android_kernel_samsung_sm8650/arch/x86/Makefile.um
David Gow 20ca409886 rust: arch/um: Disable FP/SIMD instruction to match x86
[ Upstream commit 8849818679478933dd1d9718741f4daa3f4e8b86 ]

The kernel disables all SSE and similar FP/SIMD instructions on
x86-based architectures (partly because we shouldn't be using floats in
the kernel, and partly to avoid the need for stack alignment, see:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383 )

UML does not do the same thing, which isn't in itself a problem, but
does add to the list of differences between UML and "normal" x86 builds.

In addition, there was a crash bug with LLVM < 15 / rustc < 1.65 when
building with SSE, so disabling it fixes rust builds with earlier
compiler versions, see:
https://github.com/Rust-for-Linux/linux/pull/881

Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Sergio González Collado <sergio.collado@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-03-22 13:33:53 +01:00

57 lines
1.3 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0
core-y += arch/x86/crypto/
#
# Disable SSE and other FP/SIMD instructions to match normal x86
#
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
ifeq ($(CONFIG_X86_32),y)
START := 0x8048000
KBUILD_LDFLAGS += -m elf_i386
ELF_ARCH := i386
ELF_FORMAT := elf32-i386
CHECKFLAGS += -D__i386__
KBUILD_CFLAGS += $(call cc-option,-m32)
KBUILD_AFLAGS += $(call cc-option,-m32)
LINK-y += $(call cc-option,-m32)
LDS_EXTRA := -Ui386
export LDS_EXTRA
# First of all, tune CFLAGS for the specific CPU. This actually sets cflags-y.
include arch/x86/Makefile_32.cpu
# prevent gcc from keeping the stack 16 byte aligned. Taken from i386.
cflags-y += $(call cc-option,-mpreferred-stack-boundary=2)
# Prevent sprintf in nfsd from being converted to strcpy and resulting in
# an unresolved reference.
cflags-y += -ffreestanding
KBUILD_CFLAGS += $(cflags-y)
else
START := 0x60000000
KBUILD_CFLAGS += -fno-builtin -m64
CHECKFLAGS += -m64 -D__x86_64__
KBUILD_AFLAGS += -m64
KBUILD_LDFLAGS += -m elf_x86_64
KBUILD_CPPFLAGS += -m64
ELF_ARCH := i386:x86-64
ELF_FORMAT := elf64-x86-64
# Not on all 64-bit distros /lib is a symlink to /lib64. PLD is an example.
LINK-$(CONFIG_LD_SCRIPT_DYN_RPATH) += -Wl,-rpath,/lib64
LINK-y += -m64
endif