Linux 4.6-rc6
[linux/fpc-iii.git] / arch / powerpc / mm / pgtable.c
blobde37ff445362a1215bb2e6d3956bf364f841671a
1 /*
2 * This file contains common routines for dealing with free of page tables
3 * Along with common page table handling code
5 * Derived from arch/powerpc/mm/tlb_64.c:
6 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
8 * Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
9 * and Cort Dougan (PReP) (cort@cs.nmt.edu)
10 * Copyright (C) 1996 Paul Mackerras
12 * Derived from "arch/i386/mm/init.c"
13 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
15 * Dave Engebretsen <engebret@us.ibm.com>
16 * Rework for PPC64 port.
18 * This program is free software; you can redistribute it and/or
19 * modify it under the terms of the GNU General Public License
20 * as published by the Free Software Foundation; either version
21 * 2 of the License, or (at your option) any later version.
24 #include <linux/kernel.h>
25 #include <linux/gfp.h>
26 #include <linux/mm.h>
27 #include <linux/percpu.h>
28 #include <linux/hardirq.h>
29 #include <linux/hugetlb.h>
30 #include <asm/pgalloc.h>
31 #include <asm/tlbflush.h>
32 #include <asm/tlb.h>
34 static inline int is_exec_fault(void)
36 return current->thread.regs && TRAP(current->thread.regs) == 0x400;
39 /* We only try to do i/d cache coherency on stuff that looks like
40 * reasonably "normal" PTEs. We currently require a PTE to be present
41 * and we avoid _PAGE_SPECIAL and _PAGE_NO_CACHE. We also only do that
42 * on userspace PTEs
44 static inline int pte_looks_normal(pte_t pte)
46 return (pte_val(pte) &
47 (_PAGE_PRESENT | _PAGE_SPECIAL | _PAGE_NO_CACHE | _PAGE_USER)) ==
48 (_PAGE_PRESENT | _PAGE_USER);
51 static struct page *maybe_pte_to_page(pte_t pte)
53 unsigned long pfn = pte_pfn(pte);
54 struct page *page;
56 if (unlikely(!pfn_valid(pfn)))
57 return NULL;
58 page = pfn_to_page(pfn);
59 if (PageReserved(page))
60 return NULL;
61 return page;
64 #if defined(CONFIG_PPC_STD_MMU) || _PAGE_EXEC == 0
66 /* Server-style MMU handles coherency when hashing if HW exec permission
67 * is supposed per page (currently 64-bit only). If not, then, we always
68 * flush the cache for valid PTEs in set_pte. Embedded CPU without HW exec
69 * support falls into the same category.
72 static pte_t set_pte_filter(pte_t pte)
74 pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS);
75 if (pte_looks_normal(pte) && !(cpu_has_feature(CPU_FTR_COHERENT_ICACHE) ||
76 cpu_has_feature(CPU_FTR_NOEXECUTE))) {
77 struct page *pg = maybe_pte_to_page(pte);
78 if (!pg)
79 return pte;
80 if (!test_bit(PG_arch_1, &pg->flags)) {
81 flush_dcache_icache_page(pg);
82 set_bit(PG_arch_1, &pg->flags);
85 return pte;
88 static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
89 int dirty)
91 return pte;
94 #else /* defined(CONFIG_PPC_STD_MMU) || _PAGE_EXEC == 0 */
96 /* Embedded type MMU with HW exec support. This is a bit more complicated
97 * as we don't have two bits to spare for _PAGE_EXEC and _PAGE_HWEXEC so
98 * instead we "filter out" the exec permission for non clean pages.
100 static pte_t set_pte_filter(pte_t pte)
102 struct page *pg;
104 /* No exec permission in the first place, move on */
105 if (!(pte_val(pte) & _PAGE_EXEC) || !pte_looks_normal(pte))
106 return pte;
108 /* If you set _PAGE_EXEC on weird pages you're on your own */
109 pg = maybe_pte_to_page(pte);
110 if (unlikely(!pg))
111 return pte;
113 /* If the page clean, we move on */
114 if (test_bit(PG_arch_1, &pg->flags))
115 return pte;
117 /* If it's an exec fault, we flush the cache and make it clean */
118 if (is_exec_fault()) {
119 flush_dcache_icache_page(pg);
120 set_bit(PG_arch_1, &pg->flags);
121 return pte;
124 /* Else, we filter out _PAGE_EXEC */
125 return __pte(pte_val(pte) & ~_PAGE_EXEC);
128 static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
129 int dirty)
131 struct page *pg;
133 /* So here, we only care about exec faults, as we use them
134 * to recover lost _PAGE_EXEC and perform I$/D$ coherency
135 * if necessary. Also if _PAGE_EXEC is already set, same deal,
136 * we just bail out
138 if (dirty || (pte_val(pte) & _PAGE_EXEC) || !is_exec_fault())
139 return pte;
141 #ifdef CONFIG_DEBUG_VM
142 /* So this is an exec fault, _PAGE_EXEC is not set. If it was
143 * an error we would have bailed out earlier in do_page_fault()
144 * but let's make sure of it
146 if (WARN_ON(!(vma->vm_flags & VM_EXEC)))
147 return pte;
148 #endif /* CONFIG_DEBUG_VM */
150 /* If you set _PAGE_EXEC on weird pages you're on your own */
151 pg = maybe_pte_to_page(pte);
152 if (unlikely(!pg))
153 goto bail;
155 /* If the page is already clean, we move on */
156 if (test_bit(PG_arch_1, &pg->flags))
157 goto bail;
159 /* Clean the page and set PG_arch_1 */
160 flush_dcache_icache_page(pg);
161 set_bit(PG_arch_1, &pg->flags);
163 bail:
164 return __pte(pte_val(pte) | _PAGE_EXEC);
167 #endif /* !(defined(CONFIG_PPC_STD_MMU) || _PAGE_EXEC == 0) */
170 * set_pte stores a linux PTE into the linux page table.
172 void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
173 pte_t pte)
176 * When handling numa faults, we already have the pte marked
177 * _PAGE_PRESENT, but we can be sure that it is not in hpte.
178 * Hence we can use set_pte_at for them.
180 VM_WARN_ON((pte_val(*ptep) & (_PAGE_PRESENT | _PAGE_USER)) ==
181 (_PAGE_PRESENT | _PAGE_USER));
183 * Add the pte bit when tryint set a pte
185 pte = __pte(pte_val(pte) | _PAGE_PTE);
187 /* Note: mm->context.id might not yet have been assigned as
188 * this context might not have been activated yet when this
189 * is called.
191 pte = set_pte_filter(pte);
193 /* Perform the setting of the PTE */
194 __set_pte_at(mm, addr, ptep, pte, 0);
198 * This is called when relaxing access to a PTE. It's also called in the page
199 * fault path when we don't hit any of the major fault cases, ie, a minor
200 * update of _PAGE_ACCESSED, _PAGE_DIRTY, etc... The generic code will have
201 * handled those two for us, we additionally deal with missing execute
202 * permission here on some processors
204 int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address,
205 pte_t *ptep, pte_t entry, int dirty)
207 int changed;
208 entry = set_access_flags_filter(entry, vma, dirty);
209 changed = !pte_same(*(ptep), entry);
210 if (changed) {
211 if (!is_vm_hugetlb_page(vma))
212 assert_pte_locked(vma->vm_mm, address);
213 __ptep_set_access_flags(ptep, entry);
214 flush_tlb_page_nohash(vma, address);
216 return changed;
219 #ifdef CONFIG_DEBUG_VM
220 void assert_pte_locked(struct mm_struct *mm, unsigned long addr)
222 pgd_t *pgd;
223 pud_t *pud;
224 pmd_t *pmd;
226 if (mm == &init_mm)
227 return;
228 pgd = mm->pgd + pgd_index(addr);
229 BUG_ON(pgd_none(*pgd));
230 pud = pud_offset(pgd, addr);
231 BUG_ON(pud_none(*pud));
232 pmd = pmd_offset(pud, addr);
234 * khugepaged to collapse normal pages to hugepage, first set
235 * pmd to none to force page fault/gup to take mmap_sem. After
236 * pmd is set to none, we do a pte_clear which does this assertion
237 * so if we find pmd none, return.
239 if (pmd_none(*pmd))
240 return;
241 BUG_ON(!pmd_present(*pmd));
242 assert_spin_locked(pte_lockptr(mm, pmd));
244 #endif /* CONFIG_DEBUG_VM */
246 unsigned long vmalloc_to_phys(void *va)
248 unsigned long pfn = vmalloc_to_pfn(va);
250 BUG_ON(!pfn);
251 return __pa(pfn_to_kaddr(pfn)) + offset_in_page(va);
253 EXPORT_SYMBOL_GPL(vmalloc_to_phys);