[Feature]add MT2731_MP2_MR2_SVN388 baseline version

Change-Id: Ief04314834b31e27effab435d3ca8ba33b499059
diff --git a/src/kernel/linux/v4.14/arch/powerpc/mm/pgtable-radix.c b/src/kernel/linux/v4.14/arch/powerpc/mm/pgtable-radix.c
new file mode 100644
index 0000000..ba02305
--- /dev/null
+++ b/src/kernel/linux/v4.14/arch/powerpc/mm/pgtable-radix.c
@@ -0,0 +1,998 @@
+/*
+ * Page table handling routines for radix page table.
+ *
+ * Copyright 2015-2016, Aneesh Kumar K.V, IBM Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) "radix-mmu: " fmt
+
+#include <linux/kernel.h>
+#include <linux/sched/mm.h>
+#include <linux/memblock.h>
+#include <linux/of_fdt.h>
+#include <linux/mm.h>
+#include <linux/string_helpers.h>
+#include <linux/stop_machine.h>
+
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/dma.h>
+#include <asm/machdep.h>
+#include <asm/mmu.h>
+#include <asm/firmware.h>
+#include <asm/powernv.h>
+#include <asm/sections.h>
+#include <asm/trace.h>
+
+#include <trace/events/thp.h>
+
+unsigned int mmu_pid_bits;
+unsigned int mmu_base_pid;
+
+static int native_register_process_table(unsigned long base, unsigned long pg_sz,
+					 unsigned long table_size)
+{
+	unsigned long patb0, patb1;
+
+	patb0 = be64_to_cpu(partition_tb[0].patb0);
+	patb1 = base | table_size | PATB_GR;
+
+	mmu_partition_table_set_entry(0, patb0, patb1);
+
+	return 0;
+}
+
+static __ref void *early_alloc_pgtable(unsigned long size)
+{
+	void *pt;
+
+	pt = __va(memblock_alloc_base(size, size, MEMBLOCK_ALLOC_ANYWHERE));
+	memset(pt, 0, size);
+
+	return pt;
+}
+
+int radix__map_kernel_page(unsigned long ea, unsigned long pa,
+			  pgprot_t flags,
+			  unsigned int map_page_size)
+{
+	pgd_t *pgdp;
+	pud_t *pudp;
+	pmd_t *pmdp;
+	pte_t *ptep;
+	/*
+	 * Make sure task size is correct as per the max adddr
+	 */
+	BUILD_BUG_ON(TASK_SIZE_USER64 > RADIX_PGTABLE_RANGE);
+	if (slab_is_available()) {
+		pgdp = pgd_offset_k(ea);
+		pudp = pud_alloc(&init_mm, pgdp, ea);
+		if (!pudp)
+			return -ENOMEM;
+		if (map_page_size == PUD_SIZE) {
+			ptep = (pte_t *)pudp;
+			goto set_the_pte;
+		}
+		pmdp = pmd_alloc(&init_mm, pudp, ea);
+		if (!pmdp)
+			return -ENOMEM;
+		if (map_page_size == PMD_SIZE) {
+			ptep = pmdp_ptep(pmdp);
+			goto set_the_pte;
+		}
+		ptep = pte_alloc_kernel(pmdp, ea);
+		if (!ptep)
+			return -ENOMEM;
+	} else {
+		pgdp = pgd_offset_k(ea);
+		if (pgd_none(*pgdp)) {
+			pudp = early_alloc_pgtable(PUD_TABLE_SIZE);
+			BUG_ON(pudp == NULL);
+			pgd_populate(&init_mm, pgdp, pudp);
+		}
+		pudp = pud_offset(pgdp, ea);
+		if (map_page_size == PUD_SIZE) {
+			ptep = (pte_t *)pudp;
+			goto set_the_pte;
+		}
+		if (pud_none(*pudp)) {
+			pmdp = early_alloc_pgtable(PMD_TABLE_SIZE);
+			BUG_ON(pmdp == NULL);
+			pud_populate(&init_mm, pudp, pmdp);
+		}
+		pmdp = pmd_offset(pudp, ea);
+		if (map_page_size == PMD_SIZE) {
+			ptep = pmdp_ptep(pmdp);
+			goto set_the_pte;
+		}
+		if (!pmd_present(*pmdp)) {
+			ptep = early_alloc_pgtable(PAGE_SIZE);
+			BUG_ON(ptep == NULL);
+			pmd_populate_kernel(&init_mm, pmdp, ptep);
+		}
+		ptep = pte_offset_kernel(pmdp, ea);
+	}
+
+set_the_pte:
+	set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT, flags));
+	smp_wmb();
+	return 0;
+}
+
+#ifdef CONFIG_STRICT_KERNEL_RWX
+void radix__change_memory_range(unsigned long start, unsigned long end,
+				unsigned long clear)
+{
+	unsigned long idx;
+	pgd_t *pgdp;
+	pud_t *pudp;
+	pmd_t *pmdp;
+	pte_t *ptep;
+
+	start = ALIGN_DOWN(start, PAGE_SIZE);
+	end = PAGE_ALIGN(end); // aligns up
+
+	pr_debug("Changing flags on range %lx-%lx removing 0x%lx\n",
+		 start, end, clear);
+
+	for (idx = start; idx < end; idx += PAGE_SIZE) {
+		pgdp = pgd_offset_k(idx);
+		pudp = pud_alloc(&init_mm, pgdp, idx);
+		if (!pudp)
+			continue;
+		if (pud_huge(*pudp)) {
+			ptep = (pte_t *)pudp;
+			goto update_the_pte;
+		}
+		pmdp = pmd_alloc(&init_mm, pudp, idx);
+		if (!pmdp)
+			continue;
+		if (pmd_huge(*pmdp)) {
+			ptep = pmdp_ptep(pmdp);
+			goto update_the_pte;
+		}
+		ptep = pte_alloc_kernel(pmdp, idx);
+		if (!ptep)
+			continue;
+update_the_pte:
+		radix__pte_update(&init_mm, idx, ptep, clear, 0, 0);
+	}
+
+	radix__flush_tlb_kernel_range(start, end);
+}
+
+void radix__mark_rodata_ro(void)
+{
+	unsigned long start, end;
+
+	/*
+	 * mark_rodata_ro() will mark itself as !writable at some point.
+	 * Due to DD1 workaround in radix__pte_update(), we'll end up with
+	 * an invalid pte and the system will crash quite severly.
+	 */
+	if (cpu_has_feature(CPU_FTR_POWER9_DD1)) {
+		pr_warn("Warning: Unable to mark rodata read only on P9 DD1\n");
+		return;
+	}
+
+	start = (unsigned long)_stext;
+	end = (unsigned long)__init_begin;
+
+	radix__change_memory_range(start, end, _PAGE_WRITE);
+}
+
+void radix__mark_initmem_nx(void)
+{
+	unsigned long start = (unsigned long)__init_begin;
+	unsigned long end = (unsigned long)__init_end;
+
+	radix__change_memory_range(start, end, _PAGE_EXEC);
+}
+#endif /* CONFIG_STRICT_KERNEL_RWX */
+
+static inline void __meminit print_mapping(unsigned long start,
+					   unsigned long end,
+					   unsigned long size)
+{
+	char buf[10];
+
+	if (end <= start)
+		return;
+
+	string_get_size(size, 1, STRING_UNITS_2, buf, sizeof(buf));
+
+	pr_info("Mapped 0x%016lx-0x%016lx with %s pages\n", start, end, buf);
+}
+
+static int __meminit create_physical_mapping(unsigned long start,
+					     unsigned long end)
+{
+	unsigned long vaddr, addr, mapping_size = 0;
+	pgprot_t prot;
+	unsigned long max_mapping_size;
+#ifdef CONFIG_STRICT_KERNEL_RWX
+	int split_text_mapping = 1;
+#else
+	int split_text_mapping = 0;
+#endif
+
+	start = _ALIGN_UP(start, PAGE_SIZE);
+	for (addr = start; addr < end; addr += mapping_size) {
+		unsigned long gap, previous_size;
+		int rc;
+
+		gap = end - addr;
+		previous_size = mapping_size;
+		max_mapping_size = PUD_SIZE;
+
+retry:
+		if (IS_ALIGNED(addr, PUD_SIZE) && gap >= PUD_SIZE &&
+		    mmu_psize_defs[MMU_PAGE_1G].shift &&
+		    PUD_SIZE <= max_mapping_size)
+			mapping_size = PUD_SIZE;
+		else if (IS_ALIGNED(addr, PMD_SIZE) && gap >= PMD_SIZE &&
+			 mmu_psize_defs[MMU_PAGE_2M].shift)
+			mapping_size = PMD_SIZE;
+		else
+			mapping_size = PAGE_SIZE;
+
+		if (split_text_mapping && (mapping_size == PUD_SIZE) &&
+			(addr <= __pa_symbol(__init_begin)) &&
+			(addr + mapping_size) >= __pa_symbol(_stext)) {
+			max_mapping_size = PMD_SIZE;
+			goto retry;
+		}
+
+		if (split_text_mapping && (mapping_size == PMD_SIZE) &&
+		    (addr <= __pa_symbol(__init_begin)) &&
+		    (addr + mapping_size) >= __pa_symbol(_stext))
+			mapping_size = PAGE_SIZE;
+
+		if (mapping_size != previous_size) {
+			print_mapping(start, addr, previous_size);
+			start = addr;
+		}
+
+		vaddr = (unsigned long)__va(addr);
+
+		if (overlaps_kernel_text(vaddr, vaddr + mapping_size) ||
+		    overlaps_interrupt_vector_text(vaddr, vaddr + mapping_size))
+			prot = PAGE_KERNEL_X;
+		else
+			prot = PAGE_KERNEL;
+
+		rc = radix__map_kernel_page(vaddr, addr, prot, mapping_size);
+		if (rc)
+			return rc;
+	}
+
+	print_mapping(start, addr, mapping_size);
+	return 0;
+}
+
+static void __init radix_init_pgtable(void)
+{
+	unsigned long rts_field;
+	struct memblock_region *reg;
+
+	/* We don't support slb for radix */
+	mmu_slb_size = 0;
+	/*
+	 * Create the linear mapping, using standard page size for now
+	 */
+	for_each_memblock(memory, reg)
+		WARN_ON(create_physical_mapping(reg->base,
+						reg->base + reg->size));
+
+	/* Find out how many PID bits are supported */
+	if (cpu_has_feature(CPU_FTR_HVMODE)) {
+		if (!mmu_pid_bits)
+			mmu_pid_bits = 20;
+#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+		/*
+		 * When KVM is possible, we only use the top half of the
+		 * PID space to avoid collisions between host and guest PIDs
+		 * which can cause problems due to prefetch when exiting the
+		 * guest with AIL=3
+		 */
+		mmu_base_pid = 1 << (mmu_pid_bits - 1);
+#else
+		mmu_base_pid = 1;
+#endif
+	} else {
+		/* The guest uses the bottom half of the PID space */
+		if (!mmu_pid_bits)
+			mmu_pid_bits = 19;
+		mmu_base_pid = 1;
+	}
+
+	/*
+	 * Allocate Partition table and process table for the
+	 * host.
+	 */
+	BUG_ON(PRTB_SIZE_SHIFT > 36);
+	process_tb = early_alloc_pgtable(1UL << PRTB_SIZE_SHIFT);
+	/*
+	 * Fill in the process table.
+	 */
+	rts_field = radix__get_tree_size();
+	process_tb->prtb0 = cpu_to_be64(rts_field | __pa(init_mm.pgd) | RADIX_PGD_INDEX_SIZE);
+	/*
+	 * Fill in the partition table. We are suppose to use effective address
+	 * of process table here. But our linear mapping also enable us to use
+	 * physical address here.
+	 */
+	register_process_table(__pa(process_tb), 0, PRTB_SIZE_SHIFT - 12);
+	pr_info("Process table %p and radix root for kernel: %p\n", process_tb, init_mm.pgd);
+	asm volatile("ptesync" : : : "memory");
+	asm volatile(PPC_TLBIE_5(%0,%1,2,1,1) : :
+		     "r" (TLBIEL_INVAL_SET_LPID), "r" (0));
+	asm volatile("eieio; tlbsync; ptesync" : : : "memory");
+	trace_tlbie(0, 0, TLBIEL_INVAL_SET_LPID, 0, 2, 1, 1);
+}
+
+static void __init radix_init_partition_table(void)
+{
+	unsigned long rts_field, dw0;
+
+	mmu_partition_table_init();
+	rts_field = radix__get_tree_size();
+	dw0 = rts_field | __pa(init_mm.pgd) | RADIX_PGD_INDEX_SIZE | PATB_HR;
+	mmu_partition_table_set_entry(0, dw0, 0);
+
+	pr_info("Initializing Radix MMU\n");
+	pr_info("Partition table %p\n", partition_tb);
+}
+
+void __init radix_init_native(void)
+{
+	register_process_table = native_register_process_table;
+}
+
+static int __init get_idx_from_shift(unsigned int shift)
+{
+	int idx = -1;
+
+	switch (shift) {
+	case 0xc:
+		idx = MMU_PAGE_4K;
+		break;
+	case 0x10:
+		idx = MMU_PAGE_64K;
+		break;
+	case 0x15:
+		idx = MMU_PAGE_2M;
+		break;
+	case 0x1e:
+		idx = MMU_PAGE_1G;
+		break;
+	}
+	return idx;
+}
+
+static int __init radix_dt_scan_page_sizes(unsigned long node,
+					   const char *uname, int depth,
+					   void *data)
+{
+	int size = 0;
+	int shift, idx;
+	unsigned int ap;
+	const __be32 *prop;
+	const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
+
+	/* We are scanning "cpu" nodes only */
+	if (type == NULL || strcmp(type, "cpu") != 0)
+		return 0;
+
+	/* Find MMU PID size */
+	prop = of_get_flat_dt_prop(node, "ibm,mmu-pid-bits", &size);
+	if (prop && size == 4)
+		mmu_pid_bits = be32_to_cpup(prop);
+
+	/* Grab page size encodings */
+	prop = of_get_flat_dt_prop(node, "ibm,processor-radix-AP-encodings", &size);
+	if (!prop)
+		return 0;
+
+	pr_info("Page sizes from device-tree:\n");
+	for (; size >= 4; size -= 4, ++prop) {
+
+		struct mmu_psize_def *def;
+
+		/* top 3 bit is AP encoding */
+		shift = be32_to_cpu(prop[0]) & ~(0xe << 28);
+		ap = be32_to_cpu(prop[0]) >> 29;
+		pr_info("Page size shift = %d AP=0x%x\n", shift, ap);
+
+		idx = get_idx_from_shift(shift);
+		if (idx < 0)
+			continue;
+
+		def = &mmu_psize_defs[idx];
+		def->shift = shift;
+		def->ap  = ap;
+	}
+
+	/* needed ? */
+	cur_cpu_spec->mmu_features &= ~MMU_FTR_NO_SLBIE_B;
+	return 1;
+}
+
+void __init radix__early_init_devtree(void)
+{
+	int rc;
+
+	/*
+	 * Try to find the available page sizes in the device-tree
+	 */
+	rc = of_scan_flat_dt(radix_dt_scan_page_sizes, NULL);
+	if (rc != 0)  /* Found */
+		goto found;
+	/*
+	 * let's assume we have page 4k and 64k support
+	 */
+	mmu_psize_defs[MMU_PAGE_4K].shift = 12;
+	mmu_psize_defs[MMU_PAGE_4K].ap = 0x0;
+
+	mmu_psize_defs[MMU_PAGE_64K].shift = 16;
+	mmu_psize_defs[MMU_PAGE_64K].ap = 0x5;
+found:
+	return;
+}
+
+static void update_hid_for_radix(void)
+{
+	unsigned long hid0;
+	unsigned long rb = 3UL << PPC_BITLSHIFT(53); /* IS = 3 */
+
+	asm volatile("ptesync": : :"memory");
+	/* prs = 0, ric = 2, rs = 0, r = 1 is = 3 */
+	asm volatile(PPC_TLBIE_5(%0, %4, %3, %2, %1)
+		     : : "r"(rb), "i"(1), "i"(0), "i"(2), "r"(0) : "memory");
+	/* prs = 1, ric = 2, rs = 0, r = 1 is = 3 */
+	asm volatile(PPC_TLBIE_5(%0, %4, %3, %2, %1)
+		     : : "r"(rb), "i"(1), "i"(1), "i"(2), "r"(0) : "memory");
+	asm volatile("eieio; tlbsync; ptesync; isync; slbia": : :"memory");
+	trace_tlbie(0, 0, rb, 0, 2, 0, 1);
+	trace_tlbie(0, 0, rb, 0, 2, 1, 1);
+
+	/*
+	 * now switch the HID
+	 */
+	hid0  = mfspr(SPRN_HID0);
+	hid0 |= HID0_POWER9_RADIX;
+	mtspr(SPRN_HID0, hid0);
+	asm volatile("isync": : :"memory");
+
+	/* Wait for it to happen */
+	while (!(mfspr(SPRN_HID0) & HID0_POWER9_RADIX))
+		cpu_relax();
+}
+
+static void radix_init_amor(void)
+{
+	/*
+	* In HV mode, we init AMOR (Authority Mask Override Register) so that
+	* the hypervisor and guest can setup IAMR (Instruction Authority Mask
+	* Register), enable key 0 and set it to 1.
+	*
+	* AMOR = 0b1100 .... 0000 (Mask for key 0 is 11)
+	*/
+	mtspr(SPRN_AMOR, (3ul << 62));
+}
+
+static void radix_init_iamr(void)
+{
+	unsigned long iamr;
+
+	/*
+	 * The IAMR should set to 0 on DD1.
+	 */
+	if (cpu_has_feature(CPU_FTR_POWER9_DD1))
+		iamr = 0;
+	else
+		iamr = (1ul << 62);
+
+	/*
+	 * Radix always uses key0 of the IAMR to determine if an access is
+	 * allowed. We set bit 0 (IBM bit 1) of key0, to prevent instruction
+	 * fetch.
+	 */
+	mtspr(SPRN_IAMR, iamr);
+}
+
+void __init radix__early_init_mmu(void)
+{
+	unsigned long lpcr;
+
+#ifdef CONFIG_PPC_64K_PAGES
+	/* PAGE_SIZE mappings */
+	mmu_virtual_psize = MMU_PAGE_64K;
+#else
+	mmu_virtual_psize = MMU_PAGE_4K;
+#endif
+
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+	/* vmemmap mapping */
+	if (mmu_psize_defs[MMU_PAGE_2M].shift) {
+		/*
+		 * map vmemmap using 2M if available
+		 */
+		mmu_vmemmap_psize = MMU_PAGE_2M;
+	} else
+		mmu_vmemmap_psize = mmu_virtual_psize;
+#endif
+	/*
+	 * initialize page table size
+	 */
+	__pte_index_size = RADIX_PTE_INDEX_SIZE;
+	__pmd_index_size = RADIX_PMD_INDEX_SIZE;
+	__pud_index_size = RADIX_PUD_INDEX_SIZE;
+	__pgd_index_size = RADIX_PGD_INDEX_SIZE;
+	__pmd_cache_index = RADIX_PMD_INDEX_SIZE;
+	__pte_table_size = RADIX_PTE_TABLE_SIZE;
+	__pmd_table_size = RADIX_PMD_TABLE_SIZE;
+	__pud_table_size = RADIX_PUD_TABLE_SIZE;
+	__pgd_table_size = RADIX_PGD_TABLE_SIZE;
+
+	__pmd_val_bits = RADIX_PMD_VAL_BITS;
+	__pud_val_bits = RADIX_PUD_VAL_BITS;
+	__pgd_val_bits = RADIX_PGD_VAL_BITS;
+
+	__kernel_virt_start = RADIX_KERN_VIRT_START;
+	__kernel_virt_size = RADIX_KERN_VIRT_SIZE;
+	__vmalloc_start = RADIX_VMALLOC_START;
+	__vmalloc_end = RADIX_VMALLOC_END;
+	__kernel_io_start = RADIX_KERN_IO_START;
+	vmemmap = (struct page *)RADIX_VMEMMAP_BASE;
+	ioremap_bot = IOREMAP_BASE;
+
+#ifdef CONFIG_PCI
+	pci_io_base = ISA_IO_BASE;
+#endif
+
+	/*
+	 * For now radix also use the same frag size
+	 */
+	__pte_frag_nr = H_PTE_FRAG_NR;
+	__pte_frag_size_shift = H_PTE_FRAG_SIZE_SHIFT;
+
+	if (!firmware_has_feature(FW_FEATURE_LPAR)) {
+		radix_init_native();
+		if (cpu_has_feature(CPU_FTR_POWER9_DD1))
+			update_hid_for_radix();
+		lpcr = mfspr(SPRN_LPCR);
+		mtspr(SPRN_LPCR, lpcr | LPCR_UPRT | LPCR_HR);
+		radix_init_partition_table();
+		radix_init_amor();
+	} else {
+		radix_init_pseries();
+	}
+
+	memblock_set_current_limit(MEMBLOCK_ALLOC_ANYWHERE);
+
+	radix_init_iamr();
+	radix_init_pgtable();
+}
+
+void radix__early_init_mmu_secondary(void)
+{
+	unsigned long lpcr;
+	/*
+	 * update partition table control register and UPRT
+	 */
+	if (!firmware_has_feature(FW_FEATURE_LPAR)) {
+
+		if (cpu_has_feature(CPU_FTR_POWER9_DD1))
+			update_hid_for_radix();
+
+		lpcr = mfspr(SPRN_LPCR);
+		mtspr(SPRN_LPCR, lpcr | LPCR_UPRT | LPCR_HR);
+
+		mtspr(SPRN_PTCR,
+		      __pa(partition_tb) | (PATB_SIZE_SHIFT - 12));
+		radix_init_amor();
+	}
+	radix_init_iamr();
+}
+
+void radix__mmu_cleanup_all(void)
+{
+	unsigned long lpcr;
+
+	if (!firmware_has_feature(FW_FEATURE_LPAR)) {
+		lpcr = mfspr(SPRN_LPCR);
+		mtspr(SPRN_LPCR, lpcr & ~LPCR_UPRT);
+		mtspr(SPRN_PTCR, 0);
+		powernv_set_nmmu_ptcr(0);
+		radix__flush_tlb_all();
+	}
+}
+
+void radix__setup_initial_memory_limit(phys_addr_t first_memblock_base,
+				phys_addr_t first_memblock_size)
+{
+	/* We don't currently support the first MEMBLOCK not mapping 0
+	 * physical on those processors
+	 */
+	BUG_ON(first_memblock_base != 0);
+	/*
+	 * We limit the allocation that depend on ppc64_rma_size
+	 * to first_memblock_size. We also clamp it to 1GB to
+	 * avoid some funky things such as RTAS bugs.
+	 *
+	 * On radix config we really don't have a limitation
+	 * on real mode access. But keeping it as above works
+	 * well enough.
+	 */
+	ppc64_rma_size = min_t(u64, first_memblock_size, 0x40000000);
+	/*
+	 * Finally limit subsequent allocations. We really don't want
+	 * to limit the memblock allocations to rma_size. FIXME!! should
+	 * we even limit at all ?
+	 */
+	memblock_set_current_limit(first_memblock_base + first_memblock_size);
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+static void free_pte_table(pte_t *pte_start, pmd_t *pmd)
+{
+	pte_t *pte;
+	int i;
+
+	for (i = 0; i < PTRS_PER_PTE; i++) {
+		pte = pte_start + i;
+		if (!pte_none(*pte))
+			return;
+	}
+
+	pte_free_kernel(&init_mm, pte_start);
+	pmd_clear(pmd);
+}
+
+static void free_pmd_table(pmd_t *pmd_start, pud_t *pud)
+{
+	pmd_t *pmd;
+	int i;
+
+	for (i = 0; i < PTRS_PER_PMD; i++) {
+		pmd = pmd_start + i;
+		if (!pmd_none(*pmd))
+			return;
+	}
+
+	pmd_free(&init_mm, pmd_start);
+	pud_clear(pud);
+}
+
+struct change_mapping_params {
+	pte_t *pte;
+	unsigned long start;
+	unsigned long end;
+	unsigned long aligned_start;
+	unsigned long aligned_end;
+};
+
+static int stop_machine_change_mapping(void *data)
+{
+	struct change_mapping_params *params =
+			(struct change_mapping_params *)data;
+
+	if (!data)
+		return -1;
+
+	spin_unlock(&init_mm.page_table_lock);
+	pte_clear(&init_mm, params->aligned_start, params->pte);
+	create_physical_mapping(params->aligned_start, params->start);
+	create_physical_mapping(params->end, params->aligned_end);
+	spin_lock(&init_mm.page_table_lock);
+	return 0;
+}
+
+static void remove_pte_table(pte_t *pte_start, unsigned long addr,
+			     unsigned long end)
+{
+	unsigned long next;
+	pte_t *pte;
+
+	pte = pte_start + pte_index(addr);
+	for (; addr < end; addr = next, pte++) {
+		next = (addr + PAGE_SIZE) & PAGE_MASK;
+		if (next > end)
+			next = end;
+
+		if (!pte_present(*pte))
+			continue;
+
+		if (!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(next)) {
+			/*
+			 * The vmemmap_free() and remove_section_mapping()
+			 * codepaths call us with aligned addresses.
+			 */
+			WARN_ONCE(1, "%s: unaligned range\n", __func__);
+			continue;
+		}
+
+		pte_clear(&init_mm, addr, pte);
+	}
+}
+
+/*
+ * clear the pte and potentially split the mapping helper
+ */
+static void split_kernel_mapping(unsigned long addr, unsigned long end,
+				unsigned long size, pte_t *pte)
+{
+	unsigned long mask = ~(size - 1);
+	unsigned long aligned_start = addr & mask;
+	unsigned long aligned_end = addr + size;
+	struct change_mapping_params params;
+	bool split_region = false;
+
+	if ((end - addr) < size) {
+		/*
+		 * We're going to clear the PTE, but not flushed
+		 * the mapping, time to remap and flush. The
+		 * effects if visible outside the processor or
+		 * if we are running in code close to the
+		 * mapping we cleared, we are in trouble.
+		 */
+		if (overlaps_kernel_text(aligned_start, addr) ||
+			overlaps_kernel_text(end, aligned_end)) {
+			/*
+			 * Hack, just return, don't pte_clear
+			 */
+			WARN_ONCE(1, "Linear mapping %lx->%lx overlaps kernel "
+				  "text, not splitting\n", addr, end);
+			return;
+		}
+		split_region = true;
+	}
+
+	if (split_region) {
+		params.pte = pte;
+		params.start = addr;
+		params.end = end;
+		params.aligned_start = addr & ~(size - 1);
+		params.aligned_end = min_t(unsigned long, aligned_end,
+				(unsigned long)__va(memblock_end_of_DRAM()));
+		stop_machine(stop_machine_change_mapping, &params, NULL);
+		return;
+	}
+
+	pte_clear(&init_mm, addr, pte);
+}
+
+static void remove_pmd_table(pmd_t *pmd_start, unsigned long addr,
+			     unsigned long end)
+{
+	unsigned long next;
+	pte_t *pte_base;
+	pmd_t *pmd;
+
+	pmd = pmd_start + pmd_index(addr);
+	for (; addr < end; addr = next, pmd++) {
+		next = pmd_addr_end(addr, end);
+
+		if (!pmd_present(*pmd))
+			continue;
+
+		if (pmd_huge(*pmd)) {
+			split_kernel_mapping(addr, end, PMD_SIZE, (pte_t *)pmd);
+			continue;
+		}
+
+		pte_base = (pte_t *)pmd_page_vaddr(*pmd);
+		remove_pte_table(pte_base, addr, next);
+		free_pte_table(pte_base, pmd);
+	}
+}
+
+static void remove_pud_table(pud_t *pud_start, unsigned long addr,
+			     unsigned long end)
+{
+	unsigned long next;
+	pmd_t *pmd_base;
+	pud_t *pud;
+
+	pud = pud_start + pud_index(addr);
+	for (; addr < end; addr = next, pud++) {
+		next = pud_addr_end(addr, end);
+
+		if (!pud_present(*pud))
+			continue;
+
+		if (pud_huge(*pud)) {
+			split_kernel_mapping(addr, end, PUD_SIZE, (pte_t *)pud);
+			continue;
+		}
+
+		pmd_base = (pmd_t *)pud_page_vaddr(*pud);
+		remove_pmd_table(pmd_base, addr, next);
+		free_pmd_table(pmd_base, pud);
+	}
+}
+
+static void remove_pagetable(unsigned long start, unsigned long end)
+{
+	unsigned long addr, next;
+	pud_t *pud_base;
+	pgd_t *pgd;
+
+	spin_lock(&init_mm.page_table_lock);
+
+	for (addr = start; addr < end; addr = next) {
+		next = pgd_addr_end(addr, end);
+
+		pgd = pgd_offset_k(addr);
+		if (!pgd_present(*pgd))
+			continue;
+
+		if (pgd_huge(*pgd)) {
+			split_kernel_mapping(addr, end, PGDIR_SIZE, (pte_t *)pgd);
+			continue;
+		}
+
+		pud_base = (pud_t *)pgd_page_vaddr(*pgd);
+		remove_pud_table(pud_base, addr, next);
+	}
+
+	spin_unlock(&init_mm.page_table_lock);
+	radix__flush_tlb_kernel_range(start, end);
+}
+
+int __ref radix__create_section_mapping(unsigned long start, unsigned long end)
+{
+	return create_physical_mapping(start, end);
+}
+
+int radix__remove_section_mapping(unsigned long start, unsigned long end)
+{
+	remove_pagetable(start, end);
+	return 0;
+}
+#endif /* CONFIG_MEMORY_HOTPLUG */
+
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+int __meminit radix__vmemmap_create_mapping(unsigned long start,
+				      unsigned long page_size,
+				      unsigned long phys)
+{
+	/* Create a PTE encoding */
+	unsigned long flags = _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_KERNEL_RW;
+
+	BUG_ON(radix__map_kernel_page(start, phys, __pgprot(flags), page_size));
+	return 0;
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+void radix__vmemmap_remove_mapping(unsigned long start, unsigned long page_size)
+{
+	remove_pagetable(start, start + page_size);
+}
+#endif
+#endif
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+
+unsigned long radix__pmd_hugepage_update(struct mm_struct *mm, unsigned long addr,
+				  pmd_t *pmdp, unsigned long clr,
+				  unsigned long set)
+{
+	unsigned long old;
+
+#ifdef CONFIG_DEBUG_VM
+	WARN_ON(!radix__pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp));
+	assert_spin_locked(&mm->page_table_lock);
+#endif
+
+	old = radix__pte_update(mm, addr, (pte_t *)pmdp, clr, set, 1);
+	trace_hugepage_update(addr, old, clr, set);
+
+	return old;
+}
+
+pmd_t radix__pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
+			pmd_t *pmdp)
+
+{
+	pmd_t pmd;
+
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+	VM_BUG_ON(radix__pmd_trans_huge(*pmdp));
+	VM_BUG_ON(pmd_devmap(*pmdp));
+	/*
+	 * khugepaged calls this for normal pmd
+	 */
+	pmd = *pmdp;
+	pmd_clear(pmdp);
+
+	/*FIXME!!  Verify whether we need this kick below */
+	serialize_against_pte_lookup(vma->vm_mm);
+
+	radix__flush_tlb_collapsed_pmd(vma->vm_mm, address);
+
+	return pmd;
+}
+
+/*
+ * For us pgtable_t is pte_t *. Inorder to save the deposisted
+ * page table, we consider the allocated page table as a list
+ * head. On withdraw we need to make sure we zero out the used
+ * list_head memory area.
+ */
+void radix__pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
+				 pgtable_t pgtable)
+{
+        struct list_head *lh = (struct list_head *) pgtable;
+
+        assert_spin_locked(pmd_lockptr(mm, pmdp));
+
+        /* FIFO */
+        if (!pmd_huge_pte(mm, pmdp))
+                INIT_LIST_HEAD(lh);
+        else
+                list_add(lh, (struct list_head *) pmd_huge_pte(mm, pmdp));
+        pmd_huge_pte(mm, pmdp) = pgtable;
+}
+
+pgtable_t radix__pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
+{
+        pte_t *ptep;
+        pgtable_t pgtable;
+        struct list_head *lh;
+
+        assert_spin_locked(pmd_lockptr(mm, pmdp));
+
+        /* FIFO */
+        pgtable = pmd_huge_pte(mm, pmdp);
+        lh = (struct list_head *) pgtable;
+        if (list_empty(lh))
+                pmd_huge_pte(mm, pmdp) = NULL;
+        else {
+                pmd_huge_pte(mm, pmdp) = (pgtable_t) lh->next;
+                list_del(lh);
+        }
+        ptep = (pte_t *) pgtable;
+        *ptep = __pte(0);
+        ptep++;
+        *ptep = __pte(0);
+        return pgtable;
+}
+
+
+pmd_t radix__pmdp_huge_get_and_clear(struct mm_struct *mm,
+			       unsigned long addr, pmd_t *pmdp)
+{
+	pmd_t old_pmd;
+	unsigned long old;
+
+	old = radix__pmd_hugepage_update(mm, addr, pmdp, ~0UL, 0);
+	old_pmd = __pmd(old);
+	/*
+	 * Serialize against find_current_mm_pte which does lock-less
+	 * lookup in page tables with local interrupts disabled. For huge pages
+	 * it casts pmd_t to pte_t. Since format of pte_t is different from
+	 * pmd_t we want to prevent transit from pmd pointing to page table
+	 * to pmd pointing to huge page (and back) while interrupts are disabled.
+	 * We clear pmd to possibly replace it with page table pointer in
+	 * different code paths. So make sure we wait for the parallel
+	 * find_current_mm_pte to finish.
+	 */
+	serialize_against_pte_lookup(mm);
+	return old_pmd;
+}
+
+int radix__has_transparent_hugepage(void)
+{
+	/* For radix 2M at PMD level means thp */
+	if (mmu_psize_defs[MMU_PAGE_2M].shift == PMD_SHIFT)
+		return 1;
+	return 0;
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */