powerpc: Process dynamic relocations for kernel

The following patch implements the dynamic relocation processing for
PPC32 kernel. relocate() accepts the target virtual address and relocates
 the kernel image to the same.

Currently the following relocation types are handled :

	R_PPC_RELATIVE
	R_PPC_ADDR16_LO
	R_PPC_ADDR16_HI
	R_PPC_ADDR16_HA

The last 3 relocations in the above list depends on value of Symbol indexed
whose index is encoded in the Relocation entry. Hence we need the Symbol
Table for processing such relocations.

Note: The GNU ld for ppc32 produces buggy relocations for relocation types
that depend on symbols. The value of the symbols with STB_LOCAL scope
should be assumed to be zero. - Alan Modra

Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@linux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Alan Modra <amodra@au1.ibm.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Signed-off-by: Josh Boyer <jwboyer@gmail.com>

1 files changed, 24 insertions, 17 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 8b323b7b0a61..2ad5ea827820 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -847,23 +847,30 @@ config DYNAMIC_MEMSTART
           load address. When this option is enabled, the compile time physical 
           address CONFIG_PHYSICAL_START is ignored.
 
-# Mapping based RELOCATABLE is moved to DYNAMIC_MEMSTART
-# config RELOCATABLE
-#       bool "Build a relocatable kernel (EXPERIMENTAL)"
-#       depends on EXPERIMENTAL && ADVANCED_OPTIONS && FLATMEM && (FSL_BOOKE || PPC_47x)
-#       help
-#         This builds a kernel image that is capable of running at the
-#         location the kernel is loaded at, without any alignment restrictions.
-#
-#         One use is for the kexec on panic case where the recovery kernel
-#         must live at a different physical address than the primary
-#         kernel.
-#
-#         Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
-#         it has been loaded at and the compile time physical addresses
-#         CONFIG_PHYSICAL_START is ignored.  However CONFIG_PHYSICAL_START
-#         setting can still be useful to bootwrappers that need to know the
-#         load location of the kernel (eg. u-boot/mkimage).
+          This option is overridden by CONFIG_RELOCATABLE
+
+config RELOCATABLE
+        bool "Build a relocatable kernel (EXPERIMENTAL)"
+        depends on EXPERIMENTAL && ADVANCED_OPTIONS && FLATMEM
+        select NONSTATIC_KERNEL
+        help
+          This builds a kernel image that is capable of running at the
+          location the kernel is loaded at, without any alignment restrictions.
+          This feature is a superset of DYNAMIC_MEMSTART and hence overrides it.
+
+          One use is for the kexec on panic case where the recovery kernel
+          must live at a different physical address than the primary
+          kernel.
+
+          Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
+          it has been loaded at and the compile time physical addresses
+          CONFIG_PHYSICAL_START is ignored.  However CONFIG_PHYSICAL_START
+          setting can still be useful to bootwrappers that need to know the
+          load address of the kernel (eg. u-boot/mkimage).
+
+config RELOCATABLE_PPC32
+        def_bool y
+        depends on PPC32 && RELOCATABLE
 
 config PAGE_OFFSET_BOOL
         bool "Set custom page offset address"