[PATCH v2] lib/crc: arm64: use .arch_extension to enable CRC and crypto

[PATCH v2] lib/crc: arm64: use .arch_extension to enable CRC and crypto

[Emanuele Rocca]

Use .arch_extension instead of .arch and .cpu in crc32-core.S and
crc-t10dif-core.S.

.arch and .cpu reset the assembler's feature set, dropping extensions
enabled via -march. See commit 9142c2f8f84b ("octeontx2: use
arch_extension to enable LSE"), where this caused an actual build
failure.

That is not a problem here: the instructions these files use are all
covered by the CRC and crypto extensions. Switch anyway for consistency
and to avoid surprises if the files later use instructions outside
generic+crc+crypto.

.arch_extension is supported by binutils since 2.26 and by clang since
8.0.0, both older than the minimum versions currently required to build
the kernel (2.30 and 17.0.1 respectively).

Signed-off-by: Emanuele Rocca <emanuele.rocca@arm.com>
---
Changes in v2:
  - Update crc-t10dif-core.S in addition to crc32-core.S 
  - Clarify in commit message that this is not a functional change

Link to v1:
  https://lore.kernel.org/all/20261105154145.557042-1-emanuele.rocca@arm.com/
---
 lib/crc/arm64/crc-t10dif-core.S | 2 +-
 lib/crc/arm64/crc32-core.S      | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/crc/arm64/crc-t10dif-core.S b/lib/crc/arm64/crc-t10dif-core.S
index 71388466825b..e77af0aecf5e 100644
--- a/lib/crc/arm64/crc-t10dif-core.S
+++ b/lib/crc/arm64/crc-t10dif-core.S
@@ -69,7 +69,7 @@
 #include <asm/assembler.h>
 
 	.text
-	.arch		armv8-a+crypto
+	.arch_extension	crypto
 
 	init_crc	.req	w0
 	buf		.req	x1
diff --git a/lib/crc/arm64/crc32-core.S b/lib/crc/arm64/crc32-core.S
index 49d02cc485b3..0877d07ed1bf 100644
--- a/lib/crc/arm64/crc32-core.S
+++ b/lib/crc/arm64/crc32-core.S
@@ -11,7 +11,8 @@
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 
-	.cpu		generic+crc+crypto
+	.arch_extension	crc
+	.arch_extension	crypto
 
 	.macro		bitle, reg
 	.endm
-- 
2.55.0

Re: [PATCH v2] lib/crc: arm64: use .arch_extension to enable CRC and crypto

[Eric Biggers]

On Wed, Nov 11, 2026 at 03:25:56PM +0100, Emanuele Rocca wrote:
> Use .arch_extension instead of .arch and .cpu in crc32-core.S and
> crc-t10dif-core.S.
> 
> .arch and .cpu reset the assembler's feature set, dropping extensions
> enabled via -march. See commit 9142c2f8f84b ("octeontx2: use
> arch_extension to enable LSE"), where this caused an actual build
> failure.
> 
> That is not a problem here: the instructions these files use are all
> covered by the CRC and crypto extensions. Switch anyway for consistency
> and to avoid surprises if the files later use instructions outside
> generic+crc+crypto.
> 
> .arch_extension is supported by binutils since 2.26 and by clang since
> 8.0.0, both older than the minimum versions currently required to build
> the kernel (2.30 and 17.0.1 respectively).
> 
> Signed-off-by: Emanuele Rocca <emanuele.rocca@arm.com>
> ---
> Changes in v2:
>   - Update crc-t10dif-core.S in addition to crc32-core.S 
>   - Clarify in commit message that this is not a functional change
> 
> Link to v1:
>   https://lore.kernel.org/all/20261105154145.557042-1-emanuele.rocca@arm.com/
> ---
>  lib/crc/arm64/crc-t10dif-core.S | 2 +-
>  lib/crc/arm64/crc32-core.S      | 3 ++-
>  2 files changed, 3 insertions(+), 2 deletions(-)

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git/log/?h=crc-next

- Eric