arch/arm/mm/init.c - kernel/msm-4.19 - Gitiles

 /*
  *  linux/arch/arm/mm/init.c
  *
  *  Copyright (C) 1995-2005 Russell King
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/swap.h>
 #include <linux/init.h>
 #include <linux/bootmem.h>
 #include <linux/mman.h>
 #include <linux/sched/signal.h>
 #include <linux/sched/task.h>
 #include <linux/export.h>
 #include <linux/nodemask.h>
 #include <linux/initrd.h>
 #include <linux/of_fdt.h>
 #include <linux/highmem.h>
 #include <linux/gfp.h>
 #include <linux/memblock.h>
 #include <linux/dma-contiguous.h>
 #include <linux/sizes.h>
 #include <linux/stop_machine.h>

 #include <asm/cp15.h>
 #include <asm/mach-types.h>
 #include <asm/memblock.h>
 #include <asm/memory.h>
 #include <asm/prom.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
 #include <asm/system_info.h>
 #include <asm/tlb.h>
 #include <asm/fixmap.h>

 #include <asm/mach/arch.h>
 #include <asm/mach/map.h>

 #include "mm.h"

 #ifdef CONFIG_CPU_CP15_MMU
 unsigned long __init __clear_cr(unsigned long mask)
 {
 	cr_alignment = cr_alignment & ~mask;
 	return cr_alignment;
 }
 #endif

 static phys_addr_t phys_initrd_start __initdata = 0;
 static unsigned long phys_initrd_size __initdata = 0;

 static int __init early_initrd(char *p)
 {
 	phys_addr_t start;
 	unsigned long size;
 	char *endp;

 	start = memparse(p, &endp);
 	if (*endp == ',') {
 		size = memparse(endp + 1, NULL);

 		phys_initrd_start = start;
 		phys_initrd_size = size;
 	}
 	return 0;
 }
 early_param("initrd", early_initrd);

 static int __init parse_tag_initrd(const struct tag *tag)
 {
 	pr_warn("ATAG_INITRD is deprecated; "
 		"please update your bootloader.\n");
 	phys_initrd_start = __virt_to_phys(tag->u.initrd.start);
 	phys_initrd_size = tag->u.initrd.size;
 	return 0;
 }

 __tagtable(ATAG_INITRD, parse_tag_initrd);

 static int __init parse_tag_initrd2(const struct tag *tag)
 {
 	phys_initrd_start = tag->u.initrd.start;
 	phys_initrd_size = tag->u.initrd.size;
 	return 0;
 }

 __tagtable(ATAG_INITRD2, parse_tag_initrd2);

 static void __init find_limits(unsigned long *min, unsigned long *max_low,
 			       unsigned long *max_high)
 {
 	*max_low = PFN_DOWN(memblock_get_current_limit());
 	*min = PFN_UP(memblock_start_of_DRAM());
 	*max_high = PFN_DOWN(memblock_end_of_DRAM());
 }

 #ifdef CONFIG_ZONE_DMA

 phys_addr_t arm_dma_zone_size __read_mostly;
 EXPORT_SYMBOL(arm_dma_zone_size);

 /*
  * The DMA mask corresponding to the maximum bus address allocatable
  * using GFP_DMA.  The default here places no restriction on DMA
  * allocations.  This must be the smallest DMA mask in the system,
  * so a successful GFP_DMA allocation will always satisfy this.
  */
 phys_addr_t arm_dma_limit;
 unsigned long arm_dma_pfn_limit;

 static void __init arm_adjust_dma_zone(unsigned long *size, unsigned long *hole,
 	unsigned long dma_size)
 {
 	if (size[0] <= dma_size)
 		return;

 	size[ZONE_NORMAL] = size[0] - dma_size;
 	size[ZONE_DMA] = dma_size;
 	hole[ZONE_NORMAL] = hole[0];
 	hole[ZONE_DMA] = 0;
 }
 #endif

 void __init setup_dma_zone(const struct machine_desc *mdesc)
 {
 #ifdef CONFIG_ZONE_DMA
 	if (mdesc->dma_zone_size) {
 		arm_dma_zone_size = mdesc->dma_zone_size;
 		arm_dma_limit = PHYS_OFFSET + arm_dma_zone_size - 1;
 	} else
 		arm_dma_limit = 0xffffffff;
 	arm_dma_pfn_limit = arm_dma_limit >> PAGE_SHIFT;
 #endif
 }

 static void __init zone_sizes_init(unsigned long min, unsigned long max_low,
 	unsigned long max_high)
 {
 	unsigned long zone_size[MAX_NR_ZONES], zhole_size[MAX_NR_ZONES];
 	struct memblock_region *reg;

 	/*
 	 * initialise the zones.
 	 */
 	memset(zone_size, 0, sizeof(zone_size));

 	/*
 	 * The memory size has already been determined.  If we need
 	 * to do anything fancy with the allocation of this memory
 	 * to the zones, now is the time to do it.
 	 */
 	zone_size[0] = max_low - min;
 #ifdef CONFIG_HIGHMEM
 	zone_size[ZONE_HIGHMEM] = max_high - max_low;
 #endif

 	/*
 	 * Calculate the size of the holes.
 	 *  holes = node_size - sum(bank_sizes)
 	 */
 	memcpy(zhole_size, zone_size, sizeof(zhole_size));
 	for_each_memblock(memory, reg) {
 		unsigned long start = memblock_region_memory_base_pfn(reg);
 		unsigned long end = memblock_region_memory_end_pfn(reg);

 		if (start < max_low) {
 			unsigned long low_end = min(end, max_low);
 			zhole_size[0] -= low_end - start;
 		}
 #ifdef CONFIG_HIGHMEM
 		if (end > max_low) {
 			unsigned long high_start = max(start, max_low);
 			zhole_size[ZONE_HIGHMEM] -= end - high_start;
 		}
 #endif
 	}

 #ifdef CONFIG_ZONE_DMA
 	/*
 	 * Adjust the sizes according to any special requirements for
 	 * this machine type.
 	 */
 	if (arm_dma_zone_size)
 		arm_adjust_dma_zone(zone_size, zhole_size,
 			arm_dma_zone_size >> PAGE_SHIFT);
 #endif

 	free_area_init_node(0, zone_size, min, zhole_size);
 }

 #ifdef CONFIG_HAVE_ARCH_PFN_VALID
 int pfn_valid(unsigned long pfn)
 {
 	return memblock_is_map_memory(__pfn_to_phys(pfn));
 }
 EXPORT_SYMBOL(pfn_valid);
 #endif

 #ifndef CONFIG_SPARSEMEM
 static void __init arm_memory_present(void)
 {
 }
 #else
 static void __init arm_memory_present(void)
 {
 	struct memblock_region *reg;

 	for_each_memblock(memory, reg)
 		memory_present(0, memblock_region_memory_base_pfn(reg),
 			       memblock_region_memory_end_pfn(reg));
 }
 #endif

 static bool arm_memblock_steal_permitted = true;

 phys_addr_t __init arm_memblock_steal(phys_addr_t size, phys_addr_t align)
 {
 	phys_addr_t phys;

 	BUG_ON(!arm_memblock_steal_permitted);

 	phys = memblock_alloc_base(size, align, MEMBLOCK_ALLOC_ANYWHERE);
 	memblock_free(phys, size);
 	memblock_remove(phys, size);

 	return phys;
 }

 static void __init arm_initrd_init(void)
 {
 #ifdef CONFIG_BLK_DEV_INITRD
 	phys_addr_t start;
 	unsigned long size;

 	/* FDT scan will populate initrd_start */
 	if (initrd_start && !phys_initrd_size) {
 		phys_initrd_start = __virt_to_phys(initrd_start);
 		phys_initrd_size = initrd_end - initrd_start;
 	}

 	initrd_start = initrd_end = 0;

 	if (!phys_initrd_size)
 		return;

 	/*
 	 * Round the memory region to page boundaries as per free_initrd_mem()
 	 * This allows us to detect whether the pages overlapping the initrd
 	 * are in use, but more importantly, reserves the entire set of pages
 	 * as we don't want these pages allocated for other purposes.
 	 */
 	start = round_down(phys_initrd_start, PAGE_SIZE);
 	size = phys_initrd_size + (phys_initrd_start - start);
 	size = round_up(size, PAGE_SIZE);

 	if (!memblock_is_region_memory(start, size)) {
 		pr_err("INITRD: 0x%08llx+0x%08lx is not a memory region - disabling initrd\n",
 		       (u64)start, size);
 		return;
 	}

 	if (memblock_is_region_reserved(start, size)) {
 		pr_err("INITRD: 0x%08llx+0x%08lx overlaps in-use memory region - disabling initrd\n",
 		       (u64)start, size);
 		return;
 	}

 	memblock_reserve(start, size);

 	/* Now convert initrd to virtual addresses */
 	initrd_start = __phys_to_virt(phys_initrd_start);
 	initrd_end = initrd_start + phys_initrd_size;
 #endif
 }

 void __init arm_memblock_init(const struct machine_desc *mdesc)
 {
 	/* Register the kernel text, kernel data and initrd with memblock. */
 	memblock_reserve(__pa(KERNEL_START), KERNEL_END - KERNEL_START);

 	arm_initrd_init();

 	arm_mm_memblock_reserve();

 	/* reserve any platform specific memblock areas */
 	if (mdesc->reserve)
 		mdesc->reserve();

 	early_init_fdt_reserve_self();
 	early_init_fdt_scan_reserved_mem();

 	/* reserve memory for DMA contiguous allocations */
 	dma_contiguous_reserve(arm_dma_limit);

 	arm_memblock_steal_permitted = false;
 	memblock_dump_all();
 }

 void __init bootmem_init(void)
 {
 	unsigned long min, max_low, max_high;

 	memblock_allow_resize();
 	max_low = max_high = 0;

 	find_limits(&min, &max_low, &max_high);

 	early_memtest((phys_addr_t)min << PAGE_SHIFT,
 		      (phys_addr_t)max_low << PAGE_SHIFT);

 	/*
 	 * Sparsemem tries to allocate bootmem in memory_present(),
 	 * so must be done after the fixed reservations
 	 */
 	arm_memory_present();

 	/*
 	 * sparse_init() needs the bootmem allocator up and running.
 	 */
 	sparse_init();

 	/*
 	 * Now free the memory - free_area_init_node needs
 	 * the sparse mem_map arrays initialized by sparse_init()
 	 * for memmap_init_zone(), otherwise all PFNs are invalid.
 	 */
 	zone_sizes_init(min, max_low, max_high);

 	/*
 	 * This doesn't seem to be used by the Linux memory manager any
 	 * more, but is used by ll_rw_block.  If we can get rid of it, we
 	 * also get rid of some of the stuff above as well.
 	 */
 	min_low_pfn = min;
 	max_low_pfn = max_low;
 	max_pfn = max_high;
 }

 /*
  * Poison init memory with an undefined instruction (ARM) or a branch to an
  * undefined instruction (Thumb).
  */
 static inline void poison_init_mem(void *s, size_t count)
 {
 	u32 *p = (u32 *)s;
 	for (; count != 0; count -= 4)
 		*p++ = 0xe7fddef0;
 }

 static inline void
 free_memmap(unsigned long start_pfn, unsigned long end_pfn)
 {
 	struct page *start_pg, *end_pg;
 	phys_addr_t pg, pgend;

 	/*
 	 * Convert start_pfn/end_pfn to a struct page pointer.
 	 */
 	start_pg = pfn_to_page(start_pfn - 1) + 1;
 	end_pg = pfn_to_page(end_pfn - 1) + 1;

 	/*
 	 * Convert to physical addresses, and
 	 * round start upwards and end downwards.
 	 */
 	pg = PAGE_ALIGN(__pa(start_pg));
 	pgend = __pa(end_pg) & PAGE_MASK;

 	/*
 	 * If there are free pages between these,
 	 * free the section of the memmap array.
 	 */
 	if (pg < pgend)
 		memblock_free_early(pg, pgend - pg);
 }

 /*
  * The mem_map array can get very big.  Free the unused area of the memory map.
  */
 static void __init free_unused_memmap(void)
 {
 	unsigned long start, prev_end = 0;
 	struct memblock_region *reg;

 	/*
 	 * This relies on each bank being in address order.
 	 * The banks are sorted previously in bootmem_init().
 	 */
 	for_each_memblock(memory, reg) {
 		start = memblock_region_memory_base_pfn(reg);

 #ifdef CONFIG_SPARSEMEM
 		/*
 		 * Take care not to free memmap entries that don't exist
 		 * due to SPARSEMEM sections which aren't present.
 		 */
 		start = min(start,
 				 ALIGN(prev_end, PAGES_PER_SECTION));
 #else
 		/*
 		 * Align down here since the VM subsystem insists that the
 		 * memmap entries are valid from the bank start aligned to
 		 * MAX_ORDER_NR_PAGES.
 		 */
 		start = round_down(start, MAX_ORDER_NR_PAGES);
 #endif
 		/*
 		 * If we had a previous bank, and there is a space
 		 * between the current bank and the previous, free it.
 		 */
 		if (prev_end && prev_end < start)
 			free_memmap(prev_end, start);

 		/*
 		 * Align up here since the VM subsystem insists that the
 		 * memmap entries are valid from the bank end aligned to
 		 * MAX_ORDER_NR_PAGES.
 		 */
 		prev_end = ALIGN(memblock_region_memory_end_pfn(reg),
 				 MAX_ORDER_NR_PAGES);
 	}

 #ifdef CONFIG_SPARSEMEM
 	if (!IS_ALIGNED(prev_end, PAGES_PER_SECTION))
 		free_memmap(prev_end,
 			    ALIGN(prev_end, PAGES_PER_SECTION));
 #endif
 }

 #ifdef CONFIG_HIGHMEM
 static inline void free_area_high(unsigned long pfn, unsigned long end)
 {
 	for (; pfn < end; pfn++)
 		free_highmem_page(pfn_to_page(pfn));
 }
 #endif

 static void __init free_highpages(void)
 {
 #ifdef CONFIG_HIGHMEM
 	unsigned long max_low = max_low_pfn;
 	struct memblock_region *mem, *res;

 	/* set highmem page free */
 	for_each_memblock(memory, mem) {
 		unsigned long start = memblock_region_memory_base_pfn(mem);
 		unsigned long end = memblock_region_memory_end_pfn(mem);

 		/* Ignore complete lowmem entries */
 		if (end <= max_low)
 			continue;

 		if (memblock_is_nomap(mem))
 			continue;

 		/* Truncate partial highmem entries */
 		if (start < max_low)
 			start = max_low;

 		/* Find and exclude any reserved regions */
 		for_each_memblock(reserved, res) {
 			unsigned long res_start, res_end;

 			res_start = memblock_region_reserved_base_pfn(res);
 			res_end = memblock_region_reserved_end_pfn(res);

 			if (res_end < start)
 				continue;
 			if (res_start < start)
 				res_start = start;
 			if (res_start > end)
 				res_start = end;
 			if (res_end > end)
 				res_end = end;
 			if (res_start != start)
 				free_area_high(start, res_start);
 			start = res_end;
 			if (start == end)
 				break;
 		}

 		/* And now free anything which remains */
 		if (start < end)
 			free_area_high(start, end);
 	}
 #endif
 }

 /*
  * mem_init() marks the free areas in the mem_map and tells us how much
  * memory is free.  This is done after various parts of the system have
  * claimed their memory after the kernel image.
  */
 void __init mem_init(void)
 {
 #ifdef CONFIG_HAVE_TCM
 	/* These pointers are filled in on TCM detection */
 	extern u32 dtcm_end;
 	extern u32 itcm_end;
 #endif

 	set_max_mapnr(pfn_to_page(max_pfn) - mem_map);

 	/* this will put all unused low memory onto the freelists */
 	free_unused_memmap();
 	free_all_bootmem();

 #ifdef CONFIG_SA1111
 	/* now that our DMA memory is actually so designated, we can free it */
 	free_reserved_area(__va(PHYS_OFFSET), swapper_pg_dir, -1, NULL);
 #endif

 	free_highpages();

 	mem_init_print_info(NULL);

 #define MLK(b, t) b, t, ((t) - (b)) >> 10
 #define MLM(b, t) b, t, ((t) - (b)) >> 20
 #define MLK_ROUNDUP(b, t) b, t, DIV_ROUND_UP(((t) - (b)), SZ_1K)

 	pr_notice("Virtual kernel memory layout:\n"
 			"    vector  : 0x%08lx - 0x%08lx   (%4ld kB)\n"
 #ifdef CONFIG_HAVE_TCM
 			"    DTCM    : 0x%08lx - 0x%08lx   (%4ld kB)\n"
 			"    ITCM    : 0x%08lx - 0x%08lx   (%4ld kB)\n"
 #endif
 			"    fixmap  : 0x%08lx - 0x%08lx   (%4ld kB)\n"
 			"    vmalloc : 0x%08lx - 0x%08lx   (%4ld MB)\n"
 			"    lowmem  : 0x%08lx - 0x%08lx   (%4ld MB)\n"
 #ifdef CONFIG_HIGHMEM
 			"    pkmap   : 0x%08lx - 0x%08lx   (%4ld MB)\n"
 #endif
 #ifdef CONFIG_MODULES
 			"    modules : 0x%08lx - 0x%08lx   (%4ld MB)\n"
 #endif
 			"      .text : 0x%p" " - 0x%p" "   (%4td kB)\n"
 			"      .init : 0x%p" " - 0x%p" "   (%4td kB)\n"
 			"      .data : 0x%p" " - 0x%p" "   (%4td kB)\n"
 			"       .bss : 0x%p" " - 0x%p" "   (%4td kB)\n",

 			MLK(VECTORS_BASE, VECTORS_BASE + PAGE_SIZE),
 #ifdef CONFIG_HAVE_TCM
 			MLK(DTCM_OFFSET, (unsigned long) dtcm_end),
 			MLK(ITCM_OFFSET, (unsigned long) itcm_end),
 #endif
 			MLK(FIXADDR_START, FIXADDR_END),
 			MLM(VMALLOC_START, VMALLOC_END),
 			MLM(PAGE_OFFSET, (unsigned long)high_memory),
 #ifdef CONFIG_HIGHMEM
 			MLM(PKMAP_BASE, (PKMAP_BASE) + (LAST_PKMAP) *
 				(PAGE_SIZE)),
 #endif
 #ifdef CONFIG_MODULES
 			MLM(MODULES_VADDR, MODULES_END),
 #endif

 			MLK_ROUNDUP(_text, _etext),
 			MLK_ROUNDUP(__init_begin, __init_end),
 			MLK_ROUNDUP(_sdata, _edata),
 			MLK_ROUNDUP(__bss_start, __bss_stop));

 #undef MLK
 #undef MLM
 #undef MLK_ROUNDUP

 	/*
 	 * Check boundaries twice: Some fundamental inconsistencies can
 	 * be detected at build time already.
 	 */
 #ifdef CONFIG_MMU
 	BUILD_BUG_ON(TASK_SIZE				> MODULES_VADDR);
 	BUG_ON(TASK_SIZE 				> MODULES_VADDR);
 #endif

 #ifdef CONFIG_HIGHMEM
 	BUILD_BUG_ON(PKMAP_BASE + LAST_PKMAP * PAGE_SIZE > PAGE_OFFSET);
 	BUG_ON(PKMAP_BASE + LAST_PKMAP * PAGE_SIZE	> PAGE_OFFSET);
 #endif

 	if (PAGE_SIZE >= 16384 && get_num_physpages() <= 128) {
 		extern int sysctl_overcommit_memory;
 		/*
 		 * On a machine this small we won't get
 		 * anywhere without overcommit, so turn
 		 * it on by default.
 		 */
 		sysctl_overcommit_memory = OVERCOMMIT_ALWAYS;
 	}
 }

 #ifdef CONFIG_STRICT_KERNEL_RWX
 struct section_perm {
 	const char *name;
 	unsigned long start;
 	unsigned long end;
 	pmdval_t mask;
 	pmdval_t prot;
 	pmdval_t clear;
 };

 /* First section-aligned location at or after __start_rodata. */
 extern char __start_rodata_section_aligned[];

 static struct section_perm nx_perms[] = {
 	/* Make pages tables, etc before _stext RW (set NX). */
 	{
 		.name	= "pre-text NX",
 		.start	= PAGE_OFFSET,
 		.end	= (unsigned long)_stext,
 		.mask	= ~PMD_SECT_XN,
 		.prot	= PMD_SECT_XN,
 	},
 	/* Make init RW (set NX). */
 	{
 		.name	= "init NX",
 		.start	= (unsigned long)__init_begin,
 		.end	= (unsigned long)_sdata,
 		.mask	= ~PMD_SECT_XN,
 		.prot	= PMD_SECT_XN,
 	},
 	/* Make rodata NX (set RO in ro_perms below). */
 	{
 		.name	= "rodata NX",
 		.start  = (unsigned long)__start_rodata_section_aligned,
 		.end    = (unsigned long)__init_begin,
 		.mask   = ~PMD_SECT_XN,
 		.prot   = PMD_SECT_XN,
 	},
 };

 static struct section_perm ro_perms[] = {
 	/* Make kernel code and rodata RX (set RO). */
 	{
 		.name	= "text/rodata RO",
 		.start  = (unsigned long)_stext,
 		.end    = (unsigned long)__init_begin,
 #ifdef CONFIG_ARM_LPAE
 		.mask   = ~L_PMD_SECT_RDONLY,
 		.prot   = L_PMD_SECT_RDONLY,
 #else
 		.mask   = ~(PMD_SECT_APX | PMD_SECT_AP_WRITE),
 		.prot   = PMD_SECT_APX | PMD_SECT_AP_WRITE,
 		.clear  = PMD_SECT_AP_WRITE,
 #endif
 	},
 };

 /*
  * Updates section permissions only for the current mm (sections are
  * copied into each mm). During startup, this is the init_mm. Is only
  * safe to be called with preemption disabled, as under stop_machine().
  */
 static inline void section_update(unsigned long addr, pmdval_t mask,
 				  pmdval_t prot, struct mm_struct *mm)
 {
 	pmd_t *pmd;

 	pmd = pmd_offset(pud_offset(pgd_offset(mm, addr), addr), addr);

 #ifdef CONFIG_ARM_LPAE
 	pmd[0] = __pmd((pmd_val(pmd[0]) & mask) | prot);
 #else
 	if (addr & SECTION_SIZE)
 		pmd[1] = __pmd((pmd_val(pmd[1]) & mask) | prot);
 	else
 		pmd[0] = __pmd((pmd_val(pmd[0]) & mask) | prot);
 #endif
 	flush_pmd_entry(pmd);
 	local_flush_tlb_kernel_range(addr, addr + SECTION_SIZE);
 }

 /* Make sure extended page tables are in use. */
 static inline bool arch_has_strict_perms(void)
 {
 	if (cpu_architecture() < CPU_ARCH_ARMv6)
 		return false;

 	return !!(get_cr() & CR_XP);
 }

 void set_section_perms(struct section_perm *perms, int n, bool set,
 			struct mm_struct *mm)
 {
 	size_t i;
 	unsigned long addr;

 	if (!arch_has_strict_perms())
 		return;

 	for (i = 0; i < n; i++) {
 		if (!IS_ALIGNED(perms[i].start, SECTION_SIZE) ||
 		    !IS_ALIGNED(perms[i].end, SECTION_SIZE)) {
 			pr_err("BUG: %s section %lx-%lx not aligned to %lx\n",
 				perms[i].name, perms[i].start, perms[i].end,
 				SECTION_SIZE);
 			continue;
 		}

 		for (addr = perms[i].start;
 		     addr < perms[i].end;
 		     addr += SECTION_SIZE)
 			section_update(addr, perms[i].mask,
 				set ? perms[i].prot : perms[i].clear, mm);
 	}

 }

 /**
  * update_sections_early intended to be called only through stop_machine
  * framework and executed by only one CPU while all other CPUs will spin and
  * wait, so no locking is required in this function.
  */
 static void update_sections_early(struct section_perm perms[], int n)
 {
 	struct task_struct *t, *s;

 	for_each_process(t) {
 		if (t->flags & PF_KTHREAD)
 			continue;
 		for_each_thread(t, s)
 			set_section_perms(perms, n, true, s->mm);
 	}
 	set_section_perms(perms, n, true, current->active_mm);
 	set_section_perms(perms, n, true, &init_mm);
 }

 static int __fix_kernmem_perms(void *unused)
 {
 	update_sections_early(nx_perms, ARRAY_SIZE(nx_perms));
 	return 0;
 }

 static void fix_kernmem_perms(void)
 {
 	stop_machine(__fix_kernmem_perms, NULL, NULL);
 }

 static int __mark_rodata_ro(void *unused)
 {
 	update_sections_early(ro_perms, ARRAY_SIZE(ro_perms));
 	return 0;
 }

 void mark_rodata_ro(void)
 {
 	stop_machine(__mark_rodata_ro, NULL, NULL);
 }

 void set_kernel_text_rw(void)
 {
 	set_section_perms(ro_perms, ARRAY_SIZE(ro_perms), false,
 				current->active_mm);
 }

 void set_kernel_text_ro(void)
 {
 	set_section_perms(ro_perms, ARRAY_SIZE(ro_perms), true,
 				current->active_mm);
 }

 #else
 static inline void fix_kernmem_perms(void) { }
 #endif /* CONFIG_STRICT_KERNEL_RWX */

 void free_tcmmem(void)
 {
 #ifdef CONFIG_HAVE_TCM
 	extern char __tcm_start, __tcm_end;

 	poison_init_mem(&__tcm_start, &__tcm_end - &__tcm_start);
 	free_reserved_area(&__tcm_start, &__tcm_end, -1, "TCM link");
 #endif
 }

 void free_initmem(void)
 {
 	fix_kernmem_perms();
 	free_tcmmem();

 	poison_init_mem(__init_begin, __init_end - __init_begin);
 	if (!machine_is_integrator() && !machine_is_cintegrator())
 		free_initmem_default(-1);
 }

 #ifdef CONFIG_BLK_DEV_INITRD

 static int keep_initrd;

 void free_initrd_mem(unsigned long start, unsigned long end)
 {
 	if (!keep_initrd) {
 		if (start == initrd_start)
 			start = round_down(start, PAGE_SIZE);
 		if (end == initrd_end)
 			end = round_up(end, PAGE_SIZE);

 		poison_init_mem((void *)start, PAGE_ALIGN(end) - start);
 		free_reserved_area((void *)start, (void *)end, -1, "initrd");
 	}
 }

 static int __init keepinitrd_setup(char *__unused)
 {
 	keep_initrd = 1;
 	return 1;
 }

 __setup("keepinitrd", keepinitrd_setup);
 #endif
	/*
	* linux/arch/arm/mm/init.c
	*
	* Copyright (C) 1995-2005 Russell King
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/
	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/swap.h>
	#include <linux/init.h>
	#include <linux/bootmem.h>
	#include <linux/mman.h>
	#include <linux/sched/signal.h>
	#include <linux/sched/task.h>
	#include <linux/export.h>
	#include <linux/nodemask.h>
	#include <linux/initrd.h>
	#include <linux/of_fdt.h>
	#include <linux/highmem.h>
	#include <linux/gfp.h>
	#include <linux/memblock.h>
	#include <linux/dma-contiguous.h>
	#include <linux/sizes.h>
	#include <linux/stop_machine.h>

	#include <asm/cp15.h>
	#include <asm/mach-types.h>
	#include <asm/memblock.h>
	#include <asm/memory.h>
	#include <asm/prom.h>
	#include <asm/sections.h>
	#include <asm/setup.h>
	#include <asm/system_info.h>
	#include <asm/tlb.h>
	#include <asm/fixmap.h>

	#include <asm/mach/arch.h>
	#include <asm/mach/map.h>

	#include "mm.h"

	#ifdef CONFIG_CPU_CP15_MMU
	unsigned long __init __clear_cr(unsigned long mask)
	{
	cr_alignment = cr_alignment & ~mask;
	return cr_alignment;
	}
	#endif

	static phys_addr_t phys_initrd_start __initdata = 0;
	static unsigned long phys_initrd_size __initdata = 0;

	static int __init early_initrd(char *p)
	{
	phys_addr_t start;
	unsigned long size;
	char *endp;

	start = memparse(p, &endp);
	if (*endp == ',') {
	size = memparse(endp + 1, NULL);

	phys_initrd_start = start;
	phys_initrd_size = size;
	}
	return 0;
	}
	early_param("initrd", early_initrd);

	static int __init parse_tag_initrd(const struct tag *tag)
	{
	pr_warn("ATAG_INITRD is deprecated; "
	"please update your bootloader.\n");
	phys_initrd_start = __virt_to_phys(tag->u.initrd.start);
	phys_initrd_size = tag->u.initrd.size;
	return 0;
	}

	__tagtable(ATAG_INITRD, parse_tag_initrd);

	static int __init parse_tag_initrd2(const struct tag *tag)
	{
	phys_initrd_start = tag->u.initrd.start;
	phys_initrd_size = tag->u.initrd.size;
	return 0;
	}

	__tagtable(ATAG_INITRD2, parse_tag_initrd2);

	static void __init find_limits(unsigned long min, unsigned long max_low,
	unsigned long *max_high)
	{
	*max_low = PFN_DOWN(memblock_get_current_limit());
	*min = PFN_UP(memblock_start_of_DRAM());
	*max_high = PFN_DOWN(memblock_end_of_DRAM());
	}

	#ifdef CONFIG_ZONE_DMA

	phys_addr_t arm_dma_zone_size __read_mostly;
	EXPORT_SYMBOL(arm_dma_zone_size);

	/*
	* The DMA mask corresponding to the maximum bus address allocatable
	* using GFP_DMA. The default here places no restriction on DMA
	* allocations. This must be the smallest DMA mask in the system,
	* so a successful GFP_DMA allocation will always satisfy this.
	*/
	phys_addr_t arm_dma_limit;
	unsigned long arm_dma_pfn_limit;

	static void __init arm_adjust_dma_zone(unsigned long size, unsigned long hole,
	unsigned long dma_size)
	{
	if (size[0] <= dma_size)
	return;

	size[ZONE_NORMAL] = size[0] - dma_size;
	size[ZONE_DMA] = dma_size;
	hole[ZONE_NORMAL] = hole[0];
	hole[ZONE_DMA] = 0;
	}
	#endif

	void __init setup_dma_zone(const struct machine_desc *mdesc)
	{
	#ifdef CONFIG_ZONE_DMA
	if (mdesc->dma_zone_size) {
	arm_dma_zone_size = mdesc->dma_zone_size;
	arm_dma_limit = PHYS_OFFSET + arm_dma_zone_size - 1;
	} else
	arm_dma_limit = 0xffffffff;
	arm_dma_pfn_limit = arm_dma_limit >> PAGE_SHIFT;
	#endif
	}

	static void __init zone_sizes_init(unsigned long min, unsigned long max_low,
	unsigned long max_high)
	{
	unsigned long zone_size[MAX_NR_ZONES], zhole_size[MAX_NR_ZONES];
	struct memblock_region *reg;

	/*
	* initialise the zones.
	*/
	memset(zone_size, 0, sizeof(zone_size));

	/*
	* The memory size has already been determined. If we need
	* to do anything fancy with the allocation of this memory
	* to the zones, now is the time to do it.
	*/
	zone_size[0] = max_low - min;
	#ifdef CONFIG_HIGHMEM
	zone_size[ZONE_HIGHMEM] = max_high - max_low;
	#endif

	/*
	* Calculate the size of the holes.
	* holes = node_size - sum(bank_sizes)
	*/
	memcpy(zhole_size, zone_size, sizeof(zhole_size));
	for_each_memblock(memory, reg) {
	unsigned long start = memblock_region_memory_base_pfn(reg);
	unsigned long end = memblock_region_memory_end_pfn(reg);

	if (start < max_low) {
	unsigned long low_end = min(end, max_low);
	zhole_size[0] -= low_end - start;
	}
	#ifdef CONFIG_HIGHMEM
	if (end > max_low) {
	unsigned long high_start = max(start, max_low);
	zhole_size[ZONE_HIGHMEM] -= end - high_start;
	}
	#endif
	}

	#ifdef CONFIG_ZONE_DMA
	/*
	* Adjust the sizes according to any special requirements for
	* this machine type.
	*/
	if (arm_dma_zone_size)
	arm_adjust_dma_zone(zone_size, zhole_size,
	arm_dma_zone_size >> PAGE_SHIFT);
	#endif

	free_area_init_node(0, zone_size, min, zhole_size);
	}

	#ifdef CONFIG_HAVE_ARCH_PFN_VALID
	int pfn_valid(unsigned long pfn)
	{
	return memblock_is_map_memory(__pfn_to_phys(pfn));
	}
	EXPORT_SYMBOL(pfn_valid);
	#endif

	#ifndef CONFIG_SPARSEMEM
	static void __init arm_memory_present(void)
	{
	}
	#else
	static void __init arm_memory_present(void)
	{
	struct memblock_region *reg;

	for_each_memblock(memory, reg)
	memory_present(0, memblock_region_memory_base_pfn(reg),
	memblock_region_memory_end_pfn(reg));
	}
	#endif

	static bool arm_memblock_steal_permitted = true;

	phys_addr_t __init arm_memblock_steal(phys_addr_t size, phys_addr_t align)
	{
	phys_addr_t phys;

	BUG_ON(!arm_memblock_steal_permitted);

	phys = memblock_alloc_base(size, align, MEMBLOCK_ALLOC_ANYWHERE);
	memblock_free(phys, size);
	memblock_remove(phys, size);

	return phys;
	}

	static void __init arm_initrd_init(void)
	{
	#ifdef CONFIG_BLK_DEV_INITRD
	phys_addr_t start;
	unsigned long size;

	/* FDT scan will populate initrd_start */
	if (initrd_start && !phys_initrd_size) {
	phys_initrd_start = __virt_to_phys(initrd_start);
	phys_initrd_size = initrd_end - initrd_start;
	}

	initrd_start = initrd_end = 0;

	if (!phys_initrd_size)
	return;

	/*
	* Round the memory region to page boundaries as per free_initrd_mem()
	* This allows us to detect whether the pages overlapping the initrd
	* are in use, but more importantly, reserves the entire set of pages
	* as we don't want these pages allocated for other purposes.
	*/
	start = round_down(phys_initrd_start, PAGE_SIZE);
	size = phys_initrd_size + (phys_initrd_start - start);
	size = round_up(size, PAGE_SIZE);

	if (!memblock_is_region_memory(start, size)) {
	pr_err("INITRD: 0x%08llx+0x%08lx is not a memory region - disabling initrd\n",
	(u64)start, size);
	return;
	}

	if (memblock_is_region_reserved(start, size)) {
	pr_err("INITRD: 0x%08llx+0x%08lx overlaps in-use memory region - disabling initrd\n",
	(u64)start, size);
	return;
	}

	memblock_reserve(start, size);

	/* Now convert initrd to virtual addresses */
	initrd_start = __phys_to_virt(phys_initrd_start);
	initrd_end = initrd_start + phys_initrd_size;
	#endif
	}

	void __init arm_memblock_init(const struct machine_desc *mdesc)
	{
	/* Register the kernel text, kernel data and initrd with memblock. */
	memblock_reserve(__pa(KERNEL_START), KERNEL_END - KERNEL_START);

	arm_initrd_init();

	arm_mm_memblock_reserve();

	/* reserve any platform specific memblock areas */
	if (mdesc->reserve)
	mdesc->reserve();

	early_init_fdt_reserve_self();
	early_init_fdt_scan_reserved_mem();

	/* reserve memory for DMA contiguous allocations */
	dma_contiguous_reserve(arm_dma_limit);

	arm_memblock_steal_permitted = false;
	memblock_dump_all();
	}

	void __init bootmem_init(void)
	{
	unsigned long min, max_low, max_high;

	memblock_allow_resize();
	max_low = max_high = 0;

	find_limits(&min, &max_low, &max_high);

	early_memtest((phys_addr_t)min << PAGE_SHIFT,
	(phys_addr_t)max_low << PAGE_SHIFT);

	/*
	* Sparsemem tries to allocate bootmem in memory_present(),
	* so must be done after the fixed reservations
	*/
	arm_memory_present();

	/*
	* sparse_init() needs the bootmem allocator up and running.
	*/
	sparse_init();

	/*
	* Now free the memory - free_area_init_node needs
	* the sparse mem_map arrays initialized by sparse_init()
	* for memmap_init_zone(), otherwise all PFNs are invalid.
	*/
	zone_sizes_init(min, max_low, max_high);

	/*
	* This doesn't seem to be used by the Linux memory manager any
	* more, but is used by ll_rw_block. If we can get rid of it, we
	* also get rid of some of the stuff above as well.
	*/
	min_low_pfn = min;
	max_low_pfn = max_low;
	max_pfn = max_high;
	}

	/*
	* Poison init memory with an undefined instruction (ARM) or a branch to an
	* undefined instruction (Thumb).
	*/
	static inline void poison_init_mem(void *s, size_t count)
	{
	u32 p = (u32 )s;
	for (; count != 0; count -= 4)
	*p++ = 0xe7fddef0;
	}

	static inline void
	free_memmap(unsigned long start_pfn, unsigned long end_pfn)
	{
	struct page start_pg, end_pg;
	phys_addr_t pg, pgend;

	/*
	* Convert start_pfn/end_pfn to a struct page pointer.
	*/
	start_pg = pfn_to_page(start_pfn - 1) + 1;
	end_pg = pfn_to_page(end_pfn - 1) + 1;

	/*
	* Convert to physical addresses, and
	* round start upwards and end downwards.
	*/
	pg = PAGE_ALIGN(__pa(start_pg));
	pgend = __pa(end_pg) & PAGE_MASK;

	/*
	* If there are free pages between these,
	* free the section of the memmap array.
	*/
	if (pg < pgend)
	memblock_free_early(pg, pgend - pg);
	}

	/*
	* The mem_map array can get very big. Free the unused area of the memory map.
	*/
	static void __init free_unused_memmap(void)
	{
	unsigned long start, prev_end = 0;
	struct memblock_region *reg;

	/*
	* This relies on each bank being in address order.
	* The banks are sorted previously in bootmem_init().
	*/
	for_each_memblock(memory, reg) {
	start = memblock_region_memory_base_pfn(reg);

	#ifdef CONFIG_SPARSEMEM
	/*
	* Take care not to free memmap entries that don't exist
	* due to SPARSEMEM sections which aren't present.
	*/
	start = min(start,
	ALIGN(prev_end, PAGES_PER_SECTION));
	#else
	/*
	* Align down here since the VM subsystem insists that the
	* memmap entries are valid from the bank start aligned to
	* MAX_ORDER_NR_PAGES.
	*/
	start = round_down(start, MAX_ORDER_NR_PAGES);
	#endif
	/*
	* If we had a previous bank, and there is a space
	* between the current bank and the previous, free it.
	*/
	if (prev_end && prev_end < start)
	free_memmap(prev_end, start);

	/*
	* Align up here since the VM subsystem insists that the
	* memmap entries are valid from the bank end aligned to
	* MAX_ORDER_NR_PAGES.
	*/
	prev_end = ALIGN(memblock_region_memory_end_pfn(reg),
	MAX_ORDER_NR_PAGES);
	}

	#ifdef CONFIG_SPARSEMEM
	if (!IS_ALIGNED(prev_end, PAGES_PER_SECTION))
	free_memmap(prev_end,
	ALIGN(prev_end, PAGES_PER_SECTION));
	#endif
	}

	#ifdef CONFIG_HIGHMEM
	static inline void free_area_high(unsigned long pfn, unsigned long end)
	{
	for (; pfn < end; pfn++)
	free_highmem_page(pfn_to_page(pfn));
	}
	#endif

	static void __init free_highpages(void)
	{
	#ifdef CONFIG_HIGHMEM
	unsigned long max_low = max_low_pfn;
	struct memblock_region mem, res;

	/* set highmem page free */
	for_each_memblock(memory, mem) {
	unsigned long start = memblock_region_memory_base_pfn(mem);
	unsigned long end = memblock_region_memory_end_pfn(mem);

	/* Ignore complete lowmem entries */
	if (end <= max_low)
	continue;

	if (memblock_is_nomap(mem))
	continue;

	/* Truncate partial highmem entries */
	if (start < max_low)
	start = max_low;

	/* Find and exclude any reserved regions */
	for_each_memblock(reserved, res) {
	unsigned long res_start, res_end;

	res_start = memblock_region_reserved_base_pfn(res);
	res_end = memblock_region_reserved_end_pfn(res);

	if (res_end < start)
	continue;
	if (res_start < start)
	res_start = start;
	if (res_start > end)
	res_start = end;
	if (res_end > end)
	res_end = end;
	if (res_start != start)
	free_area_high(start, res_start);
	start = res_end;
	if (start == end)
	break;
	}

	/* And now free anything which remains */
	if (start < end)
	free_area_high(start, end);
	}
	#endif
	}

	/*
	* mem_init() marks the free areas in the mem_map and tells us how much
	* memory is free. This is done after various parts of the system have
	* claimed their memory after the kernel image.
	*/
	void __init mem_init(void)
	{
	#ifdef CONFIG_HAVE_TCM
	/* These pointers are filled in on TCM detection */
	extern u32 dtcm_end;
	extern u32 itcm_end;
	#endif

	set_max_mapnr(pfn_to_page(max_pfn) - mem_map);

	/* this will put all unused low memory onto the freelists */
	free_unused_memmap();
	free_all_bootmem();

	#ifdef CONFIG_SA1111
	/* now that our DMA memory is actually so designated, we can free it */
	free_reserved_area(__va(PHYS_OFFSET), swapper_pg_dir, -1, NULL);
	#endif

	free_highpages();

	mem_init_print_info(NULL);

	#define MLK(b, t) b, t, ((t) - (b)) >> 10
	#define MLM(b, t) b, t, ((t) - (b)) >> 20
	#define MLK_ROUNDUP(b, t) b, t, DIV_ROUND_UP(((t) - (b)), SZ_1K)

	pr_notice("Virtual kernel memory layout:\n"
	" vector : 0x%08lx - 0x%08lx (%4ld kB)\n"
	#ifdef CONFIG_HAVE_TCM
	" DTCM : 0x%08lx - 0x%08lx (%4ld kB)\n"
	" ITCM : 0x%08lx - 0x%08lx (%4ld kB)\n"
	#endif
	" fixmap : 0x%08lx - 0x%08lx (%4ld kB)\n"
	" vmalloc : 0x%08lx - 0x%08lx (%4ld MB)\n"
	" lowmem : 0x%08lx - 0x%08lx (%4ld MB)\n"
	#ifdef CONFIG_HIGHMEM
	" pkmap : 0x%08lx - 0x%08lx (%4ld MB)\n"
	#endif
	#ifdef CONFIG_MODULES
	" modules : 0x%08lx - 0x%08lx (%4ld MB)\n"
	#endif
	" .text : 0x%p" " - 0x%p" " (%4td kB)\n"
	" .init : 0x%p" " - 0x%p" " (%4td kB)\n"
	" .data : 0x%p" " - 0x%p" " (%4td kB)\n"
	" .bss : 0x%p" " - 0x%p" " (%4td kB)\n",

	MLK(VECTORS_BASE, VECTORS_BASE + PAGE_SIZE),
	#ifdef CONFIG_HAVE_TCM
	MLK(DTCM_OFFSET, (unsigned long) dtcm_end),
	MLK(ITCM_OFFSET, (unsigned long) itcm_end),
	#endif
	MLK(FIXADDR_START, FIXADDR_END),
	MLM(VMALLOC_START, VMALLOC_END),
	MLM(PAGE_OFFSET, (unsigned long)high_memory),
	#ifdef CONFIG_HIGHMEM
	MLM(PKMAP_BASE, (PKMAP_BASE) + (LAST_PKMAP) *
	(PAGE_SIZE)),
	#endif
	#ifdef CONFIG_MODULES
	MLM(MODULES_VADDR, MODULES_END),
	#endif

	MLK_ROUNDUP(_text, _etext),
	MLK_ROUNDUP(__init_begin, __init_end),
	MLK_ROUNDUP(_sdata, _edata),
	MLK_ROUNDUP(__bss_start, __bss_stop));

	#undef MLK
	#undef MLM
	#undef MLK_ROUNDUP

	/*
	* Check boundaries twice: Some fundamental inconsistencies can
	* be detected at build time already.
	*/
	#ifdef CONFIG_MMU
	BUILD_BUG_ON(TASK_SIZE > MODULES_VADDR);
	BUG_ON(TASK_SIZE > MODULES_VADDR);
	#endif

	#ifdef CONFIG_HIGHMEM
	BUILD_BUG_ON(PKMAP_BASE + LAST_PKMAP * PAGE_SIZE > PAGE_OFFSET);
	BUG_ON(PKMAP_BASE + LAST_PKMAP * PAGE_SIZE > PAGE_OFFSET);
	#endif

	if (PAGE_SIZE >= 16384 && get_num_physpages() <= 128) {
	extern int sysctl_overcommit_memory;
	/*
	* On a machine this small we won't get
	* anywhere without overcommit, so turn
	* it on by default.
	*/
	sysctl_overcommit_memory = OVERCOMMIT_ALWAYS;
	}
	}

	#ifdef CONFIG_STRICT_KERNEL_RWX
	struct section_perm {
	const char *name;
	unsigned long start;
	unsigned long end;
	pmdval_t mask;
	pmdval_t prot;
	pmdval_t clear;
	};

	/* First section-aligned location at or after __start_rodata. */
	extern char __start_rodata_section_aligned[];

	static struct section_perm nx_perms[] = {
	/* Make pages tables, etc before _stext RW (set NX). */
	{
	.name = "pre-text NX",
	.start = PAGE_OFFSET,
	.end = (unsigned long)_stext,
	.mask = ~PMD_SECT_XN,
	.prot = PMD_SECT_XN,
	},
	/* Make init RW (set NX). */
	{
	.name = "init NX",
	.start = (unsigned long)__init_begin,
	.end = (unsigned long)_sdata,
	.mask = ~PMD_SECT_XN,
	.prot = PMD_SECT_XN,
	},
	/* Make rodata NX (set RO in ro_perms below). */
	{
	.name = "rodata NX",
	.start = (unsigned long)__start_rodata_section_aligned,
	.end = (unsigned long)__init_begin,
	.mask = ~PMD_SECT_XN,
	.prot = PMD_SECT_XN,
	},
	};

	static struct section_perm ro_perms[] = {
	/* Make kernel code and rodata RX (set RO). */
	{
	.name = "text/rodata RO",
	.start = (unsigned long)_stext,
	.end = (unsigned long)__init_begin,
	#ifdef CONFIG_ARM_LPAE
	.mask = ~L_PMD_SECT_RDONLY,
	.prot = L_PMD_SECT_RDONLY,
	#else
	.mask = ~(PMD_SECT_APX \| PMD_SECT_AP_WRITE),
	.prot = PMD_SECT_APX \| PMD_SECT_AP_WRITE,
	.clear = PMD_SECT_AP_WRITE,
	#endif
	},
	};

	/*
	* Updates section permissions only for the current mm (sections are
	* copied into each mm). During startup, this is the init_mm. Is only
	* safe to be called with preemption disabled, as under stop_machine().
	*/
	static inline void section_update(unsigned long addr, pmdval_t mask,
	pmdval_t prot, struct mm_struct *mm)
	{
	pmd_t *pmd;

	pmd = pmd_offset(pud_offset(pgd_offset(mm, addr), addr), addr);

	#ifdef CONFIG_ARM_LPAE
	pmd[0] = __pmd((pmd_val(pmd[0]) & mask) \| prot);
	#else
	if (addr & SECTION_SIZE)
	pmd[1] = __pmd((pmd_val(pmd[1]) & mask) \| prot);
	else
	pmd[0] = __pmd((pmd_val(pmd[0]) & mask) \| prot);
	#endif
	flush_pmd_entry(pmd);
	local_flush_tlb_kernel_range(addr, addr + SECTION_SIZE);
	}

	/* Make sure extended page tables are in use. */
	static inline bool arch_has_strict_perms(void)
	{
	if (cpu_architecture() < CPU_ARCH_ARMv6)
	return false;

	return !!(get_cr() & CR_XP);
	}

	void set_section_perms(struct section_perm *perms, int n, bool set,
	struct mm_struct *mm)
	{
	size_t i;
	unsigned long addr;

	if (!arch_has_strict_perms())
	return;

	for (i = 0; i < n; i++) {
	if (!IS_ALIGNED(perms[i].start, SECTION_SIZE) \|\|
	!IS_ALIGNED(perms[i].end, SECTION_SIZE)) {
	pr_err("BUG: %s section %lx-%lx not aligned to %lx\n",
	perms[i].name, perms[i].start, perms[i].end,
	SECTION_SIZE);
	continue;
	}

	for (addr = perms[i].start;
	addr < perms[i].end;
	addr += SECTION_SIZE)
	section_update(addr, perms[i].mask,
	set ? perms[i].prot : perms[i].clear, mm);
	}

	}

	/**
	* update_sections_early intended to be called only through stop_machine
	* framework and executed by only one CPU while all other CPUs will spin and
	* wait, so no locking is required in this function.
	*/
	static void update_sections_early(struct section_perm perms[], int n)
	{
	struct task_struct t, s;

	for_each_process(t) {
	if (t->flags & PF_KTHREAD)
	continue;
	for_each_thread(t, s)
	set_section_perms(perms, n, true, s->mm);
	}
	set_section_perms(perms, n, true, current->active_mm);
	set_section_perms(perms, n, true, &init_mm);
	}

	static int __fix_kernmem_perms(void *unused)
	{
	update_sections_early(nx_perms, ARRAY_SIZE(nx_perms));
	return 0;
	}

	static void fix_kernmem_perms(void)
	{
	stop_machine(__fix_kernmem_perms, NULL, NULL);
	}

	static int __mark_rodata_ro(void *unused)
	{
	update_sections_early(ro_perms, ARRAY_SIZE(ro_perms));
	return 0;
	}

	void mark_rodata_ro(void)
	{
	stop_machine(__mark_rodata_ro, NULL, NULL);
	}

	void set_kernel_text_rw(void)
	{
	set_section_perms(ro_perms, ARRAY_SIZE(ro_perms), false,
	current->active_mm);
	}

	void set_kernel_text_ro(void)
	{
	set_section_perms(ro_perms, ARRAY_SIZE(ro_perms), true,
	current->active_mm);
	}

	#else
	static inline void fix_kernmem_perms(void) { }
	#endif /* CONFIG_STRICT_KERNEL_RWX */

	void free_tcmmem(void)
	{
	#ifdef CONFIG_HAVE_TCM
	extern char __tcm_start, __tcm_end;

	poison_init_mem(&__tcm_start, &__tcm_end - &__tcm_start);
	free_reserved_area(&__tcm_start, &__tcm_end, -1, "TCM link");
	#endif
	}

	void free_initmem(void)
	{
	fix_kernmem_perms();
	free_tcmmem();

	poison_init_mem(__init_begin, __init_end - __init_begin);
	if (!machine_is_integrator() && !machine_is_cintegrator())
	free_initmem_default(-1);
	}

	#ifdef CONFIG_BLK_DEV_INITRD

	static int keep_initrd;

	void free_initrd_mem(unsigned long start, unsigned long end)
	{
	if (!keep_initrd) {
	if (start == initrd_start)
	start = round_down(start, PAGE_SIZE);
	if (end == initrd_end)
	end = round_up(end, PAGE_SIZE);

	poison_init_mem((void *)start, PAGE_ALIGN(end) - start);
	free_reserved_area((void )start, (void )end, -1, "initrd");
	}
	}

	static int __init keepinitrd_setup(char *__unused)
	{
	keep_initrd = 1;
	return 1;
	}

	__setup("keepinitrd", keepinitrd_setup);
	#endif