linux-kernel - Re: [PATCH 10/14] x86/unwind/orc: Prevent unwinding before ORC initialization

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Date:   Fri, 13 Mar 2020 13:24:09 +0100 (CET)
From:   Miroslav Benes <mbenes@...e.cz>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Vince Weaver <vincent.weaver@...ne.edu>,
        Dave Jones <dsj@...com>, Jann Horn <jannh@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 10/14] x86/unwind/orc: Prevent unwinding before ORC
 initialization

On Thu, 12 Mar 2020, Josh Poimboeuf wrote:

> If the unwinder is called before the ORC data has been initialized,
> orc_find() returns NULL, and it tries to fall back to using frame
> pointers.  This can cause some unexpected warnings during boot.
> 
> Move the 'orc_init' check from orc_find() to __unwind_init(), so that it

s/__unwind_init()/__unwind_start()/

>  void __unwind_start(struct unwind_state *state, struct task_struct *task,
>  		    struct pt_regs *regs, unsigned long *first_frame)
>  {
> +	if (!orc_init)
> +		goto done;
> +
>  	memset(state, 0, sizeof(*state));
>  	state->task = task;

Miroslav