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Date: Thu, 5 Apr 2018 21:33:09 +0200
From: Greg KH <greg@kroah.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: stable@vger.kernel.org, mark.brown@linaro.org,
        ard.biesheuvel@linaro.org, marc.zyngier@arm.com,
        will.deacon@arm.com
Subject: Re: [PATCH v4.9.y 09/27] arm64: mm: Map entry trampoline into
 trampoline and kernel page tables
Message-ID: <20180405193309.GA21484@kroah.com>
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 <20180403111505.lyl3gimida3uriwm@lakrids.cambridge.arm.com>
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On Tue, Apr 03, 2018 at 12:15:06PM +0100, Mark Rutland wrote:
> On Tue, Apr 03, 2018 at 12:09:05PM +0100, Mark Rutland wrote:
> > From: Will Deacon <will.deacon@arm.com>
> > 
> > commit 51a0048beb44 upstream.
> > 
> > The exception entry trampoline needs to be mapped at the same virtual
> > address in both the trampoline page table (which maps nothing else)
> > and also the kernel page table, so that we can swizzle TTBR1_EL1 on
> > exceptions from and return to EL0.
> > 
> > This patch maps the trampoline at a fixed virtual address in the fixmap
> > area of the kernel virtual address space, which allows the kernel proper
> > to be randomized with respect to the trampoline when KASLR is enabled.
> > 
> > Reviewed-by: Mark Rutland <mark.rutland@arm.com>
> > Tested-by: Laura Abbott <labbott@redhat.com>
> > Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
> > Signed-off-by: Will Deacon <will.deacon@arm.com>
> > Signed-off-by: Alex Shi <alex.shi@linaro.org>
> > Reviewed-by: Mark Rutland <mark.rutland@arm.com> [v4.9 backport]
> 
> It has just been pointed out to me that I messed up the SoB chain here,
> and this should be:
> 
> Signed-off-by: Mark Rutland <mark.rutland@arm.com> [v4.9 backport]
> 
> Otherwise, the patch itself is fine. Sorry for the noise there -- I hope
> this can be fixed up when applying?

I'll go fix it up...