From 6cbd1d6d36c5d8312de99d1dfa3bec40ac840ce0 Mon Sep 17 00:00:00 2001
From: Samuel Holland <samuel.holland@sifive.com>
Date: Fri, 29 Mar 2024 00:18:16 -0700
Subject: arch: add ARCH_HAS_KERNEL_FPU_SUPPORT
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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.

Link: https://lkml.kernel.org/r/20240329072441.591471-2-samuel.holland@sifive.com
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicolas Schier <nicolas@fjasle.eu>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: WANG Xuerui <git@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 arch/Kconfig | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'arch/Kconfig')

diff --git a/arch/Kconfig b/arch/Kconfig
index b34946d90e4b..975dd22a2dbd 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1594,6 +1594,12 @@ 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
+	  Architectures that select this option can run floating-point code in
+	  the kernel, as described in Documentation/core-api/floating-point.rst.
+
 source "kernel/gcov/Kconfig"
 
 source "scripts/gcc-plugins/Kconfig"
-- 
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