From 069fd766271de65ec4dc2eb8d15f7f44727b1ea1 Mon Sep 17 00:00:00 2001 From: Matt Redfearn Date: Thu, 31 Mar 2016 10:05:34 +0100 Subject: [PATCH] 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 Cc: Aaro Koskinen Cc: David Daney Cc: Jonas Gorski 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 --- arch/mips/Kconfig | 16 ++++++++++++++++ arch/mips/kernel/vmlinux.lds.S | 21 +++++++++++++++++++++ 2 files changed, 37 insertions(+) diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index b5609111a3bd..99ec21f35433 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -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" diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S index 54d653ee17e1..a82c178d0bb9 100644 --- a/arch/mips/kernel/vmlinux.lds.S +++ b/arch/mips/kernel/vmlinux.lds.S @@ -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 */ -- 2.20.1