From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Michael Neuling <mikey@neuling.org>, mpe@ellerman.id.au
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 1/2] powerpc: Fix user data corruption with P9N DD2.1 VSX CI load workaround emulation
Date: Tue, 20 Oct 2020 23:23:52 +1100 (AEDT) [thread overview]
Message-ID: <160319651092.2348169.1397044759676064722.b4-ty@ellerman.id.au> (raw)
In-Reply-To: <20201013043741.743413-1-mikey@neuling.org>
On Tue, 13 Oct 2020 15:37:40 +1100, Michael Neuling wrote:
> __get_user_atomic_128_aligned() stores to kaddr using stvx which is a
> VMX store instruction, hence kaddr must be 16 byte aligned otherwise
> the store won't occur as expected.
>
> Unfortunately when we call __get_user_atomic_128_aligned() in
> p9_hmi_special_emu(), the buffer we pass as kaddr (ie. vbuf) isn't
> guaranteed to be 16B aligned. This means that the write to vbuf in
> __get_user_atomic_128_aligned() has the bottom bits of the address
> truncated. This results in other local variables being
> overwritten. Also vbuf will not contain the correct data which results
> in the userspace emulation being wrong and hence user data corruption.
>
> [...]
Applied to powerpc/fixes.
[1/2] powerpc: Fix undetected data corruption with P9N DD2.1 VSX CI load emulation
https://git.kernel.org/powerpc/c/1da4a0272c5469169f78cd76cf175ff984f52f06
[2/2] selftests/powerpc: Make alignment handler test P9N DD2.1 vector CI load workaround
https://git.kernel.org/powerpc/c/d1781f23704707d350b8c9006e2bdf5394bf91b2
cheers
prev parent reply other threads:[~2020-10-20 12:39 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-13 4:37 [PATCH 1/2] powerpc: Fix user data corruption with P9N DD2.1 VSX CI load workaround emulation Michael Neuling
2020-10-13 4:37 ` [PATCH 2/2] selftests/powerpc: Make alignment handler test P9N DD2.1 vector CI load workaround Michael Neuling
2020-10-14 0:13 ` [PATCH 1/2] powerpc: Fix user data corruption with P9N DD2.1 VSX CI load workaround emulation Michael Ellerman
2020-10-14 0:32 ` Michael Ellerman
2020-10-20 12:23 ` Michael Ellerman [this message]
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