powerpc/fsl_booke: set the tlb entry for the kernel address in AS1

We use the tlb1 entries to map low mem to the kernel space. In the
current code, it assumes that the first tlb entry would cover the
kernel image. But this is not true for some special cases, such as
when we run a relocatable kernel above the 64M or set
CONFIG_KERNEL_START above 64M. So we choose to switch to address
space 1 before setting these tlb entries.

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

arch/powerpc/mm/fsl_booke_mmu.c

@@ -222,7 +222,9 @@ void __init adjust_total_lowmem(void)
 	/* adjust lowmem size to __max_low_memory */
 	ram = min((phys_addr_t)__max_low_memory, (phys_addr_t)total_lowmem);
 
+	i = switch_to_as1();
 	__max_low_memory = map_mem_in_cams(ram, CONFIG_LOWMEM_CAM_NUM);
+	restore_to_as0(i);
 
 	pr_info("Memory CAM mapping: ");
 	for (i = 0; i < tlbcam_index - 1; i++)

arch/powerpc/mm/mmu_decl.h

@@ -148,6 +148,8 @@ extern unsigned long calc_cam_sz(unsigned long ram, unsigned long virt,
 extern void MMU_init_hw(void);
 extern unsigned long mmu_mapin_ram(unsigned long top);
 extern void adjust_total_lowmem(void);
+extern int switch_to_as1(void);
+extern void restore_to_as0(int esel);
 #endif
 extern void loadcam_entry(unsigned int index);