linux-kernel - Re: [PATCH v3 03/12] x86/alternatives: Disable LASS when patching kernel alternatives

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Date:   Mon, 31 Jul 2023 22:41:17 +0000
From:   "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To:     "Lutomirski, Andy" <luto@...nel.org>,
        "alexander.shishkin@...ux.intel.com" 
        <alexander.shishkin@...ux.intel.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Luck, Tony" <tony.luck@...el.com>,
        "Mehta, Sohil" <sohil.mehta@...el.com>
Subject: Re: [PATCH v3 03/12] x86/alternatives: Disable LASS when patching
 kernel alternatives

On Fri, 2023-06-09 at 21:36 +0300, Alexander Shishkin wrote:
> +/*
> + * poking_init() initializes the text poking address from the lower
> half of the
> + * address space. Relax LASS enforcement when accessing the poking
> address.
> + */
>  static void text_poke_memcpy(void *dst, const void *src, size_t len)
>  {
> -       memcpy(dst, src, len);
> +       stac();
> +       __inline_memcpy(dst, src, len);
> +       clac();
>  }
>  
>  static void text_poke_memset(void *dst, const void *src, size_t len)
>  {
>         int c = *(const int *)src;
>  
> -       memset(dst, c, len);
> +       stac();
> +       __inline_memset(dst, c, len);
> +       clac();
>  }

Why not do stac/clac in a single place inside __text_poke()?