2 * IA-32 Huge TLB Page Support for Kernel.
4 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
7 #include <linux/init.h>
10 #include <linux/hugetlb.h>
11 #include <linux/pagemap.h>
12 #include <linux/slab.h>
13 #include <linux/err.h>
14 #include <linux/sysctl.h>
17 #include <asm/tlbflush.h>
18 #include <asm/pgalloc.h>
20 static unsigned long page_table_shareable(struct vm_area_struct *svma,
21 struct vm_area_struct *vma,
22 unsigned long addr, pgoff_t idx)
24 unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) +
26 unsigned long sbase = saddr & PUD_MASK;
27 unsigned long s_end = sbase + PUD_SIZE;
30 * match the virtual addresses, permission and the alignment of the
33 if (pmd_index(addr) != pmd_index(saddr) ||
34 vma->vm_flags != svma->vm_flags ||
35 sbase < svma->vm_start || svma->vm_end < s_end)
41 static int vma_shareable(struct vm_area_struct *vma, unsigned long addr)
43 unsigned long base = addr & PUD_MASK;
44 unsigned long end = base + PUD_SIZE;
47 * check on proper vm_flags and page table alignment
49 if (vma->vm_flags & VM_MAYSHARE &&
50 vma->vm_start <= base && end <= vma->vm_end)
56 * search for a shareable pmd page for hugetlb.
58 static void huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
60 struct vm_area_struct *vma = find_vma(mm, addr);
61 struct address_space *mapping = vma->vm_file->f_mapping;
62 pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
64 struct prio_tree_iter iter;
65 struct vm_area_struct *svma;
69 if (!vma_shareable(vma, addr))
72 spin_lock(&mapping->i_mmap_lock);
73 vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, idx, idx) {
77 saddr = page_table_shareable(svma, vma, addr, idx);
79 spte = huge_pte_offset(svma->vm_mm, saddr);
81 get_page(virt_to_page(spte));
90 spin_lock(&mm->page_table_lock);
92 pud_populate(mm, pud, (pmd_t *)((unsigned long)spte & PAGE_MASK));
94 put_page(virt_to_page(spte));
95 spin_unlock(&mm->page_table_lock);
97 spin_unlock(&mapping->i_mmap_lock);
101 * unmap huge page backed by shared pte.
103 * Hugetlb pte page is ref counted at the time of mapping. If pte is shared
104 * indicated by page_count > 1, unmap is achieved by clearing pud and
105 * decrementing the ref count. If count == 1, the pte page is not shared.
107 * called with vma->vm_mm->page_table_lock held.
109 * returns: 1 successfully unmapped a shared pte page
110 * 0 the underlying pte page is not shared, or it is the last user
112 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
114 pgd_t *pgd = pgd_offset(mm, *addr);
115 pud_t *pud = pud_offset(pgd, *addr);
117 BUG_ON(page_count(virt_to_page(ptep)) == 0);
118 if (page_count(virt_to_page(ptep)) == 1)
122 put_page(virt_to_page(ptep));
123 *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE;
127 pte_t *huge_pte_alloc(struct mm_struct *mm,
128 unsigned long addr, unsigned long sz)
134 pgd = pgd_offset(mm, addr);
135 pud = pud_alloc(mm, pgd, addr);
138 huge_pmd_share(mm, addr, pud);
139 pte = (pte_t *) pmd_alloc(mm, pud, addr);
141 BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte));
146 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
152 pgd = pgd_offset(mm, addr);
153 if (pgd_present(*pgd)) {
154 pud = pud_offset(pgd, addr);
155 if (pud_present(*pud))
156 pmd = pmd_offset(pud, addr);
158 return (pte_t *) pmd;
161 #if 0 /* This is just for testing */
163 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
165 unsigned long start = address;
169 struct vm_area_struct *vma;
171 vma = find_vma(mm, addr);
172 if (!vma || !is_vm_hugetlb_page(vma))
173 return ERR_PTR(-EINVAL);
175 pte = huge_pte_offset(mm, address);
177 /* hugetlb should be locked, and hence, prefaulted */
178 WARN_ON(!pte || pte_none(*pte));
180 page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
182 WARN_ON(!PageHead(page));
187 int pmd_huge(pmd_t pmd)
193 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
194 pmd_t *pmd, int write)
202 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
204 return ERR_PTR(-EINVAL);
207 int pmd_huge(pmd_t pmd)
209 return !!(pmd_val(pmd) & _PAGE_PSE);
213 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
214 pmd_t *pmd, int write)
218 page = pte_page(*(pte_t *)pmd);
220 page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
225 /* x86_64 also uses this file */
227 #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
228 static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
229 unsigned long addr, unsigned long len,
230 unsigned long pgoff, unsigned long flags)
232 struct mm_struct *mm = current->mm;
233 struct vm_area_struct *vma;
234 unsigned long start_addr;
236 if (len > mm->cached_hole_size) {
237 start_addr = mm->free_area_cache;
239 start_addr = TASK_UNMAPPED_BASE;
240 mm->cached_hole_size = 0;
244 addr = ALIGN(start_addr, HPAGE_SIZE);
246 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
247 /* At this point: (!vma || addr < vma->vm_end). */
248 if (TASK_SIZE - len < addr) {
250 * Start a new search - just in case we missed
253 if (start_addr != TASK_UNMAPPED_BASE) {
254 start_addr = TASK_UNMAPPED_BASE;
255 mm->cached_hole_size = 0;
260 if (!vma || addr + len <= vma->vm_start) {
261 mm->free_area_cache = addr + len;
264 if (addr + mm->cached_hole_size < vma->vm_start)
265 mm->cached_hole_size = vma->vm_start - addr;
266 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
270 static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
271 unsigned long addr0, unsigned long len,
272 unsigned long pgoff, unsigned long flags)
274 struct mm_struct *mm = current->mm;
275 struct vm_area_struct *vma, *prev_vma;
276 unsigned long base = mm->mmap_base, addr = addr0;
277 unsigned long largest_hole = mm->cached_hole_size;
280 /* don't allow allocations above current base */
281 if (mm->free_area_cache > base)
282 mm->free_area_cache = base;
284 if (len <= largest_hole) {
286 mm->free_area_cache = base;
289 /* make sure it can fit in the remaining address space */
290 if (mm->free_area_cache < len)
293 /* either no address requested or cant fit in requested address hole */
294 addr = (mm->free_area_cache - len) & HPAGE_MASK;
297 * Lookup failure means no vma is above this address,
298 * i.e. return with success:
300 if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
304 * new region fits between prev_vma->vm_end and
305 * vma->vm_start, use it:
307 if (addr + len <= vma->vm_start &&
308 (!prev_vma || (addr >= prev_vma->vm_end))) {
309 /* remember the address as a hint for next time */
310 mm->cached_hole_size = largest_hole;
311 return (mm->free_area_cache = addr);
313 /* pull free_area_cache down to the first hole */
314 if (mm->free_area_cache == vma->vm_end) {
315 mm->free_area_cache = vma->vm_start;
316 mm->cached_hole_size = largest_hole;
320 /* remember the largest hole we saw so far */
321 if (addr + largest_hole < vma->vm_start)
322 largest_hole = vma->vm_start - addr;
324 /* try just below the current vma->vm_start */
325 addr = (vma->vm_start - len) & HPAGE_MASK;
326 } while (len <= vma->vm_start);
330 * if hint left us with no space for the requested
331 * mapping then try again:
334 mm->free_area_cache = base;
340 * A failed mmap() very likely causes application failure,
341 * so fall back to the bottom-up function here. This scenario
342 * can happen with large stack limits and large mmap()
345 mm->free_area_cache = TASK_UNMAPPED_BASE;
346 mm->cached_hole_size = ~0UL;
347 addr = hugetlb_get_unmapped_area_bottomup(file, addr0,
351 * Restore the topdown base:
353 mm->free_area_cache = base;
354 mm->cached_hole_size = ~0UL;
360 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
361 unsigned long len, unsigned long pgoff, unsigned long flags)
363 struct mm_struct *mm = current->mm;
364 struct vm_area_struct *vma;
366 if (len & ~HPAGE_MASK)
371 if (flags & MAP_FIXED) {
372 if (prepare_hugepage_range(file, addr, len))
378 addr = ALIGN(addr, HPAGE_SIZE);
379 vma = find_vma(mm, addr);
380 if (TASK_SIZE - len >= addr &&
381 (!vma || addr + len <= vma->vm_start))
384 if (mm->get_unmapped_area == arch_get_unmapped_area)
385 return hugetlb_get_unmapped_area_bottomup(file, addr, len,
388 return hugetlb_get_unmapped_area_topdown(file, addr, len,
392 #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/