2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation, version 2.
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 * NON INFRINGEMENT. See the GNU General Public License for
15 #include <linux/highmem.h>
16 #include <linux/module.h>
17 #include <linux/pagemap.h>
18 #include <asm/homecache.h>
20 #define kmap_get_pte(vaddr) \
21 pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)),\
25 void *kmap(struct page *page)
32 if (!PageHighMem(page))
33 return page_address(page);
34 kva = kmap_high(page);
37 * Rewrite the PTE under the lock. This ensures that the page
38 * is not currently migrating.
40 ptep = kmap_get_pte((unsigned long)kva);
41 flags = homecache_kpte_lock();
42 set_pte_at(&init_mm, kva, ptep, mk_pte(page, page_to_kpgprot(page)));
43 homecache_kpte_unlock(flags);
49 void kunmap(struct page *page)
53 if (!PageHighMem(page))
57 EXPORT_SYMBOL(kunmap);
59 static void debug_kmap_atomic_prot(enum km_type type)
61 #ifdef CONFIG_DEBUG_HIGHMEM
62 static unsigned warn_count = 10;
64 if (unlikely(warn_count == 0))
67 if (unlikely(in_interrupt())) {
69 if (type != KM_IRQ0 && type != KM_IRQ1 &&
70 type != KM_BIO_SRC_IRQ &&
71 /* type != KM_BIO_DST_IRQ && */
72 type != KM_BOUNCE_READ) {
76 } else if (!irqs_disabled()) { /* softirq */
77 if (type != KM_IRQ0 && type != KM_IRQ1 &&
78 type != KM_SOFTIRQ0 && type != KM_SOFTIRQ1 &&
79 type != KM_SKB_SUNRPC_DATA &&
80 type != KM_SKB_DATA_SOFTIRQ &&
81 type != KM_BOUNCE_READ) {
88 if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ ||
89 type == KM_BIO_SRC_IRQ /* || type == KM_BIO_DST_IRQ */) {
90 if (!irqs_disabled()) {
94 } else if (type == KM_SOFTIRQ0 || type == KM_SOFTIRQ1) {
95 if (irq_count() == 0 && !irqs_disabled()) {
104 * Describe a single atomic mapping of a page on a given cpu at a
105 * given address, and allow it to be linked into a list.
107 struct atomic_mapped_page {
108 struct list_head list;
114 static spinlock_t amp_lock = __SPIN_LOCK_UNLOCKED(&_lock);
115 static struct list_head amp_list = LIST_HEAD_INIT(amp_list);
118 * Combining this structure with a per-cpu declaration lets us give
119 * each cpu an atomic_mapped_page structure per type.
122 struct atomic_mapped_page per_type[KM_TYPE_NR];
124 static DEFINE_PER_CPU(struct kmap_amps, amps);
127 * Add a page and va, on this cpu, to the list of kmap_atomic pages,
128 * and write the new pte to memory. Writing the new PTE under the
129 * lock guarantees that it is either on the list before migration starts
130 * (if we won the race), or set_pte() sets the migrating bit in the PTE
131 * (if we lost the race). And doing it under the lock guarantees
132 * that when kmap_atomic_fix_one_pte() comes along, it finds a valid
133 * PTE in memory, iff the mapping is still on the amp_list.
135 * Finally, doing it under the lock lets us safely examine the page
136 * to see if it is immutable or not, for the generic kmap_atomic() case.
137 * If we examine it earlier we are exposed to a race where it looks
138 * writable earlier, but becomes immutable before we write the PTE.
140 static void kmap_atomic_register(struct page *page, enum km_type type,
141 unsigned long va, pte_t *ptep, pte_t pteval)
144 struct atomic_mapped_page *amp;
146 flags = homecache_kpte_lock();
147 spin_lock(&_lock);
149 /* With interrupts disabled, now fill in the per-cpu info. */
150 amp = &__get_cpu_var(amps).per_type[type];
152 amp->cpu = smp_processor_id();
155 /* For generic kmap_atomic(), choose the PTE writability now. */
156 if (!pte_read(pteval))
157 pteval = mk_pte(page, page_to_kpgprot(page));
159 list_add(&->list, &_list);
160 set_pte(ptep, pteval);
161 arch_flush_lazy_mmu_mode();
163 spin_unlock(&_lock);
164 homecache_kpte_unlock(flags);
168 * Remove a page and va, on this cpu, from the list of kmap_atomic pages.
169 * Linear-time search, but we count on the lists being short.
170 * We don't need to adjust the PTE under the lock (as opposed to the
171 * kmap_atomic_register() case), since we're just unconditionally
172 * zeroing the PTE after it's off the list.
174 static void kmap_atomic_unregister(struct page *page, unsigned long va)
177 struct atomic_mapped_page *amp;
178 int cpu = smp_processor_id();
179 spin_lock_irqsave(&_lock, flags);
180 list_for_each_entry(amp, &_list, list) {
181 if (amp->page == page && amp->cpu == cpu && amp->va == va)
184 BUG_ON(&->list == &_list);
185 list_del(&->list);
186 spin_unlock_irqrestore(&_lock, flags);
189 /* Helper routine for kmap_atomic_fix_kpte(), below. */
190 static void kmap_atomic_fix_one_kpte(struct atomic_mapped_page *amp,
193 pte_t *ptep = kmap_get_pte(amp->va);
195 set_pte(ptep, pte_mkmigrate(*ptep));
196 flush_remote(0, 0, NULL, amp->va, PAGE_SIZE, PAGE_SIZE,
197 cpumask_of(amp->cpu), NULL, 0);
200 * Rewrite a default kernel PTE for this page.
201 * We rely on the fact that set_pte() writes the
202 * present+migrating bits last.
204 pte_t pte = mk_pte(amp->page, page_to_kpgprot(amp->page));
210 * This routine is a helper function for homecache_fix_kpte(); see
211 * its comments for more information on the "finished" argument here.
213 * Note that we hold the lock while doing the remote flushes, which
214 * will stall any unrelated cpus trying to do kmap_atomic operations.
215 * We could just update the PTEs under the lock, and save away copies
216 * of the structs (or just the va+cpu), then flush them after we
217 * release the lock, but it seems easier just to do it all under the lock.
219 void kmap_atomic_fix_kpte(struct page *page, int finished)
221 struct atomic_mapped_page *amp;
223 spin_lock_irqsave(&_lock, flags);
224 list_for_each_entry(amp, &_list, list) {
225 if (amp->page == page)
226 kmap_atomic_fix_one_kpte(amp, finished);
228 spin_unlock_irqrestore(&_lock, flags);
232 * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap
233 * because the kmap code must perform a global TLB invalidation when
234 * the kmap pool wraps.
236 * Note that they may be slower than on x86 (etc.) because unlike on
237 * those platforms, we do have to take a global lock to map and unmap
238 * pages on Tile (see above).
240 * When holding an atomic kmap is is not legal to sleep, so atomic
241 * kmaps are appropriate for short, tight code paths only.
243 void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
245 enum fixed_addresses idx;
249 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
252 /* Avoid icache flushes by disallowing atomic executable mappings. */
253 BUG_ON(pte_exec(prot));
255 if (!PageHighMem(page))
256 return page_address(page);
258 debug_kmap_atomic_prot(type);
260 idx = type + KM_TYPE_NR*smp_processor_id();
261 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
262 pte = kmap_get_pte(vaddr);
263 BUG_ON(!pte_none(*pte));
265 /* Register that this page is mapped atomically on this cpu. */
266 kmap_atomic_register(page, type, vaddr, pte, mk_pte(page, prot));
268 return (void *)vaddr;
270 EXPORT_SYMBOL(kmap_atomic_prot);
272 void *kmap_atomic(struct page *page, enum km_type type)
274 /* PAGE_NONE is a magic value that tells us to check immutability. */
275 return kmap_atomic_prot(page, type, PAGE_NONE);
277 EXPORT_SYMBOL(kmap_atomic);
279 void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type)
281 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
282 enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
285 * Force other mappings to Oops if they try to access this pte without
286 * first remapping it. Keeping stale mappings around is a bad idea.
288 if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx)) {
289 pte_t *pte = kmap_get_pte(vaddr);
291 BUG_ON(!pte_present(pteval) && !pte_migrating(pteval));
292 kmap_atomic_unregister(pte_page(pteval), vaddr);
293 kpte_clear_flush(pte, vaddr);
295 /* Must be a lowmem page */
296 BUG_ON(vaddr < PAGE_OFFSET);
297 BUG_ON(vaddr >= (unsigned long)high_memory);
300 arch_flush_lazy_mmu_mode();
303 EXPORT_SYMBOL(kunmap_atomic_notypecheck);
306 * This API is supposed to allow us to map memory without a "struct page".
307 * Currently we don't support this, though this may change in the future.
309 void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
311 return kmap_atomic(pfn_to_page(pfn), type);
313 void *kmap_atomic_prot_pfn(unsigned long pfn, enum km_type type, pgprot_t prot)
315 return kmap_atomic_prot(pfn_to_page(pfn), type, prot);
318 struct page *kmap_atomic_to_page(void *ptr)
321 unsigned long vaddr = (unsigned long)ptr;
323 if (vaddr < FIXADDR_START)
324 return virt_to_page(ptr);
326 pte = kmap_get_pte(vaddr);
327 return pte_page(*pte);