powerpc: enable the relocatable support for the fsl booke 32bit kernel

This is based on the codes in the head_44x.S. The difference is that
the init tlb size we used is 64M. With this patch we can only load the
kernel at address between memstart_addr ~ memstart_addr + 64M. We will
fix this restriction in the following patches.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/arch/powerpc/mm/fsl_booke_mmu.c b/arch/powerpc/mm/fsl_booke_mmu.c
index 07ba45b0f07c..ce4a1163ddd3 100644
--- a/arch/powerpc/mm/fsl_booke_mmu.c
+++ b/arch/powerpc/mm/fsl_booke_mmu.c
@@ -241,4 +241,32 @@ void setup_initial_memory_limit(phys_addr_t first_memblock_base,
         /* 64M mapped initially according to head_fsl_booke.S */
         memblock_set_current_limit(min_t(u64, limit, 0x04000000));
 }
+
+#ifdef CONFIG_RELOCATABLE
+notrace void __init relocate_init(phys_addr_t start)
+{
+        unsigned long base = KERNELBASE;
+
+        /*
+         * Relocatable kernel support based on processing of dynamic
+         * relocation entries.
+         * Compute the virt_phys_offset :
+         * virt_phys_offset = stext.run - kernstart_addr
+         *
+         * stext.run = (KERNELBASE & ~0x3ffffff) + (kernstart_addr & 0x3ffffff)
+         * When we relocate, we have :
+         *
+         *      (kernstart_addr & 0x3ffffff) = (stext.run & 0x3ffffff)
+         *
+         * hence:
+         *  virt_phys_offset = (KERNELBASE & ~0x3ffffff) -
+         *                              (kernstart_addr & ~0x3ffffff)
+         *
+         */
+        kernstart_addr = start;
+        start &= ~0x3ffffff;
+        base &= ~0x3ffffff;
+        virt_phys_offset = base - start;
+}
+#endif
 #endif