From: Dave Hansen <dave.hansen-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
To: Florian Weimer <fweimer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
linux-mm <linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>,
x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
linux-arch <linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
linux-x86_64-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Linux API <linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: pkeys: Support setting access rights for signal handlers
Date: Sat, 9 Dec 2017 16:17:36 -0800 [thread overview]
Message-ID: <c034f693-95d1-65b8-2031-b969c2771fed@intel.com> (raw)
In-Reply-To: <5fee976a-42d4-d469-7058-b78ad8897219-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
On 12/09/2017 01:16 PM, Florian Weimer wrote:
> The attached patch addresses a problem with the current x86 pkey
> implementation, which makes default-readable pkeys unusable from signal
> handlers because the default init_pkru value blocks access.
Thanks for looking into this!
What do you mean by "default-readable pkeys"?
I think you mean that, for any data that needs to be accessed to enter a
signal handler, it must be set to pkey=0 with the current
implementation. All other keys are inaccessible when entering a signal
handler because the "init" value disables access.
My only nit with this is whether it is the *right* interface. The
signal vs. XSAVE state thing is pretty x86 specific and I doubt that
this will be the last feature that we encounter that needs special
signal behavior.
A question more for the x86 maintainers is whether they would rather see
a pkeys-specific interface for this, or an XSAVE-specific interface
where you could specify a non-init XSAVE state for a set of XSAVE
components.
WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave.hansen@intel.com>
To: Florian Weimer <fweimer@redhat.com>,
linux-mm <linux-mm@kvack.org>,
x86@kernel.org, linux-arch <linux-arch@vger.kernel.org>,
linux-x86_64@vger.kernel.org,
Linux API <linux-api@vger.kernel.org>
Subject: Re: pkeys: Support setting access rights for signal handlers
Date: Sat, 9 Dec 2017 16:17:36 -0800 [thread overview]
Message-ID: <c034f693-95d1-65b8-2031-b969c2771fed@intel.com> (raw)
Message-ID: <20171210001736.FV9oKoqgbQo87ANz_nLo-Hk3RuhYHvCa-EGktjo_Yhk@z> (raw)
In-Reply-To: <5fee976a-42d4-d469-7058-b78ad8897219@redhat.com>
On 12/09/2017 01:16 PM, Florian Weimer wrote:
> The attached patch addresses a problem with the current x86 pkey
> implementation, which makes default-readable pkeys unusable from signal
> handlers because the default init_pkru value blocks access.
Thanks for looking into this!
What do you mean by "default-readable pkeys"?
I think you mean that, for any data that needs to be accessed to enter a
signal handler, it must be set to pkey=0 with the current
implementation. All other keys are inaccessible when entering a signal
handler because the "init" value disables access.
My only nit with this is whether it is the *right* interface. The
signal vs. XSAVE state thing is pretty x86 specific and I doubt that
this will be the last feature that we encounter that needs special
signal behavior.
A question more for the x86 maintainers is whether they would rather see
a pkeys-specific interface for this, or an XSAVE-specific interface
where you could specify a non-init XSAVE state for a set of XSAVE
components.
WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave.hansen@intel.com>
To: Florian Weimer <fweimer@redhat.com>,
linux-mm <linux-mm@kvack.org>,
x86@kernel.org, linux-arch <linux-arch@vger.kernel.org>,
linux-x86_64@vger.kernel.org,
Linux API <linux-api@vger.kernel.org>
Subject: Re: pkeys: Support setting access rights for signal handlers
Date: Sat, 9 Dec 2017 16:17:36 -0800 [thread overview]
Message-ID: <c034f693-95d1-65b8-2031-b969c2771fed@intel.com> (raw)
In-Reply-To: <5fee976a-42d4-d469-7058-b78ad8897219@redhat.com>
On 12/09/2017 01:16 PM, Florian Weimer wrote:
> The attached patch addresses a problem with the current x86 pkey
> implementation, which makes default-readable pkeys unusable from signal
> handlers because the default init_pkru value blocks access.
Thanks for looking into this!
What do you mean by "default-readable pkeys"?
I think you mean that, for any data that needs to be accessed to enter a
signal handler, it must be set to pkey=0 with the current
implementation. All other keys are inaccessible when entering a signal
handler because the "init" value disables access.
My only nit with this is whether it is the *right* interface. The
signal vs. XSAVE state thing is pretty x86 specific and I doubt that
this will be the last feature that we encounter that needs special
signal behavior.
A question more for the x86 maintainers is whether they would rather see
a pkeys-specific interface for this, or an XSAVE-specific interface
where you could specify a non-init XSAVE state for a set of XSAVE
components.
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next prev parent reply other threads:[~2017-12-10 0:17 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-09 21:16 pkeys: Support setting access rights for signal handlers Florian Weimer
[not found] ` <5fee976a-42d4-d469-7058-b78ad8897219-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-12-10 0:17 ` Dave Hansen [this message]
2017-12-10 0:17 ` Dave Hansen
2017-12-10 0:17 ` Dave Hansen
2017-12-10 6:42 ` Florian Weimer
2017-12-10 6:42 ` Florian Weimer
2017-12-11 16:13 ` Dave Hansen
2017-12-11 16:13 ` Dave Hansen
2017-12-12 23:13 ` Ram Pai
2017-12-12 23:13 ` Ram Pai
2017-12-13 2:14 ` Florian Weimer
2017-12-13 2:14 ` Florian Weimer
2017-12-13 11:35 ` Ram Pai
2017-12-13 11:35 ` Ram Pai
[not found] ` <20171213113544.GG5460-LOE2q6NSToAxGrZ80giIafUQ3DHhIser@public.gmane.org>
2017-12-13 15:08 ` Florian Weimer
2017-12-13 15:08 ` Florian Weimer
2017-12-13 15:08 ` Florian Weimer
2017-12-13 15:22 ` Dave Hansen
2017-12-13 15:22 ` Dave Hansen
2017-12-13 15:40 ` Florian Weimer
2017-12-13 15:40 ` Florian Weimer
2017-12-14 0:17 ` Ram Pai
2017-12-14 0:17 ` Ram Pai
2017-12-14 11:21 ` Florian Weimer
2017-12-16 15:09 ` Ram Pai
2017-12-16 15:09 ` Ram Pai
2017-12-16 15:25 ` Florian Weimer
2017-12-16 15:25 ` Florian Weimer
[not found] ` <2eba29f4-804d-b211-1293-52a567739cad-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-12-16 17:20 ` Ram Pai
2017-12-16 17:20 ` Ram Pai
2017-12-16 17:20 ` Ram Pai
2017-12-18 11:00 ` Florian Weimer
2017-12-18 11:00 ` Florian Weimer
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