[PATCH 4.17 161/324] crypto: arm/speck - fix building in Thumb2 mode

Greg Kroah-Hartman
2018-08-23T08:53:54Z

From: Eric Biggers <ebiggers@google.com>

[ Upstream commit a068b94d74ddb7776ca707b6d39d1ac0d2d057e6 ]

Building the kernel with CONFIG_THUMB2_KERNEL=y and
CONFIG_CRYPTO_SPECK_NEON set fails with the following errors:

arch/arm/crypto/speck-neon-core.S: Assembler messages:

arch/arm/crypto/speck-neon-core.S:419: Error: r13 not allowed here -- `bic sp,#0xf'
arch/arm/crypto/speck-neon-core.S:423: Error: r13 not allowed here -- `bic sp,#0xf'
arch/arm/crypto/speck-neon-core.S:427: Error: r13 not allowed here -- `bic sp,#0xf'
arch/arm/crypto/speck-neon-core.S:431: Error: r13 not allowed here -- `bic sp,#0xf'

The problem is that the 'bic' instruction can't operate on the 'sp'
register in Thumb2 mode. Fix it by using a temporary register. This
isn't in the main loop, so the performance difference is negligible.
This also matches what aes-neonbs-core.S does.

Reported-by: Stefan Agner <stefan@agner.ch>
Fixes: ede9622162fa ("crypto: arm/speck - add NEON-accelerated implementation of Speck-XTS")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm/crypto/speck-neon-core.S | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/arch/arm/crypto/speck-neon-core.S
+++ b/arch/arm/crypto/speck-neon-core.S
@@ -272,9 +272,11 @@
* Allocate stack space to store 128 bytes worth of tweaks. For
* performance, this space is aligned to a 16-byte boundary so that we
* can use the load/store instructions that declare 16-byte alignment.
+ * For Thumb2 compatibility, don't do the 'bic' directly on 'sp'.
*/
- sub sp, #128
- bic sp, #0xf
+ sub r12, sp, #128
+ bic r12, #0xf
+ mov sp, r12

.if \n == 64
// Load first tweak