From: Ard Biesheuvel Subject: Re: [PATCH] crypto: arm/speck - fix building in Thumb2 mode Date: Tue, 19 Jun 2018 08:38:13 +0200 Message-ID: References: <20180618223323.130072-1-ebiggers@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Stefan Agner , "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" , linux-arm-kernel , Herbert Xu To: Eric Biggers Return-path: In-Reply-To: <20180618223323.130072-1-ebiggers@google.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org List-Id: linux-crypto.vger.kernel.org On 19 June 2018 at 00:33, Eric Biggers wrote: > 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 > Fixes: ede9622162fa ("crypto: arm/speck - add NEON-accelerated implementation of Speck-XTS") > Signed-off-by: Eric Biggers > --- > arch/arm/crypto/speck-neon-core.S | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/crypto/speck-neon-core.S b/arch/arm/crypto/speck-neon-core.S > index 3c1e203e53b9..57caa742016e 100644 > --- 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 Acked-by: Ard Biesheuvel