From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42100 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729873AbgDWRSf (ORCPT ); Thu, 23 Apr 2020 13:18:35 -0400 From: Nathan Chancellor Subject: [PATCH v3 3/4] MIPS: VDSO: Use $(LD) instead of $(CC) to link VDSO Date: Thu, 23 Apr 2020 10:18:06 -0700 Message-Id: <20200423171807.29713-3-natechancellor@gmail.com> In-Reply-To: <20200423171807.29713-1-natechancellor@gmail.com> References: <20200419202128.20571-1-natechancellor@gmail.com> <20200423171807.29713-1-natechancellor@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: Thomas Bogendoerfer , Masahiro Yamada Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, linux-kbuild@vger.kernel.org, Nick Desaulniers , Sami Tolvanen , Dmitry Golovin , Sedat Dilek , Nathan Chancellor Currently, the VDSO is being linked through $(CC). This does not match how the rest of the kernel links objects, which is through the $(LD) variable. When clang is built in a default configuration, it first attempts to use the target triple's default linker then the system's default linker, unless told otherwise through -fuse-ld=... We do not use -fuse-ld= because it can be brittle and we have support for invoking $(LD) directly. See commit fe00e50b2db8c ("ARM: 8858/1: vdso: use $(LD) instead of $(CC) to link VDSO") and commit 691efbedc60d2 ("arm64: vdso: use $(LD) instead of $(CC) to link VDSO") for examples of doing this in the VDSO. Do the same thing here. Replace the custom linking logic with $(cmd_ld) and ldflags-y so that $(LD) is respected. Before this patch, LD=ld.lld did nothing: $ llvm-readelf -p.comment arch/mips/vdso/vdso.so.dbg | sed 's/(.*//' String dump of section '.comment': [ 0] ClangBuiltLinux clang version 11.0.0 After this patch, it does: $ llvm-readelf -p.comment arch/mips/vdso/vdso.so.dbg | sed 's/(.*//' String dump of section '.comment': [ 0] Linker: LLD 11.0.0 [ 62] ClangBuiltLinux clang version 11.0.0 Signed-off-by: Nathan Chancellor --- v2 -> v3: * New patch. arch/mips/vdso/Makefile | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile index 92b53d1df42c3..da5db947072d5 100644 --- a/arch/mips/vdso/Makefile +++ b/arch/mips/vdso/Makefile @@ -60,10 +60,9 @@ ifdef CONFIG_MIPS_DISABLE_VDSO endif # VDSO linker flags. -VDSO_LDFLAGS := \ - -Wl,-Bsymbolic -Wl,--no-undefined -Wl,-soname=linux-vdso.so.1 \ - $(addprefix -Wl$(comma),$(filter -E%,$(KBUILD_CFLAGS))) \ - -nostdlib -shared -Wl,--hash-style=sysv -Wl,--build-id +ldflags-y := -Bsymbolic --no-undefined -soname=linux-vdso.so.1 \ + $(filter -E%,$(KBUILD_CFLAGS)) -nostdlib -shared \ + --hash-style=sysv --build-id -T CFLAGS_REMOVE_vdso.o = -pg @@ -82,11 +81,7 @@ quiet_cmd_vdso_mips_check = VDSOCHK $@ # quiet_cmd_vdsold_and_vdso_check = LD $@ - cmd_vdsold_and_vdso_check = $(cmd_vdsold); $(cmd_vdso_check); $(cmd_vdso_mips_check) - -quiet_cmd_vdsold = VDSO $@ - cmd_vdsold = $(CC) $(c_flags) $(VDSO_LDFLAGS) \ - -Wl,-T $(filter %.lds,$^) $(filter %.o,$^) -o $@ + cmd_vdsold_and_vdso_check = $(cmd_ld); $(cmd_vdso_check); $(cmd_vdso_mips_check) quiet_cmd_vdsoas_o_S = AS $@ cmd_vdsoas_o_S = $(CC) $(a_flags) -c -o $@ $< -- 2.26.2