@@ -29,6 +29,10 @@ LDFLAGS_vmlinux += --fix-cortex-a53-843419
endif
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 += --orphan-handling=warn
+
ifeq ($(CONFIG_ARM64_USE_LSE_ATOMICS), y)
ifneq ($(CONFIG_ARM64_LSE_ATOMICS), y)
$(warning LSE atomics not supported by binutils)
@@ -94,7 +94,8 @@ SECTIONS
/DISCARD/ : {
*(.interp .dynamic)
*(.dynsym .dynstr .hash .gnu.hash)
- *(.eh_frame)
+ *(.plt) *(.data.rel.ro)
+ *(.igot.*) *(.iplt)
}
. = KIMAGE_VADDR + TEXT_OFFSET;
@@ -244,9 +245,17 @@ SECTIONS
_end = .;
STABS_DEBUG
+ DWARF_DEBUG
ELF_DETAILS
HEAD_SYMBOLS
+
+ /*
+ * Make sure that the .got.plt is either completely empty or it
+ * contains only the lazy dispatch entries.
+ */
+ .got.plt (INFO) : { *(.got.plt) }
+ ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0x18, ".got.plt not empty")
}
#include "image-vars.h"
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. Remove .eh_frame, since there are none left. Add .plt, .data.rel.ro, .igot.*, and .iplt to discards as they are not actually used. While .got.plt is also not used, it must be included otherwise ld.bfd will fail to link with the error: aarch64-linux-gnu-ld: discarded output section: `.got.plt' However, as it'd be better to validate that it stays effectively empty, add an assert, as suggested by Ard Biesheuvel. Explicitly include debug sections when they're present. Finally, enable orphan section warnings. Acked-by: Will Deacon <will@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> --- arch/arm64/Makefile | 4 ++++ arch/arm64/kernel/vmlinux.lds.S | 11 ++++++++++- 2 files changed, 14 insertions(+), 1 deletion(-)