From: Samuel Holland <samuel.holland@sifive.com>
To: linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev,
linuxppc-dev@lists.ozlabs.org, x86@kernel.org,
linux-riscv@lists.infradead.org,
Christoph Hellwig <hch@infradead.org>
Cc: linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org,
linux-arch@vger.kernel.org,
Samuel Holland <samuel.holland@sifive.com>
Subject: [RFC PATCH 01/12] arch: Add ARCH_HAS_KERNEL_FPU_SUPPORT
Date: Thu, 7 Dec 2023 21:54:31 -0800 [thread overview]
Message-ID: <20231208055501.2916202-2-samuel.holland@sifive.com> (raw)
In-Reply-To: <20231208055501.2916202-1-samuel.holland@sifive.com>
Several architectures provide an API to enable the FPU and run
floating-point SIMD code in kernel space. However, the function names,
header locations, and semantics are inconsistent across architectures,
and FPU support may be gated behind other Kconfig options.
Provide a standard way for architectures to declare that kernel space
FPU support is available. Architectures selecting this option must
implement what is currently the most common API (kernel_fpu_begin() and
kernel_fpu_end(), plus a new function kernel_fpu_available()) and
provide the appropriate CFLAGS for compiling floating-point C code.
Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
---
Makefile | 4 ++++
arch/Kconfig | 9 +++++++++
2 files changed, 13 insertions(+)
diff --git a/Makefile b/Makefile
index 511b5616aa41..e65c186cf2c9 100644
--- a/Makefile
+++ b/Makefile
@@ -969,6 +969,10 @@ KBUILD_CFLAGS += $(CC_FLAGS_CFI)
export CC_FLAGS_CFI
endif
+# Architectures can define flags to add/remove for floating-point support
+export CC_FLAGS_FPU
+export CC_FLAGS_NO_FPU
+
ifneq ($(CONFIG_FUNCTION_ALIGNMENT),0)
KBUILD_CFLAGS += -falign-functions=$(CONFIG_FUNCTION_ALIGNMENT)
endif
diff --git a/arch/Kconfig b/arch/Kconfig
index f4b210ab0612..6df834e18e9c 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1478,6 +1478,15 @@ config ARCH_HAS_NONLEAF_PMD_YOUNG
address translations. Page table walkers that clear the accessed bit
may use this capability to reduce their search space.
+config ARCH_HAS_KERNEL_FPU_SUPPORT
+ bool
+ help
+ An architecture should select this option if it supports running
+ floating-point code in kernel space. It must export the functions
+ kernel_fpu_available(), kernel_fpu_begin(), and kernel_fpu_end() from
+ <asm/fpu.h>, and define CC_FLAGS_FPU and/or CC_FLAGS_NO_FPU as
+ necessary in its Makefile.
+
source "kernel/gcov/Kconfig"
source "scripts/gcc-plugins/Kconfig"
--
2.42.0
next prev parent reply other threads:[~2023-12-08 5:55 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-08 5:54 [RFC PATCH 00/12] Unified cross-architecture kernel-mode FPU API Samuel Holland
2023-12-08 5:54 ` Samuel Holland [this message]
2023-12-11 16:02 ` [RFC PATCH 01/12] arch: Add ARCH_HAS_KERNEL_FPU_SUPPORT Christoph Hellwig
2023-12-08 5:54 ` [RFC PATCH 02/12] ARM: Implement ARCH_HAS_KERNEL_FPU_SUPPORT Samuel Holland
2023-12-11 16:04 ` Christoph Hellwig
2023-12-08 5:54 ` [RFC PATCH 03/12] ARM: crypto: Use CC_FLAGS_FPU for NEON CFLAGS Samuel Holland
2023-12-11 16:04 ` Christoph Hellwig
2023-12-08 5:54 ` [RFC PATCH 04/12] arm64: Implement ARCH_HAS_KERNEL_FPU_SUPPORT Samuel Holland
2023-12-11 16:05 ` Christoph Hellwig
2023-12-13 16:19 ` Will Deacon
2023-12-08 5:54 ` [RFC PATCH 05/12] lib/raid6: Use CC_FLAGS_FPU for NEON CFLAGS Samuel Holland
2023-12-11 16:07 ` Christoph Hellwig
2023-12-11 16:12 ` Samuel Holland
2023-12-12 7:11 ` Christoph Hellwig
2023-12-08 5:54 ` [RFC PATCH 06/12] LoongArch: Implement ARCH_HAS_KERNEL_FPU_SUPPORT Samuel Holland
2023-12-11 16:07 ` Christoph Hellwig
2023-12-13 16:13 ` WANG Xuerui
2023-12-08 5:54 ` [RFC PATCH 07/12] powerpc: " Samuel Holland
2023-12-11 16:08 ` Christoph Hellwig
2023-12-08 5:54 ` [RFC PATCH 08/12] x86: " Samuel Holland
2023-12-11 16:08 ` Christoph Hellwig
2023-12-08 5:54 ` [RFC PATCH 09/12] riscv: Add support for kernel-mode FPU Samuel Holland
2023-12-11 16:11 ` Christoph Hellwig
2023-12-11 16:16 ` Samuel Holland
2023-12-08 5:54 ` [RFC PATCH 10/12] drm/amd/display: Use ARCH_HAS_KERNEL_FPU_SUPPORT Samuel Holland
2023-12-11 12:23 ` Michael Ellerman
2023-12-14 1:03 ` Samuel Holland
2023-12-14 3:13 ` Timothy Pearson
2023-12-14 4:45 ` Michael Ellerman
2023-12-08 5:54 ` [RFC PATCH 11/12] selftests/fpu: Move FP code to a separate translation unit Samuel Holland
2023-12-11 16:18 ` Christoph Hellwig
2023-12-08 5:54 ` [RFC PATCH 12/12] selftests/fpu: Allow building on other architectures Samuel Holland
2023-12-11 16:19 ` Christoph Hellwig
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