From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 4/6] s390: add system call to run tasks with modified
 branch prediction
Date: Wed, 17 Jan 2018 12:50:21 +0100
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Cc: Heiko Carstens <heiko.carstens@de.ibm.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jon Masters <jcm@redhat.com>,
        Marcus Meissner <meissner@suse.de>,
        Jiri Kosina <jkosina@suse.cz>
To: Christian Borntraeger <borntraeger@de.ibm.com>,
        Florian Weimer <fweimer@redhat.com>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
        kvm@vger.kernel.org
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On 17/01/2018 12:14, Christian Borntraeger wrote:
> 
> 
> On 01/17/2018 11:03 AM, Florian Weimer wrote:
>> On 01/17/2018 10:48 AM, Martin Schwidefsky wrote:
>>>          rc = syscall(__NR_s390_modify_bp);
>>>          if (rc) {
>>>                  perror("s390_modify_bp");
>>>                  exit(EXIT_FAILURE);
>>>          }
>>
>> Isn't this traditionally done through personality or prctl?
> 
> I think we want this per thread (and not per process). So I assume personality
> will not work out. Can a prctl be done per thread?

Yes, prctls can be either per-process (e.g. PR_SET_CHILD_SUBREAPER or
PR_SET_DUMPABLE) or per-thread (e.g. PR_SET_NAME or PR_SET_SECCOMP).

Paolo