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a3046a618a
As part of the Rust support for UML, we disable SSE (and similar flags)
to match the normal x86 builds. This both makes sense (we ideally want a
similar configuration to x86), and works around a crash bug with SSE
generation under Rust with LLVM.
However, this breaks compiling stdlib.h under gcc < 11, as the x86_64
ABI requires floating-point return values be stored in an SSE register.
gcc 11 fixes this by only doing register allocation when a function is
actually used, and since we never use atof(), it shouldn't be a problem:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99652
Nevertheless, only disable SSE on clang setups, as that's a simple way
of working around everyone's bugs.
Fixes: 8849818679 ("rust: arch/um: Disable FP/SIMD instruction to match x86")
Reported-by: Roberto Sassu <roberto.sassu@huaweicloud.com>
Link: https://lore.kernel.org/linux-um/6df2ecef9011d85654a82acd607fdcbc93ad593c.camel@huaweicloud.com/
Tested-by: Roberto Sassu <roberto.sassu@huaweicloud.com>
Tested-by: SeongJae Park <sj@kernel.org>
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Tested-by: Arthur Grillo <arthurgrillo@riseup.net>
Signed-off-by: Richard Weinberger <richard@nod.at>
61 lines
1.5 KiB
Text
61 lines
1.5 KiB
Text
# SPDX-License-Identifier: GPL-2.0
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core-y += arch/x86/crypto/
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#
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# Disable SSE and other FP/SIMD instructions to match normal x86
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# This is required to work around issues in older LLVM versions, but breaks
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# GCC versions < 11. See:
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# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99652
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#
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ifeq ($(CONFIG_CC_IS_CLANG),y)
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KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
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KBUILD_RUSTFLAGS += -Ctarget-feature=-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2
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endif
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ifeq ($(CONFIG_X86_32),y)
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START := 0x8048000
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KBUILD_LDFLAGS += -m elf_i386
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ELF_ARCH := i386
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ELF_FORMAT := elf32-i386
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CHECKFLAGS += -D__i386__
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KBUILD_CFLAGS += $(call cc-option,-m32)
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KBUILD_AFLAGS += $(call cc-option,-m32)
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LINK-y += $(call cc-option,-m32)
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LDS_EXTRA := -Ui386
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export LDS_EXTRA
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# First of all, tune CFLAGS for the specific CPU. This actually sets cflags-y.
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include $(srctree)/arch/x86/Makefile_32.cpu
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# prevent gcc from keeping the stack 16 byte aligned. Taken from i386.
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cflags-y += $(call cc-option,-mpreferred-stack-boundary=2)
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# Prevent sprintf in nfsd from being converted to strcpy and resulting in
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# an unresolved reference.
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cflags-y += -ffreestanding
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KBUILD_CFLAGS += $(cflags-y)
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else
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START := 0x60000000
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KBUILD_CFLAGS += -fno-builtin -m64
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CHECKFLAGS += -m64 -D__x86_64__
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KBUILD_AFLAGS += -m64
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KBUILD_LDFLAGS += -m elf_x86_64
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KBUILD_CPPFLAGS += -m64
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ELF_ARCH := i386:x86-64
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ELF_FORMAT := elf64-x86-64
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# Not on all 64-bit distros /lib is a symlink to /lib64. PLD is an example.
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LINK-$(CONFIG_LD_SCRIPT_DYN_RPATH) += -Wl,-rpath,/lib64
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LINK-y += -m64
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endif
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