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 08/12] x86: Implement ARCH_HAS_KERNEL_FPU_SUPPORT
Date: Thu, 7 Dec 2023 21:54:38 -0800 [thread overview]
Message-ID: <20231208055501.2916202-9-samuel.holland@sifive.com> (raw)
In-Reply-To: <20231208055501.2916202-1-samuel.holland@sifive.com>
x86 already provides kernel_fpu_begin() and kernel_fpu_end(), but in a
different header. Add a wrapper header, and export the CFLAGS
adjustments as found in lib/Makefile.
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
---
arch/x86/Kconfig | 1 +
arch/x86/Makefile | 20 ++++++++++++++++++++
arch/x86/include/asm/fpu.h | 13 +++++++++++++
3 files changed, 34 insertions(+)
create mode 100644 arch/x86/include/asm/fpu.h
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 3762f41bb092..1fe7f2d8d017 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -81,6 +81,7 @@ config X86
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_GCOV_PROFILE_ALL
select ARCH_HAS_KCOV if X86_64
+ select ARCH_HAS_KERNEL_FPU_SUPPORT
select ARCH_HAS_MEM_ENCRYPT
select ARCH_HAS_MEMBARRIER_SYNC_CORE
select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 1a068de12a56..71576c8dbe79 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -70,6 +70,26 @@ export BITS
KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
KBUILD_RUSTFLAGS += -Ctarget-feature=-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2
+#
+# CFLAGS for compiling floating point code inside the kernel.
+#
+CC_FLAGS_FPU := -msse -msse2
+ifdef CONFIG_CC_IS_GCC
+# Stack alignment mismatch, proceed with caution.
+# GCC < 7.1 cannot compile code using `double` and -mpreferred-stack-boundary=3
+# (8B stack alignment).
+# See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
+#
+# The "-msse" in the first argument is there so that the
+# -mpreferred-stack-boundary=3 build error:
+#
+# -mpreferred-stack-boundary=3 is not between 4 and 12
+#
+# can be triggered. Otherwise gcc doesn't complain.
+CC_FLAGS_FPU += -mhard-float
+CC_FLAGS_FPU += $(call cc-option,-msse -mpreferred-stack-boundary=3,-mpreferred-stack-boundary=4)
+endif
+
ifeq ($(CONFIG_X86_KERNEL_IBT),y)
#
# Kernel IBT has S_CET.NOTRACK_EN=0, as such the compilers must not generate
diff --git a/arch/x86/include/asm/fpu.h b/arch/x86/include/asm/fpu.h
new file mode 100644
index 000000000000..b2743fe19339
--- /dev/null
+++ b/arch/x86/include/asm/fpu.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2023 SiFive
+ */
+
+#ifndef _ASM_X86_FPU_H
+#define _ASM_X86_FPU_H
+
+#include <asm/fpu/api.h>
+
+#define kernel_fpu_available() true
+
+#endif /* ! _ASM_X86_FPU_H */
--
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 ` [RFC PATCH 01/12] arch: Add ARCH_HAS_KERNEL_FPU_SUPPORT Samuel Holland
2023-12-11 16:02 ` 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 ` Samuel Holland [this message]
2023-12-11 16:08 ` [RFC PATCH 08/12] x86: " 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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