linux-stable/arch/riscv/mm/init.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012 Regents of the University of California
 * Copyright (C) 2019 Western Digital Corporation or its affiliates.
 * Copyright (C) 2020 FORTH-ICS/CARV
 *  Nick Kossifidis <mick@ics.forth.gr>
 */

#include <linux/init.h>
#include <linux/mm.h>
#include <linux/memblock.h>
#include <linux/initrd.h>
#include <linux/swap.h>
#include <linux/swiotlb.h>
#include <linux/sizes.h>
#include <linux/of_fdt.h>
#include <linux/of_reserved_mem.h>
#include <linux/libfdt.h>
#include <linux/set_memory.h>
#include <linux/dma-map-ops.h>
#include <linux/crash_dump.h>
#include <linux/hugetlb.h>

#include <asm/fixmap.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
#include <asm/soc.h>
#include <asm/io.h>
#include <asm/ptdump.h>
#include <asm/numa.h>

#include "../kernel/head.h"

struct kernel_mapping kernel_map __ro_after_init;
EXPORT_SYMBOL(kernel_map);
#ifdef CONFIG_XIP_KERNEL
#define kernel_map	(*(struct kernel_mapping *)XIP_FIXUP(&kernel_map))
#endif

phys_addr_t phys_ram_base __ro_after_init;
EXPORT_SYMBOL(phys_ram_base);

#ifdef CONFIG_XIP_KERNEL
extern char _xiprom[], _exiprom[], __data_loc;
#endif

unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
							__page_aligned_bss;
EXPORT_SYMBOL(empty_zero_page);

extern char _start[];
#define DTB_EARLY_BASE_VA      PGDIR_SIZE
void *_dtb_early_va __initdata;
uintptr_t _dtb_early_pa __initdata;

struct pt_alloc_ops {
	pte_t *(*get_pte_virt)(phys_addr_t pa);
	phys_addr_t (*alloc_pte)(uintptr_t va);
#ifndef __PAGETABLE_PMD_FOLDED
	pmd_t *(*get_pmd_virt)(phys_addr_t pa);
	phys_addr_t (*alloc_pmd)(uintptr_t va);
#endif
};

static phys_addr_t dma32_phys_limit __initdata;

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

#ifdef CONFIG_ZONE_DMA32
	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(dma32_phys_limit);
#endif
	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;

	free_area_init(max_zone_pfns);
}

#if defined(CONFIG_MMU) && defined(CONFIG_DEBUG_VM)
static inline void print_mlk(char *name, unsigned long b, unsigned long t)
{
	pr_notice("%12s : 0x%08lx - 0x%08lx   (%4ld kB)\n", name, b, t,
		  (((t) - (b)) >> 10));
}

static inline void print_mlm(char *name, unsigned long b, unsigned long t)
{
	pr_notice("%12s : 0x%08lx - 0x%08lx   (%4ld MB)\n", name, b, t,
		  (((t) - (b)) >> 20));
}

static void __init print_vm_layout(void)
{
	pr_notice("Virtual kernel memory layout:\n");
	print_mlk("fixmap", (unsigned long)FIXADDR_START,
		  (unsigned long)FIXADDR_TOP);
	print_mlm("pci io", (unsigned long)PCI_IO_START,
		  (unsigned long)PCI_IO_END);
	print_mlm("vmemmap", (unsigned long)VMEMMAP_START,
		  (unsigned long)VMEMMAP_END);
	print_mlm("vmalloc", (unsigned long)VMALLOC_START,
		  (unsigned long)VMALLOC_END);
	print_mlm("lowmem", (unsigned long)PAGE_OFFSET,
		  (unsigned long)high_memory);
#ifdef CONFIG_64BIT
	print_mlm("kernel", (unsigned long)KERNEL_LINK_ADDR,
		  (unsigned long)ADDRESS_SPACE_END);
#endif
}
#else
static void print_vm_layout(void) { }
#endif /* CONFIG_DEBUG_VM */

void __init mem_init(void)
{
#ifdef CONFIG_FLATMEM
	BUG_ON(!mem_map);
#endif /* CONFIG_FLATMEM */

#ifdef CONFIG_SWIOTLB
	if (swiotlb_force == SWIOTLB_FORCE ||
	    max_pfn > PFN_DOWN(dma32_phys_limit))
		swiotlb_init(1);
	else
		swiotlb_force = SWIOTLB_NO_FORCE;
#endif
	high_memory = (void *)(__va(PFN_PHYS(max_low_pfn)));
	memblock_free_all();

	print_vm_layout();
}

/*
 * The default maximal physical memory size is -PAGE_OFFSET for 32-bit kernel,
 * whereas for 64-bit kernel, the end of the virtual address space is occupied
 * by the modules/BPF/kernel mappings which reduces the available size of the
 * linear mapping.
 * Limit the memory size via mem.
 */
#ifdef CONFIG_64BIT
static phys_addr_t memory_limit = -PAGE_OFFSET - SZ_4G;
#else
static phys_addr_t memory_limit = -PAGE_OFFSET;
#endif

static int __init early_mem(char *p)
{
	u64 size;

	if (!p)
		return 1;

	size = memparse(p, &p) & PAGE_MASK;
	memory_limit = min_t(u64, size, memory_limit);

	pr_notice("Memory limited to %lldMB\n", (u64)memory_limit >> 20);

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

static void __init setup_bootmem(void)
{
	phys_addr_t vmlinux_end = __pa_symbol(&_end);
	phys_addr_t vmlinux_start = __pa_symbol(&_start);
	phys_addr_t __maybe_unused max_mapped_addr;
	phys_addr_t phys_ram_end;

#ifdef CONFIG_XIP_KERNEL
	vmlinux_start = __pa_symbol(&_sdata);
#endif

	memblock_enforce_memory_limit(memory_limit);

	/*
	 * Reserve from the start of the kernel to the end of the kernel
	 */
#if defined(CONFIG_64BIT) && defined(CONFIG_STRICT_KERNEL_RWX)
	/*
	 * Make sure we align the reservation on PMD_SIZE since we will
	 * map the kernel in the linear mapping as read-only: we do not want
	 * any allocation to happen between _end and the next pmd aligned page.
	 */
	vmlinux_end = (vmlinux_end + PMD_SIZE - 1) & PMD_MASK;
#endif
	memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);


	phys_ram_end = memblock_end_of_DRAM();
#ifndef CONFIG_64BIT
#ifndef CONFIG_XIP_KERNEL
	phys_ram_base = memblock_start_of_DRAM();
#endif
	/*
	 * memblock allocator is not aware of the fact that last 4K bytes of
	 * the addressable memory can not be mapped because of IS_ERR_VALUE
	 * macro. Make sure that last 4k bytes are not usable by memblock
	 * if end of dram is equal to maximum addressable memory.  For 64-bit
	 * kernel, this problem can't happen here as the end of the virtual
	 * address space is occupied by the kernel mapping then this check must
	 * be done as soon as the kernel mapping base address is determined.
	 */
	max_mapped_addr = __pa(~(ulong)0);
	if (max_mapped_addr == (phys_ram_end - 1))
		memblock_set_current_limit(max_mapped_addr - 4096);
#endif

	min_low_pfn = PFN_UP(phys_ram_base);
	max_low_pfn = max_pfn = PFN_DOWN(phys_ram_end);

	dma32_phys_limit = min(4UL * SZ_1G, (unsigned long)PFN_PHYS(max_low_pfn));
	set_max_mapnr(max_low_pfn - ARCH_PFN_OFFSET);

	reserve_initrd_mem();
	/*
	 * If DTB is built in, no need to reserve its memblock.
	 * Otherwise, do reserve it but avoid using
	 * early_init_fdt_reserve_self() since __pa() does
	 * not work for DTB pointers that are fixmap addresses
	 */
	if (!IS_ENABLED(CONFIG_BUILTIN_DTB))
		memblock_reserve(dtb_early_pa, fdt_totalsize(dtb_early_va));

	early_init_fdt_scan_reserved_mem();
	dma_contiguous_reserve(dma32_phys_limit);
	if (IS_ENABLED(CONFIG_64BIT))
		hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
	memblock_allow_resize();
}

#ifdef CONFIG_MMU
static struct pt_alloc_ops _pt_ops __initdata;

#ifdef CONFIG_XIP_KERNEL
#define pt_ops (*(struct pt_alloc_ops *)XIP_FIXUP(&_pt_ops))
#else
#define pt_ops _pt_ops
#endif

unsigned long riscv_pfn_base __ro_after_init;
EXPORT_SYMBOL(riscv_pfn_base);

pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
pgd_t trampoline_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
static pte_t fixmap_pte[PTRS_PER_PTE] __page_aligned_bss;

pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
static pmd_t __maybe_unused early_dtb_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);

#ifdef CONFIG_XIP_KERNEL
#define trampoline_pg_dir      ((pgd_t *)XIP_FIXUP(trampoline_pg_dir))
#define fixmap_pte             ((pte_t *)XIP_FIXUP(fixmap_pte))
#define early_pg_dir           ((pgd_t *)XIP_FIXUP(early_pg_dir))
#endif /* CONFIG_XIP_KERNEL */

void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot)
{
	unsigned long addr = __fix_to_virt(idx);
	pte_t *ptep;

	BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses);

	ptep = &fixmap_pte[pte_index(addr)];

	if (pgprot_val(prot))
		set_pte(ptep, pfn_pte(phys >> PAGE_SHIFT, prot));
	else
		pte_clear(&init_mm, addr, ptep);
	local_flush_tlb_page(addr);
}

static inline pte_t *__init get_pte_virt_early(phys_addr_t pa)
{
	return (pte_t *)((uintptr_t)pa);
}

static inline pte_t *__init get_pte_virt_fixmap(phys_addr_t pa)
{
	clear_fixmap(FIX_PTE);
	return (pte_t *)set_fixmap_offset(FIX_PTE, pa);
}

static inline pte_t *__init get_pte_virt_late(phys_addr_t pa)
{
	return (pte_t *) __va(pa);
}

static inline phys_addr_t __init alloc_pte_early(uintptr_t va)
{
	/*
	 * We only create PMD or PGD early mappings so we
	 * should never reach here with MMU disabled.
	 */
	BUG();
}

static inline phys_addr_t __init alloc_pte_fixmap(uintptr_t va)
{
	return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
}

static phys_addr_t __init alloc_pte_late(uintptr_t va)
{
	unsigned long vaddr;

	vaddr = __get_free_page(GFP_KERNEL);
	BUG_ON(!vaddr || !pgtable_pte_page_ctor(virt_to_page(vaddr)));

	return __pa(vaddr);
}

static void __init create_pte_mapping(pte_t *ptep,
				      uintptr_t va, phys_addr_t pa,
				      phys_addr_t sz, pgprot_t prot)
{
	uintptr_t pte_idx = pte_index(va);

	BUG_ON(sz != PAGE_SIZE);

	if (pte_none(ptep[pte_idx]))
		ptep[pte_idx] = pfn_pte(PFN_DOWN(pa), prot);
}

#ifndef __PAGETABLE_PMD_FOLDED

static pmd_t trampoline_pmd[PTRS_PER_PMD] __page_aligned_bss;
static pmd_t fixmap_pmd[PTRS_PER_PMD] __page_aligned_bss;
static pmd_t early_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);

#ifdef CONFIG_XIP_KERNEL
#define trampoline_pmd ((pmd_t *)XIP_FIXUP(trampoline_pmd))
#define fixmap_pmd     ((pmd_t *)XIP_FIXUP(fixmap_pmd))
#define early_pmd      ((pmd_t *)XIP_FIXUP(early_pmd))
#endif /* CONFIG_XIP_KERNEL */

static pmd_t *__init get_pmd_virt_early(phys_addr_t pa)
{
	/* Before MMU is enabled */
	return (pmd_t *)((uintptr_t)pa);
}

static pmd_t *__init get_pmd_virt_fixmap(phys_addr_t pa)
{
	clear_fixmap(FIX_PMD);
	return (pmd_t *)set_fixmap_offset(FIX_PMD, pa);
}

static pmd_t *__init get_pmd_virt_late(phys_addr_t pa)
{
	return (pmd_t *) __va(pa);
}

static phys_addr_t __init alloc_pmd_early(uintptr_t va)
{
	BUG_ON((va - kernel_map.virt_addr) >> PGDIR_SHIFT);

	return (uintptr_t)early_pmd;
}

static phys_addr_t __init alloc_pmd_fixmap(uintptr_t va)
{
	return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
}

static phys_addr_t __init alloc_pmd_late(uintptr_t va)
{
	unsigned long vaddr;

	vaddr = __get_free_page(GFP_KERNEL);
	BUG_ON(!vaddr);
	return __pa(vaddr);
}

static void __init create_pmd_mapping(pmd_t *pmdp,
				      uintptr_t va, phys_addr_t pa,
				      phys_addr_t sz, pgprot_t prot)
{
	pte_t *ptep;
	phys_addr_t pte_phys;
	uintptr_t pmd_idx = pmd_index(va);

	if (sz == PMD_SIZE) {
		if (pmd_none(pmdp[pmd_idx]))
			pmdp[pmd_idx] = pfn_pmd(PFN_DOWN(pa), prot);
		return;
	}

	if (pmd_none(pmdp[pmd_idx])) {
		pte_phys = pt_ops.alloc_pte(va);
		pmdp[pmd_idx] = pfn_pmd(PFN_DOWN(pte_phys), PAGE_TABLE);
		ptep = pt_ops.get_pte_virt(pte_phys);
		memset(ptep, 0, PAGE_SIZE);
	} else {
		pte_phys = PFN_PHYS(_pmd_pfn(pmdp[pmd_idx]));
		ptep = pt_ops.get_pte_virt(pte_phys);
	}

	create_pte_mapping(ptep, va, pa, sz, prot);
}

#define pgd_next_t		pmd_t
#define alloc_pgd_next(__va)	pt_ops.alloc_pmd(__va)
#define get_pgd_next_virt(__pa)	pt_ops.get_pmd_virt(__pa)
#define create_pgd_next_mapping(__nextp, __va, __pa, __sz, __prot)	\
	create_pmd_mapping(__nextp, __va, __pa, __sz, __prot)
#define fixmap_pgd_next		fixmap_pmd
#else
#define pgd_next_t		pte_t
#define alloc_pgd_next(__va)	pt_ops.alloc_pte(__va)
#define get_pgd_next_virt(__pa)	pt_ops.get_pte_virt(__pa)
#define create_pgd_next_mapping(__nextp, __va, __pa, __sz, __prot)	\
	create_pte_mapping(__nextp, __va, __pa, __sz, __prot)
#define fixmap_pgd_next		fixmap_pte
#define create_pmd_mapping(__pmdp, __va, __pa, __sz, __prot)
#endif

void __init create_pgd_mapping(pgd_t *pgdp,
				      uintptr_t va, phys_addr_t pa,
				      phys_addr_t sz, pgprot_t prot)
{
	pgd_next_t *nextp;
	phys_addr_t next_phys;
	uintptr_t pgd_idx = pgd_index(va);

	if (sz == PGDIR_SIZE) {
		if (pgd_val(pgdp[pgd_idx]) == 0)
			pgdp[pgd_idx] = pfn_pgd(PFN_DOWN(pa), prot);
		return;
	}

	if (pgd_val(pgdp[pgd_idx]) == 0) {
		next_phys = alloc_pgd_next(va);
		pgdp[pgd_idx] = pfn_pgd(PFN_DOWN(next_phys), PAGE_TABLE);
		nextp = get_pgd_next_virt(next_phys);
		memset(nextp, 0, PAGE_SIZE);
	} else {
		next_phys = PFN_PHYS(_pgd_pfn(pgdp[pgd_idx]));
		nextp = get_pgd_next_virt(next_phys);
	}

	create_pgd_next_mapping(nextp, va, pa, sz, prot);
}

static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size)
{
	/* Upgrade to PMD_SIZE mappings whenever possible */
	if ((base & (PMD_SIZE - 1)) || (size & (PMD_SIZE - 1)))
		return PAGE_SIZE;

	return PMD_SIZE;
}

#ifdef CONFIG_XIP_KERNEL
/* called from head.S with MMU off */
asmlinkage void __init __copy_data(void)
{
	void *from = (void *)(&__data_loc);
	void *to = (void *)CONFIG_PHYS_RAM_BASE;
	size_t sz = (size_t)((uintptr_t)(&_end) - (uintptr_t)(&_sdata));

	memcpy(to, from, sz);
}
#endif

#ifdef CONFIG_STRICT_KERNEL_RWX
static __init pgprot_t pgprot_from_va(uintptr_t va)
{
	if (is_va_kernel_text(va))
		return PAGE_KERNEL_READ_EXEC;

	/*
	 * In 64-bit kernel, the kernel mapping is outside the linear mapping so
	 * we must protect its linear mapping alias from being executed and
	 * written.
	 * And rodata section is marked readonly in mark_rodata_ro.
	 */
	if (IS_ENABLED(CONFIG_64BIT) && is_va_kernel_lm_alias_text(va))
		return PAGE_KERNEL_READ;

	return PAGE_KERNEL;
}

void mark_rodata_ro(void)
{
	set_kernel_memory(__start_rodata, _data, set_memory_ro);
	if (IS_ENABLED(CONFIG_64BIT))
		set_kernel_memory(lm_alias(__start_rodata), lm_alias(_data),
				  set_memory_ro);

	debug_checkwx();
}
#else
static __init pgprot_t pgprot_from_va(uintptr_t va)
{
	if (IS_ENABLED(CONFIG_64BIT) && !is_kernel_mapping(va))
		return PAGE_KERNEL;

	return PAGE_KERNEL_EXEC;
}
#endif /* CONFIG_STRICT_KERNEL_RWX */

/*
 * setup_vm() is called from head.S with MMU-off.
 *
 * Following requirements should be honoured for setup_vm() to work
 * correctly:
 * 1) It should use PC-relative addressing for accessing kernel symbols.
 *    To achieve this we always use GCC cmodel=medany.
 * 2) The compiler instrumentation for FTRACE will not work for setup_vm()
 *    so disable compiler instrumentation when FTRACE is enabled.
 *
 * Currently, the above requirements are honoured by using custom CFLAGS
 * for init.o in mm/Makefile.
 */

#ifndef __riscv_cmodel_medany
#error "setup_vm() is called from head.S before relocate so it should not use absolute addressing."
#endif

#ifdef CONFIG_XIP_KERNEL
static void __init create_kernel_page_table(pgd_t *pgdir,
					    __always_unused bool early)
{
	uintptr_t va, end_va;

	/* Map the flash resident part */
	end_va = kernel_map.virt_addr + kernel_map.xiprom_sz;
	for (va = kernel_map.virt_addr; va < end_va; va += PMD_SIZE)
		create_pgd_mapping(pgdir, va,
				   kernel_map.xiprom + (va - kernel_map.virt_addr),
				   PMD_SIZE, PAGE_KERNEL_EXEC);

	/* Map the data in RAM */
	end_va = kernel_map.virt_addr + XIP_OFFSET + kernel_map.size;
	for (va = kernel_map.virt_addr + XIP_OFFSET; va < end_va; va += PMD_SIZE)
		create_pgd_mapping(pgdir, va,
				   kernel_map.phys_addr + (va - (kernel_map.virt_addr + XIP_OFFSET)),
				   PMD_SIZE, PAGE_KERNEL);
}
#else
static void __init create_kernel_page_table(pgd_t *pgdir, bool early)
{
	uintptr_t va, end_va;

	end_va = kernel_map.virt_addr + kernel_map.size;
	for (va = kernel_map.virt_addr; va < end_va; va += PMD_SIZE)
		create_pgd_mapping(pgdir, va,
				   kernel_map.phys_addr + (va - kernel_map.virt_addr),
				   PMD_SIZE,
				   early ?
					PAGE_KERNEL_EXEC : pgprot_from_va(va));
}
#endif

/*
 * Setup a 4MB mapping that encompasses the device tree: for 64-bit kernel,
 * this means 2 PMD entries whereas for 32-bit kernel, this is only 1 PGDIR
 * entry.
 */
static void __init create_fdt_early_page_table(pgd_t *pgdir, uintptr_t dtb_pa)
{
#ifndef CONFIG_BUILTIN_DTB
	uintptr_t pa = dtb_pa & ~(PMD_SIZE - 1);

	create_pgd_mapping(early_pg_dir, DTB_EARLY_BASE_VA,
			   IS_ENABLED(CONFIG_64BIT) ? (uintptr_t)early_dtb_pmd : pa,
			   PGDIR_SIZE,
			   IS_ENABLED(CONFIG_64BIT) ? PAGE_TABLE : PAGE_KERNEL);

	if (IS_ENABLED(CONFIG_64BIT)) {
		create_pmd_mapping(early_dtb_pmd, DTB_EARLY_BASE_VA,
				   pa, PMD_SIZE, PAGE_KERNEL);
		create_pmd_mapping(early_dtb_pmd, DTB_EARLY_BASE_VA + PMD_SIZE,
				   pa + PMD_SIZE, PMD_SIZE, PAGE_KERNEL);
	}

	dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PMD_SIZE - 1));
#else
	/*
	 * For 64-bit kernel, __va can't be used since it would return a linear
	 * mapping address whereas dtb_early_va will be used before
	 * setup_vm_final installs the linear mapping. For 32-bit kernel, as the
	 * kernel is mapped in the linear mapping, that makes no difference.
	 */
	dtb_early_va = kernel_mapping_pa_to_va(XIP_FIXUP(dtb_pa));
#endif

	dtb_early_pa = dtb_pa;
}

asmlinkage void __init setup_vm(uintptr_t dtb_pa)
{
	pmd_t __maybe_unused fix_bmap_spmd, fix_bmap_epmd;

	kernel_map.virt_addr = KERNEL_LINK_ADDR;

#ifdef CONFIG_XIP_KERNEL
	kernel_map.xiprom = (uintptr_t)CONFIG_XIP_PHYS_ADDR;
	kernel_map.xiprom_sz = (uintptr_t)(&_exiprom) - (uintptr_t)(&_xiprom);

	phys_ram_base = CONFIG_PHYS_RAM_BASE;
	kernel_map.phys_addr = (uintptr_t)CONFIG_PHYS_RAM_BASE;
	kernel_map.size = (uintptr_t)(&_end) - (uintptr_t)(&_sdata);

	kernel_map.va_kernel_xip_pa_offset = kernel_map.virt_addr - kernel_map.xiprom;
#else
	kernel_map.phys_addr = (uintptr_t)(&_start);
	kernel_map.size = (uintptr_t)(&_end) - kernel_map.phys_addr;
#endif
	kernel_map.va_pa_offset = PAGE_OFFSET - kernel_map.phys_addr;
	kernel_map.va_kernel_pa_offset = kernel_map.virt_addr - kernel_map.phys_addr;

	riscv_pfn_base = PFN_DOWN(kernel_map.phys_addr);

	/* Sanity check alignment and size */
	BUG_ON((PAGE_OFFSET % PGDIR_SIZE) != 0);
	BUG_ON((kernel_map.phys_addr % PMD_SIZE) != 0);

#ifdef CONFIG_64BIT
	/*
	 * The last 4K bytes of the addressable memory can not be mapped because
	 * of IS_ERR_VALUE macro.
	 */
	BUG_ON((kernel_map.virt_addr + kernel_map.size) > ADDRESS_SPACE_END - SZ_4K);
#endif

	pt_ops.alloc_pte = alloc_pte_early;
	pt_ops.get_pte_virt = get_pte_virt_early;
#ifndef __PAGETABLE_PMD_FOLDED
	pt_ops.alloc_pmd = alloc_pmd_early;
	pt_ops.get_pmd_virt = get_pmd_virt_early;
#endif
	/* Setup early PGD for fixmap */
	create_pgd_mapping(early_pg_dir, FIXADDR_START,
			   (uintptr_t)fixmap_pgd_next, PGDIR_SIZE, PAGE_TABLE);

#ifndef __PAGETABLE_PMD_FOLDED
	/* Setup fixmap PMD */
	create_pmd_mapping(fixmap_pmd, FIXADDR_START,
			   (uintptr_t)fixmap_pte, PMD_SIZE, PAGE_TABLE);
	/* Setup trampoline PGD and PMD */
	create_pgd_mapping(trampoline_pg_dir, kernel_map.virt_addr,
			   (uintptr_t)trampoline_pmd, PGDIR_SIZE, PAGE_TABLE);
#ifdef CONFIG_XIP_KERNEL
	create_pmd_mapping(trampoline_pmd, kernel_map.virt_addr,
			   kernel_map.xiprom, PMD_SIZE, PAGE_KERNEL_EXEC);
#else
	create_pmd_mapping(trampoline_pmd, kernel_map.virt_addr,
			   kernel_map.phys_addr, PMD_SIZE, PAGE_KERNEL_EXEC);
#endif
#else
	/* Setup trampoline PGD */
	create_pgd_mapping(trampoline_pg_dir, kernel_map.virt_addr,
			   kernel_map.phys_addr, PGDIR_SIZE, PAGE_KERNEL_EXEC);
#endif

	/*
	 * Setup early PGD covering entire kernel which will allow
	 * us to reach paging_init(). We map all memory banks later
	 * in setup_vm_final() below.
	 */
	create_kernel_page_table(early_pg_dir, true);

	/* Setup early mapping for FDT early scan */
	create_fdt_early_page_table(early_pg_dir, dtb_pa);

	/*
	 * Bootime fixmap only can handle PMD_SIZE mapping. Thus, boot-ioremap
	 * range can not span multiple pmds.
	 */
	BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT)
		     != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT));

#ifndef __PAGETABLE_PMD_FOLDED
	/*
	 * Early ioremap fixmap is already created as it lies within first 2MB
	 * of fixmap region. We always map PMD_SIZE. Thus, both FIX_BTMAP_END
	 * FIX_BTMAP_BEGIN should lie in the same pmd. Verify that and warn
	 * the user if not.
	 */
	fix_bmap_spmd = fixmap_pmd[pmd_index(__fix_to_virt(FIX_BTMAP_BEGIN))];
	fix_bmap_epmd = fixmap_pmd[pmd_index(__fix_to_virt(FIX_BTMAP_END))];
	if (pmd_val(fix_bmap_spmd) != pmd_val(fix_bmap_epmd)) {
		WARN_ON(1);
		pr_warn("fixmap btmap start [%08lx] != end [%08lx]\n",
			pmd_val(fix_bmap_spmd), pmd_val(fix_bmap_epmd));
		pr_warn("fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n",
			fix_to_virt(FIX_BTMAP_BEGIN));
		pr_warn("fix_to_virt(FIX_BTMAP_END):   %08lx\n",
			fix_to_virt(FIX_BTMAP_END));

		pr_warn("FIX_BTMAP_END:       %d\n", FIX_BTMAP_END);
		pr_warn("FIX_BTMAP_BEGIN:     %d\n", FIX_BTMAP_BEGIN);
	}
#endif
}

static void __init setup_vm_final(void)
{
	uintptr_t va, map_size;
	phys_addr_t pa, start, end;
	u64 i;

	/**
	 * MMU is enabled at this point. But page table setup is not complete yet.
	 * fixmap page table alloc functions should be used at this point
	 */
	pt_ops.alloc_pte = alloc_pte_fixmap;
	pt_ops.get_pte_virt = get_pte_virt_fixmap;
#ifndef __PAGETABLE_PMD_FOLDED
	pt_ops.alloc_pmd = alloc_pmd_fixmap;
	pt_ops.get_pmd_virt = get_pmd_virt_fixmap;
#endif
	/* Setup swapper PGD for fixmap */
	create_pgd_mapping(swapper_pg_dir, FIXADDR_START,
			   __pa_symbol(fixmap_pgd_next),
			   PGDIR_SIZE, PAGE_TABLE);

	/* Map all memory banks in the linear mapping */
	for_each_mem_range(i, &start, &end) {
		if (start >= end)
			break;
		if (start <= __pa(PAGE_OFFSET) &&
		    __pa(PAGE_OFFSET) < end)
			start = __pa(PAGE_OFFSET);
		if (end >= __pa(PAGE_OFFSET) + memory_limit)
			end = __pa(PAGE_OFFSET) + memory_limit;

		map_size = best_map_size(start, end - start);
		for (pa = start; pa < end; pa += map_size) {
			va = (uintptr_t)__va(pa);

			create_pgd_mapping(swapper_pg_dir, va, pa, map_size,
					   pgprot_from_va(va));
		}
	}

#ifdef CONFIG_64BIT
	/* Map the kernel */
	create_kernel_page_table(swapper_pg_dir, false);
#endif

	/* Clear fixmap PTE and PMD mappings */
	clear_fixmap(FIX_PTE);
	clear_fixmap(FIX_PMD);

	/* Move to swapper page table */
	csr_write(CSR_SATP, PFN_DOWN(__pa_symbol(swapper_pg_dir)) | SATP_MODE);
	local_flush_tlb_all();

	/* generic page allocation functions must be used to setup page table */
	pt_ops.alloc_pte = alloc_pte_late;
	pt_ops.get_pte_virt = get_pte_virt_late;
#ifndef __PAGETABLE_PMD_FOLDED
	pt_ops.alloc_pmd = alloc_pmd_late;
	pt_ops.get_pmd_virt = get_pmd_virt_late;
#endif
}
#else
asmlinkage void __init setup_vm(uintptr_t dtb_pa)
{
	dtb_early_va = (void *)dtb_pa;
	dtb_early_pa = dtb_pa;
}

static inline void setup_vm_final(void)
{
}
#endif /* CONFIG_MMU */

#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 = 0;
	unsigned long long crash_size = 0;
	unsigned long search_start = memblock_start_of_DRAM();
	unsigned long search_end = memblock_end_of_DRAM();

	int ret = 0;

	/*
	 * Don't reserve a region for a crash kernel on a crash kernel
	 * since it doesn't make much sense and we have limited memory
	 * resources.
	 */
#ifdef CONFIG_CRASH_DUMP
	if (is_kdump_kernel()) {
		pr_info("crashkernel: ignoring reservation request\n");
		return;
	}
#endif

	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
				&crash_size, &crash_base);
	if (ret || !crash_size)
		return;

	crash_size = PAGE_ALIGN(crash_size);

	if (crash_base) {
		search_start = crash_base;
		search_end = crash_base + crash_size;
	}

	/*
	 * Current riscv boot protocol requires 2MB alignment for
	 * RV64 and 4MB alignment for RV32 (hugepage size)
	 */
	crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE,
					       search_start, search_end);
	if (crash_base == 0) {
		pr_warn("crashkernel: couldn't allocate %lldKB\n",
			crash_size >> 10);
		return;
	}

	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;
}
#endif /* CONFIG_KEXEC_CORE */

void __init paging_init(void)
{
	setup_bootmem();
	setup_vm_final();
}

void __init misc_mem_init(void)
{
	early_memtest(min_low_pfn << PAGE_SHIFT, max_low_pfn << PAGE_SHIFT);
	arch_numa_init();
	sparse_init();
	zone_sizes_init();
#ifdef CONFIG_KEXEC_CORE
	reserve_crashkernel();
#endif
	memblock_dump_all();
}

#ifdef CONFIG_SPARSEMEM_VMEMMAP
int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
			       struct vmem_altmap *altmap)
{
	return vmemmap_populate_basepages(start, end, node, NULL);
}
#endif