Re: [PATCH 04/16] vmlinux.lds: Move DATA_LE32() from arm64 to the common linker script

From: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Ard Biesheuvel <ardb@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Jonathan Corbet <corbet@lwn.net>, David Sterba <dsterba@suse.com>,
	Ilias Apalodimas <ilias.apalodimas@linaro.org>,
	linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-doc@vger.kernel.org, linux-efi@vger.kernel.org,
	linux-riscv@lists.infradead.org,
	Mark Rutland <mark.rutland@arm.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <pjw@kernel.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	Simon Glass <sjg@chromium.org>,
	Shuah Khan <skhan@linuxfoundation.org>,
	Nick Terrell <terrelln@fb.com>, Will Deacon <will@kernel.org>,
	Alexandre Ghiti <alexghiti@rivosinc.com>,
	Conor Dooley <conor.dooley@microchip.com>,
	linux-integrity@vger.kernel.org,
	Palmer Dabbelt <palmer@rivosinc.com>,
	patches@lists.linux.dev,
	Ross Philipson <ross.philipson@gmail.com>,
	Sami Tolvanen <samitolvanen@google.com>,
	Song Shuai <songshuaishuai@tinylab.org>,
	Will Deacon <will@kernel.org>
Subject: Re: [PATCH 04/16] vmlinux.lds: Move DATA_LE32() from arm64 to the common linker script
Date: Thu, 24 Sep 2026 15:53:07 -0700	[thread overview]
Message-ID: <20260924155307.00007dfc@oss.qualcomm.com> (raw)
In-Reply-To: <4-v1-27d06b313981+8b-arm64_drtm_jgg@nvidia.com>

On Thu, 24 Sep 2026 10:53:07 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:

> Other arches may want to use this to get consistent fixed endian output.

You will have to grab it quickly!
https://lore.kernel.org/all/20260918145217.1669-10-will@kernel.org/#Z31arch:arm64:kernel:image.h
drops that definition as part of ripping out arm64 big endian support.

+CC Will for awareness.

> 
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
>  arch/arm64/kernel/image.h         | 14 --------------
>  include/asm-generic/vmlinux.lds.h | 15 +++++++++++++++
>  2 files changed, 15 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/arm64/kernel/image.h b/arch/arm64/kernel/image.h
> index 7bc3ba89790191..1bff6b061b6cab 100644
> --- a/arch/arm64/kernel/image.h
> +++ b/arch/arm64/kernel/image.h
> @@ -14,26 +14,12 @@
>  #include <asm/image.h>
>  
>  /*
> - * There aren't any ELF relocations we can use to endian-swap values known only
> - * at link time (e.g. the subtraction of two symbol addresses), so we must get
> - * the linker to endian-swap certain values before emitting them.
> - *
>   * Note that, in order for this to work when building the ELF64 PIE executable
>   * (for KASLR), these values should not be referenced via R_AARCH64_ABS64
>   * relocations, since these are fixed up at runtime rather than at build time
>   * when PIE is in effect. So we need to split them up in 32-bit high and low
>   * words.
>   */
> -#ifdef CONFIG_CPU_BIG_ENDIAN
> -#define DATA_LE32(data)				\
> -	((((data) & 0x000000ff) << 24) |	\
> -	 (((data) & 0x0000ff00) << 8)  |	\
> -	 (((data) & 0x00ff0000) >> 8)  |	\
> -	 (((data) & 0xff000000) >> 24))
> -#else
> -#define DATA_LE32(data) ((data) & 0xffffffff)
> -#endif
> -
>  #define DEFINE_IMAGE_LE64(sym, data)				\
>  	sym##_lo32 = DATA_LE32((data) & 0xffffffff);		\
>  	sym##_hi32 = DATA_LE32((data) >> 32)
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index b2988aa12f6645..1786a8e4323b9f 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -56,6 +56,21 @@
>  #define LOAD_OFFSET 0
>  #endif
>  
> +/*
> + * There aren't any ELF relocations we can use to endian-swap values known only
> + * at link time (e.g. the subtraction of two symbol addresses), so we must get
> + * the linker to endian-swap certain values before emitting them.
> + */
> +#ifdef CONFIG_CPU_BIG_ENDIAN
> +#define DATA_LE32(data)				\
> +	((((data) & 0x000000ff) << 24) |	\
> +	 (((data) & 0x0000ff00) << 8)  |	\
> +	 (((data) & 0x00ff0000) >> 8)  |	\
> +	 (((data) & 0xff000000) >> 24))
> +#else
> +#define DATA_LE32(data) ((data) & 0xffffffff)
> +#endif
> +
>  /*
>   * Only some architectures want to have the .notes segment visible in
>   * a separate PT_NOTE ELF Program Header. When this happens, it needs