linux-kernel - Re: [PATCH] arm64/mm: Fix annotated branch unbootable kernel

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Message-ID: <74f52o5tq2nodc3otsvknrsf2rpzphtaba7lxia5u3i7322vni@giqfw3ofnnyk>
Date: Mon, 12 Jan 2026 01:42:47 -0800
From: Breno Leitao <leitao@...ian.org>
To: Steven Rostedt <rostedt@...nel.org>
Cc: Will Deacon <will@...nel.org>, 
	Catalin Marinas <catalin.marinas@....com>, Mark Rutland <mark.rutland@....com>, 
	Laura Abbott <labbott@...hat.com>, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org, 
	Masami Hiramatsu <mhiramat@...nel.org>, puranjay@...nel.org, usamaarif642@...il.com, 
	kernel-team@...a.com, stable@...r.kernel.org
Subject: Re: [PATCH] arm64/mm: Fix annotated branch unbootable kernel

Hello Steven,

On Fri, Jan 09, 2026 at 02:50:22PM -0500, Steven Rostedt wrote:
> [ Resending with my kernel.org email, as I received a bunch of messages from gmail saying it's blocking me :-p ]
> 
> On Mon, 5 Jan 2026 21:15:40 +0000
> Will Deacon <will@...nel.org> wrote:
> 
> > > Another approach is to disable profiling on all arch/arm64 code, similarly to
> > > x86, where DISABLE_BRANCH_PROFILING is called for all arch/x86 code. See
> > > commit 2cbb20b008dba ("tracing: Disable branch profiling in noinstr
> > > code").  
> > 
> > Yes, let's start with arch/arm64/. We know that's safe and then if
> > somebody wants to make it finer-grained, it's on them to figure out a
> > way to do it without playing whack-a-mole.
> 
> OK, so by adding -DDISABLE_BRANCH_PROFILING to the Makefile configs and for
> the files that were audited, could be opt-in?

How to do the audit in this case? I suppose we want to disable branch
profiling for files that have any function that would eventually call
noinstr functions, right?