From: Robin Murphy <robin.murphy@arm.com>
To: Dongjiu Geng <gengdongjiu@huawei.com>,
catalin.marinas@arm.com, will.deacon@arm.com,
marc.zyngier@arm.com, christoffer.dall@linaro.org,
james.morse@arm.com, mark.rutland@arm.com,
ard.biesheuvel@linaro.org, cov@codeaurora.org,
Dave.Martin@arm.com, suzuki.poulose@arm.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH v1 1/3] arm64: add a macro for SError synchronization
Date: Wed, 1 Nov 2017 11:24:59 +0000 [thread overview]
Message-ID: <6dc82768-8564-a54e-041b-3b9965fa038b@arm.com> (raw)
In-Reply-To: <1509563697-6359-2-git-send-email-gengdongjiu@huawei.com>
On 01/11/17 19:14, Dongjiu Geng wrote:
> ARMv8.2 adds a control bit to each SCTLR_ELx to insert implicit
> Error Synchronization Barrier(IESB) operations at exception handler entry
> and exit. But not all hardware platform which support RAS Extension
> can support IESB. So for this case, software needs to manually insert
> Error Synchronization Barrier(ESB) operations.
>
> In this macros, if system supports RAS Extensdddon instead of IESB,
> it will insert an ESB instruction.
>
> Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
> ---
> arch/arm64/include/asm/assembler.h | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
> index d4c0adf..e6c79c4 100644
> --- a/arch/arm64/include/asm/assembler.h
> +++ b/arch/arm64/include/asm/assembler.h
> @@ -517,4 +517,13 @@
> #endif
> .endm
>
> + .macro error_synchronize
> +alternative_if ARM64_HAS_IESB
> + b 1f
> +alternative_else_nop_endif
> +alternative_if ARM64_HAS_RAS_EXTN
> + esb
> +alternative_else_nop_endif
> +1:
> + .endm
Having a branch in here is pretty horrible, and furthermore using label
number 1 has a pretty high chance of subtly breaking code where this
macro is inserted.
Can we not somehow nest or combine the alternative conditions here?
Robin.
> #endif /* __ASM_ASSEMBLER_H */
>
next prev parent reply other threads:[~2017-11-01 11:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-01 19:14 [PATCH v1 0/3] manually add Error Synchronization Barrier at exception handler entry and exit Dongjiu Geng
2017-11-01 11:21 ` Robin Murphy
2017-11-01 11:32 ` James Morse
2017-11-01 12:44 ` gengdongjiu
2017-11-01 19:14 ` [PATCH v1 1/3] arm64: add a macro for SError synchronization Dongjiu Geng
2017-11-01 11:24 ` Robin Murphy [this message]
2017-11-01 12:54 ` gengdongjiu
2017-11-01 13:31 ` Robin Murphy
2017-11-01 14:16 ` Mark Rutland
2017-11-02 8:52 ` gengdongjiu
2017-11-01 19:14 ` [PATCH v1 2/3] arm64: add error synchronization barrier in kernel_entry/kernel_exit Dongjiu Geng
2017-11-04 17:34 ` kbuild test robot
2017-11-01 19:14 ` [PATCH v1 3/3] KVM: arm64: add ESB in exception handler entry and exit Dongjiu Geng
2017-11-04 18:49 ` kbuild test robot
-- strict thread matches above, loose matches on Subject: below --
2017-11-01 14:13 [PATCH v1 1/3] arm64: add a macro for SError synchronization gengdongjiu
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