The patch below does not apply to the 4.19-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@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 76d7fff22be3e4185ee5f9da2eecbd8188e76b2c Mon Sep 17 00:00:00 2001

From: Nathan Chancellor nathan@kernel.org Date: Fri, 15 Jan 2021 12:26:22 -0700 Subject: [PATCH] MIPS: VDSO: Use CLANG_FLAGS instead of filtering out '--target='

Commit ee67855ecd9d ("MIPS: vdso: Allow clang's --target flag in VDSO cflags") allowed the '--target=' flag from the main Makefile to filter through to the vDSO. However, it did not bring any of the other clang specific flags for controlling the integrated assembler and the GNU tools locations (--prefix=, --gcc-toolchain=, and -no-integrated-as). Without these, we will get a warning (visible with tinyconfig):

arch/mips/vdso/elf.S:14:1: warning: DWARF2 only supports one section per compilation unit .pushsection .note.Linux, "a",@note ; .balign 4 ; .long 2f - 1f ; .long 4484f - 3f ; .long 0 ; 1:.asciz "Linux" ; 2:.balign 4 ; 3: ^ arch/mips/vdso/elf.S:34:2: warning: DWARF2 only supports one section per compilation unit .section .mips_abiflags, "a" ^

All of these flags are bundled up under CLANG_FLAGS in the main Makefile and exported so that they can be added to Makefiles that set their own CFLAGS. Use this value instead of filtering out '--target=' so there is no warning and all of the tools are properly used.

Cc: stable@vger.kernel.org Fixes: ee67855ecd9d ("MIPS: vdso: Allow clang's --target flag in VDSO cflags") Link: https://github.com/ClangBuiltLinux/linux/issues/1256 Reported-by: Anders Roxell anders.roxell@linaro.org Signed-off-by: Nathan Chancellor natechancellor@gmail.com Tested-by: Anders Roxell anders.roxell@linaro.org Signed-off-by: Thomas Bogendoerfer tsbogend@alpha.franken.de

diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile index 5810cc12bc1d..2131d3fd7333 100644 --- a/arch/mips/vdso/Makefile +++ b/arch/mips/vdso/Makefile @@ -16,16 +16,13 @@ ccflags-vdso := \ $(filter -march=%,$(KBUILD_CFLAGS)) \ $(filter -m%-float,$(KBUILD_CFLAGS)) \ $(filter -mno-loongson-%,$(KBUILD_CFLAGS)) \ + $(CLANG_FLAGS) \ -D__VDSO__

ifndef CONFIG_64BIT ccflags-vdso += -DBUILD_VDSO32 endif

-ifdef CONFIG_CC_IS_CLANG -ccflags-vdso += $(filter --target=%,$(KBUILD_CFLAGS)) -endif - # # The -fno-jump-tables flag only prevents the compiler from generating # jump tables but does not prevent the compiler from emitting absolute