linux-kernel - Re: [PATCH 3/3] lib/vsprintf: Use pr_crit() instead of long fancy messages

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Date:   Mon, 17 May 2021 08:21:12 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>, Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        John Ogness <john.ogness@...utronix.de>,
        Marco Elver <elver@...gle.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Linux IOMMU <iommu@...ts.linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Embedded <linux-embedded@...r.kernel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: Re: [PATCH 3/3] lib/vsprintf: Use pr_crit() instead of long fancy messages

On Wed, Mar 31, 2021 at 11:59 AM Geert Uytterhoeven
<geert+renesas@...der.be> wrote:
> While long fancy messages have a higher probability of being seen than
> small messages, they may scroll of the screen fast, if visible at all,
> and may still be missed.  In addition, they increase boot time and
> kernel size.
>
> The correct mechanism to increase importance of a kernel message is not
> to draw fancy boxes with more text, but to shout louder, i.e. increase
> the message's reporting level.  Making sure the administrator of the
> system is aware of such a message is a system policy, and is the
> responsability of a user-space log daemon.
>
> Fix this by increasing the reporting level from KERN_WARNING to
> KERN_CRIT, and removing irrelevant text and graphics.
>
> This reduces kernel size by ca. 0.5 KiB.
>
> Fixes: 5ead723a20e0447b ("lib/vsprintf: no_hash_pointers prints all addresses as unhashed")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>

No comments?
Unlike the cases handled by the other two patches in this series,
this one cannot be configured out.

Thanks!

> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -2193,20 +2193,9 @@ static int __init no_hash_pointers_enable(char *str)
>
>         no_hash_pointers = true;
>
> -       pr_warn("**********************************************************\n");
> -       pr_warn("**   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **\n");
> -       pr_warn("**                                                      **\n");
> -       pr_warn("** This system shows unhashed kernel memory addresses   **\n");
> -       pr_warn("** via the console, logs, and other interfaces. This    **\n");
> -       pr_warn("** might reduce the security of your system.            **\n");
> -       pr_warn("**                                                      **\n");
> -       pr_warn("** If you see this message and you are not debugging    **\n");
> -       pr_warn("** the kernel, report this immediately to your system   **\n");
> -       pr_warn("** administrator!                                       **\n");
> -       pr_warn("**                                                      **\n");
> -       pr_warn("**   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **\n");
> -       pr_warn("**********************************************************\n");
> -
> +       pr_crit("This system shows unhashed kernel memory addresses\n");
> +       pr_crit("via the console, logs, and other interfaces. This\n");
> +       pr_crit("might reduce the security of your system.\n");
>         return 0;
>  }
>  early_param("no_hash_pointers", no_hash_pointers_enable);

Gr{oetje,eeting}s,

                        Geert


--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds