From da8c0551ffcdcc8f0ee0901d6be8ad7fbbab6a82 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Mon, 12 Oct 2020 12:41:31 -0700 Subject: [PATCH] FROMLIST: arm64: vdso32: Allow ld.lld to properly link the VDSO As it stands now, the vdso32 Makefile hardcodes the linker to ld.bfd using -fuse-ld=bfd with $(CC). This was taken from the arm vDSO Makefile, as the comment notes, done in commit d2b30cd4b722 ("ARM: 8384/1: VDSO: force use of BFD linker"). Commit fe00e50b2db8 ("ARM: 8858/1: vdso: use $(LD) instead of $(CC) to link VDSO") changed that Makefile to use $(LD) directly instead of through $(CC), which matches how the rest of the kernel operates. Since then, LD=ld.lld means that the arm vDSO will be linked with ld.lld, which has shown no problems so far. Allow ld.lld to link this vDSO as we do the regular arm vDSO. To do this, we need to do a few things: * Add a LD_COMPAT variable, which defaults to $(CROSS_COMPILE_COMPAT)ld with gcc and $(LD) if LLVM is 1, which will be ld.lld, or $(CROSS_COMPILE_COMPAT)ld if not, which matches the logic of the main Makefile. It is overrideable for further customization and avoiding breakage. * Eliminate cc32-ldoption, which matches commit 055efab3120b ("kbuild: drop support for cc-ldoption"). With those, we can use $(LD_COMPAT) in cmd_ldvdso and change the flags from compiler linker flags to linker flags directly. We eliminate -mfloat-abi=soft because it is not handled by the linker. Link: https://github.com/ClangBuiltLinux/linux/issues/1033 Reported-by: Nick Desaulniers Signed-off-by: Nathan Chancellor Bug: 141693040 Test: BUILD_CONFIG=common/build.config.gki.aarch64 ./build/build.sh Link: https://lore.kernel.org/linux-arm-kernel/20201013033947.2257501-1-natechancellor@gmail.com/ Change-Id: I8a7e5736294a2cb9b60edcfdddb4937003fe6c01 Signed-off-by: Nick Desaulniers --- arch/arm64/kernel/vdso32/Makefile | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile index 3e8490769..d3b4224b1 100755 --- a/arch/arm64/kernel/vdso32/Makefile +++ b/arch/arm64/kernel/vdso32/Makefile @@ -22,16 +22,21 @@ endif CC_COMPAT ?= $(CC) CC_COMPAT += $(CC_COMPAT_CLANG_FLAGS) + +ifeq ($(LLVM),1) +LD_COMPAT ?= $(LD) +else +LD_COMPAT ?= $(CROSS_COMPILE_COMPAT)ld +endif else CC_COMPAT ?= $(CROSS_COMPILE_COMPAT)gcc +LD_COMPAT ?= $(CROSS_COMPILE_COMPAT)ld endif cc32-option = $(call try-run,\ $(CC_COMPAT) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2)) cc32-disable-warning = $(call try-run,\ $(CC_COMPAT) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1))) -cc32-ldoption = $(call try-run,\ - $(CC_COMPAT) $(1) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2)) cc32-as-instr = $(call try-run,\ printf "%b\n" "$(1)" | $(CC_COMPAT) $(VDSO_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3)) @@ -115,14 +120,10 @@ dmbinstr := $(call cc32-as-instr,dmb ishld,-DCONFIG_AS_DMB_ISHLD=1) VDSO_CFLAGS += $(dmbinstr) VDSO_AFLAGS += $(dmbinstr) -VDSO_LDFLAGS := $(VDSO_CPPFLAGS) # From arm vDSO Makefile -VDSO_LDFLAGS += -Wl,-Bsymbolic -Wl,--no-undefined -Wl,-soname=linux-vdso.so.1 -VDSO_LDFLAGS += -Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096 -VDSO_LDFLAGS += -nostdlib -shared -mfloat-abi=soft -VDSO_LDFLAGS += -Wl,--hash-style=sysv -VDSO_LDFLAGS += -Wl,--build-id -VDSO_LDFLAGS += $(call cc32-ldoption,-fuse-ld=bfd) +VDSO_LDFLAGS += -Bsymbolic --no-undefined -soname=linux-vdso.so.1 +VDSO_LDFLAGS += -z max-page-size=4096 -z common-page-size=4096 +VDSO_LDFLAGS += -nostdlib -shared --hash-style=sysv --build-id # Borrow vdsomunge.c from the arm vDSO @@ -183,8 +184,8 @@ quiet_cmd_vdsold_and_vdso_check = LD32 $@ cmd_vdsold_and_vdso_check = $(cmd_vdsold); $(cmd_vdso_check) quiet_cmd_vdsold = LD32 $@ - cmd_vdsold = $(CC_COMPAT) -Wp,-MD,$(depfile) $(VDSO_LDFLAGS) \ - -Wl,-T $(filter %.lds,$^) $(filter %.o,$^) -o $@ + cmd_vdsold = $(LD_COMPAT) $(VDSO_LDFLAGS) \ + -T $(filter %.lds,$^) $(filter %.o,$^) -o $@ quiet_cmd_vdsocc = CC32 $@ cmd_vdsocc = $(CC_COMPAT) -Wp,-MD,$(depfile) $(VDSO_CFLAGS) -c -o $@ $< quiet_cmd_vdsocc_gettimeofday = CC32 $@