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[v7,2/5] arm/build: Warn on orphan section placement

Message ID 20200902025347.2504702-3-keescook@chromium.org (mailing list archive)
State New, archived
Headers show
Series Warn on orphan section placement | expand

Commit Message

Kees Cook Sept. 2, 2020, 2:53 a.m. UTC 
We don't want to depend on the linker's orphan section placement
heuristics as these can vary between linkers, and may change between
versions. All sections need to be explicitly handled in the linker
script.

Specifically, this would have made a recently fixed bug very obvious:

ld: warning: orphan section `.fixup' from `arch/arm/lib/copy_from_user.o' being placed in section `.fixup'

With all sections handled, enable orphan section warning.

Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/arm/Makefile | 4 ++++
 1 file changed, 4 insertions(+)
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Patch

diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 4e877354515f..e589da3c8949 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -16,6 +16,10 @@  LDFLAGS_vmlinux	+= --be8
 KBUILD_LDFLAGS_MODULE	+= --be8
 endif
 
+# We never want expected sections to be placed heuristically by the
+# linker. All sections should be explicitly named in the linker script.
+LDFLAGS_vmlinux += $(call ld-option, --orphan-handling=warn)
+
 ifeq ($(CONFIG_ARM_MODULE_PLTS),y)
 KBUILD_LDS_MODULE	+= $(srctree)/arch/arm/kernel/module.lds
 endif