From: gengdongjiu <gengdongjiu@huawei.com>
To: Robin Murphy <robin.murphy@arm.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 20:54:44 +0800 [thread overview]
Message-ID: <d7b8b779-9e00-8e8f-b44e-48e3d7e37058@huawei.com> (raw)
In-Reply-To: <6dc82768-8564-a54e-041b-3b9965fa038b@arm.com>
Hi Robin,
On 2017/11/1 19:24, Robin Murphy wrote:
>> + 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?
I found it will report error if combine the alternative conditions here.
For example:
+ .macro error_synchronize
+alternative_if ARM64_HAS_IESB
+alternative_if ARM64_HAS_RAS_EXTN
+ esb
+alternative_else_nop_endif
+alternative_else_nop_endif
+ .endm
And even using b.eq/cbz instruction in the alternative instruction in arch/arm64/kernel/entry.S,
it will report Error.
For example below
alternative_if ARM64_HAS_PAN
xxxxxxxxxxxxxxxxxxxx
b.eq xxxxx
alternative_else_nop_endif
I do not dig it deeply, do you know the reason about it or good suggestion about that?
Thanks a lot in advance.
>
> Robin.
>
>> #endif /* __ASM_ASSEMBLER_H */
next prev parent reply other threads:[~2017-11-01 12:59 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
2017-11-01 12:54 ` gengdongjiu [this message]
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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