MIPS: Generate relocation table when CONFIG_RELOCATABLE
When CONFIG_RELOCATABLE is enabled (added in later patch) add
--emit-relocs to vmlinux LDFLAGS so that fully linked vmlinux contains
relocation information.
Run the previously added relocs tool to fill in the .data.relocs section
of vmlinux with a table of relocations. The relocs tool will also remove
(mark as 0 length) the relocation sections added to vmlinux.
When vmlinux is passed to the boot makefile for conversion into a boot
image the now empty relocation sections will be removed and the
populated relocation table will be included in the binary image.
Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: kernel-hardening@lists.openwall.com
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12983/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index a61031e..c0b002a 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -96,6 +96,10 @@
KBUILD_AFLAGS_MODULE += -mlong-calls
KBUILD_CFLAGS_MODULE += -mlong-calls
+ifeq ($(CONFIG_RELOCATABLE),y)
+LDFLAGS_vmlinux += --emit-relocs
+endif
+
#
# pass -msoft-float to GAS if it supports it. However on newer binutils
# (specifically newer than 2.24.51.20140728) we then also need to explicitly
@@ -313,6 +317,10 @@
$(bootvars-y) $@
endif
+CMD_RELOCS = arch/mips/boot/tools/relocs
+quiet_cmd_relocs = RELOCS $<
+ cmd_relocs = $(CMD_RELOCS) $<
+
#
# Some machines like the Indy need 32-bit ELF binaries for booting purposes.
# Other need ECOFF, so we build a 32-bit ELF binary for them which we then
@@ -321,6 +329,11 @@
quiet_cmd_32 = OBJCOPY $@
cmd_32 = $(OBJCOPY) -O $(32bit-bfd) $(OBJCOPYFLAGS) $< $@
vmlinux.32: vmlinux
+ifeq ($(CONFIG_RELOCATABLE)$(CONFIG_64BIT),yy)
+# Currently, objcopy fails to handle the relocations in the elf64
+# So the relocs tool must be run here to remove them first
+ $(call cmd,relocs)
+endif
$(call cmd,32)
#
@@ -336,6 +349,9 @@
# boot
$(boot-y): $(vmlinux-32) FORCE
+ifeq ($(CONFIG_RELOCATABLE)$(CONFIG_32BIT),yy)
+ $(call cmd,relocs)
+endif
$(Q)$(MAKE) $(build)=arch/mips/boot VMLINUX=$(vmlinux-32) \
$(bootvars-y) arch/mips/boot/$@