arch/x86/mm/hugetlbpage.c

// SPDX-License-Identifier: GPL-2.0
/*
 * IA-32 Huge TLB Page Support for Kernel.
 *
 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
 */

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/sched/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/err.h>
#include <linux/sysctl.h>
#include <linux/compat.h>
#include <asm/mman.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/elf.h>

#ifdef CONFIG_HUGETLB_PAGE
static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
		unsigned long addr, unsigned long len,
		unsigned long pgoff, unsigned long flags)
{
	struct hstate *h = hstate_file(file);
	struct vm_unmapped_area_info info = {};

	info.length = len;
	info.low_limit = get_mmap_base(1);

	/*
	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
	 * in the full address space.
	 */
	info.high_limit = in_32bit_syscall() ?
		task_size_32bit() : task_size_64bit(addr > DEFAULT_MAP_WINDOW);

	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
	return vm_unmapped_area(&info);
}

static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
		unsigned long addr, unsigned long len,
		unsigned long pgoff, unsigned long flags)
{
	struct hstate *h = hstate_file(file);
	struct vm_unmapped_area_info info = {};

	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
	info.length = len;
	info.low_limit = PAGE_SIZE;
	info.high_limit = get_mmap_base(0);

	/*
	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
	 * in the full address space.
	 */
	if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall())
		info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;

	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
	addr = vm_unmapped_area(&info);

	/*
	 * A failed mmap() very likely causes application failure,
	 * so fall back to the bottom-up function here. This scenario
	 * can happen with large stack limits and large mmap()
	 * allocations.
	 */
	if (addr & ~PAGE_MASK) {
		VM_BUG_ON(addr != -ENOMEM);
		info.flags = 0;
		info.low_limit = TASK_UNMAPPED_BASE;
		info.high_limit = TASK_SIZE_LOW;
		addr = vm_unmapped_area(&info);
	}

	return addr;
}

unsigned long
hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
		unsigned long len, unsigned long pgoff, unsigned long flags)
{
	struct hstate *h = hstate_file(file);
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;

	if (len & ~huge_page_mask(h))
		return -EINVAL;

	if (len > TASK_SIZE)
		return -ENOMEM;

	/* No address checking. See comment at mmap_address_hint_valid() */
	if (flags & MAP_FIXED) {
		if (prepare_hugepage_range(file, addr, len))
			return -EINVAL;
		return addr;
	}

	if (addr) {
		addr &= huge_page_mask(h);
		if (!mmap_address_hint_valid(addr, len))
			goto get_unmapped_area;

		vma = find_vma(mm, addr);
		if (!vma || addr + len <= vm_start_gap(vma))
			return addr;
	}

get_unmapped_area:
	if (!test_bit(MMF_TOPDOWN, &mm->flags))
		return hugetlb_get_unmapped_area_bottomup(file, addr, len,
				pgoff, flags);
	else
		return hugetlb_get_unmapped_area_topdown(file, addr, len,
				pgoff, flags);
}
#endif /* CONFIG_HUGETLB_PAGE */

#ifdef CONFIG_X86_64
bool __init arch_hugetlb_valid_size(unsigned long size)
{
	if (size == PMD_SIZE)
		return true;
	else if (size == PUD_SIZE && boot_cpu_has(X86_FEATURE_GBPAGES))
		return true;
	else
		return false;
}

#ifdef CONFIG_CONTIG_ALLOC
static __init int gigantic_pages_init(void)
{
	/* With compaction or CMA we can allocate gigantic pages at runtime */
	if (boot_cpu_has(X86_FEATURE_GBPAGES))
		hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
	return 0;
}
arch_initcall(gigantic_pages_init);
#endif
#endif