1/*
2 * IA-32 Huge TLB Page Support for Kernel.
3 *
4 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
5 */
6
7#include <linux/init.h>
8#include <linux/fs.h>
9#include <linux/mm.h>
10#include <linux/hugetlb.h>
11#include <linux/pagemap.h>
12#include <linux/err.h>
13#include <linux/sysctl.h>
14#include <asm/mman.h>
15#include <asm/tlb.h>
16#include <asm/tlbflush.h>
17#include <asm/pgalloc.h>
18
19#if 0	/* This is just for testing */
20struct page *
21follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
22{
23	unsigned long start = address;
24	int length = 1;
25	int nr;
26	struct page *page;
27	struct vm_area_struct *vma;
28
29	vma = find_vma(mm, addr);
30	if (!vma || !is_vm_hugetlb_page(vma))
31		return ERR_PTR(-EINVAL);
32
33	pte = huge_pte_offset(mm, address);
34
35	/* hugetlb should be locked, and hence, prefaulted */
36	WARN_ON(!pte || pte_none(*pte));
37
38	page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
39
40	WARN_ON(!PageHead(page));
41
42	return page;
43}
44
45int pmd_huge(pmd_t pmd)
46{
47	return 0;
48}
49
50int pud_huge(pud_t pud)
51{
52	return 0;
53}
54
55#else
56
57/*
58 * pmd_huge() returns 1 if @pmd is hugetlb related entry, that is normal
59 * hugetlb entry or non-present (migration or hwpoisoned) hugetlb entry.
60 * Otherwise, returns 0.
61 */
62int pmd_huge(pmd_t pmd)
63{
64	return !pmd_none(pmd) &&
65		(pmd_val(pmd) & (_PAGE_PRESENT|_PAGE_PSE)) != _PAGE_PRESENT;
66}
67
68int pud_huge(pud_t pud)
69{
70	return !!(pud_val(pud) & _PAGE_PSE);
71}
72#endif
73
74#ifdef CONFIG_HUGETLB_PAGE
75static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
76		unsigned long addr, unsigned long len,
77		unsigned long pgoff, unsigned long flags)
78{
79	struct hstate *h = hstate_file(file);
80	struct vm_unmapped_area_info info;
81
82	info.flags = 0;
83	info.length = len;
84	info.low_limit = current->mm->mmap_legacy_base;
85	info.high_limit = TASK_SIZE;
86	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
87	info.align_offset = 0;
88	return vm_unmapped_area(&info);
89}
90
91static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
92		unsigned long addr0, unsigned long len,
93		unsigned long pgoff, unsigned long flags)
94{
95	struct hstate *h = hstate_file(file);
96	struct vm_unmapped_area_info info;
97	unsigned long addr;
98
99	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
100	info.length = len;
101	info.low_limit = PAGE_SIZE;
102	info.high_limit = current->mm->mmap_base;
103	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
104	info.align_offset = 0;
105	addr = vm_unmapped_area(&info);
106
107	/*
108	 * A failed mmap() very likely causes application failure,
109	 * so fall back to the bottom-up function here. This scenario
110	 * can happen with large stack limits and large mmap()
111	 * allocations.
112	 */
113	if (addr & ~PAGE_MASK) {
114		VM_BUG_ON(addr != -ENOMEM);
115		info.flags = 0;
116		info.low_limit = TASK_UNMAPPED_BASE;
117		info.high_limit = TASK_SIZE;
118		addr = vm_unmapped_area(&info);
119	}
120
121	return addr;
122}
123
124unsigned long
125hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
126		unsigned long len, unsigned long pgoff, unsigned long flags)
127{
128	struct hstate *h = hstate_file(file);
129	struct mm_struct *mm = current->mm;
130	struct vm_area_struct *vma;
131
132	if (len & ~huge_page_mask(h))
133		return -EINVAL;
134	if (len > TASK_SIZE)
135		return -ENOMEM;
136
137	if (flags & MAP_FIXED) {
138		if (prepare_hugepage_range(file, addr, len))
139			return -EINVAL;
140		return addr;
141	}
142
143	if (addr) {
144		addr = ALIGN(addr, huge_page_size(h));
145		vma = find_vma(mm, addr);
146		if (TASK_SIZE - len >= addr &&
147		    (!vma || addr + len <= vma->vm_start))
148			return addr;
149	}
150	if (mm->get_unmapped_area == arch_get_unmapped_area)
151		return hugetlb_get_unmapped_area_bottomup(file, addr, len,
152				pgoff, flags);
153	else
154		return hugetlb_get_unmapped_area_topdown(file, addr, len,
155				pgoff, flags);
156}
157#endif /* CONFIG_HUGETLB_PAGE */
158
159#ifdef CONFIG_X86_64
160static __init int setup_hugepagesz(char *opt)
161{
162	unsigned long ps = memparse(opt, &opt);
163	if (ps == PMD_SIZE) {
164		hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
165	} else if (ps == PUD_SIZE && cpu_has_gbpages) {
166		hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
167	} else {
168		printk(KERN_ERR "hugepagesz: Unsupported page size %lu M\n",
169			ps >> 20);
170		return 0;
171	}
172	return 1;
173}
174__setup("hugepagesz=", setup_hugepagesz);
175
176#ifdef CONFIG_CMA
177static __init int gigantic_pages_init(void)
178{
179	/* With CMA we can allocate gigantic pages at runtime */
180	if (cpu_has_gbpages && !size_to_hstate(1UL << PUD_SHIFT))
181		hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
182	return 0;
183}
184arch_initcall(gigantic_pages_init);
185#endif
186#endif
187