linux-kernel - Re: [RFC PATCH 2/5] entry: Add calls for save/restore auxiliary pt

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Date:   Tue, 9 Aug 2022 20:49:47 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Ira Weiny <ira.weiny@...el.com>
Cc:     Rik van Riel <riel@...riel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, kernel-team@...com
Subject: Re: [RFC PATCH 2/5] entry: Add calls for save/restore auxiliary
 pt_regs

On Tue, Aug 09, 2022 at 11:38:03AM -0700, Ira Weiny wrote:
> Thomas did a lot of work to make the entry code generic. So I was
> keeping that work consistent. This also helps to ensure I did not miss
> any places.

How about you worry about the other arches when you actually cross that
bridge?

> I don't believe this is correct because instrumentation is not enabled
> here.

Why do you have to run

	arch_save_aux_pt_regs()

with instrumentation enabled?

Patch 5 does

+       struct pt_regs_auxiliary *aux_pt_regs = &to_extended_pt_regs(regs)->aux;
+
+       aux_pt_regs->cpu = raw_smp_processor_id();

only?

Why does that need to run with instrumentation enabled?

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette