linux-kernel - Re: [PATCH] kdb: print real address of pointers instead of hashed addresses

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Message-ID: <ed907623-d636-0d18-95b0-33249c3d88cf@windriver.com>
Date:   Mon, 1 Oct 2018 14:55:57 -0500
From:   Jason Wessel <jason.wessel@...driver.com>
To:     Christophe Leroy <christophe.leroy@....fr>,
        Daniel Thompson <daniel.thompson@...aro.org>
CC:     Michael Ellerman <mpe@...erman.id.au>,
        <linux-kernel@...r.kernel.org>, <linuxppc-dev@...ts.ozlabs.org>,
        <kgdb-bugreport@...ts.sourceforge.net>, <stable@...r.kernel.org>
Subject: Re: [PATCH] kdb: print real address of pointers instead of hashed
 addresses

On 09/27/2018 12:17 PM, Christophe Leroy wrote:
> Since commit ad67b74d2469 ("printk: hash addresses printed with %p"),
> all pointers printed with %p are printed with hashed addresses
> instead of real addresses in order to avoid leaking addresses in
> dmesg and syslog. But this applies to kdb too, with is unfortunate:
> 
>      Entering kdb (current=0x(ptrval), pid 329) due to Keyboard Entry
>      kdb> ps
>      15 sleeping system daemon (state M) processes suppressed,
>      use 'ps A' to see all.
>      Task Addr       Pid   Parent [*] cpu State Thread     Command
>      0x(ptrval)      329      328  1    0   R  0x(ptrval) *sh
> 
>      0x(ptrval)        1        0  0    0   S  0x(ptrval)  init
>      0x(ptrval)        3        2  0    0   D  0x(ptrval)  rcu_gp
>      0x(ptrval)        4        2  0    0   D  0x(ptrval)  rcu_par_gp
>      0x(ptrval)        5        2  0    0   D  0x(ptrval)  kworker/0:0
>      0x(ptrval)        6        2  0    0   D  0x(ptrval)  kworker/0:0H
>      0x(ptrval)        7        2  0    0   D  0x(ptrval)  kworker/u2:0
>      0x(ptrval)        8        2  0    0   D  0x(ptrval)  mm_percpu_wq
>      0x(ptrval)       10        2  0    0   D  0x(ptrval)  rcu_preempt
> 
> The whole purpose of kdb is to debug, and for debugging real addresses
> need to be known. In addition, data displayed by kdb doesn't go into
> dmesg.
> 

I completely agree.  This is added to the merge queue.

Cheers,
Jason.