From: Mark Rutland <mark.rutland@arm.com>
To: Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Shuah Khan <shuah@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v1] kselftest/arm64: Use preferred form for predicate load/stores
Date: Thu, 17 Nov 2022 11:52:22 +0000 [thread overview]
Message-ID: <Y3YgdloFYx3pQUO0@FVFF77S0Q05N> (raw)
In-Reply-To: <20221117114130.687261-1-broonie@kernel.org>
On Thu, Nov 17, 2022 at 11:41:30AM +0000, Mark Brown wrote:
> The preferred form of the str/ldr for predicate registers with an immediate
> of zero is to omit the zero, and the clang built in assembler rejects the
> zero immediate. Drop the immediate.
Rejecting that outright seems like a bug in clang, given there are legitimate
reasons to write code that way (e.g. using asm-offsets style definitions); has
that been reported so that it can be fixed?
Regardless, the patch itself looks fine, and I don't mean to block this as-is!
Thanks,
Mark.
>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
> tools/testing/selftests/arm64/abi/syscall-abi-asm.S | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/arm64/abi/syscall-abi-asm.S b/tools/testing/selftests/arm64/abi/syscall-abi-asm.S
> index b523c21c2278..acd5e9f3bc0b 100644
> --- a/tools/testing/selftests/arm64/abi/syscall-abi-asm.S
> +++ b/tools/testing/selftests/arm64/abi/syscall-abi-asm.S
> @@ -153,7 +153,7 @@ do_syscall:
> // Only set a non-zero FFR, test patterns must be zero since the
> // syscall should clear it - this lets us handle FA64.
> ldr x2, =ffr_in
> - ldr p0, [x2, #0]
> + ldr p0, [x2]
> ldr x2, [x2, #0]
> cbz x2, 2f
> wrffr p0.b
> @@ -298,7 +298,7 @@ do_syscall:
> cbz x2, 1f
> ldr x2, =ffr_out
> rdffr p0.b
> - str p0, [x2, #0]
> + str p0, [x2]
> 1:
>
> // Restore callee saved registers x19-x30
>
> base-commit: 30a0b95b1335e12efef89dd78518ed3e4a71a763
> --
> 2.30.2
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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next prev parent reply other threads:[~2022-11-17 11:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-17 11:41 [PATCH v1] kselftest/arm64: Use preferred form for predicate load/stores Mark Brown
2022-11-17 11:52 ` Mark Rutland [this message]
2022-11-17 12:52 ` Mark Brown
2022-11-18 19:40 ` Will Deacon
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