linux-kernel - Re: [PATCH v6 15/17] static

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Message-ID: <20200714153806.5649b2dc@oasis.local.home>
Date:   Tue, 14 Jul 2020 15:38:06 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, mhiramat@...nel.org,
        bristot@...hat.com, jbaron@...mai.com,
        torvalds@...ux-foundation.org, tglx@...utronix.de,
        mingo@...nel.org, namit@...are.com, hpa@...or.com, luto@...nel.org,
        ard.biesheuvel@...aro.org, jpoimboe@...hat.com,
        pbonzini@...hat.com, mathieu.desnoyers@...icios.com,
        linux@...musvillemoes.dk
Subject: Re: [PATCH v6 15/17] static_call: Allow early init

On Tue, 14 Jul 2020 20:31:43 +0200
Peter Zijlstra <peterz@...radead.org> wrote:

> On Tue, Jul 14, 2020 at 12:07:01PM -0400, Steven Rostedt wrote:
> > Can we add a statement that says something like: "Because x86 now calls
> > static_call_init() before the setup of the memory allocator, we must
> > avoid using kmalloc() and friends for core kernel static calls." ?
> > 
> > This was the missing piece for me.  
> 
> It now reads like this.
> 
> ---
> Subject: static_call: Allow early init
> From: Peter Zijlstra <peterz@...radead.org>
> Date: Fri, 4 Oct 17:21:10 CEST 2019
> 
> In order to use static_call() to wire up x86_pmu, we need to
> initialize earlier, specifically before memory allocation works; copy
> some of the tricks from jump_label to enable this.
> 
> Primarily we overload key->next to store a sites pointer when there
> are no modules, this avoids having to use kmalloc() to initialize the
> sites and allows us to run much earlier.

All the pieces lie in place. Thanks!

Reviewed-by: Steven Rostedt (VMware) <rostedt@...dmis.org>

-- Steve

> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---