From: Nicholas Piggin <npiggin@gmail.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@ozlabs.org, msuchanek@suse.de, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/6] powerpc/64s: Add barrier_nospec
Date: Tue, 24 Apr 2018 15:44:57 +1000 [thread overview]
Message-ID: <20180424154457.78fe8c09@roar.ozlabs.ibm.com> (raw)
In-Reply-To: <20180424041559.32410-1-mpe@ellerman.id.au>
On Tue, 24 Apr 2018 14:15:54 +1000
Michael Ellerman <mpe@ellerman.id.au> wrote:
> From: Michal Suchanek <msuchanek@suse.de>
>
> A no-op form of ori (or immediate of 0 into r31 and the result stored
> in r31) has been re-tasked as a speculation barrier. The instruction
> only acts as a barrier on newer machines with appropriate firmware
> support. On older CPUs it remains a harmless no-op.
>
> Implement barrier_nospec using this instruction.
>
> mpe: The semantics of the instruction are believed to be that it
> prevents execution of subsequent instructions until preceding branches
> have been fully resolved and are no longer executing speculatively.
> There is no further documentation available at this time.
>
> Signed-off-by: Michal Suchanek <msuchanek@suse.de>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> ---
> mpe: Make it Book3S64 only, update comment & change log, add a
> memory clobber to the asm.
These all seem good to me. Thanks Michal.
We should (eventually) work on the module patching problem too.
Thanks,
Nick
next prev parent reply other threads:[~2018-04-24 5:45 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-24 4:15 [PATCH 1/6] powerpc/64s: Add barrier_nospec Michael Ellerman
2018-04-24 4:15 ` [PATCH 2/6] powerpc/64s: Add support for ori barrier_nospec patching Michael Ellerman
2018-04-26 16:10 ` Michal Suchánek
2018-05-01 12:25 ` Michael Ellerman
2018-04-24 4:15 ` [PATCH 3/6] powerpc/64s: Patch barrier_nospec in modules Michael Ellerman
2018-05-03 13:15 ` Michal Suchánek
2018-04-24 4:15 ` [PATCH 4/6] powerpc/64s: Enable barrier_nospec based on firmware settings Michael Ellerman
2018-04-26 16:02 ` Michal Suchánek
2018-05-01 11:11 ` Michael Ellerman
2018-05-02 11:41 ` Michal Suchánek
2018-05-04 0:58 ` Michael Ellerman
2018-04-24 4:15 ` [PATCH 5/6] powerpc: Use barrier_nospec in copy_from_user() Michael Ellerman
2018-04-24 4:15 ` [PATCH 6/6] powerpc/64: Use barrier_nospec in syscall entry Michael Ellerman
2018-04-24 5:44 ` Nicholas Piggin [this message]
2018-05-28 13:19 ` [PATCH] powerpc/64s: Enhance the information in cpu_show_spectre_v1() Michal Suchanek
2018-05-29 14:03 ` kbuild test robot
2018-05-29 14:13 ` Christophe LEROY
2018-05-29 14:46 ` Michal Suchánek
2018-05-29 15:24 ` Christophe Leroy
2018-05-29 16:15 ` Joe Perches
2018-06-04 14:11 ` Michael Ellerman
2018-06-04 14:10 ` [1/6] powerpc/64s: Add barrier_nospec Michael Ellerman
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