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Commit 069fd766 authored by Matt Redfearn's avatar Matt Redfearn Committed by Ralf Baechle
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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: default avatarMatt 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: default avatarRalf Baechle <ralf@linux-mips.org>
parent aadeec4d

arch/mips/Kconfig

+16 −0
Original line number Diff line number Diff line
@@ -2473,6 +2473,22 @@ config NUMA 
config SYS_SUPPORTS_NUMA

	bool



config RELOCATION_TABLE_SIZE

	hex "Relocation table size"

	depends on RELOCATABLE

	range 0x0 0x01000000

	default "0x00100000"

	---help---

	  A table of relocation data will be appended to the kernel binary

	  and parsed at boot to fix up the relocated kernel.



	  This option allows the amount of space reserved for the table to be

	  adjusted, although the default of 1Mb should be ok in most cases.



	  The build will fail and a valid size suggested if this is too small.



	  If unsure, leave at the default value.



config NODES_SHIFT

	int

	default "6"

arch/mips/kernel/vmlinux.lds.S

+21 −0
Original line number Diff line number Diff line
@@ -136,6 +136,27 @@ SECTIONS 
#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 */