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

From: Sebastian Andrzej Siewior
Date: Fri Dec 01 2017 - 05:43:39 EST


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@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
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