From 0648e50e548d881d025b9419a1a168753c8e2bf7 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Mon, 28 Jan 2019 22:21:17 +0000 Subject: 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 Reported-by: Kevin Hilman Reported-by: Guenter Roeck Tested-by: Kevin Hilman References: https://lore.kernel.org/linux-mips/1477843551-21813-1-git-send-email-linux@roeck-us.net/ References: https://kernelci.org/build/id/5c4e4ae059b5142a249ad004/logs/ Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO") Cc: Maciej W. Rozycki Cc: linux-mips@vger.kernel.org Cc: stable@vger.kernel.org # v4.4+ --- arch/mips/vdso/Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/mips/vdso/Makefile') 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 -- cgit v1.2.3 From 67fc5dc8a541e8f458d7f08bf88ff55933bf9f9d Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Mon, 28 Jan 2019 23:16:22 +0000 Subject: MIPS: VDSO: Include $(ccflags-vdso) in o32,n32 .lds builds When generating vdso-o32.lds & vdso-n32.lds for use with programs running as compat ABIs under 64b kernels, we previously haven't included the compiler flags that are supposedly common to all ABIs - ie. those in the ccflags-vdso variable. This is problematic in cases where we need to provide the -m%-float flag in order to ensure that we don't attempt to use a floating point ABI that's incompatible with the target CPU & ABI. For example a toolchain using current gcc trunk configured --with-fp-32=xx fails to build a 64r6el_defconfig kernel with the following error: cc1: error: '-march=mips1' requires '-mfp32' make[2]: *** [arch/mips/vdso/Makefile:135: arch/mips/vdso/vdso-o32.lds] Error 1 Include $(ccflags-vdso) for the compat VDSO .lds builds, just as it is included for the native VDSO .lds & when compiling objects for the compat VDSOs. This ensures we consistently provide the -msoft-float flag amongst others, avoiding the problem by ensuring we're agnostic to the toolchain defaults. Signed-off-by: Paul Burton Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO") Cc: linux-mips@vger.kernel.org Cc: Kevin Hilman Cc: Guenter Roeck Cc: Maciej W . Rozycki Cc: stable@vger.kernel.org # v4.4+ --- arch/mips/vdso/Makefile | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/mips/vdso/Makefile') diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile index 314949b2261d..0ede4deb8181 100644 --- a/arch/mips/vdso/Makefile +++ b/arch/mips/vdso/Makefile @@ -130,7 +130,7 @@ $(obj)/%-o32.o: $(src)/%.c FORCE $(call cmd,force_checksrc) $(call if_changed_rule,cc_o_c) -$(obj)/vdso-o32.lds: KBUILD_CPPFLAGS := -mabi=32 +$(obj)/vdso-o32.lds: KBUILD_CPPFLAGS := $(ccflags-vdso) -mabi=32 $(obj)/vdso-o32.lds: $(src)/vdso.lds.S FORCE $(call if_changed_dep,cpp_lds_S) @@ -170,7 +170,7 @@ $(obj)/%-n32.o: $(src)/%.c FORCE $(call cmd,force_checksrc) $(call if_changed_rule,cc_o_c) -$(obj)/vdso-n32.lds: KBUILD_CPPFLAGS := -mabi=n32 +$(obj)/vdso-n32.lds: KBUILD_CPPFLAGS := $(ccflags-vdso) -mabi=n32 $(obj)/vdso-n32.lds: $(src)/vdso.lds.S FORCE $(call if_changed_dep,cpp_lds_S) -- cgit v1.2.3