arch/arm64/mm/init.c - kernel/msm-4.19 - Gitiles

 /*
  * Based on arch/arm/mm/init.c
  *
  * Copyright (C) 1995-2005 Russell King
  * Copyright (C) 2012 ARM Ltd.
  *
  * 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.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */

 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/errno.h>
 #include <linux/swap.h>
 #include <linux/init.h>
 #include <linux/bootmem.h>
 #include <linux/cache.h>
 #include <linux/mman.h>
 #include <linux/nodemask.h>
 #include <linux/initrd.h>
 #include <linux/gfp.h>
 #include <linux/memblock.h>
 #include <linux/sort.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
 #include <linux/dma-mapping.h>
 #include <linux/dma-contiguous.h>
 #include <linux/efi.h>
 #include <linux/swiotlb.h>
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
 #include <linux/kexec.h>
 #include <linux/crash_dump.h>

 #include <asm/boot.h>
 #include <asm/fixmap.h>
 #include <asm/kasan.h>
 #include <asm/kernel-pgtable.h>
 #include <asm/memory.h>
 #include <asm/numa.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
 #include <asm/sizes.h>
 #include <asm/tlb.h>
 #include <asm/alternative.h>

 /*
  * We need to be able to catch inadvertent references to memstart_addr
  * that occur (potentially in generic code) before arm64_memblock_init()
  * executes, which assigns it its actual value. So use a default value
  * that cannot be mistaken for a real physical address.
  */
 s64 memstart_addr __ro_after_init = -1;
 phys_addr_t arm64_dma_phys_limit __ro_after_init;

 #ifdef CONFIG_BLK_DEV_INITRD
 static int __init early_initrd(char *p)
 {
 	unsigned long start, size;
 	char *endp;

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

 		initrd_start = start;
 		initrd_end = start + size;
 	}
 	return 0;
 }
 early_param("initrd", early_initrd);
 #endif

 #ifdef CONFIG_KEXEC_CORE
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
  *
  * This function reserves memory area given in "crashkernel=" kernel command
  * line parameter. The memory reserved is used by dump capture kernel when
  * primary kernel is crashing.
  */
 static void __init reserve_crashkernel(void)
 {
 	unsigned long long crash_base, crash_size;
 	int ret;

 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
 				&crash_size, &crash_base);
 	/* no crashkernel= or invalid value specified */
 	if (ret || !crash_size)
 		return;

 	crash_size = PAGE_ALIGN(crash_size);

 	if (crash_base == 0) {
 		/* Current arm64 boot protocol requires 2MB alignment */
 		crash_base = memblock_find_in_range(0, ARCH_LOW_ADDRESS_LIMIT,
 				crash_size, SZ_2M);
 		if (crash_base == 0) {
 			pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
 				crash_size);
 			return;
 		}
 	} else {
 		/* User specifies base address explicitly. */
 		if (!memblock_is_region_memory(crash_base, crash_size)) {
 			pr_warn("cannot reserve crashkernel: region is not memory\n");
 			return;
 		}

 		if (memblock_is_region_reserved(crash_base, crash_size)) {
 			pr_warn("cannot reserve crashkernel: region overlaps reserved memory\n");
 			return;
 		}

 		if (!IS_ALIGNED(crash_base, SZ_2M)) {
 			pr_warn("cannot reserve crashkernel: base address is not 2MB aligned\n");
 			return;
 		}
 	}
 	memblock_reserve(crash_base, crash_size);

 	pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
 		crash_base, crash_base + crash_size, crash_size >> 20);

 	crashk_res.start = crash_base;
 	crashk_res.end = crash_base + crash_size - 1;
 }

 static void __init kexec_reserve_crashkres_pages(void)
 {
 #ifdef CONFIG_HIBERNATION
 	phys_addr_t addr;
 	struct page *page;

 	if (!crashk_res.end)
 		return;

 	/*
 	 * To reduce the size of hibernation image, all the pages are
 	 * marked as Reserved initially.
 	 */
 	for (addr = crashk_res.start; addr < (crashk_res.end + 1);
 			addr += PAGE_SIZE) {
 		page = phys_to_page(addr);
 		SetPageReserved(page);
 	}
 #endif
 }
 #else
 static void __init reserve_crashkernel(void)
 {
 }

 static void __init kexec_reserve_crashkres_pages(void)
 {
 }
 #endif /* CONFIG_KEXEC_CORE */

 #ifdef CONFIG_CRASH_DUMP
 static int __init early_init_dt_scan_elfcorehdr(unsigned long node,
 		const char *uname, int depth, void *data)
 {
 	const __be32 *reg;
 	int len;

 	if (depth != 1 || strcmp(uname, "chosen") != 0)
 		return 0;

 	reg = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len);
 	if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
 		return 1;

 	elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, &reg);
 	elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, &reg);

 	return 1;
 }

 /*
  * reserve_elfcorehdr() - reserves memory for elf core header
  *
  * This function reserves the memory occupied by an elf core header
  * described in the device tree. This region contains all the
  * information about primary kernel's core image and is used by a dump
  * capture kernel to access the system memory on primary kernel.
  */
 static void __init reserve_elfcorehdr(void)
 {
 	of_scan_flat_dt(early_init_dt_scan_elfcorehdr, NULL);

 	if (!elfcorehdr_size)
 		return;

 	if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) {
 		pr_warn("elfcorehdr is overlapped\n");
 		return;
 	}

 	memblock_reserve(elfcorehdr_addr, elfcorehdr_size);

 	pr_info("Reserving %lldKB of memory at 0x%llx for elfcorehdr\n",
 		elfcorehdr_size >> 10, elfcorehdr_addr);
 }
 #else
 static void __init reserve_elfcorehdr(void)
 {
 }
 #endif /* CONFIG_CRASH_DUMP */
 /*
  * Return the maximum physical address for ZONE_DMA (DMA_BIT_MASK(32)). It
  * currently assumes that for memory starting above 4G, 32-bit devices will
  * use a DMA offset.
  */
 static phys_addr_t __init max_zone_dma_phys(void)
 {
 	phys_addr_t offset = memblock_start_of_DRAM() & GENMASK_ULL(63, 32);
 	return min(offset + (1ULL << 32), memblock_end_of_DRAM());
 }

 #ifdef CONFIG_NUMA

 static void __init zone_sizes_init(unsigned long min, unsigned long max)
 {
 	unsigned long max_zone_pfns[MAX_NR_ZONES]  = {0};

 	if (IS_ENABLED(CONFIG_ZONE_DMA))
 		max_zone_pfns[ZONE_DMA] = PFN_DOWN(max_zone_dma_phys());
 	max_zone_pfns[ZONE_NORMAL] = max;

 	free_area_init_nodes(max_zone_pfns);
 }

 #else

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

 	memset(zone_size, 0, sizeof(zone_size));

 	/* 4GB maximum for 32-bit only capable devices */
 #ifdef CONFIG_ZONE_DMA
 	max_dma = PFN_DOWN(arm64_dma_phys_limit);
 	zone_size[ZONE_DMA] = max_dma - min;
 #endif
 	zone_size[ZONE_NORMAL] = max - max_dma;

 	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)
 			continue;

 #ifdef CONFIG_ZONE_DMA
 		if (start < max_dma) {
 			unsigned long dma_end = min(end, max_dma);
 			zhole_size[ZONE_DMA] -= dma_end - start;
 		}
 #endif
 		if (end > max_dma) {
 			unsigned long normal_end = min(end, max);
 			unsigned long normal_start = max(start, max_dma);
 			zhole_size[ZONE_NORMAL] -= normal_end - normal_start;
 		}
 	}

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

 #endif /* CONFIG_NUMA */

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

 #ifndef CONFIG_SPARSEMEM
 static void __init arm64_memory_present(void)
 {
 }
 #else
 static void __init arm64_memory_present(void)
 {
 	struct memblock_region *reg;

 	for_each_memblock(memory, reg) {
 		int nid = memblock_get_region_node(reg);

 		memory_present(nid, memblock_region_memory_base_pfn(reg),
 				memblock_region_memory_end_pfn(reg));
 	}
 }
 #endif

 static phys_addr_t memory_limit = (phys_addr_t)ULLONG_MAX;

 /*
  * Limit the memory size that was specified via FDT.
  */
 static int __init early_mem(char *p)
 {
 	if (!p)
 		return 1;

 	memory_limit = memparse(p, &p) & PAGE_MASK;
 	pr_notice("Memory limited to %lldMB\n", memory_limit >> 20);

 	return 0;
 }
 early_param("mem", early_mem);

 static int __init early_init_dt_scan_usablemem(unsigned long node,
 		const char *uname, int depth, void *data)
 {
 	struct memblock_region *usablemem = data;
 	const __be32 *reg;
 	int len;

 	if (depth != 1 || strcmp(uname, "chosen") != 0)
 		return 0;

 	reg = of_get_flat_dt_prop(node, "linux,usable-memory-range", &len);
 	if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
 		return 1;

 	usablemem->base = dt_mem_next_cell(dt_root_addr_cells, &reg);
 	usablemem->size = dt_mem_next_cell(dt_root_size_cells, &reg);

 	return 1;
 }

 static void __init fdt_enforce_memory_region(void)
 {
 	struct memblock_region reg = {
 		.size = 0,
 	};

 	of_scan_flat_dt(early_init_dt_scan_usablemem, &reg);

 	if (reg.size)
 		memblock_cap_memory_range(reg.base, reg.size);
 }

 void __init arm64_memblock_init(void)
 {
 	const s64 linear_region_size = -(s64)PAGE_OFFSET;

 	/* Handle linux,usable-memory-range property */
 	fdt_enforce_memory_region();

 	/* Remove memory above our supported physical address size */
 	memblock_remove(1ULL << PHYS_MASK_SHIFT, ULLONG_MAX);

 	/*
 	 * Ensure that the linear region takes up exactly half of the kernel
 	 * virtual address space. This way, we can distinguish a linear address
 	 * from a kernel/module/vmalloc address by testing a single bit.
 	 */
 	BUILD_BUG_ON(linear_region_size != BIT(VA_BITS - 1));

 	/*
 	 * Select a suitable value for the base of physical memory.
 	 */
 	memstart_addr = round_down(memblock_start_of_DRAM(),
 				   ARM64_MEMSTART_ALIGN);

 	/*
 	 * Remove the memory that we will not be able to cover with the
 	 * linear mapping. Take care not to clip the kernel which may be
 	 * high in memory.
 	 */
 	memblock_remove(max_t(u64, memstart_addr + linear_region_size,
 			__pa_symbol(_end)), ULLONG_MAX);
 	if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {
 		/* ensure that memstart_addr remains sufficiently aligned */
 		memstart_addr = round_up(memblock_end_of_DRAM() - linear_region_size,
 					 ARM64_MEMSTART_ALIGN);
 		memblock_remove(0, memstart_addr);
 	}

 	/*
 	 * Apply the memory limit if it was set. Since the kernel may be loaded
 	 * high up in memory, add back the kernel region that must be accessible
 	 * via the linear mapping.
 	 */
 	if (memory_limit != (phys_addr_t)ULLONG_MAX) {
 		memblock_mem_limit_remove_map(memory_limit);
 		memblock_add(__pa_symbol(_text), (u64)(_end - _text));
 	}

 	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) {
 		/*
 		 * Add back the memory we just removed if it results in the
 		 * initrd to become inaccessible via the linear mapping.
 		 * Otherwise, this is a no-op
 		 */
 		u64 base = initrd_start & PAGE_MASK;
 		u64 size = PAGE_ALIGN(initrd_end) - base;

 		/*
 		 * We can only add back the initrd memory if we don't end up
 		 * with more memory than we can address via the linear mapping.
 		 * It is up to the bootloader to position the kernel and the
 		 * initrd reasonably close to each other (i.e., within 32 GB of
 		 * each other) so that all granule/#levels combinations can
 		 * always access both.
 		 */
 		if (WARN(base < memblock_start_of_DRAM() ||
 			 base + size > memblock_start_of_DRAM() +
 				       linear_region_size,
 			"initrd not fully accessible via the linear mapping -- please check your bootloader ...\n")) {
 			initrd_start = 0;
 		} else {
 			memblock_remove(base, size); /* clear MEMBLOCK_ flags */
 			memblock_add(base, size);
 			memblock_reserve(base, size);
 		}
 	}

 	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
 		extern u16 memstart_offset_seed;
 		u64 range = linear_region_size -
 			    (memblock_end_of_DRAM() - memblock_start_of_DRAM());

 		/*
 		 * If the size of the linear region exceeds, by a sufficient
 		 * margin, the size of the region that the available physical
 		 * memory spans, randomize the linear region as well.
 		 */
 		if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
 			range = range / ARM64_MEMSTART_ALIGN + 1;
 			memstart_addr -= ARM64_MEMSTART_ALIGN *
 					 ((range * memstart_offset_seed) >> 16);
 		}
 	}

 	/*
 	 * Register the kernel text, kernel data, initrd, and initial
 	 * pagetables with memblock.
 	 */
 	memblock_reserve(__pa_symbol(_text), _end - _text);
 #ifdef CONFIG_BLK_DEV_INITRD
 	if (initrd_start) {
 		memblock_reserve(initrd_start, initrd_end - initrd_start);

 		/* the generic initrd code expects virtual addresses */
 		initrd_start = __phys_to_virt(initrd_start);
 		initrd_end = __phys_to_virt(initrd_end);
 	}
 #endif

 	early_init_fdt_scan_reserved_mem();

 	/* 4GB maximum for 32-bit only capable devices */
 	if (IS_ENABLED(CONFIG_ZONE_DMA))
 		arm64_dma_phys_limit = max_zone_dma_phys();
 	else
 		arm64_dma_phys_limit = PHYS_MASK + 1;

 	reserve_crashkernel();

 	reserve_elfcorehdr();

 	dma_contiguous_reserve(arm64_dma_phys_limit);

 	memblock_allow_resize();
 }

 void __init bootmem_init(void)
 {
 	unsigned long min, max;

 	min = PFN_UP(memblock_start_of_DRAM());
 	max = PFN_DOWN(memblock_end_of_DRAM());

 	early_memtest(min << PAGE_SHIFT, max << PAGE_SHIFT);

 	max_pfn = max_low_pfn = max;

 	arm64_numa_init();
 	/*
 	 * Sparsemem tries to allocate bootmem in memory_present(), so must be
 	 * done after the fixed reservations.
 	 */
 	arm64_memory_present();

 	sparse_init();
 	zone_sizes_init(min, max);

 	high_memory = __va((max << PAGE_SHIFT) - 1) + 1;
 	memblock_dump_all();
 }

 #ifndef CONFIG_SPARSEMEM_VMEMMAP
 static inline void free_memmap(unsigned long start_pfn, unsigned long end_pfn)
 {
 	struct page *start_pg, *end_pg;
 	unsigned long 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 = (unsigned long)PAGE_ALIGN(__pa(start_pg));
 	pgend = (unsigned long)__pa(end_pg) & PAGE_MASK;

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

 	for_each_memblock(memory, reg) {
 		start = __phys_to_pfn(reg->base);

 #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));
 #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(__phys_to_pfn(reg->base + reg->size),
 				 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
 }
 #endif	/* !CONFIG_SPARSEMEM_VMEMMAP */

 /*
  * 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)
 {
 	if (swiotlb_force == SWIOTLB_FORCE ||
 	    max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))
 		swiotlb_init(1);
 	else
 		swiotlb_force = SWIOTLB_NO_FORCE;

 	set_max_mapnr(pfn_to_page(max_pfn) - mem_map);

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

 	kexec_reserve_crashkres_pages();

 	mem_init_print_info(NULL);

 	/*
 	 * Check boundaries twice: Some fundamental inconsistencies can be
 	 * detected at build time already.
 	 */
 #ifdef CONFIG_COMPAT
 	BUILD_BUG_ON(TASK_SIZE_32			> TASK_SIZE_64);
 #endif

 	/*
 	 * Make sure we chose the upper bound of sizeof(struct page)
 	 * correctly.
 	 */
 	BUILD_BUG_ON(sizeof(struct page) > (1 << STRUCT_PAGE_MAX_SHIFT));

 	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;
 	}
 }

 void free_initmem(void)
 {
 	free_reserved_area(lm_alias(__init_begin),
 			   lm_alias(__init_end),
 			   0, "unused kernel");
 	/*
 	 * Unmap the __init region but leave the VM area in place. This
 	 * prevents the region from being reused for kernel modules, which
 	 * is not supported by kallsyms.
 	 */
 	unmap_kernel_range((u64)__init_begin, (u64)(__init_end - __init_begin));
 }

 #ifdef CONFIG_BLK_DEV_INITRD

 static int keep_initrd __initdata;

 void __init free_initrd_mem(unsigned long start, unsigned long end)
 {
 	if (!keep_initrd)
 		free_reserved_area((void *)start, (void *)end, 0, "initrd");
 }

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

 __setup("keepinitrd", keepinitrd_setup);
 #endif

 /*
  * Dump out memory limit information on panic.
  */
 static int dump_mem_limit(struct notifier_block *self, unsigned long v, void *p)
 {
 	if (memory_limit != (phys_addr_t)ULLONG_MAX) {
 		pr_emerg("Memory Limit: %llu MB\n", memory_limit >> 20);
 	} else {
 		pr_emerg("Memory Limit: none\n");
 	}
 	return 0;
 }

 static struct notifier_block mem_limit_notifier = {
 	.notifier_call = dump_mem_limit,
 };

 static int __init register_mem_limit_dumper(void)
 {
 	atomic_notifier_chain_register(&panic_notifier_list,
 				       &mem_limit_notifier);
 	return 0;
 }
 __initcall(register_mem_limit_dumper);
	/*
	* Based on arch/arm/mm/init.c
	*
	* Copyright (C) 1995-2005 Russell King
	* Copyright (C) 2012 ARM Ltd.
	*
	* 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.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include <linux/kernel.h>
	#include <linux/export.h>
	#include <linux/errno.h>
	#include <linux/swap.h>
	#include <linux/init.h>
	#include <linux/bootmem.h>
	#include <linux/cache.h>
	#include <linux/mman.h>
	#include <linux/nodemask.h>
	#include <linux/initrd.h>
	#include <linux/gfp.h>
	#include <linux/memblock.h>
	#include <linux/sort.h>
	#include <linux/of.h>
	#include <linux/of_fdt.h>
	#include <linux/dma-mapping.h>
	#include <linux/dma-contiguous.h>
	#include <linux/efi.h>
	#include <linux/swiotlb.h>
	#include <linux/vmalloc.h>
	#include <linux/mm.h>
	#include <linux/kexec.h>
	#include <linux/crash_dump.h>

	#include <asm/boot.h>
	#include <asm/fixmap.h>
	#include <asm/kasan.h>
	#include <asm/kernel-pgtable.h>
	#include <asm/memory.h>
	#include <asm/numa.h>
	#include <asm/sections.h>
	#include <asm/setup.h>
	#include <asm/sizes.h>
	#include <asm/tlb.h>
	#include <asm/alternative.h>

	/*
	* We need to be able to catch inadvertent references to memstart_addr
	* that occur (potentially in generic code) before arm64_memblock_init()
	* executes, which assigns it its actual value. So use a default value
	* that cannot be mistaken for a real physical address.
	*/
	s64 memstart_addr __ro_after_init = -1;
	phys_addr_t arm64_dma_phys_limit __ro_after_init;

	#ifdef CONFIG_BLK_DEV_INITRD
	static int __init early_initrd(char *p)
	{
	unsigned long start, size;
	char *endp;

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

	initrd_start = start;
	initrd_end = start + size;
	}
	return 0;
	}
	early_param("initrd", early_initrd);
	#endif

	#ifdef CONFIG_KEXEC_CORE
	/*
	* reserve_crashkernel() - reserves memory for crash kernel
	*
	* This function reserves memory area given in "crashkernel=" kernel command
	* line parameter. The memory reserved is used by dump capture kernel when
	* primary kernel is crashing.
	*/
	static void __init reserve_crashkernel(void)
	{
	unsigned long long crash_base, crash_size;
	int ret;

	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
	&crash_size, &crash_base);
	/* no crashkernel= or invalid value specified */
	if (ret \|\| !crash_size)
	return;

	crash_size = PAGE_ALIGN(crash_size);

	if (crash_base == 0) {
	/* Current arm64 boot protocol requires 2MB alignment */
	crash_base = memblock_find_in_range(0, ARCH_LOW_ADDRESS_LIMIT,
	crash_size, SZ_2M);
	if (crash_base == 0) {
	pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
	crash_size);
	return;
	}
	} else {
	/* User specifies base address explicitly. */
	if (!memblock_is_region_memory(crash_base, crash_size)) {
	pr_warn("cannot reserve crashkernel: region is not memory\n");
	return;
	}

	if (memblock_is_region_reserved(crash_base, crash_size)) {
	pr_warn("cannot reserve crashkernel: region overlaps reserved memory\n");
	return;
	}

	if (!IS_ALIGNED(crash_base, SZ_2M)) {
	pr_warn("cannot reserve crashkernel: base address is not 2MB aligned\n");
	return;
	}
	}
	memblock_reserve(crash_base, crash_size);

	pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
	crash_base, crash_base + crash_size, crash_size >> 20);

	crashk_res.start = crash_base;
	crashk_res.end = crash_base + crash_size - 1;
	}

	static void __init kexec_reserve_crashkres_pages(void)
	{
	#ifdef CONFIG_HIBERNATION
	phys_addr_t addr;
	struct page *page;

	if (!crashk_res.end)
	return;

	/*
	* To reduce the size of hibernation image, all the pages are
	* marked as Reserved initially.
	*/
	for (addr = crashk_res.start; addr < (crashk_res.end + 1);
	addr += PAGE_SIZE) {
	page = phys_to_page(addr);
	SetPageReserved(page);
	}
	#endif
	}
	#else
	static void __init reserve_crashkernel(void)
	{
	}

	static void __init kexec_reserve_crashkres_pages(void)
	{
	}
	#endif /* CONFIG_KEXEC_CORE */

	#ifdef CONFIG_CRASH_DUMP
	static int __init early_init_dt_scan_elfcorehdr(unsigned long node,
	const char uname, int depth, void data)
	{
	const __be32 *reg;
	int len;

	if (depth != 1 \|\| strcmp(uname, "chosen") != 0)
	return 0;

	reg = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len);
	if (!reg \|\| (len < (dt_root_addr_cells + dt_root_size_cells)))
	return 1;

	elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, &reg);
	elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, &reg);

	return 1;
	}

	/*
	* reserve_elfcorehdr() - reserves memory for elf core header
	*
	* This function reserves the memory occupied by an elf core header
	* described in the device tree. This region contains all the
	* information about primary kernel's core image and is used by a dump
	* capture kernel to access the system memory on primary kernel.
	*/
	static void __init reserve_elfcorehdr(void)
	{
	of_scan_flat_dt(early_init_dt_scan_elfcorehdr, NULL);

	if (!elfcorehdr_size)
	return;

	if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) {
	pr_warn("elfcorehdr is overlapped\n");
	return;
	}

	memblock_reserve(elfcorehdr_addr, elfcorehdr_size);

	pr_info("Reserving %lldKB of memory at 0x%llx for elfcorehdr\n",
	elfcorehdr_size >> 10, elfcorehdr_addr);
	}
	#else
	static void __init reserve_elfcorehdr(void)
	{
	}
	#endif /* CONFIG_CRASH_DUMP */
	/*
	* Return the maximum physical address for ZONE_DMA (DMA_BIT_MASK(32)). It
	* currently assumes that for memory starting above 4G, 32-bit devices will
	* use a DMA offset.
	*/
	static phys_addr_t __init max_zone_dma_phys(void)
	{
	phys_addr_t offset = memblock_start_of_DRAM() & GENMASK_ULL(63, 32);
	return min(offset + (1ULL << 32), memblock_end_of_DRAM());
	}

	#ifdef CONFIG_NUMA

	static void __init zone_sizes_init(unsigned long min, unsigned long max)
	{
	unsigned long max_zone_pfns[MAX_NR_ZONES] = {0};

	if (IS_ENABLED(CONFIG_ZONE_DMA))
	max_zone_pfns[ZONE_DMA] = PFN_DOWN(max_zone_dma_phys());
	max_zone_pfns[ZONE_NORMAL] = max;

	free_area_init_nodes(max_zone_pfns);
	}

	#else

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

	memset(zone_size, 0, sizeof(zone_size));

	/* 4GB maximum for 32-bit only capable devices */
	#ifdef CONFIG_ZONE_DMA
	max_dma = PFN_DOWN(arm64_dma_phys_limit);
	zone_size[ZONE_DMA] = max_dma - min;
	#endif
	zone_size[ZONE_NORMAL] = max - max_dma;

	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)
	continue;

	#ifdef CONFIG_ZONE_DMA
	if (start < max_dma) {
	unsigned long dma_end = min(end, max_dma);
	zhole_size[ZONE_DMA] -= dma_end - start;
	}
	#endif
	if (end > max_dma) {
	unsigned long normal_end = min(end, max);
	unsigned long normal_start = max(start, max_dma);
	zhole_size[ZONE_NORMAL] -= normal_end - normal_start;
	}
	}

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

	#endif /* CONFIG_NUMA */

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

	#ifndef CONFIG_SPARSEMEM
	static void __init arm64_memory_present(void)
	{
	}
	#else
	static void __init arm64_memory_present(void)
	{
	struct memblock_region *reg;

	for_each_memblock(memory, reg) {
	int nid = memblock_get_region_node(reg);

	memory_present(nid, memblock_region_memory_base_pfn(reg),
	memblock_region_memory_end_pfn(reg));
	}
	}
	#endif

	static phys_addr_t memory_limit = (phys_addr_t)ULLONG_MAX;

	/*
	* Limit the memory size that was specified via FDT.
	*/
	static int __init early_mem(char *p)
	{
	if (!p)
	return 1;

	memory_limit = memparse(p, &p) & PAGE_MASK;
	pr_notice("Memory limited to %lldMB\n", memory_limit >> 20);

	return 0;
	}
	early_param("mem", early_mem);

	static int __init early_init_dt_scan_usablemem(unsigned long node,
	const char uname, int depth, void data)
	{
	struct memblock_region *usablemem = data;
	const __be32 *reg;
	int len;

	if (depth != 1 \|\| strcmp(uname, "chosen") != 0)
	return 0;

	reg = of_get_flat_dt_prop(node, "linux,usable-memory-range", &len);
	if (!reg \|\| (len < (dt_root_addr_cells + dt_root_size_cells)))
	return 1;

	usablemem->base = dt_mem_next_cell(dt_root_addr_cells, &reg);
	usablemem->size = dt_mem_next_cell(dt_root_size_cells, &reg);

	return 1;
	}

	static void __init fdt_enforce_memory_region(void)
	{
	struct memblock_region reg = {
	.size = 0,
	};

	of_scan_flat_dt(early_init_dt_scan_usablemem, &reg);

	if (reg.size)
	memblock_cap_memory_range(reg.base, reg.size);
	}

	void __init arm64_memblock_init(void)
	{
	const s64 linear_region_size = -(s64)PAGE_OFFSET;

	/* Handle linux,usable-memory-range property */
	fdt_enforce_memory_region();

	/* Remove memory above our supported physical address size */
	memblock_remove(1ULL << PHYS_MASK_SHIFT, ULLONG_MAX);

	/*
	* Ensure that the linear region takes up exactly half of the kernel
	* virtual address space. This way, we can distinguish a linear address
	* from a kernel/module/vmalloc address by testing a single bit.
	*/
	BUILD_BUG_ON(linear_region_size != BIT(VA_BITS - 1));

	/*
	* Select a suitable value for the base of physical memory.
	*/
	memstart_addr = round_down(memblock_start_of_DRAM(),
	ARM64_MEMSTART_ALIGN);

	/*
	* Remove the memory that we will not be able to cover with the
	* linear mapping. Take care not to clip the kernel which may be
	* high in memory.
	*/
	memblock_remove(max_t(u64, memstart_addr + linear_region_size,
	__pa_symbol(_end)), ULLONG_MAX);
	if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {
	/* ensure that memstart_addr remains sufficiently aligned */
	memstart_addr = round_up(memblock_end_of_DRAM() - linear_region_size,
	ARM64_MEMSTART_ALIGN);
	memblock_remove(0, memstart_addr);
	}

	/*
	* Apply the memory limit if it was set. Since the kernel may be loaded
	* high up in memory, add back the kernel region that must be accessible
	* via the linear mapping.
	*/
	if (memory_limit != (phys_addr_t)ULLONG_MAX) {
	memblock_mem_limit_remove_map(memory_limit);
	memblock_add(__pa_symbol(_text), (u64)(_end - _text));
	}

	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) {
	/*
	* Add back the memory we just removed if it results in the
	* initrd to become inaccessible via the linear mapping.
	* Otherwise, this is a no-op
	*/
	u64 base = initrd_start & PAGE_MASK;
	u64 size = PAGE_ALIGN(initrd_end) - base;

	/*
	* We can only add back the initrd memory if we don't end up
	* with more memory than we can address via the linear mapping.
	* It is up to the bootloader to position the kernel and the
	* initrd reasonably close to each other (i.e., within 32 GB of
	* each other) so that all granule/#levels combinations can
	* always access both.
	*/
	if (WARN(base < memblock_start_of_DRAM() \|\|
	base + size > memblock_start_of_DRAM() +
	linear_region_size,
	"initrd not fully accessible via the linear mapping -- please check your bootloader ...\n")) {
	initrd_start = 0;
	} else {
	memblock_remove(base, size); /* clear MEMBLOCK_ flags */
	memblock_add(base, size);
	memblock_reserve(base, size);
	}
	}

	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
	extern u16 memstart_offset_seed;
	u64 range = linear_region_size -
	(memblock_end_of_DRAM() - memblock_start_of_DRAM());

	/*
	* If the size of the linear region exceeds, by a sufficient
	* margin, the size of the region that the available physical
	* memory spans, randomize the linear region as well.
	*/
	if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
	range = range / ARM64_MEMSTART_ALIGN + 1;
	memstart_addr -= ARM64_MEMSTART_ALIGN *
	((range * memstart_offset_seed) >> 16);
	}
	}

	/*
	* Register the kernel text, kernel data, initrd, and initial
	* pagetables with memblock.
	*/
	memblock_reserve(__pa_symbol(_text), _end - _text);
	#ifdef CONFIG_BLK_DEV_INITRD
	if (initrd_start) {
	memblock_reserve(initrd_start, initrd_end - initrd_start);

	/* the generic initrd code expects virtual addresses */
	initrd_start = __phys_to_virt(initrd_start);
	initrd_end = __phys_to_virt(initrd_end);
	}
	#endif

	early_init_fdt_scan_reserved_mem();

	/* 4GB maximum for 32-bit only capable devices */
	if (IS_ENABLED(CONFIG_ZONE_DMA))
	arm64_dma_phys_limit = max_zone_dma_phys();
	else
	arm64_dma_phys_limit = PHYS_MASK + 1;

	reserve_crashkernel();

	reserve_elfcorehdr();

	dma_contiguous_reserve(arm64_dma_phys_limit);

	memblock_allow_resize();
	}

	void __init bootmem_init(void)
	{
	unsigned long min, max;

	min = PFN_UP(memblock_start_of_DRAM());
	max = PFN_DOWN(memblock_end_of_DRAM());

	early_memtest(min << PAGE_SHIFT, max << PAGE_SHIFT);

	max_pfn = max_low_pfn = max;

	arm64_numa_init();
	/*
	* Sparsemem tries to allocate bootmem in memory_present(), so must be
	* done after the fixed reservations.
	*/
	arm64_memory_present();

	sparse_init();
	zone_sizes_init(min, max);

	high_memory = __va((max << PAGE_SHIFT) - 1) + 1;
	memblock_dump_all();
	}

	#ifndef CONFIG_SPARSEMEM_VMEMMAP
	static inline void free_memmap(unsigned long start_pfn, unsigned long end_pfn)
	{
	struct page start_pg, end_pg;
	unsigned long 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 = (unsigned long)PAGE_ALIGN(__pa(start_pg));
	pgend = (unsigned long)__pa(end_pg) & PAGE_MASK;

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

	for_each_memblock(memory, reg) {
	start = __phys_to_pfn(reg->base);

	#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));
	#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(__phys_to_pfn(reg->base + reg->size),
	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
	}
	#endif /* !CONFIG_SPARSEMEM_VMEMMAP */

	/*
	* 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)
	{
	if (swiotlb_force == SWIOTLB_FORCE \|\|
	max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))
	swiotlb_init(1);
	else
	swiotlb_force = SWIOTLB_NO_FORCE;

	set_max_mapnr(pfn_to_page(max_pfn) - mem_map);

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

	kexec_reserve_crashkres_pages();

	mem_init_print_info(NULL);

	/*
	* Check boundaries twice: Some fundamental inconsistencies can be
	* detected at build time already.
	*/
	#ifdef CONFIG_COMPAT
	BUILD_BUG_ON(TASK_SIZE_32 > TASK_SIZE_64);
	#endif

	/*
	* Make sure we chose the upper bound of sizeof(struct page)
	* correctly.
	*/
	BUILD_BUG_ON(sizeof(struct page) > (1 << STRUCT_PAGE_MAX_SHIFT));

	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;
	}
	}

	void free_initmem(void)
	{
	free_reserved_area(lm_alias(__init_begin),
	lm_alias(__init_end),
	0, "unused kernel");
	/*
	* Unmap the __init region but leave the VM area in place. This
	* prevents the region from being reused for kernel modules, which
	* is not supported by kallsyms.
	*/
	unmap_kernel_range((u64)__init_begin, (u64)(__init_end - __init_begin));
	}

	#ifdef CONFIG_BLK_DEV_INITRD

	static int keep_initrd __initdata;

	void __init free_initrd_mem(unsigned long start, unsigned long end)
	{
	if (!keep_initrd)
	free_reserved_area((void )start, (void )end, 0, "initrd");
	}

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

	__setup("keepinitrd", keepinitrd_setup);
	#endif

	/*
	* Dump out memory limit information on panic.
	*/
	static int dump_mem_limit(struct notifier_block self, unsigned long v, void p)
	{
	if (memory_limit != (phys_addr_t)ULLONG_MAX) {
	pr_emerg("Memory Limit: %llu MB\n", memory_limit >> 20);
	} else {
	pr_emerg("Memory Limit: none\n");
	}
	return 0;
	}

	static struct notifier_block mem_limit_notifier = {
	.notifier_call = dump_mem_limit,
	};

	static int __init register_mem_limit_dumper(void)
	{
	atomic_notifier_chain_register(&panic_notifier_list,
	&mem_limit_notifier);
	return 0;
	}
	__initcall(register_mem_limit_dumper);