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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/arch/arm/mm/fault-armv.c
3 *
4 * Copyright (C) 1995 Linus Torvalds
5 * Modifications for ARM processor (c) 1995-2002 Russell King
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#include <linux/sched.h>
12#include <linux/kernel.h>
13#include <linux/mm.h>
14#include <linux/bitops.h>
15#include <linux/vmalloc.h>
16#include <linux/init.h>
17#include <linux/pagemap.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090018#include <linux/gfp.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019
Russell King09d9bae2008-09-05 14:08:44 +010020#include <asm/bugs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <asm/cacheflush.h>
Russell King46097c72008-08-10 18:10:19 +010022#include <asm/cachetype.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <asm/pgtable.h>
24#include <asm/tlbflush.h>
25
Russell King7b0a1002009-10-24 14:11:59 +010026#include "mm.h"
27
Russell Kingf6e33542010-11-16 00:22:09 +000028static pteval_t shared_pte_mask = L_PTE_MT_BUFFERABLE;
Linus Torvalds1da177e2005-04-16 15:20:36 -070029
Catalin Marinas60121912010-09-13 15:58:06 +010030#if __LINUX_ARM_ARCH__ < 6
Linus Torvalds1da177e2005-04-16 15:20:36 -070031/*
32 * We take the easy way out of this problem - we make the
33 * PTE uncacheable. However, we leave the write buffer on.
Hugh Dickins69b04752005-10-29 18:16:36 -070034 *
35 * Note that the pte lock held when calling update_mmu_cache must also
36 * guard the pte (somewhere else in the same mm) that we modify here.
37 * Therefore those configurations which might call adjust_pte (those
38 * without CONFIG_CPU_CACHE_VIPT) cannot support split page_table_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 */
Russell Kingc26c20b2009-12-18 16:21:35 +000040static int do_adjust_pte(struct vm_area_struct *vma, unsigned long address,
Russell Kinged42aca2009-12-18 16:31:38 +000041 unsigned long pfn, pte_t *ptep)
Linus Torvalds1da177e2005-04-16 15:20:36 -070042{
Russell Kingc26c20b2009-12-18 16:21:35 +000043 pte_t entry = *ptep;
Russell King53cdb272008-07-27 10:35:54 +010044 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 /*
Russell King53cdb272008-07-27 10:35:54 +010047 * If this page is present, it's actually being shared.
48 */
49 ret = pte_present(entry);
50
51 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 * If this page isn't present, or is already setup to
53 * fault (ie, is old), we can safely ignore any issues.
54 */
Russell Kingbb30f362008-09-06 20:04:59 +010055 if (ret && (pte_val(entry) & L_PTE_MT_MASK) != shared_pte_mask) {
Nicolas Pitre08e445b2009-01-16 23:02:54 +010056 flush_cache_page(vma, address, pfn);
57 outer_flush_range((pfn << PAGE_SHIFT),
58 (pfn << PAGE_SHIFT) + PAGE_SIZE);
Russell Kingbb30f362008-09-06 20:04:59 +010059 pte_val(entry) &= ~L_PTE_MT_MASK;
60 pte_val(entry) |= shared_pte_mask;
Russell Kingc26c20b2009-12-18 16:21:35 +000061 set_pte_at(vma->vm_mm, address, ptep, entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 flush_tlb_page(vma, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 }
Russell Kingc26c20b2009-12-18 16:21:35 +000064
65 return ret;
66}
67
Mika Westerberg4e54d932010-10-28 11:45:22 +010068#if USE_SPLIT_PTLOCKS
69/*
70 * If we are using split PTE locks, then we need to take the page
71 * lock here. Otherwise we are using shared mm->page_table_lock
72 * which is already locked, thus cannot take it.
73 */
74static inline void do_pte_lock(spinlock_t *ptl)
75{
76 /*
77 * Use nested version here to indicate that we are already
78 * holding one similar spinlock.
79 */
80 spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
81}
82
83static inline void do_pte_unlock(spinlock_t *ptl)
84{
85 spin_unlock(ptl);
86}
87#else /* !USE_SPLIT_PTLOCKS */
88static inline void do_pte_lock(spinlock_t *ptl) {}
89static inline void do_pte_unlock(spinlock_t *ptl) {}
90#endif /* USE_SPLIT_PTLOCKS */
91
Russell Kinged42aca2009-12-18 16:31:38 +000092static int adjust_pte(struct vm_area_struct *vma, unsigned long address,
93 unsigned long pfn)
Russell Kingc26c20b2009-12-18 16:21:35 +000094{
Russell King56dd4702009-12-18 16:24:34 +000095 spinlock_t *ptl;
Russell Kingc26c20b2009-12-18 16:21:35 +000096 pgd_t *pgd;
Russell King516295e2010-11-21 16:27:49 +000097 pud_t *pud;
Russell Kingc26c20b2009-12-18 16:21:35 +000098 pmd_t *pmd;
99 pte_t *pte;
100 int ret;
101
102 pgd = pgd_offset(vma->vm_mm, address);
Russell Kingf8a85f12009-12-18 16:23:44 +0000103 if (pgd_none_or_clear_bad(pgd))
104 return 0;
Russell Kingc26c20b2009-12-18 16:21:35 +0000105
Russell King516295e2010-11-21 16:27:49 +0000106 pud = pud_offset(pgd, address);
107 if (pud_none_or_clear_bad(pud))
108 return 0;
109
110 pmd = pmd_offset(pud, address);
Russell Kingf8a85f12009-12-18 16:23:44 +0000111 if (pmd_none_or_clear_bad(pmd))
112 return 0;
Russell Kingc26c20b2009-12-18 16:21:35 +0000113
Russell King56dd4702009-12-18 16:24:34 +0000114 /*
115 * This is called while another page table is mapped, so we
116 * must use the nested version. This also means we need to
117 * open-code the spin-locking.
118 */
119 ptl = pte_lockptr(vma->vm_mm, pmd);
Peter Zijlstraece0e2b2010-10-26 14:21:52 -0700120 pte = pte_offset_map(pmd, address);
Mika Westerberg4e54d932010-10-28 11:45:22 +0100121 do_pte_lock(ptl);
Russell Kingc26c20b2009-12-18 16:21:35 +0000122
Russell Kinged42aca2009-12-18 16:31:38 +0000123 ret = do_adjust_pte(vma, address, pfn, pte);
Russell Kingc26c20b2009-12-18 16:21:35 +0000124
Mika Westerberg4e54d932010-10-28 11:45:22 +0100125 do_pte_unlock(ptl);
Peter Zijlstraece0e2b2010-10-26 14:21:52 -0700126 pte_unmap(pte);
Russell Kingc26c20b2009-12-18 16:21:35 +0000127
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129}
130
131static void
Russell Kingae140202009-12-18 16:43:57 +0000132make_coherent(struct address_space *mapping, struct vm_area_struct *vma,
133 unsigned long addr, pte_t *ptep, unsigned long pfn)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 struct mm_struct *mm = vma->vm_mm;
136 struct vm_area_struct *mpnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 unsigned long offset;
138 pgoff_t pgoff;
139 int aliases = 0;
140
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT);
142
143 /*
144 * If we have any shared mappings that are in the same mm
145 * space, then we need to handle them specially to maintain
146 * cache coherency.
147 */
148 flush_dcache_mmap_lock(mapping);
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -0700149 vma_interval_tree_foreach(mpnt, &mapping->i_mmap, pgoff, pgoff) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 /*
151 * If this VMA is not in our MM, we can ignore it.
152 * Note that we intentionally mask out the VMA
153 * that we are fixing up.
154 */
155 if (mpnt->vm_mm != mm || mpnt == vma)
156 continue;
157 if (!(mpnt->vm_flags & VM_MAYSHARE))
158 continue;
159 offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
Russell Kinged42aca2009-12-18 16:31:38 +0000160 aliases += adjust_pte(mpnt, mpnt->vm_start + offset, pfn);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 }
162 flush_dcache_mmap_unlock(mapping);
163 if (aliases)
Russell Kingae140202009-12-18 16:43:57 +0000164 do_adjust_pte(vma, addr, pfn, ptep);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165}
166
167/*
168 * Take care of architecture specific things when placing a new PTE into
169 * a page table, or changing an existing PTE. Basically, there are two
170 * things that we need to take care of:
171 *
Catalin Marinasc0177802010-09-13 15:57:36 +0100172 * 1. If PG_dcache_clean is not set for the page, we need to ensure
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 * that any cache entries for the kernels virtual memory
174 * range are written back to the page.
175 * 2. If we have multiple shared mappings of the same space in
176 * an object, we need to deal with the cache aliasing issues.
177 *
Hugh Dickins69b04752005-10-29 18:16:36 -0700178 * Note that the pte lock will be held.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 */
Russell King4b3073e2009-12-18 16:40:18 +0000180void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
181 pte_t *ptep)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182{
Russell King4b3073e2009-12-18 16:40:18 +0000183 unsigned long pfn = pte_pfn(*ptep);
Russell King8830f042005-06-20 09:51:03 +0100184 struct address_space *mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 struct page *page;
186
187 if (!pfn_valid(pfn))
188 return;
Russell King8830f042005-06-20 09:51:03 +0100189
Russell King421fe932009-10-25 10:23:04 +0000190 /*
191 * The zero page is never written to, so never has any dirty
192 * cache lines, and therefore never needs to be flushed.
193 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 page = pfn_to_page(pfn);
Russell King421fe932009-10-25 10:23:04 +0000195 if (page == ZERO_PAGE(0))
196 return;
197
Russell King8830f042005-06-20 09:51:03 +0100198 mapping = page_mapping(page);
Catalin Marinasc0177802010-09-13 15:57:36 +0100199 if (!test_and_set_bit(PG_dcache_clean, &page->flags))
Nitin Gupta787b2fa2009-10-12 14:20:23 +0530200 __flush_dcache_page(mapping, page);
Nitin Gupta787b2fa2009-10-12 14:20:23 +0530201 if (mapping) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202 if (cache_is_vivt())
Russell Kingae140202009-12-18 16:43:57 +0000203 make_coherent(mapping, vma, addr, ptep, pfn);
Catalin Marinas826cbda2008-06-13 10:28:36 +0100204 else if (vma->vm_flags & VM_EXEC)
205 __flush_icache_all();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 }
207}
Catalin Marinas60121912010-09-13 15:58:06 +0100208#endif /* __LINUX_ARM_ARCH__ < 6 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209
210/*
211 * Check whether the write buffer has physical address aliasing
212 * issues. If it has, we need to avoid them for the case where
213 * we have several shared mappings of the same object in user
214 * space.
215 */
216static int __init check_writebuffer(unsigned long *p1, unsigned long *p2)
217{
218 register unsigned long zero = 0, one = 1, val;
219
220 local_irq_disable();
221 mb();
222 *p1 = one;
223 mb();
224 *p2 = zero;
225 mb();
226 val = *p1;
227 mb();
228 local_irq_enable();
229 return val != zero;
230}
231
232void __init check_writebuffer_bugs(void)
233{
234 struct page *page;
235 const char *reason;
236 unsigned long v = 1;
237
238 printk(KERN_INFO "CPU: Testing write buffer coherency: ");
239
240 page = alloc_page(GFP_KERNEL);
241 if (page) {
242 unsigned long *p1, *p2;
Russell King52e8bfd2009-12-23 19:54:31 +0000243 pgprot_t prot = __pgprot_modify(PAGE_KERNEL,
244 L_PTE_MT_MASK, L_PTE_MT_BUFFERABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245
246 p1 = vmap(&page, 1, VM_IOREMAP, prot);
247 p2 = vmap(&page, 1, VM_IOREMAP, prot);
248
249 if (p1 && p2) {
250 v = check_writebuffer(p1, p2);
251 reason = "enabling work-around";
252 } else {
253 reason = "unable to map memory\n";
254 }
255
256 vunmap(p1);
257 vunmap(p2);
258 put_page(page);
259 } else {
260 reason = "unable to grab page\n";
261 }
262
263 if (v) {
264 printk("failed, %s\n", reason);
Russell Kingbb30f362008-09-06 20:04:59 +0100265 shared_pte_mask = L_PTE_MT_UNCACHED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266 } else {
267 printk("ok\n");
268 }
269}