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Subject: Re: pkeys on POWER: Access rights not reset on execve
References: <53828769-23c4-b2e3-cf59-239936819c3e@redhat.com>
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From: Florian Weimer <fweimer@redhat.com>
Message-ID: <4e53b91f-80a7-816a-3e9b-56d7be7cd092@redhat.com>
Date: Mon, 4 Jun 2018 12:12:07 +0200
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To: Ram Pai <linuxram@us.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>, Linux-MM <linux-mm@kvack.org>, linuxppc-dev <linuxppc-dev@lists.ozlabs.org>, Dave Hansen <dave.hansen@intel.com>

On 06/03/2018 10:18 PM, Ram Pai wrote:
> On Mon, May 21, 2018 at 01:29:11PM +0200, Florian Weimer wrote:
>> On 05/20/2018 09:11 PM, Ram Pai wrote:
>>> Florian,
>>>
>>> 	Does the following patch fix the problem for you?  Just like x86
>>> 	I am enabling all keys in the UAMOR register during
>>> 	initialization itself. Hence any key created by any thread at
>>> 	any time, will get activated on all threads. So any thread
>>> 	can change the permission on that key. Smoke tested it
>>> 	with your test program.
>>
>> I think this goes in the right direction, but the AMR value after
>> fork is still strange:
>>
>> AMR (PID 34912): 0x0000000000000000
>> AMR after fork (PID 34913): 0x0000000000000000
>> AMR (PID 34913): 0x0000000000000000
>> Allocated key in subprocess (PID 34913): 2
>> Allocated key (PID 34912): 2
>> Setting AMR: 0xffffffffffffffff
>> New AMR value (PID 34912): 0x0fffffffffffffff
>> About to call execl (PID 34912) ...
>> AMR (PID 34912): 0x0fffffffffffffff
>> AMR after fork (PID 34914): 0x0000000000000003
>> AMR (PID 34914): 0x0000000000000003
>> Allocated key in subprocess (PID 34914): 2
>> Allocated key (PID 34912): 2
>> Setting AMR: 0xffffffffffffffff
>> New AMR value (PID 34912): 0x0fffffffffffffff
>>
>> I mean this line:
>>
>> AMR after fork (PID 34914): 0x0000000000000003
>>
>> Shouldn't it be the same as in the parent process?
> 
> Fixed it. Please try this patch. If it all works to your satisfaction, I
> will clean it up further and send to Michael Ellermen(ppc maintainer).
> 
> 
> commit 51f4208ed5baeab1edb9b0f8b68d7144449b3527
> Author: Ram Pai <linuxram@us.ibm.com>
> Date:   Sun Jun 3 14:44:32 2018 -0500
> 
>      Fix for the fork bug.
>      
>      Signed-off-by: Ram Pai <linuxram@us.ibm.com>

Is this on top of the previous patch, or a separate fix?

Thanks,
Florian