Re: [PATCH RT] arm*: disable NEON in kernel mode

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

+arm folks, to let you know

On 2017-12-01 11:43:32 [+0100], To linux-rt-users@vger.kernel.org wrote:
> NEON in kernel mode is used by the crypto algorithms and raid6 code.
> While the raid6 code looks okay, the crypto algorithms do not: NEON
> is enabled on first invocation and may allocate/free/map memory before
> the NEON mode is disabled again.
> This needs to be changed until it can be enabled.
> On ARM NEON in kernel mode can be simply disabled. on ARM64 it needs to
> stay on due to possible EFI callbacks so here I disable each algorithm.
> 
> Cc: stable-rt@vger.kernel.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>  arch/arm/Kconfig                  |  2 +-
>  arch/arm64/crypto/Kconfig         | 20 ++++++++++----------
>  arch/arm64/crypto/crc32-ce-glue.c |  3 ++-
>  3 files changed, 13 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index d1346a160760..914fecb088a8 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -2164,7 +2164,7 @@ config NEON
>  
>  config KERNEL_MODE_NEON
>  	bool "Support for NEON in kernel mode"
> -	depends on NEON && AEABI
> +	depends on NEON && AEABI && !PREEMPT_RT_BASE
>  	help
>  	  Say Y to include support for NEON in kernel mode.
>  
> diff --git a/arch/arm64/crypto/Kconfig b/arch/arm64/crypto/Kconfig
> index 70c517aa4501..2a5f05b5a19a 100644
> --- a/arch/arm64/crypto/Kconfig
> +++ b/arch/arm64/crypto/Kconfig
> @@ -19,19 +19,19 @@ config CRYPTO_SHA512_ARM64
>  
>  config CRYPTO_SHA1_ARM64_CE
>  	tristate "SHA-1 digest algorithm (ARMv8 Crypto Extensions)"
> -	depends on KERNEL_MODE_NEON
> +	depends on KERNEL_MODE_NEON && !PREEMPT_RT_BASE
>  	select CRYPTO_HASH
>  	select CRYPTO_SHA1
>  
>  config CRYPTO_SHA2_ARM64_CE
>  	tristate "SHA-224/SHA-256 digest algorithm (ARMv8 Crypto Extensions)"
> -	depends on KERNEL_MODE_NEON
> +	depends on KERNEL_MODE_NEON && !PREEMPT_RT_BASE
>  	select CRYPTO_HASH
>  	select CRYPTO_SHA256_ARM64
>  
>  config CRYPTO_GHASH_ARM64_CE
>  	tristate "GHASH/AES-GCM using ARMv8 Crypto Extensions"
> -	depends on KERNEL_MODE_NEON
> +	depends on KERNEL_MODE_NEON && !PREEMPT_RT_BASE
>  	select CRYPTO_HASH
>  	select CRYPTO_GF128MUL
>  	select CRYPTO_AES
> @@ -39,7 +39,7 @@ config CRYPTO_GHASH_ARM64_CE
>  
>  config CRYPTO_CRCT10DIF_ARM64_CE
>  	tristate "CRCT10DIF digest algorithm using PMULL instructions"
> -	depends on KERNEL_MODE_NEON && CRC_T10DIF
> +	depends on KERNEL_MODE_NEON && CRC_T10DIF && !PREEMPT_RT_BASE
>  	select CRYPTO_HASH
>  
>  config CRYPTO_CRC32_ARM64_CE
> @@ -53,13 +53,13 @@ config CRYPTO_AES_ARM64
>  
>  config CRYPTO_AES_ARM64_CE
>  	tristate "AES core cipher using ARMv8 Crypto Extensions"
> -	depends on ARM64 && KERNEL_MODE_NEON
> +	depends on ARM64 && KERNEL_MODE_NEON && !PREEMPT_RT_BASE
>  	select CRYPTO_ALGAPI
>  	select CRYPTO_AES_ARM64
>  
>  config CRYPTO_AES_ARM64_CE_CCM
>  	tristate "AES in CCM mode using ARMv8 Crypto Extensions"
> -	depends on ARM64 && KERNEL_MODE_NEON
> +	depends on ARM64 && KERNEL_MODE_NEON && !PREEMPT_RT_BASE
>  	select CRYPTO_ALGAPI
>  	select CRYPTO_AES_ARM64_CE
>  	select CRYPTO_AES_ARM64
> @@ -67,7 +67,7 @@ config CRYPTO_AES_ARM64_CE_CCM
>  
>  config CRYPTO_AES_ARM64_CE_BLK
>  	tristate "AES in ECB/CBC/CTR/XTS modes using ARMv8 Crypto Extensions"
> -	depends on KERNEL_MODE_NEON
> +	depends on KERNEL_MODE_NEON && !PREEMPT_RT_BASE
>  	select CRYPTO_BLKCIPHER
>  	select CRYPTO_AES_ARM64_CE
>  	select CRYPTO_AES_ARM64
> @@ -75,7 +75,7 @@ config CRYPTO_AES_ARM64_CE_BLK
>  
>  config CRYPTO_AES_ARM64_NEON_BLK
>  	tristate "AES in ECB/CBC/CTR/XTS modes using NEON instructions"
> -	depends on KERNEL_MODE_NEON
> +	depends on KERNEL_MODE_NEON && !PREEMPT_RT_BASE
>  	select CRYPTO_BLKCIPHER
>  	select CRYPTO_AES_ARM64
>  	select CRYPTO_AES
> @@ -83,13 +83,13 @@ config CRYPTO_AES_ARM64_NEON_BLK
>  
>  config CRYPTO_CHACHA20_NEON
>  	tristate "NEON accelerated ChaCha20 symmetric cipher"
> -	depends on KERNEL_MODE_NEON
> +	depends on KERNEL_MODE_NEON && !PREEMPT_RT_BASE
>  	select CRYPTO_BLKCIPHER
>  	select CRYPTO_CHACHA20
>  
>  config CRYPTO_AES_ARM64_BS
>  	tristate "AES in ECB/CBC/CTR/XTS modes using bit-sliced NEON algorithm"
> -	depends on KERNEL_MODE_NEON
> +	depends on KERNEL_MODE_NEON && !PREEMPT_RT_BASE
>  	select CRYPTO_BLKCIPHER
>  	select CRYPTO_AES_ARM64_NEON_BLK
>  	select CRYPTO_AES_ARM64
> diff --git a/arch/arm64/crypto/crc32-ce-glue.c b/arch/arm64/crypto/crc32-ce-glue.c
> index 624f4137918c..599de95cd86d 100644
> --- a/arch/arm64/crypto/crc32-ce-glue.c
> +++ b/arch/arm64/crypto/crc32-ce-glue.c
> @@ -206,7 +206,8 @@ static struct shash_alg crc32_pmull_algs[] = { {
>  
>  static int __init crc32_pmull_mod_init(void)
>  {
> -	if (IS_ENABLED(CONFIG_KERNEL_MODE_NEON) && (elf_hwcap & HWCAP_PMULL)) {
> +	if (IS_ENABLED(CONFIG_KERNEL_MODE_NEON) &&
> +	    !IS_ENABLED(CONFIG_PREEMPT_RT_BASE) && (elf_hwcap & HWCAP_PMULL)) {
>  		crc32_pmull_algs[0].update = crc32_pmull_update;
>  		crc32_pmull_algs[1].update = crc32c_pmull_update;
>  
> -- 
> 2.15.0