This is a note to let you know that I've just added the patch titled
rust: arch/um: Disable FP/SIMD instruction to match x86
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rust-arch-um-disable-fp-simd-instruction-to-match-x8.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 4cd7b8184f841ac7054c8842e070fbdafc54d8d4
Author: David Gow <davidgow@xxxxxxxxxx>
Date: Sat Dec 17 12:44:35 2022 +0800
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@xxxxxxxxxx>
Reviewed-by: Sergio González Collado <sergio.collado@xxxxxxxxx>
Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/Makefile.um b/arch/x86/Makefile.um
index 91085a08de6cb..3694beda02c8a 100644
--- a/arch/x86/Makefile.um
+++ b/arch/x86/Makefile.um
@@ -1,6 +1,12 @@
# 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
