From: Ram Pai <linuxram@us.ibm.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Florian Weimer <fweimer@redhat.com>,
linux-arch <linux-arch@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
Linux API <linux-api@vger.kernel.org>, X86 ML <x86@kernel.org>,
Dave Hansen <dave.hansen@intel.com>,
linux-x86_64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] pkeys: Introduce PKEY_ALLOC_SIGNALINHERIT and change signal semantics
Date: Wed, 2 May 2018 16:38:48 -0700 [thread overview]
Message-ID: <20180502233848.GB5863@ram.oc3035372033.ibm.com> (raw)
In-Reply-To: <CALCETrUfO=vXg5rT-n=y8pLktcq5+ORvgpsOXCHG4GaugB3k2A@mail.gmail.com>
On Wed, May 02, 2018 at 09:18:11PM +0000, Andy Lutomirski wrote:
> On Wed, May 2, 2018 at 2:13 PM Ram Pai <linuxram@us.ibm.com> wrote:
>
>
> > > Ram, would you please comment?
>
> > on POWER the pkey behavior will remain the same at entry or at exit from
> > the signal handler. For eg: if a key is read-disabled on entry into
> > the signal handler, and gets read-enabled in the signal handler, than it
> > will continue to be read-enabled on return from the signal handler.
>
> > In other words, changes to key permissions persist across signal
> > boundaries.
>
> I don't know about POWER's ISA, but this is crappy behavior. If a thread
> temporarily grants itself access to a restrictive memory key and then gets
> a signal, the signal handler should *not* have access to that key.
This is a new requirement that I was not aware off. Its not documented
anywhere AFAICT. Regardless of how the ISA behaves, its still a kernel
behavior that needs to be clearly defined.
--
Ram Pai
WARNING: multiple messages have this Message-ID (diff)
From: Ram Pai <linuxram@us.ibm.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Florian Weimer <fweimer@redhat.com>,
Dave Hansen <dave.hansen@intel.com>,
Linux-MM <linux-mm@kvack.org>,
Linux API <linux-api@vger.kernel.org>,
linux-x86_64@vger.kernel.org,
linux-arch <linux-arch@vger.kernel.org>, X86 ML <x86@kernel.org>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] pkeys: Introduce PKEY_ALLOC_SIGNALINHERIT and change signal semantics
Date: Wed, 2 May 2018 16:38:48 -0700 [thread overview]
Message-ID: <20180502233848.GB5863@ram.oc3035372033.ibm.com> (raw)
Message-ID: <20180502233848.w5mKaN-YiozFLMr06Zq1dN9keGV65w3YwiMuDLb4GII@z> (raw)
In-Reply-To: <CALCETrUfO=vXg5rT-n=y8pLktcq5+ORvgpsOXCHG4GaugB3k2A@mail.gmail.com>
On Wed, May 02, 2018 at 09:18:11PM +0000, Andy Lutomirski wrote:
> On Wed, May 2, 2018 at 2:13 PM Ram Pai <linuxram@us.ibm.com> wrote:
>
>
> > > Ram, would you please comment?
>
> > on POWER the pkey behavior will remain the same at entry or at exit from
> > the signal handler. For eg: if a key is read-disabled on entry into
> > the signal handler, and gets read-enabled in the signal handler, than it
> > will continue to be read-enabled on return from the signal handler.
>
> > In other words, changes to key permissions persist across signal
> > boundaries.
>
> I don't know about POWER's ISA, but this is crappy behavior. If a thread
> temporarily grants itself access to a restrictive memory key and then gets
> a signal, the signal handler should *not* have access to that key.
This is a new requirement that I was not aware off. Its not documented
anywhere AFAICT. Regardless of how the ISA behaves, its still a kernel
behavior that needs to be clearly defined.
--
Ram Pai
next prev parent reply other threads:[~2018-05-02 23:38 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-02 13:26 [PATCH] pkeys: Introduce PKEY_ALLOC_SIGNALINHERIT and change signal semantics Florian Weimer
2018-05-02 14:30 ` Dave Hansen
2018-05-02 15:12 ` Florian Weimer
2018-05-02 15:12 ` Florian Weimer
2018-05-02 15:28 ` Dave Hansen
2018-05-02 15:28 ` Dave Hansen
2018-05-02 21:08 ` Florian Weimer
2018-05-02 22:03 ` Dave Hansen
2018-05-02 22:03 ` Dave Hansen
2018-05-07 9:47 ` Florian Weimer
2018-05-07 9:47 ` Florian Weimer
2018-05-02 17:09 ` Andy Lutomirski
2018-05-02 17:17 ` Florian Weimer
2018-05-02 17:17 ` Florian Weimer
2018-05-02 20:41 ` Andy Lutomirski
2018-05-02 21:06 ` Florian Weimer
2018-05-02 21:06 ` Florian Weimer
2018-05-02 21:23 ` Andy Lutomirski
2018-05-02 22:08 ` Dave Hansen
2018-05-02 22:22 ` Andy Lutomirski
2018-05-02 22:32 ` Dave Hansen
2018-05-02 23:32 ` Andy Lutomirski
2018-05-02 23:58 ` Dave Hansen
2018-05-02 23:58 ` Dave Hansen
2018-05-03 1:14 ` Andy Lutomirski
2018-05-03 14:42 ` Dave Hansen
2018-05-03 14:42 ` Dave Hansen
2018-05-03 14:42 ` Florian Weimer
2018-05-03 14:42 ` Florian Weimer
2018-05-03 2:10 ` Ram Pai
2018-05-03 4:05 ` Andy Lutomirski
2018-05-07 9:48 ` Florian Weimer
2018-05-08 2:49 ` Andy Lutomirski
2018-05-08 2:49 ` Andy Lutomirski
2018-05-08 12:40 ` Florian Weimer
2018-05-08 12:40 ` Florian Weimer
2018-05-09 14:41 ` Andy Lutomirski
2018-05-09 14:41 ` Andy Lutomirski
2018-05-14 12:01 ` Florian Weimer
2018-05-14 12:01 ` Florian Weimer
2018-05-14 15:32 ` Andy Lutomirski
2018-05-14 15:32 ` Andy Lutomirski
2018-05-14 15:32 ` Andy Lutomirski
2018-05-14 15:34 ` Florian Weimer
2018-05-14 15:34 ` Florian Weimer
2018-05-14 15:34 ` Florian Weimer
2018-05-16 17:01 ` Dave Hansen
2018-05-16 17:01 ` Dave Hansen
2018-05-16 17:01 ` Dave Hansen
2018-05-16 20:52 ` Ram Pai
2018-05-16 20:52 ` Ram Pai
2018-05-16 20:54 ` Andy Lutomirski
2018-05-16 20:54 ` Andy Lutomirski
2018-05-16 20:35 ` Ram Pai
2018-05-16 20:35 ` Ram Pai
2018-05-16 20:37 ` Andy Lutomirski
2018-05-16 20:37 ` Andy Lutomirski
2018-05-16 21:07 ` Ram Pai
2018-05-16 21:07 ` Ram Pai
2018-05-17 10:09 ` Florian Weimer
2018-05-17 10:09 ` Florian Weimer
2018-05-17 10:11 ` Florian Weimer
2018-05-17 10:11 ` Florian Weimer
2018-05-03 14:37 ` Florian Weimer
2018-05-02 21:12 ` Ram Pai
2018-05-02 21:12 ` Ram Pai
2018-05-02 21:18 ` Andy Lutomirski
2018-05-02 23:38 ` Ram Pai [this message]
2018-05-02 23:38 ` Ram Pai
2018-05-07 9:47 ` Florian Weimer
2018-05-07 9:47 ` Florian Weimer
2018-05-07 9:43 ` Florian Weimer
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