From mboxrd@z Thu Jan 1 00:00:00 1970 From: ard.biesheuvel@linaro.org (Ard Biesheuvel) Date: Thu, 27 Jun 2013 08:09:33 +0200 Subject: [PATCH v2] arm64: add support for kernel mode NEON Message-ID: <1372313373-30718-1-git-send-email-ard.biesheuvel@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Add containing kernel_neon_begin/kernel_neon_end function declarations and corresponding definitions in fpsimd.c These are needed to wrap uses of NEON in kernel mode. The names are identical to the ones used in arm/ so code using intrinsics or vectorized by GCC can be shared between arm and arm64. Signed-off-by: Ard Biesheuvel --- Catalin, Following a discussion with Will Deacon, I have switched back to just using preempt_disable, which should spot any violations of the no-sleep rule in a kernel_neon section in all configurations except non-PREEMPT combined with !CONFIG_DEBUG_ATOMIC_SLEEP (which probably accounts for all production servers, unfortunately) -- Ard. arch/arm64/Kconfig | 3 +++ arch/arm64/include/asm/neon.h | 14 ++++++++++++++ arch/arm64/kernel/fpsimd.c | 32 ++++++++++++++++++++++++++++++++ 3 files changed, 49 insertions(+) create mode 100644 arch/arm64/include/asm/neon.h diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 56b3f6d..46ba680 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -95,6 +95,9 @@ config SWIOTLB config IOMMU_HELPER def_bool SWIOTLB +config KERNEL_MODE_NEON + def_bool y + source "init/Kconfig" source "kernel/Kconfig.freezer" diff --git a/arch/arm64/include/asm/neon.h b/arch/arm64/include/asm/neon.h new file mode 100644 index 0000000..b0cc58a9 --- /dev/null +++ b/arch/arm64/include/asm/neon.h @@ -0,0 +1,14 @@ +/* + * linux/arch/arm64/include/asm/neon.h + * + * Copyright (C) 2013 Linaro Ltd + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#define cpu_has_neon() (1) + +void kernel_neon_begin(void); +void kernel_neon_end(void); diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index e8b8357..07641c8 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -19,6 +19,7 @@ #include #include +#include #include #include @@ -83,6 +84,37 @@ void fpsimd_flush_thread(void) fpsimd_load_state(¤t->thread.fpsimd_state); } +#ifdef CONFIG_KERNEL_MODE_NEON + +/* + * Kernel-side NEON support functions + */ +void kernel_neon_begin(void) +{ + /* + * Kernel mode NEON is only allowed outside of interrupt context + * with preemption disabled. This will make sure that the kernel + * mode NEON register contents never need to be preserved. + */ + BUG_ON(in_interrupt()); + preempt_disable(); + + if (current->mm) + fpsimd_save_state(¤t->thread.fpsimd_state); +} +EXPORT_SYMBOL(kernel_neon_begin); + +void kernel_neon_end(void) +{ + if (current->mm) + fpsimd_load_state(¤t->thread.fpsimd_state); + + preempt_enable(); +} +EXPORT_SYMBOL(kernel_neon_end); + +#endif /* CONFIG_KERNEL_MODE_NEON */ + /* * FP/SIMD support code initialisation. */ -- 1.8.1.2