinstr-safe > +subdir-ccflags-$(CONFIG_TRACE_BRANCH_PROFILING) += -DDISABLE_BRANCH_PROFILING > + > obj-y += kernel/ mm/ net/ > obj-$(CONFIG_KVM) += kvm/ > obj-$(CONFIG_XEN) += xen/ > > --- > base-commit: c8ebd433459bcbf068682b09544e830acd7ed222 > change-id: 20251231-annotated-75de3f33cd7b > > Best regards, > -- > Breno Leitao >