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From: Catalin Marinas <catalin.marinas@arm.com>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: Kees Cook <keescook@chromium.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
	Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2] arm64/alternatives: move length validation inside the subsection
Date: Thu, 30 Jul 2020 18:24:31 +0100	[thread overview]
Message-ID: <20200730172430.GC3128@gaia> (raw)
In-Reply-To: <20200730153701.3892953-1-samitolvanen@google.com>

On Thu, Jul 30, 2020 at 08:37:01AM -0700, Sami Tolvanen wrote:
> Commit f7b93d42945c ("arm64/alternatives: use subsections for replacement
> sequences") breaks LLVM's integrated assembler, because due to its
> one-pass design, it cannot compute instruction sequence lengths before the
> layout for the subsection has been finalized. This change fixes the build
> by moving the .org directives inside the subsection, so they are processed
> after the subsection layout is known.
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/1078
> Fixes: f7b93d42945c ("arm64/alternatives: use subsections for replacement sequences")
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> ---
> v1 -> v2:
> - Added the missing Fixes tag and dropped CC: stable@.
> 
> ---
>  arch/arm64/include/asm/alternative.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h
> index 12f0eb56a1cc..619db9b4c9d5 100644
> --- a/arch/arm64/include/asm/alternative.h
> +++ b/arch/arm64/include/asm/alternative.h
> @@ -77,9 +77,9 @@ static inline void apply_alternatives_module(void *start, size_t length) { }
>  	"663:\n\t"							\
>  	newinstr "\n"							\
>  	"664:\n\t"							\
> -	".previous\n\t"							\
>  	".org	. - (664b-663b) + (662b-661b)\n\t"			\
> -	".org	. - (662b-661b) + (664b-663b)\n"			\
> +	".org	. - (662b-661b) + (664b-663b)\n\t"			\
> +	".previous\n"							\
>  	".endif\n"

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

There are a few instances of the .org test outside the subsection,
though using in .S files. Are those ok?

-- 
Catalin

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Catalin Marinas <catalin.marinas@arm.com>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Kees Cook <keescook@chromium.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: Re: [PATCH v2] arm64/alternatives: move length validation inside the subsection
Date: Thu, 30 Jul 2020 18:24:31 +0100	[thread overview]
Message-ID: <20200730172430.GC3128@gaia> (raw)
In-Reply-To: <20200730153701.3892953-1-samitolvanen@google.com>

On Thu, Jul 30, 2020 at 08:37:01AM -0700, Sami Tolvanen wrote:
> Commit f7b93d42945c ("arm64/alternatives: use subsections for replacement
> sequences") breaks LLVM's integrated assembler, because due to its
> one-pass design, it cannot compute instruction sequence lengths before the
> layout for the subsection has been finalized. This change fixes the build
> by moving the .org directives inside the subsection, so they are processed
> after the subsection layout is known.
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/1078
> Fixes: f7b93d42945c ("arm64/alternatives: use subsections for replacement sequences")
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> ---
> v1 -> v2:
> - Added the missing Fixes tag and dropped CC: stable@.
> 
> ---
>  arch/arm64/include/asm/alternative.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h
> index 12f0eb56a1cc..619db9b4c9d5 100644
> --- a/arch/arm64/include/asm/alternative.h
> +++ b/arch/arm64/include/asm/alternative.h
> @@ -77,9 +77,9 @@ static inline void apply_alternatives_module(void *start, size_t length) { }
>  	"663:\n\t"							\
>  	newinstr "\n"							\
>  	"664:\n\t"							\
> -	".previous\n\t"							\
>  	".org	. - (664b-663b) + (662b-661b)\n\t"			\
> -	".org	. - (662b-661b) + (664b-663b)\n"			\
> +	".org	. - (662b-661b) + (664b-663b)\n\t"			\
> +	".previous\n"							\
>  	".endif\n"

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

There are a few instances of the .org test outside the subsection,
though using in .S files. Are those ok?

-- 
Catalin

  parent reply	other threads:[~2020-07-30 17:26 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-29 21:51 [PATCH] arm64/alternatives: move length validation inside the subsection Sami Tolvanen
2020-07-29 21:51 ` Sami Tolvanen
2020-07-30 12:22 ` Catalin Marinas
2020-07-30 12:22   ` Catalin Marinas
2020-07-30 15:13   ` Sami Tolvanen
2020-07-30 15:13     ` Sami Tolvanen
2020-07-30 15:23     ` Catalin Marinas
2020-07-30 15:23       ` Catalin Marinas
2020-07-31  6:49       ` Greg KH
2020-07-31  6:49         ` Greg KH
2020-07-31  9:31         ` Catalin Marinas
2020-07-31  9:31           ` Catalin Marinas
2020-07-30 15:37 ` [PATCH v2] " Sami Tolvanen
2020-07-30 15:37   ` Sami Tolvanen
2020-07-30 16:52   ` Will Deacon
2020-07-30 16:52     ` Will Deacon
2020-07-30 16:57   ` Nathan Chancellor
2020-07-30 16:57     ` Nathan Chancellor
2020-07-30 17:24   ` Catalin Marinas [this message]
2020-07-30 17:24     ` Catalin Marinas
2020-07-30 17:34     ` Sami Tolvanen
2020-07-30 17:34       ` Sami Tolvanen

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