MIPS: Reserve space for relocation table
When CONFIG_RELOCATABLE is enabled, add a new section in the memory map
to be filled with relocation data.
CONFIG_RELOCATION_TABLE_SIZE allows the amount of space reserved to be
adjusted if necessary.
The relocs tool will populate this reserved space with relocation
information. The space is reserved within the elf by filling it with
0's, and an invalid entry is left at the start of the space such that
kernel relocation will be aborted if the table is empty.
Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Aaro Koskinen <aaro.koskinen@nokia.com>
Cc: David Daney <ddaney@caviumnetworks.com>
Cc: Jonas Gorski <jogo@openwrt.org>
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/12982/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index 54d653e..a82c178 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -136,6 +136,27 @@
#ifdef CONFIG_SMP
PERCPU_SECTION(1 << CONFIG_MIPS_L1_CACHE_SHIFT)
#endif
+
+#ifdef CONFIG_RELOCATABLE
+ . = ALIGN(4);
+
+ .data.reloc : {
+ _relocation_start = .;
+ /*
+ * Space for relocation table
+ * This needs to be filled so that the
+ * relocs tool can overwrite the content.
+ * An invalid value is left at the start of the
+ * section to abort relocation if the table
+ * has not been filled in.
+ */
+ LONG(0xFFFFFFFF);
+ FILL(0);
+ . += CONFIG_RELOCATION_TABLE_SIZE - 4;
+ _relocation_end = .;
+ }
+#endif
+
#ifdef CONFIG_MIPS_RAW_APPENDED_DTB
__appended_dtb = .;
/* leave space for appended DTB */