linux-kernel - Re: [PATCH] modules: Fix display of wrong module .text address

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Date:   Tue, 17 Apr 2018 19:34:52 +0200
From:   Christian Borntraeger <borntraeger@...ibm.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Thomas Richter <tmricht@...ux.ibm.com>, jeyu@...nel.org,
        torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
        schwidefsky@...ibm.com, brueckner@...ux.vnet.ibm.com,
        heiko.carstens@...ibm.com, peterz@...radead.org, me@...in.cc,
        keescook@...omium.org
Subject: Re: [PATCH] modules: Fix display of wrong module .text address



On 04/17/2018 06:20 PM, Arnaldo Carvalho de Melo wrote:
> Em Tue, Apr 17, 2018 at 10:24:35AM +0200, Christian Borntraeger escreveu:
>>
>>
>> On 04/17/2018 10:20 AM, Thomas Richter wrote:
>>> In kernel v4.16.0 the module .text address is displayed
>>> wrong when using /sys/module/*/sections/.text file.
>>> Commit ef0010a30935 ("vsprintf: don't use 'restricted_pointer()' when
>>> not restricting")
>>> is the first bad commit.
>>>
>>> Here is the issue, using module qeth_l2 on s390 which is the
>>> ethernet device driver:
>>>
>>> [root@...lp76 ~]# lsmod
>>> Module                  Size  Used by
>>> qeth_l2                94208  1
>>> ...
>>>
>>> [root@...lp76 ~]# cat /proc/modules | egrep '^qeth_l2'
>>> qeth_l2 94208 1 - Live 0x000003ff80401000
>>>                        ^ This is the correct address in memory
>>> [root@...lp76 ~]# cat /sys/module/qeth_l2/sections/.text
>>> 0x0000000018ea8363      <---- This is a wrong address
>>> [root@...lp76 ~]#
>>>
>>> This breaks the perf tool which uses this address on s390
>>> to calculate start of .text section in memory.
>>>
>>> Fix this by printing the correct (unhashed) address.
>>>
>>> Thanks to Jessica Yu for helping on this.
>>>
>>> Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
>>> Signed-off-by: Thomas Richter <tmricht@...ux.ibm.com>
>>> Cc: Jessica Yu <jeyu@...nel.org>
>>
>> CC stable?
> 
> Adding the missing:
> 
> Fixes: ef0010a30935 ("vsprintf: don't use 'restricted_pointer()' when not restricting")
> 
> Should be enough?

Even better.