Commit e1789d7c authored by Xin Li's avatar Xin Li Committed by Kees Cook
Browse files

kbuild: upgrade the orphan section warning to an error if CONFIG_WERROR is set 



Andrew Cooper suggested upgrading the orphan section warning to a hard link
error. However Nathan Chancellor said outright turning the warning into an
error with no escape hatch might be too aggressive, as we have had these
warnings triggered by new compiler generated sections, and suggested turning
orphan sections into an error only if CONFIG_WERROR is set. Kees Cook echoed
and emphasized that the mandate from Linus is that we should avoid breaking
builds. It wrecks bisection, it causes problems across compiler versions, etc.

Thus upgrade the orphan section warning to a hard link error only if
CONFIG_WERROR is set.

Suggested-by: default avatarAndrew Cooper <andrew.cooper3@citrix.com>
Suggested-by: default avatarNathan Chancellor <nathan@kernel.org>
Signed-off-by: default avatarXin Li <xin3.li@intel.com>
Reviewed-by: default avatarNathan Chancellor <nathan@kernel.org>
Tested-by: default avatarNathan Chancellor <nathan@kernel.org>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221025073023.16137-2-xin3.li@intel.com
parent 5a17f040

Makefile

+1 −1
Original line number Diff line number Diff line
@@ -1118,7 +1118,7 @@ endif 
# We never want expected sections to be placed heuristically by the

# linker. All sections should be explicitly named in the linker script.

ifdef CONFIG_LD_ORPHAN_WARN

LDFLAGS_vmlinux += --orphan-handling=warn

LDFLAGS_vmlinux += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)

endif



# Align the bit size of userspace programs with the kernel

arch/arm/boot/compressed/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -123,7 +123,7 @@ LDFLAGS_vmlinux += --no-undefined 
LDFLAGS_vmlinux += -X

# Report orphan sections

ifdef CONFIG_LD_ORPHAN_WARN

LDFLAGS_vmlinux += --orphan-handling=warn

LDFLAGS_vmlinux += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)

endif

# Next argument is a linker script

LDFLAGS_vmlinux += -T

arch/arm64/kernel/vdso/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -27,7 +27,7 @@ ldflags-y := -shared -soname=linux-vdso.so.1 --hash-style=sysv \ 
	     -Bsymbolic --build-id=sha1 -n $(btildflags-y)



ifdef CONFIG_LD_ORPHAN_WARN

  ldflags-y += --orphan-handling=warn

  ldflags-y += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)

endif



ldflags-y += -T

arch/arm64/kernel/vdso32/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -104,7 +104,7 @@ VDSO_AFLAGS += -D__ASSEMBLY__ 
VDSO_LDFLAGS += -Bsymbolic --no-undefined -soname=linux-vdso.so.1

VDSO_LDFLAGS += -z max-page-size=4096 -z common-page-size=4096

VDSO_LDFLAGS += -shared --hash-style=sysv --build-id=sha1

VDSO_LDFLAGS += --orphan-handling=warn

VDSO_LDFLAGS += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)





# Borrow vdsomunge.c from the arm vDSO

arch/x86/boot/compressed/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -68,7 +68,7 @@ KBUILD_LDFLAGS += $(call ld-option,--no-ld-generated-unwind-info) 
# address by the bootloader.

LDFLAGS_vmlinux := -pie $(call ld-option, --no-dynamic-linker)

ifdef CONFIG_LD_ORPHAN_WARN

LDFLAGS_vmlinux += --orphan-handling=warn

LDFLAGS_vmlinux += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)

endif

LDFLAGS_vmlinux += -z noexecstack

ifeq ($(CONFIG_LD_IS_BFD),y)