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Date: Fri, 6 Mar 2020 09:04:40 +0100
From: Geert Uytterhoeven <>
To: John Paul Adrian Glaubitz <>
Cc: Arvind Sankar <>, Kees Cook <>, 
	"Tobin C . Harding" <>, Tycho Andersen <>,, 
	Yoshinori Sato <>, Rich Felker <>, 
	Linux-sh list <>, 
	Linux Kernel Mailing List <>
Subject: Re: [PATCH] sh: Stop printing the virtual memory layout

Hi Adrian,

On Thu, Mar 5, 2020 at 4:18 PM John Paul Adrian Glaubitz
<> wrote:
> On 3/5/20 4:10 PM, Arvind Sankar wrote:
> > For security, don't display the kernel's virtual memory layout.
> >
> > Kees Cook points out:
> > "These have been entirely removed on other architectures, so let's
> > just do the same for ia32 and remove it unconditionally."
> >
> > 071929dbdd86 ("arm64: Stop printing the virtual memory layout")
> > 1c31d4e96b8c ("ARM: 8820/1: mm: Stop printing the virtual memory layout")
> > 31833332f798 ("m68k/mm: Stop printing the virtual memory layout")
> > fd8d0ca25631 ("parisc: Hide virtual kernel memory layout")
> > adb1fe9ae2ee ("mm/page_alloc: Remove kernel address exposure in free_reserved_area()")
> Aww, why wasn't this made configurable? I found these memory map printouts
> very useful for development.

In most of the above (but not in this patch), "%p" was used to print
addresses, which started showing useless hashed addresses since commit
ad67b74d2469d9b8 ("printk: hash addresses printed with %p").

Instead of changing them all to print usable addresses instead, it was
agreed upon to just remove them.



Geert Uytterhoeven -- There's lots of Linux beyond ia32 --

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

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