From a5b8ca97fbf8300a5e21c393df25ce6f521e7939 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Fri, 18 Dec 2020 11:45:40 +0900 Subject: [PATCH] arm64: do not descend to vdso directories twice arm64 descends into each vdso directory twice; first in vdso_prepare, second during the ordinary build process. PPC mimicked it and uncovered a problem [1]. In the first descend, Kbuild directly visits the vdso directories, therefore it does not inherit subdir-ccflags-y from upper directories. This means the command line parameters may differ between the two. If it happens, the offset values in the generated headers might be different from real offsets of vdso.so in the kernel. This potential danger should be avoided. The vdso directories are built in the vdso_prepare stage, so the second descend is unneeded. [1]: https://lore.kernel.org/linux-kbuild/CAK7LNARAkJ3_-4gX0VA2UkapbOftuzfSTVMBbgbw=HD8n7N+7w@mail.gmail.com/T/#ma10dcb961fda13f36d42d58fa6cb2da988b7e73a Signed-off-by: Masahiro Yamada Link: https://lore.kernel.org/r/20201218024540.1102650-1-masahiroy@kernel.org Signed-off-by: Will Deacon --- arch/arm64/Makefile | 10 ++++++---- arch/arm64/kernel/Makefile | 5 +++-- arch/arm64/kernel/{vdso/vdso.S => vdso-wrap.S} | 0 arch/arm64/kernel/vdso/Makefile | 1 - arch/arm64/kernel/{vdso32/vdso.S => vdso32-wrap.S} | 0 arch/arm64/kernel/vdso32/Makefile | 1 - 6 files changed, 9 insertions(+), 8 deletions(-) rename arch/arm64/kernel/{vdso/vdso.S => vdso-wrap.S} (100%) rename arch/arm64/kernel/{vdso32/vdso.S => vdso32-wrap.S} (100%) diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 90309208bb28..5b84aec31ed3 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -188,10 +188,12 @@ ifeq ($(KBUILD_EXTMOD),) # this hack. prepare: vdso_prepare vdso_prepare: prepare0 - $(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso include/generated/vdso-offsets.h - $(if $(CONFIG_COMPAT_VDSO),$(Q)$(MAKE) \ - $(build)=arch/arm64/kernel/vdso32 \ - include/generated/vdso32-offsets.h) + $(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso \ + include/generated/vdso-offsets.h arch/arm64/kernel/vdso/vdso.so +ifdef CONFIG_COMPAT_VDSO + $(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 \ + include/generated/vdso32-offsets.h arch/arm64/kernel/vdso32/vdso.so +endif endif define archhelp diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 86364ab6f13f..42f6ad2c7eac 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -59,9 +59,10 @@ obj-$(CONFIG_CRASH_CORE) += crash_core.o obj-$(CONFIG_ARM_SDE_INTERFACE) += sdei.o obj-$(CONFIG_ARM64_PTR_AUTH) += pointer_auth.o obj-$(CONFIG_ARM64_MTE) += mte.o +obj-y += vdso-wrap.o +obj-$(CONFIG_COMPAT_VDSO) += vdso32-wrap.o -obj-y += vdso/ probes/ -obj-$(CONFIG_COMPAT_VDSO) += vdso32/ +obj-y += probes/ head-y := head.o extra-y += $(head-y) vmlinux.lds diff --git a/arch/arm64/kernel/vdso/vdso.S b/arch/arm64/kernel/vdso-wrap.S similarity index 100% rename from arch/arm64/kernel/vdso/vdso.S rename to arch/arm64/kernel/vdso-wrap.S diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile index cd9c3fa25902..76c0255ecc91 100644 --- a/arch/arm64/kernel/vdso/Makefile +++ b/arch/arm64/kernel/vdso/Makefile @@ -44,7 +44,6 @@ endif # Disable gcov profiling for VDSO code GCOV_PROFILE := n -obj-y += vdso.o targets += vdso.lds CPPFLAGS_vdso.lds += -P -C -U$(ARCH) diff --git a/arch/arm64/kernel/vdso32/vdso.S b/arch/arm64/kernel/vdso32-wrap.S similarity index 100% rename from arch/arm64/kernel/vdso32/vdso.S rename to arch/arm64/kernel/vdso32-wrap.S diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile index a1e0f91e6cea..789ad420f16b 100644 --- a/arch/arm64/kernel/vdso32/Makefile +++ b/arch/arm64/kernel/vdso32/Makefile @@ -155,7 +155,6 @@ c-obj-vdso-gettimeofday := $(addprefix $(obj)/, $(c-obj-vdso-gettimeofday)) asm-obj-vdso := $(addprefix $(obj)/, $(asm-obj-vdso)) obj-vdso := $(c-obj-vdso) $(c-obj-vdso-gettimeofday) $(asm-obj-vdso) -obj-y += vdso.o targets += vdso.lds CPPFLAGS_vdso.lds += -P -C -U$(ARCH)