arch/ia64/mm/init.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Initialize MMU support.
  *
  * Copyright (C) 1998-2003 Hewlett-Packard Co
  *	David Mosberger-Tang <davidm@hpl.hp.com>
  */
 #include <linux/kernel.h>
 #include <linux/init.h>

 #include <linux/dma-map-ops.h>
 #include <linux/dmar.h>
 #include <linux/efi.h>
 #include <linux/elf.h>
 #include <linux/memblock.h>
 #include <linux/mm.h>
 #include <linux/sched/signal.h>
 #include <linux/mmzone.h>
 #include <linux/module.h>
 #include <linux/personality.h>
 #include <linux/reboot.h>
 #include <linux/slab.h>
 #include <linux/swap.h>
 #include <linux/proc_fs.h>
 #include <linux/bitops.h>
 #include <linux/kexec.h>
 #include <linux/swiotlb.h>

 #include <asm/dma.h>
 #include <asm/efi.h>
 #include <asm/io.h>
 #include <asm/numa.h>
 #include <asm/patch.h>
 #include <asm/pgalloc.h>
 #include <asm/sal.h>
 #include <asm/sections.h>
 #include <asm/tlb.h>
 #include <linux/uaccess.h>
 #include <asm/unistd.h>
 #include <asm/mca.h>

 extern void ia64_tlb_init (void);

 unsigned long MAX_DMA_ADDRESS = PAGE_OFFSET + 0x100000000UL;

 struct page *zero_page_memmap_ptr;	/* map entry for zero page */
 EXPORT_SYMBOL(zero_page_memmap_ptr);

 void
 __ia64_sync_icache_dcache (pte_t pte)
 {
 	unsigned long addr;
 	struct folio *folio;

 	folio = page_folio(pte_page(pte));
 	addr = (unsigned long)folio_address(folio);

 	if (test_bit(PG_arch_1, &folio->flags))
 		return;				/* i-cache is already coherent with d-cache */

 	flush_icache_range(addr, addr + folio_size(folio));
 	set_bit(PG_arch_1, &folio->flags);	/* mark page as clean */
 }

 /*
  * Since DMA is i-cache coherent, any (complete) folios that were written via
  * DMA can be marked as "clean" so that lazy_mmu_prot_update() doesn't have to
  * flush them when they get mapped into an executable vm-area.
  */
 void arch_dma_mark_clean(phys_addr_t paddr, size_t size)
 {
 	unsigned long pfn = PHYS_PFN(paddr);
 	struct folio *folio = page_folio(pfn_to_page(pfn));
 	ssize_t left = size;
 	size_t offset = offset_in_folio(folio, paddr);

 	if (offset) {
 		left -= folio_size(folio) - offset;
 		if (left <= 0)
 			return;
 		folio = folio_next(folio);
 	}

 	while (left >= (ssize_t)folio_size(folio)) {
 		left -= folio_size(folio);
 		set_bit(PG_arch_1, &pfn_to_page(pfn)->flags);
 		if (!left)
 			break;
 		folio = folio_next(folio);
 	}
 }

 inline void
 ia64_set_rbs_bot (void)
 {
 	unsigned long stack_size = rlimit_max(RLIMIT_STACK) & -16;

 	if (stack_size > MAX_USER_STACK_SIZE)
 		stack_size = MAX_USER_STACK_SIZE;
 	current->thread.rbs_bot = PAGE_ALIGN(current->mm->start_stack - stack_size);
 }

 /*
  * This performs some platform-dependent address space initialization.
  * On IA-64, we want to setup the VM area for the register backing
  * store (which grows upwards) and install the gateway page which is
  * used for signal trampolines, etc.
  */
 void
 ia64_init_addr_space (void)
 {
 	struct vm_area_struct *vma;

 	ia64_set_rbs_bot();

 	/*
 	 * If we're out of memory and kmem_cache_alloc() returns NULL, we simply ignore
 	 * the problem.  When the process attempts to write to the register backing store
 	 * for the first time, it will get a SEGFAULT in this case.
 	 */
 	vma = vm_area_alloc(current->mm);
 	if (vma) {
 		vma_set_anonymous(vma);
 		vma->vm_start = current->thread.rbs_bot & PAGE_MASK;
 		vma->vm_end = vma->vm_start + PAGE_SIZE;
 		vm_flags_init(vma, VM_DATA_DEFAULT_FLAGS|VM_GROWSUP|VM_ACCOUNT);
 		vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 		mmap_write_lock(current->mm);
 		if (insert_vm_struct(current->mm, vma)) {
 			mmap_write_unlock(current->mm);
 			vm_area_free(vma);
 			return;
 		}
 		mmap_write_unlock(current->mm);
 	}

 	/* map NaT-page at address zero to speed up speculative dereferencing of NULL: */
 	if (!(current->personality & MMAP_PAGE_ZERO)) {
 		vma = vm_area_alloc(current->mm);
 		if (vma) {
 			vma_set_anonymous(vma);
 			vma->vm_end = PAGE_SIZE;
 			vma->vm_page_prot = __pgprot(pgprot_val(PAGE_READONLY) | _PAGE_MA_NAT);
 			vm_flags_init(vma, VM_READ | VM_MAYREAD | VM_IO |
 				      VM_DONTEXPAND | VM_DONTDUMP);
 			mmap_write_lock(current->mm);
 			if (insert_vm_struct(current->mm, vma)) {
 				mmap_write_unlock(current->mm);
 				vm_area_free(vma);
 				return;
 			}
 			mmap_write_unlock(current->mm);
 		}
 	}
 }

 void
 free_initmem (void)
 {
 	free_reserved_area(ia64_imva(__init_begin), ia64_imva(__init_end),
 			   -1, "unused kernel");
 }

 void __init
 free_initrd_mem (unsigned long start, unsigned long end)
 {
 	/*
 	 * EFI uses 4KB pages while the kernel can use 4KB or bigger.
 	 * Thus EFI and the kernel may have different page sizes. It is
 	 * therefore possible to have the initrd share the same page as
 	 * the end of the kernel (given current setup).
 	 *
 	 * To avoid freeing/using the wrong page (kernel sized) we:
 	 *	- align up the beginning of initrd
 	 *	- align down the end of initrd
 	 *
 	 *  |             |
 	 *  |=============| a000
 	 *  |             |
 	 *  |             |
 	 *  |             | 9000
 	 *  |/////////////|
 	 *  |/////////////|
 	 *  |=============| 8000
 	 *  |///INITRD////|
 	 *  |/////////////|
 	 *  |/////////////| 7000
 	 *  |             |
 	 *  |KKKKKKKKKKKKK|
 	 *  |=============| 6000
 	 *  |KKKKKKKKKKKKK|
 	 *  |KKKKKKKKKKKKK|
 	 *  K=kernel using 8KB pages
 	 *
 	 * In this example, we must free page 8000 ONLY. So we must align up
 	 * initrd_start and keep initrd_end as is.
 	 */
 	start = PAGE_ALIGN(start);
 	end = end & PAGE_MASK;

 	if (start < end)
 		printk(KERN_INFO "Freeing initrd memory: %ldkB freed\n", (end - start) >> 10);

 	for (; start < end; start += PAGE_SIZE) {
 		if (!virt_addr_valid(start))
 			continue;
 		free_reserved_page(virt_to_page(start));
 	}
 }

 /*
  * This installs a clean page in the kernel's page table.
  */
 static struct page * __init
 put_kernel_page (struct page *page, unsigned long address, pgprot_t pgprot)
 {
 	pgd_t *pgd;
 	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;

 	pgd = pgd_offset_k(address);		/* note: this is NOT pgd_offset()! */

 	{
 		p4d = p4d_alloc(&init_mm, pgd, address);
 		if (!p4d)
 			goto out;
 		pud = pud_alloc(&init_mm, p4d, address);
 		if (!pud)
 			goto out;
 		pmd = pmd_alloc(&init_mm, pud, address);
 		if (!pmd)
 			goto out;
 		pte = pte_alloc_kernel(pmd, address);
 		if (!pte)
 			goto out;
 		if (!pte_none(*pte))
 			goto out;
 		set_pte(pte, mk_pte(page, pgprot));
 	}
   out:
 	/* no need for flush_tlb */
 	return page;
 }

 static void __init
 setup_gate (void)
 {
 	struct page *page;

 	/*
 	 * Map the gate page twice: once read-only to export the ELF
 	 * headers etc. and once execute-only page to enable
 	 * privilege-promotion via "epc":
 	 */
 	page = virt_to_page(ia64_imva(__start_gate_section));
 	put_kernel_page(page, GATE_ADDR, PAGE_READONLY);
 #ifdef HAVE_BUGGY_SEGREL
 	page = virt_to_page(ia64_imva(__start_gate_section + PAGE_SIZE));
 	put_kernel_page(page, GATE_ADDR + PAGE_SIZE, PAGE_GATE);
 #else
 	put_kernel_page(page, GATE_ADDR + PERCPU_PAGE_SIZE, PAGE_GATE);
 	/* Fill in the holes (if any) with read-only zero pages: */
 	{
 		unsigned long addr;

 		for (addr = GATE_ADDR + PAGE_SIZE;
 		     addr < GATE_ADDR + PERCPU_PAGE_SIZE;
 		     addr += PAGE_SIZE)
 		{
 			put_kernel_page(ZERO_PAGE(0), addr,
 					PAGE_READONLY);
 			put_kernel_page(ZERO_PAGE(0), addr + PERCPU_PAGE_SIZE,
 					PAGE_READONLY);
 		}
 	}
 #endif
 	ia64_patch_gate();
 }

 static struct vm_area_struct gate_vma;

 static int __init gate_vma_init(void)
 {
 	vma_init(&gate_vma, NULL);
 	gate_vma.vm_start = FIXADDR_USER_START;
 	gate_vma.vm_end = FIXADDR_USER_END;
 	vm_flags_init(&gate_vma, VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC);
 	gate_vma.vm_page_prot = __pgprot(__ACCESS_BITS | _PAGE_PL_3 | _PAGE_AR_RX);

 	return 0;
 }
 __initcall(gate_vma_init);

 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
 {
 	return &gate_vma;
 }

 int in_gate_area_no_mm(unsigned long addr)
 {
 	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
 		return 1;
 	return 0;
 }

 int in_gate_area(struct mm_struct *mm, unsigned long addr)
 {
 	return in_gate_area_no_mm(addr);
 }

 void ia64_mmu_init(void *my_cpu_data)
 {
 	unsigned long pta, impl_va_bits;
 	extern void tlb_init(void);

 #ifdef CONFIG_DISABLE_VHPT
 #	define VHPT_ENABLE_BIT	0
 #else
 #	define VHPT_ENABLE_BIT	1
 #endif

 	/*
 	 * Check if the virtually mapped linear page table (VMLPT) overlaps with a mapped
 	 * address space.  The IA-64 architecture guarantees that at least 50 bits of
 	 * virtual address space are implemented but if we pick a large enough page size
 	 * (e.g., 64KB), the mapped address space is big enough that it will overlap with
 	 * VMLPT.  I assume that once we run on machines big enough to warrant 64KB pages,
 	 * IMPL_VA_MSB will be significantly bigger, so this is unlikely to become a
 	 * problem in practice.  Alternatively, we could truncate the top of the mapped
 	 * address space to not permit mappings that would overlap with the VMLPT.
 	 * --davidm 00/12/06
 	 */
 #	define pte_bits			3
 #	define mapped_space_bits	(3*(PAGE_SHIFT - pte_bits) + PAGE_SHIFT)
 	/*
 	 * The virtual page table has to cover the entire implemented address space within
 	 * a region even though not all of this space may be mappable.  The reason for
 	 * this is that the Access bit and Dirty bit fault handlers perform
 	 * non-speculative accesses to the virtual page table, so the address range of the
 	 * virtual page table itself needs to be covered by virtual page table.
 	 */
 #	define vmlpt_bits		(impl_va_bits - PAGE_SHIFT + pte_bits)
 #	define POW2(n)			(1ULL << (n))

 	impl_va_bits = ffz(~(local_cpu_data->unimpl_va_mask | (7UL << 61)));

 	if (impl_va_bits < 51 || impl_va_bits > 61)
 		panic("CPU has bogus IMPL_VA_MSB value of %lu!\n", impl_va_bits - 1);
 	/*
 	 * mapped_space_bits - PAGE_SHIFT is the total number of ptes we need,
 	 * which must fit into "vmlpt_bits - pte_bits" slots. Second half of
 	 * the test makes sure that our mapped space doesn't overlap the
 	 * unimplemented hole in the middle of the region.
 	 */
 	if ((mapped_space_bits - PAGE_SHIFT > vmlpt_bits - pte_bits) ||
 	    (mapped_space_bits > impl_va_bits - 1))
 		panic("Cannot build a big enough virtual-linear page table"
 		      " to cover mapped address space.\n"
 		      " Try using a smaller page size.\n");


 	/* place the VMLPT at the end of each page-table mapped region: */
 	pta = POW2(61) - POW2(vmlpt_bits);

 	/*
 	 * Set the (virtually mapped linear) page table address.  Bit
 	 * 8 selects between the short and long format, bits 2-7 the
 	 * size of the table, and bit 0 whether the VHPT walker is
 	 * enabled.
 	 */
 	ia64_set_pta(pta | (0 << 8) | (vmlpt_bits << 2) | VHPT_ENABLE_BIT);

 	ia64_tlb_init();

 #ifdef	CONFIG_HUGETLB_PAGE
 	ia64_set_rr(HPAGE_REGION_BASE, HPAGE_SHIFT << 2);
 	ia64_srlz_d();
 #endif
 }

 int __init register_active_ranges(u64 start, u64 len, int nid)
 {
 	u64 end = start + len;

 #ifdef CONFIG_KEXEC
 	if (start > crashk_res.start && start < crashk_res.end)
 		start = crashk_res.end;
 	if (end > crashk_res.start && end < crashk_res.end)
 		end = crashk_res.start;
 #endif

 	if (start < end)
 		memblock_add_node(__pa(start), end - start, nid, MEMBLOCK_NONE);
 	return 0;
 }

 int
 find_max_min_low_pfn (u64 start, u64 end, void *arg)
 {
 	unsigned long pfn_start, pfn_end;
 #ifdef CONFIG_FLATMEM
 	pfn_start = (PAGE_ALIGN(__pa(start))) >> PAGE_SHIFT;
 	pfn_end = (PAGE_ALIGN(__pa(end - 1))) >> PAGE_SHIFT;
 #else
 	pfn_start = GRANULEROUNDDOWN(__pa(start)) >> PAGE_SHIFT;
 	pfn_end = GRANULEROUNDUP(__pa(end - 1)) >> PAGE_SHIFT;
 #endif
 	min_low_pfn = min(min_low_pfn, pfn_start);
 	max_low_pfn = max(max_low_pfn, pfn_end);
 	return 0;
 }

 /*
  * Boot command-line option "nolwsys" can be used to disable the use of any light-weight
  * system call handler.  When this option is in effect, all fsyscalls will end up bubbling
  * down into the kernel and calling the normal (heavy-weight) syscall handler.  This is
  * useful for performance testing, but conceivably could also come in handy for debugging
  * purposes.
  */

 static int nolwsys __initdata;

 static int __init
 nolwsys_setup (char *s)
 {
 	nolwsys = 1;
 	return 1;
 }

 __setup("nolwsys", nolwsys_setup);

 void __init
 mem_init (void)
 {
 	int i;

 	BUG_ON(PTRS_PER_PGD * sizeof(pgd_t) != PAGE_SIZE);
 	BUG_ON(PTRS_PER_PMD * sizeof(pmd_t) != PAGE_SIZE);
 	BUG_ON(PTRS_PER_PTE * sizeof(pte_t) != PAGE_SIZE);

 	/*
 	 * This needs to be called _after_ the command line has been parsed but
 	 * _before_ any drivers that may need the PCI DMA interface are
 	 * initialized or bootmem has been freed.
 	 */
 	do {
 #ifdef CONFIG_INTEL_IOMMU
 		detect_intel_iommu();
 		if (iommu_detected)
 			break;
 #endif
 		swiotlb_init(true, SWIOTLB_VERBOSE);
 	} while (0);

 #ifdef CONFIG_FLATMEM
 	BUG_ON(!mem_map);
 #endif

 	set_max_mapnr(max_low_pfn);
 	high_memory = __va(max_low_pfn * PAGE_SIZE);
 	memblock_free_all();

 	/*
 	 * For fsyscall entrypoints with no light-weight handler, use the ordinary
 	 * (heavy-weight) handler, but mark it by setting bit 0, so the fsyscall entry
 	 * code can tell them apart.
 	 */
 	for (i = 0; i < NR_syscalls; ++i) {
 		extern unsigned long fsyscall_table[NR_syscalls];
 		extern unsigned long sys_call_table[NR_syscalls];

 		if (!fsyscall_table[i] || nolwsys)
 			fsyscall_table[i] = sys_call_table[i] | 1;
 	}
 	setup_gate();
 }

 #ifdef CONFIG_MEMORY_HOTPLUG
 int arch_add_memory(int nid, u64 start, u64 size,
 		    struct mhp_params *params)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	int ret;

 	if (WARN_ON_ONCE(params->pgprot.pgprot != PAGE_KERNEL.pgprot))
 		return -EINVAL;

 	ret = __add_pages(nid, start_pfn, nr_pages, params);
 	if (ret)
 		printk("%s: Problem encountered in __add_pages() as ret=%d\n",
 		       __func__,  ret);

 	return ret;
 }

 void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;

 	__remove_pages(start_pfn, nr_pages, altmap);
 }
 #endif

 static const pgprot_t protection_map[16] = {
 	[VM_NONE]					= PAGE_NONE,
 	[VM_READ]					= PAGE_READONLY,
 	[VM_WRITE]					= PAGE_READONLY,
 	[VM_WRITE | VM_READ]				= PAGE_READONLY,
 	[VM_EXEC]					= __pgprot(__ACCESS_BITS | _PAGE_PL_3 |
 								   _PAGE_AR_X_RX),
 	[VM_EXEC | VM_READ]				= __pgprot(__ACCESS_BITS | _PAGE_PL_3 |
 								   _PAGE_AR_RX),
 	[VM_EXEC | VM_WRITE]				= PAGE_COPY_EXEC,
 	[VM_EXEC | VM_WRITE | VM_READ]			= PAGE_COPY_EXEC,
 	[VM_SHARED]					= PAGE_NONE,
 	[VM_SHARED | VM_READ]				= PAGE_READONLY,
 	[VM_SHARED | VM_WRITE]				= PAGE_SHARED,
 	[VM_SHARED | VM_WRITE | VM_READ]		= PAGE_SHARED,
 	[VM_SHARED | VM_EXEC]				= __pgprot(__ACCESS_BITS | _PAGE_PL_3 |
 								   _PAGE_AR_X_RX),
 	[VM_SHARED | VM_EXEC | VM_READ]			= __pgprot(__ACCESS_BITS | _PAGE_PL_3 |
 								   _PAGE_AR_RX),
 	[VM_SHARED | VM_EXEC | VM_WRITE]		= __pgprot(__ACCESS_BITS | _PAGE_PL_3 |
 								   _PAGE_AR_RWX),
 	[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]	= __pgprot(__ACCESS_BITS | _PAGE_PL_3 |
 								   _PAGE_AR_RWX)
 };
 DECLARE_VM_GET_PAGE_PROT
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Initialize MMU support.
	*
	* Copyright (C) 1998-2003 Hewlett-Packard Co
	* David Mosberger-Tang <davidm@hpl.hp.com>
	*/
	#include <linux/kernel.h>
	#include <linux/init.h>

	#include <linux/dma-map-ops.h>
	#include <linux/dmar.h>
	#include <linux/efi.h>
	#include <linux/elf.h>
	#include <linux/memblock.h>
	#include <linux/mm.h>
	#include <linux/sched/signal.h>
	#include <linux/mmzone.h>
	#include <linux/module.h>
	#include <linux/personality.h>
	#include <linux/reboot.h>
	#include <linux/slab.h>
	#include <linux/swap.h>
	#include <linux/proc_fs.h>
	#include <linux/bitops.h>
	#include <linux/kexec.h>
	#include <linux/swiotlb.h>

	#include <asm/dma.h>
	#include <asm/efi.h>
	#include <asm/io.h>
	#include <asm/numa.h>
	#include <asm/patch.h>
	#include <asm/pgalloc.h>
	#include <asm/sal.h>
	#include <asm/sections.h>
	#include <asm/tlb.h>
	#include <linux/uaccess.h>
	#include <asm/unistd.h>
	#include <asm/mca.h>

	extern void ia64_tlb_init (void);

	unsigned long MAX_DMA_ADDRESS = PAGE_OFFSET + 0x100000000UL;

	struct page zero_page_memmap_ptr; / map entry for zero page */
	EXPORT_SYMBOL(zero_page_memmap_ptr);

	void
	__ia64_sync_icache_dcache (pte_t pte)
	{
	unsigned long addr;
	struct folio *folio;

	folio = page_folio(pte_page(pte));
	addr = (unsigned long)folio_address(folio);

	if (test_bit(PG_arch_1, &folio->flags))
	return; /* i-cache is already coherent with d-cache */

	flush_icache_range(addr, addr + folio_size(folio));
	set_bit(PG_arch_1, &folio->flags); /* mark page as clean */
	}

	/*
	* Since DMA is i-cache coherent, any (complete) folios that were written via
	* DMA can be marked as "clean" so that lazy_mmu_prot_update() doesn't have to
	* flush them when they get mapped into an executable vm-area.
	*/
	void arch_dma_mark_clean(phys_addr_t paddr, size_t size)
	{
	unsigned long pfn = PHYS_PFN(paddr);
	struct folio *folio = page_folio(pfn_to_page(pfn));
	ssize_t left = size;
	size_t offset = offset_in_folio(folio, paddr);

	if (offset) {
	left -= folio_size(folio) - offset;
	if (left <= 0)
	return;
	folio = folio_next(folio);
	}

	while (left >= (ssize_t)folio_size(folio)) {
	left -= folio_size(folio);
	set_bit(PG_arch_1, &pfn_to_page(pfn)->flags);
	if (!left)
	break;
	folio = folio_next(folio);
	}
	}

	inline void
	ia64_set_rbs_bot (void)
	{
	unsigned long stack_size = rlimit_max(RLIMIT_STACK) & -16;

	if (stack_size > MAX_USER_STACK_SIZE)
	stack_size = MAX_USER_STACK_SIZE;
	current->thread.rbs_bot = PAGE_ALIGN(current->mm->start_stack - stack_size);
	}

	/*
	* This performs some platform-dependent address space initialization.
	* On IA-64, we want to setup the VM area for the register backing
	* store (which grows upwards) and install the gateway page which is
	* used for signal trampolines, etc.
	*/
	void
	ia64_init_addr_space (void)
	{
	struct vm_area_struct *vma;

	ia64_set_rbs_bot();

	/*
	* If we're out of memory and kmem_cache_alloc() returns NULL, we simply ignore
	* the problem. When the process attempts to write to the register backing store
	* for the first time, it will get a SEGFAULT in this case.
	*/
	vma = vm_area_alloc(current->mm);
	if (vma) {
	vma_set_anonymous(vma);
	vma->vm_start = current->thread.rbs_bot & PAGE_MASK;
	vma->vm_end = vma->vm_start + PAGE_SIZE;
	vm_flags_init(vma, VM_DATA_DEFAULT_FLAGS\|VM_GROWSUP\|VM_ACCOUNT);
	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
	mmap_write_lock(current->mm);
	if (insert_vm_struct(current->mm, vma)) {
	mmap_write_unlock(current->mm);
	vm_area_free(vma);
	return;
	}
	mmap_write_unlock(current->mm);
	}

	/* map NaT-page at address zero to speed up speculative dereferencing of NULL: */
	if (!(current->personality & MMAP_PAGE_ZERO)) {
	vma = vm_area_alloc(current->mm);
	if (vma) {
	vma_set_anonymous(vma);
	vma->vm_end = PAGE_SIZE;
	vma->vm_page_prot = __pgprot(pgprot_val(PAGE_READONLY) \| _PAGE_MA_NAT);
	vm_flags_init(vma, VM_READ \| VM_MAYREAD \| VM_IO \|
	VM_DONTEXPAND \| VM_DONTDUMP);
	mmap_write_lock(current->mm);
	if (insert_vm_struct(current->mm, vma)) {
	mmap_write_unlock(current->mm);
	vm_area_free(vma);
	return;
	}
	mmap_write_unlock(current->mm);
	}
	}
	}

	void
	free_initmem (void)
	{
	free_reserved_area(ia64_imva(__init_begin), ia64_imva(__init_end),
	-1, "unused kernel");
	}

	void __init
	free_initrd_mem (unsigned long start, unsigned long end)
	{
	/*
	* EFI uses 4KB pages while the kernel can use 4KB or bigger.
	* Thus EFI and the kernel may have different page sizes. It is
	* therefore possible to have the initrd share the same page as
	* the end of the kernel (given current setup).
	*
	* To avoid freeing/using the wrong page (kernel sized) we:
	* - align up the beginning of initrd
	* - align down the end of initrd
	*
	* \| \|
	* \|=============\| a000
	* \| \|
	* \| \|
	* \| \| 9000
	* \|/////////////\|
	* \|/////////////\|
	* \|=============\| 8000
	* \|///INITRD////\|
	* \|/////////////\|
	* \|/////////////\| 7000
	* \| \|
	* \|KKKKKKKKKKKKK\|
	* \|=============\| 6000
	* \|KKKKKKKKKKKKK\|
	* \|KKKKKKKKKKKKK\|
	* K=kernel using 8KB pages
	*
	* In this example, we must free page 8000 ONLY. So we must align up
	* initrd_start and keep initrd_end as is.
	*/
	start = PAGE_ALIGN(start);
	end = end & PAGE_MASK;

	if (start < end)
	printk(KERN_INFO "Freeing initrd memory: %ldkB freed\n", (end - start) >> 10);

	for (; start < end; start += PAGE_SIZE) {
	if (!virt_addr_valid(start))
	continue;
	free_reserved_page(virt_to_page(start));
	}
	}

	/*
	* This installs a clean page in the kernel's page table.
	*/
	static struct page * __init
	put_kernel_page (struct page *page, unsigned long address, pgprot_t pgprot)
	{
	pgd_t *pgd;
	p4d_t *p4d;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	pgd = pgd_offset_k(address); /* note: this is NOT pgd_offset()! */

	{
	p4d = p4d_alloc(&init_mm, pgd, address);
	if (!p4d)
	goto out;
	pud = pud_alloc(&init_mm, p4d, address);
	if (!pud)
	goto out;
	pmd = pmd_alloc(&init_mm, pud, address);
	if (!pmd)
	goto out;
	pte = pte_alloc_kernel(pmd, address);
	if (!pte)
	goto out;
	if (!pte_none(*pte))
	goto out;
	set_pte(pte, mk_pte(page, pgprot));
	}
	out:
	/* no need for flush_tlb */
	return page;
	}

	static void __init
	setup_gate (void)
	{
	struct page *page;

	/*
	* Map the gate page twice: once read-only to export the ELF
	* headers etc. and once execute-only page to enable
	* privilege-promotion via "epc":
	*/
	page = virt_to_page(ia64_imva(__start_gate_section));
	put_kernel_page(page, GATE_ADDR, PAGE_READONLY);
	#ifdef HAVE_BUGGY_SEGREL
	page = virt_to_page(ia64_imva(__start_gate_section + PAGE_SIZE));
	put_kernel_page(page, GATE_ADDR + PAGE_SIZE, PAGE_GATE);
	#else
	put_kernel_page(page, GATE_ADDR + PERCPU_PAGE_SIZE, PAGE_GATE);
	/* Fill in the holes (if any) with read-only zero pages: */
	{
	unsigned long addr;

	for (addr = GATE_ADDR + PAGE_SIZE;
	addr < GATE_ADDR + PERCPU_PAGE_SIZE;
	addr += PAGE_SIZE)
	{
	put_kernel_page(ZERO_PAGE(0), addr,
	PAGE_READONLY);
	put_kernel_page(ZERO_PAGE(0), addr + PERCPU_PAGE_SIZE,
	PAGE_READONLY);
	}
	}
	#endif
	ia64_patch_gate();
	}

	static struct vm_area_struct gate_vma;

	static int __init gate_vma_init(void)
	{
	vma_init(&gate_vma, NULL);
	gate_vma.vm_start = FIXADDR_USER_START;
	gate_vma.vm_end = FIXADDR_USER_END;
	vm_flags_init(&gate_vma, VM_READ \| VM_MAYREAD \| VM_EXEC \| VM_MAYEXEC);
	gate_vma.vm_page_prot = __pgprot(__ACCESS_BITS \| _PAGE_PL_3 \| _PAGE_AR_RX);

	return 0;
	}
	__initcall(gate_vma_init);

	struct vm_area_struct get_gate_vma(struct mm_struct mm)
	{
	return &gate_vma;
	}

	int in_gate_area_no_mm(unsigned long addr)
	{
	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
	return 1;
	return 0;
	}

	int in_gate_area(struct mm_struct *mm, unsigned long addr)
	{
	return in_gate_area_no_mm(addr);
	}

	void ia64_mmu_init(void *my_cpu_data)
	{
	unsigned long pta, impl_va_bits;
	extern void tlb_init(void);

	#ifdef CONFIG_DISABLE_VHPT
	# define VHPT_ENABLE_BIT 0
	#else
	# define VHPT_ENABLE_BIT 1
	#endif

	/*
	* Check if the virtually mapped linear page table (VMLPT) overlaps with a mapped
	* address space. The IA-64 architecture guarantees that at least 50 bits of
	* virtual address space are implemented but if we pick a large enough page size
	* (e.g., 64KB), the mapped address space is big enough that it will overlap with
	* VMLPT. I assume that once we run on machines big enough to warrant 64KB pages,
	* IMPL_VA_MSB will be significantly bigger, so this is unlikely to become a
	* problem in practice. Alternatively, we could truncate the top of the mapped
	* address space to not permit mappings that would overlap with the VMLPT.
	* --davidm 00/12/06
	*/
	# define pte_bits 3
	# define mapped_space_bits (3*(PAGE_SHIFT - pte_bits) + PAGE_SHIFT)
	/*
	* The virtual page table has to cover the entire implemented address space within
	* a region even though not all of this space may be mappable. The reason for
	* this is that the Access bit and Dirty bit fault handlers perform
	* non-speculative accesses to the virtual page table, so the address range of the
	* virtual page table itself needs to be covered by virtual page table.
	*/
	# define vmlpt_bits (impl_va_bits - PAGE_SHIFT + pte_bits)
	# define POW2(n) (1ULL << (n))

	impl_va_bits = ffz(~(local_cpu_data->unimpl_va_mask \| (7UL << 61)));

	if (impl_va_bits < 51 \|\| impl_va_bits > 61)
	panic("CPU has bogus IMPL_VA_MSB value of %lu!\n", impl_va_bits - 1);
	/*
	* mapped_space_bits - PAGE_SHIFT is the total number of ptes we need,
	* which must fit into "vmlpt_bits - pte_bits" slots. Second half of
	* the test makes sure that our mapped space doesn't overlap the
	* unimplemented hole in the middle of the region.
	*/
	if ((mapped_space_bits - PAGE_SHIFT > vmlpt_bits - pte_bits) \|\|
	(mapped_space_bits > impl_va_bits - 1))
	panic("Cannot build a big enough virtual-linear page table"
	" to cover mapped address space.\n"
	" Try using a smaller page size.\n");


	/* place the VMLPT at the end of each page-table mapped region: */
	pta = POW2(61) - POW2(vmlpt_bits);

	/*
	* Set the (virtually mapped linear) page table address. Bit
	* 8 selects between the short and long format, bits 2-7 the
	* size of the table, and bit 0 whether the VHPT walker is
	* enabled.
	*/
	ia64_set_pta(pta \| (0 << 8) \| (vmlpt_bits << 2) \| VHPT_ENABLE_BIT);

	ia64_tlb_init();

	#ifdef CONFIG_HUGETLB_PAGE
	ia64_set_rr(HPAGE_REGION_BASE, HPAGE_SHIFT << 2);
	ia64_srlz_d();
	#endif
	}

	int __init register_active_ranges(u64 start, u64 len, int nid)
	{
	u64 end = start + len;

	#ifdef CONFIG_KEXEC
	if (start > crashk_res.start && start < crashk_res.end)
	start = crashk_res.end;
	if (end > crashk_res.start && end < crashk_res.end)
	end = crashk_res.start;
	#endif

	if (start < end)
	memblock_add_node(__pa(start), end - start, nid, MEMBLOCK_NONE);
	return 0;
	}

	int
	find_max_min_low_pfn (u64 start, u64 end, void *arg)
	{
	unsigned long pfn_start, pfn_end;
	#ifdef CONFIG_FLATMEM
	pfn_start = (PAGE_ALIGN(__pa(start))) >> PAGE_SHIFT;
	pfn_end = (PAGE_ALIGN(__pa(end - 1))) >> PAGE_SHIFT;
	#else
	pfn_start = GRANULEROUNDDOWN(__pa(start)) >> PAGE_SHIFT;
	pfn_end = GRANULEROUNDUP(__pa(end - 1)) >> PAGE_SHIFT;
	#endif
	min_low_pfn = min(min_low_pfn, pfn_start);
	max_low_pfn = max(max_low_pfn, pfn_end);
	return 0;
	}

	/*
	* Boot command-line option "nolwsys" can be used to disable the use of any light-weight
	* system call handler. When this option is in effect, all fsyscalls will end up bubbling
	* down into the kernel and calling the normal (heavy-weight) syscall handler. This is
	* useful for performance testing, but conceivably could also come in handy for debugging
	* purposes.
	*/

	static int nolwsys __initdata;

	static int __init
	nolwsys_setup (char *s)
	{
	nolwsys = 1;
	return 1;
	}

	__setup("nolwsys", nolwsys_setup);

	void __init
	mem_init (void)
	{
	int i;

	BUG_ON(PTRS_PER_PGD * sizeof(pgd_t) != PAGE_SIZE);
	BUG_ON(PTRS_PER_PMD * sizeof(pmd_t) != PAGE_SIZE);
	BUG_ON(PTRS_PER_PTE * sizeof(pte_t) != PAGE_SIZE);

	/*
	* This needs to be called _after_ the command line has been parsed but
	* _before_ any drivers that may need the PCI DMA interface are
	* initialized or bootmem has been freed.
	*/
	do {
	#ifdef CONFIG_INTEL_IOMMU
	detect_intel_iommu();
	if (iommu_detected)
	break;
	#endif
	swiotlb_init(true, SWIOTLB_VERBOSE);
	} while (0);

	#ifdef CONFIG_FLATMEM
	BUG_ON(!mem_map);
	#endif

	set_max_mapnr(max_low_pfn);
	high_memory = __va(max_low_pfn * PAGE_SIZE);
	memblock_free_all();

	/*
	* For fsyscall entrypoints with no light-weight handler, use the ordinary
	* (heavy-weight) handler, but mark it by setting bit 0, so the fsyscall entry
	* code can tell them apart.
	*/
	for (i = 0; i < NR_syscalls; ++i) {
	extern unsigned long fsyscall_table[NR_syscalls];
	extern unsigned long sys_call_table[NR_syscalls];

	if (!fsyscall_table[i] \|\| nolwsys)
	fsyscall_table[i] = sys_call_table[i] \| 1;
	}
	setup_gate();
	}

	#ifdef CONFIG_MEMORY_HOTPLUG
	int arch_add_memory(int nid, u64 start, u64 size,
	struct mhp_params *params)
	{
	unsigned long start_pfn = start >> PAGE_SHIFT;
	unsigned long nr_pages = size >> PAGE_SHIFT;
	int ret;

	if (WARN_ON_ONCE(params->pgprot.pgprot != PAGE_KERNEL.pgprot))
	return -EINVAL;

	ret = __add_pages(nid, start_pfn, nr_pages, params);
	if (ret)
	printk("%s: Problem encountered in __add_pages() as ret=%d\n",
	__func__, ret);

	return ret;
	}

	void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
	{
	unsigned long start_pfn = start >> PAGE_SHIFT;
	unsigned long nr_pages = size >> PAGE_SHIFT;

	__remove_pages(start_pfn, nr_pages, altmap);
	}
	#endif

	static const pgprot_t protection_map[16] = {
	[VM_NONE] = PAGE_NONE,
	[VM_READ] = PAGE_READONLY,
	[VM_WRITE] = PAGE_READONLY,
	[VM_WRITE \| VM_READ] = PAGE_READONLY,
	[VM_EXEC] = __pgprot(__ACCESS_BITS \| _PAGE_PL_3 \|
	_PAGE_AR_X_RX),
	[VM_EXEC \| VM_READ] = __pgprot(__ACCESS_BITS \| _PAGE_PL_3 \|
	_PAGE_AR_RX),
	[VM_EXEC \| VM_WRITE] = PAGE_COPY_EXEC,
	[VM_EXEC \| VM_WRITE \| VM_READ] = PAGE_COPY_EXEC,
	[VM_SHARED] = PAGE_NONE,
	[VM_SHARED \| VM_READ] = PAGE_READONLY,
	[VM_SHARED \| VM_WRITE] = PAGE_SHARED,
	[VM_SHARED \| VM_WRITE \| VM_READ] = PAGE_SHARED,
	[VM_SHARED \| VM_EXEC] = __pgprot(__ACCESS_BITS \| _PAGE_PL_3 \|
	_PAGE_AR_X_RX),
	[VM_SHARED \| VM_EXEC \| VM_READ] = __pgprot(__ACCESS_BITS \| _PAGE_PL_3 \|
	_PAGE_AR_RX),
	[VM_SHARED \| VM_EXEC \| VM_WRITE] = __pgprot(__ACCESS_BITS \| _PAGE_PL_3 \|
	_PAGE_AR_RWX),
	[VM_SHARED \| VM_EXEC \| VM_WRITE \| VM_READ] = __pgprot(__ACCESS_BITS \| _PAGE_PL_3 \|
	_PAGE_AR_RWX)
	};
	DECLARE_VM_GET_PAGE_PROT