diff mbox series

[v3,5/9] x86/boot: Warn on orphan section placement

Message ID 20200624014940.1204448-6-keescook@chromium.org
State New
Headers show
Series [v3,1/9] vmlinux.lds.h: Add .gnu.version* to DISCARDS | expand

Commit Message

Kees Cook June 24, 2020, 1:49 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 named in the linker
script.

Add the common debugging sections. Discard the unused note, rel, plt,
dyn, and hash sections that are not needed in the compressed vmlinux.
Disable .eh_frame generation in the linker and enable orphan section
warnings.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/x86/boot/compressed/Makefile      |  3 ++-
 arch/x86/boot/compressed/vmlinux.lds.S | 11 +++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 7619742f91c9..646720a05f89 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -48,6 +48,7 @@  GCOV_PROFILE := n
 UBSAN_SANITIZE :=n
 
 KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
+KBUILD_LDFLAGS += $(call ld-option,--no-ld-generated-unwind-info)
 # Compressed kernel should be built as PIE since it may be loaded at any
 # address by the bootloader.
 ifeq ($(CONFIG_X86_32),y)
@@ -59,7 +60,7 @@  else
 KBUILD_LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \
 	&& echo "-z noreloc-overflow -pie --no-dynamic-linker")
 endif
-LDFLAGS_vmlinux := -T
+LDFLAGS_vmlinux := --orphan-handling=warn -T
 
 hostprogs	:= mkpiggy
 HOST_EXTRACFLAGS += -I$(srctree)/tools/include
diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S
index 8f1025d1f681..6fe3ecdfd685 100644
--- a/arch/x86/boot/compressed/vmlinux.lds.S
+++ b/arch/x86/boot/compressed/vmlinux.lds.S
@@ -75,5 +75,16 @@  SECTIONS
 	. = ALIGN(PAGE_SIZE);	/* keep ZO size page aligned */
 	_end = .;
 
+	STABS_DEBUG
+	DWARF_DEBUG
+
 	DISCARDS
+	/DISCARD/ : {
+		*(.note.*)
+		*(.rela.*) *(.rela_*)
+		*(.rel.*) *(.rel_*)
+		*(.plt) *(.plt.*)
+		*(.dyn*)
+		*(.hash) *(.gnu.hash)
+	}
 }