[kernel-hardening] [PATCH v2 08/11] MIPS: Add CONFIG_RELOCATABLE Kconfig option

Matt Redfearn
2016-03-31T09:05:39Z

Add option to KConfig to enable the kernel to relocate itself at
runtime.

Relocation is supported R2 and later of the MIPS architecture, 32bit
and 64bit. The platform is also required to provide support through
plat_get_fdt() added in a later patch.

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
---

Changes in v2: None

arch/mips/Kconfig | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 6f55e1a5d645..4bf1814e57a5 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -473,6 +473,7 @@ config MIPS_MALTA
select SYS_SUPPORTS_MULTITHREADING
select SYS_SUPPORTS_SMARTMIPS
select SYS_SUPPORTS_ZBOOT
+ select SYS_SUPPORTS_RELOCATABLE
select USE_OF
select ZONE_DMA32 if 64BIT
select BUILTIN_DTB
@@ -516,6 +517,7 @@ config MIPS_SEAD3
select SYS_SUPPORTS_SMARTMIPS
select SYS_SUPPORTS_MICROMIPS
select SYS_SUPPORTS_MIPS16
+ select SYS_SUPPORTS_RELOCATABLE
select USB_EHCI_BIG_ENDIAN_DESC
select USB_EHCI_BIG_ENDIAN_MMIO
select USE_OF
@@ -1156,6 +1158,13 @@ config ISA_DMA_API
config HOLES_IN_ZONE
bool

+config SYS_SUPPORTS_RELOCATABLE
+ bool
+ help
+ Selected if the platform supports relocating the kernel.
+ The platform must provide plat_get_fdt() if it selects CONFIG_USE_OF
+ to allow access to command line and entropy sources.
+
#
# Endianness selection. Sufficiently obscure so many users don't know what to
# answer,so we try hard to limit the available choices. Also the use of a
@@ -2478,6 +2487,15 @@ config NUMA
config SYS_SUPPORTS_NUMA
bool

+config RELOCATABLE
+ bool "Relocatable kernel"
+ depends on SYS_SUPPORTS_RELOCATABLE && (CPU_MIPS32_R2 || CPU_MIPS64_R2 || CPU_MIPS32_R6 || CPU_MIPS64_R6)
+ help
+ This builds a kernel image that retains relocation information
+ so it can be loaded someplace besides the default 1MB.
+ The relocations make the kernel binary about 15% larger,
+ but are discarded at runtime
+
config RELOCATION_TABLE_SIZE
hex "Relocation table size"
depends on RELOCATABLE
--
2.5.0