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Date: Thu, 15 Sep 2016 16:19:05 +0100
From: Mark Rutland <mark.rutland@....com>
To: Catalin Marinas <catalin.marinas@....com>
Cc: linux-arm-kernel@...ts.infradead.org, Will Deacon <will.deacon@....com>,
James Morse <james.morse@....com>,
Kees Cook <keescook@...omium.org>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
AKASHI Takahiro <takahiro.akashi@...aro.org>,
kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH v3 2/7] arm64: Factor out TTBR0_EL1 post-update
workaround into a specific asm macro
On Tue, Sep 13, 2016 at 06:46:32PM +0100, Catalin Marinas wrote:
> This patch takes the errata workaround code out of cpu_do_switch_mm into
> a dedicated post_ttbr0_update_workaround macro which will be reused in a
> subsequent patch.
>
> Cc: Will Deacon <will.deacon@....com>
> Cc: James Morse <james.morse@....com>
> Cc: Kees Cook <keescook@...omium.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Signed-off-by: Catalin Marinas <catalin.marinas@....com>
> ---
> arch/arm64/include/asm/assembler.h | 17 +++++++++++++++++
> arch/arm64/mm/proc.S | 11 +----------
> 2 files changed, 18 insertions(+), 10 deletions(-)
>
> diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
> index d5025c69ca81..0a47632787d9 100644
> --- a/arch/arm64/include/asm/assembler.h
> +++ b/arch/arm64/include/asm/assembler.h
> @@ -350,4 +350,21 @@ alternative_endif
> movk \reg, :abs_g0_nc:\val
> .endm
>
> +/*
> + * Errata workaround post TTBR0_EL1 update.
> + */
> + .macro post_ttbr0_update_workaround
> +#ifdef CONFIG_CAVIUM_ERRATUM_27456
> +alternative_if_not ARM64_WORKAROUND_CAVIUM_27456
> + nop
> + nop
> + nop
> +alternative_else
> + ic iallu
> + dsb nsh
> + isb
> +alternative_endif
> +#endif
> + .endm
> +
> #endif /* __ASM_ASSEMBLER_H */
As a general note, it's unfortunate that we put asm with alternatives in
<asm/assembler.h>, as that's included by <asm/alternative.h>, so we're
relying on things that aren't defined yet, and users have to remember to
include <asm/alternative.h>.
That's already the case for dcache_by_line_op, so I guess that's
something to deal with another day.
Otherwise, this looks good, and I guess this wil be auto-nopped in a
subsqeuent version, so FWIW:
Reviewed-by: Mark Rutland <mark.rutland@....com>
Thanks,
Mark.
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