linux-kernel - Re: [PATCH v2 0/4] Introduce %rip-relative addressing to PER_CPU

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Date:   Thu, 12 Oct 2023 14:21:39 -0700
From:   "H. Peter Anvin" <hpa@...or.com>
To:     Uros Bizjak <ubizjak@...il.com>
Cc:     Dave Hansen <dave.hansen@...el.com>, x86@...nel.org,
        xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH v2 0/4] Introduce %rip-relative addressing to PER_CPU_VAR
 macro

On 10/12/23 14:17, Uros Bizjak wrote:
>>
>> Are you PIC-adjusting the percpu variables as well?
> 
> After this patch (and after fixing percpu_stable_op to use "a" operand
> modifier on GCC), the only *one* remaining absolute reference to
> percpu variable remain in xen-head.S, where:
> 
>      movq    $INIT_PER_CPU_VAR(fixed_percpu_data),%rax
> 
> should be changed to use leaq.
> 
> All others should then be (%rip)-relative.
> 

I mean, the symbols themselves are relative, not absolute?

	-hpa