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 <20240610214446.3380115-1-jeffxu@chromium.org> <C89ABF81-0EF8-40CB-8B04-B71868B79316@oracle.com>
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From: Jeff Xu <jeffxu@chromium.org>
Date: Tue, 11 Jun 2024 15:16:51 -0700
Message-ID: <CABi2SkV6znRR2QirETncu4u7PN7x0jQEij7s1wD4-aTJTO_UBQ@mail.gmail.com>
Subject: Re: Re [PATCH v5 4/5] x86/pkeys: Restore altstack before sigcontext
To: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Cc: "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>, Keith Lucas <keith.lucas@oracle.com>, 
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@kernel.org>, 
	Thomas Gleixner <tglx@linutronix.de>, "x86@kernel.org" <x86@kernel.org>, 
	Andrew Brownsword <andrew.brownsword@oracle.com>, 
	Matthias Neugschwandtner <matthias.neugschwandtner@oracle.com>, 
	"jeffxu@google.com" <jeffxu@google.com>, "jannh@google.com" <jannh@google.com>, 
	"keescook@chromium.org" <keescook@chromium.org>, "sroettger@google.com" <sroettger@google.com>, 
	"jorgelo@chromium.org" <jorgelo@chromium.org>, 
	"rick.p.edgecombe@intel.com" <rick.p.edgecombe@intel.com>
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On Tue, Jun 11, 2024 at 7:08=E2=80=AFAM Aruna Ramakrishna
<aruna.ramakrishna@oracle.com> wrote:
>
>
>
> > On Jun 10, 2024, at 2:44=E2=80=AFPM, jeffxu@chromium.org wrote:
> >
> > Can we we move this patch to the first of the series? this can be an
> > independent patch, the problem not only affect PKRU, but also other
> > scenarios, as Rick pointed out in [1]
> >
> > [1] https://lore.kernel.org/lkml/d0162c76c25bc8e1c876aebe8e243ff2e68623=
59.camel@intel.com/
> >
> > -Jeff
>
> For this patch set, the issue with rt_sigreturn() is only exposed after p=
atch 3/5 - i.e., when
> copy_fpregs_to_sigframe() calls update_pkru_in_sigframe() to update the P=
KRU value to
> user-specified PKRU that might disable pkey 0 access, thus breaking resto=
re_altstack().
> So it seemed logical to me to have this fix as patch 4/5 of this series. =
I=E2=80=99m not strongly
> opposed to moving this to patch 1/5, but this ordering is easier to under=
stand (I think).
> But if this patch needs to be broken out of this patchset and submitted i=
ndependently
> (for the other scenarios you mentioned) - I can do that.
>
My main thought  is that Rick mentioned this can be a cross-arch changes [1=
]
and we can start with x86/64 and other arches might follow.

[1] https://lore.kernel.org/lkml/20231107182251.91276-1-rick.p.edgecombe@in=
tel.com/

Thanks
-Jeff

> Thanks,
> Aruna