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

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