The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 0648e50e548d881d025b9419a1a168753c8e2bf7 Mon Sep 17 00:00:00 2001
From: Paul Burton <paul.burton@xxxxxxxx>
Date: Mon, 28 Jan 2019 22:21:17 +0000
Subject: [PATCH] MIPS: VDSO: Use same -m%-float cflag as the kernel proper
The MIPS VDSO build currently doesn't provide the -msoft-float flag to
the compiler as the kernel proper does. This results in an attempt to
use the compiler's default floating point configuration, which can be
problematic in cases where this is incompatible with the target CPU's
-march= flag. For example decstation_defconfig fails to build using
toolchains in which gcc was configured --with-fp-32=xx with the
following error:
LDS arch/mips/vdso/vdso.lds
cc1: error: '-march=r3000' requires '-mfp32'
make[2]: *** [scripts/Makefile.build:379: arch/mips/vdso/vdso.lds] Error 1
The kernel proper avoids this error because we build with the
-msoft-float compiler flag, rather than using the compiler's default.
Pass this flag through to the VDSO build so that it too becomes agnostic
to the toolchain's floating point configuration.
Note that this is filtered out from KBUILD_CFLAGS rather than simply
always using -msoft-float such that if we switch the kernel to use
-mno-float in the future the VDSO will automatically inherit the change.
The VDSO doesn't actually include any floating point code, and its
.MIPS.abiflags section is already manually generated to specify that
it's compatible with any floating point ABI. As such this change should
have no effect on the resulting VDSO, apart from fixing the build
failure for affected toolchains.
Signed-off-by: Paul Burton <paul.burton@xxxxxxxx>
Reported-by: Kevin Hilman <khilman@xxxxxxxxxxxx>
Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Tested-by: Kevin Hilman <khilman@xxxxxxxxxxxx>
References: https://lore.kernel.org/linux-mips/1477843551-21813-1-git-send-email-linux@xxxxxxxxxxxx/
References: https://kernelci.org/build/id/5c4e4ae059b5142a249ad004/logs/
Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
Cc: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx # v4.4+
diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile
index f6fd340e39c2..314949b2261d 100644
--- a/arch/mips/vdso/Makefile
+++ b/arch/mips/vdso/Makefile
@@ -8,6 +8,7 @@ ccflags-vdso := \
$(filter -E%,$(KBUILD_CFLAGS)) \
$(filter -mmicromips,$(KBUILD_CFLAGS)) \
$(filter -march=%,$(KBUILD_CFLAGS)) \
+ $(filter -m%-float,$(KBUILD_CFLAGS)) \
-D__VDSO__
ifdef CONFIG_CC_IS_CLANG
