linux-kernel - Re: [RFC PATCH 14/26] x86/alternatives: Handle native insns in text_poke

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Date:   Wed, 8 Apr 2020 13:11:22 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Ankur Arora <ankur.a.arora@...cle.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org, hpa@...or.com,
        jpoimboe@...hat.com, namit@...are.com, mhiramat@...nel.org,
        jgross@...e.com, bp@...en8.de, vkuznets@...hat.com,
        pbonzini@...hat.com, boris.ostrovsky@...cle.com,
        mihai.carabas@...cle.com, kvm@...r.kernel.org,
        xen-devel@...ts.xenproject.org,
        virtualization@...ts.linux-foundation.org
Subject: Re: [RFC PATCH 14/26] x86/alternatives: Handle native insns in
 text_poke_loc*()

On Tue, Apr 07, 2020 at 10:03:11PM -0700, Ankur Arora wrote:
>  struct text_poke_loc {
>  	s32 rel_addr; /* addr := _stext + rel_addr */
> -	s32 rel32;
> -	u8 opcode;
> +	union {
> +		struct {
> +			s32 rel32;
> +			u8 opcode;
> +		} emulated;
> +		struct {
> +			u8 len;
> +		} native;
> +	};
>  	const u8 text[POKE_MAX_OPCODE_SIZE];
>  };

NAK, this grows the structure from 16 to 20 bytes.