linux-kernel - Re: powerpc: dump as a single line areas mapping a single physical page.

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Message-Id: <445RNM72H2z9sDX@ozlabs.org>
Date:   Fri, 22 Feb 2019 20:48:03 +1100 (AEDT)
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     Christophe Leroy <christophe.leroy@....fr>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: powerpc: dump as a single line areas mapping a single physical page.

On Mon, 2019-02-18 at 12:25:20 UTC, Christophe Leroy wrote:
> When using KASAN, there are parts of the shadow area where all
> pages are mapped to the kasan_early_shadow_page. It is pointless
> to dump one line for each of those pages (in the example below there
> are 7168 entries pointing to the same physical page).
> 
> ~# cat /sys/kernel/debug/kernel_page_tables
>  ...
> ---[ kasan shadow mem start ]---
> 0xf7c00000-0xf8bfffff 0x06fac000       16M        rw       present           dirty  accessed
> 0xf8c00000-0xf8c03fff 0x00cd0000       16K        r        present           dirty  accessed
> 0xf8c04000-0xf8c07fff 0x00cd0000       16K        r        present           dirty  accessed
> 0xf8c08000-0xf8c0bfff 0x00cd0000       16K        r        present           dirty  accessed
> 0xf8c0c000-0xf8c0ffff 0x00cd0000       16K        r        present           dirty  accessed
> 0xf8c10000-0xf8c13fff 0x00cd0000       16K        r        present           dirty  accessed
>  ... 7168 identical lines
> 0xffbfc000-0xffbfffff 0x00cd0000       16K        r        present           dirty  accessed
> ---[ kasan shadow mem end ]---
>  ...
> 
> This patch modifies linux table dump to dump as a single line areas
> where all addresses points to the same physical page. That physical
> address is put inside [] to show that all virt pages points to the
> same phys page.
> 
> ~# cat /sys/kernel/debug/kernel_page_tables
>  ...
> ---[ kasan shadow mem start ]---
> 0xf7c00000-0xf8bfffff  0x06fac000        16M        rw       present           dirty  accessed
> 0xf8c00000-0xffbfffff [0x00cd0000]       16K        r        present           dirty  accessed
> ---[ kasan shadow mem end ]---
>  ...
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/cabe8138b23c92e851b92c6a20ffb135

cheers