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1// SPDX-License-Identifier: GPL-2.02/*3 * High memory handling common code and variables.4 *5 * (C) 1999 Andrea Arcangeli, SuSE GmbH, andrea@suse.de6 * Gerhard Wichert, Siemens AG, Gerhard.Wichert@pdb.siemens.de7 *8 *9 * Redesigned the x86 32-bit VM architecture to deal with10 * 64-bit physical space. With current x86 CPUs this11 * means up to 64 Gigabytes physical RAM.12 *13 * Rewrote high memory support to move the page cache into14 * high memory. Implemented permanent (schedulable) kmaps15 * based on Linus' idea.16 *17 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>18 */19 20#include <linux/mm.h>21#include <linux/export.h>22#include <linux/swap.h>23#include <linux/bio.h>24#include <linux/pagemap.h>25#include <linux/mempool.h>26#include <linux/init.h>27#include <linux/hash.h>28#include <linux/highmem.h>29#include <linux/kgdb.h>30#include <asm/tlbflush.h>31#include <linux/vmalloc.h>32 33#ifdef CONFIG_KMAP_LOCAL34static inline int kmap_local_calc_idx(int idx)35{36 return idx + KM_MAX_IDX * smp_processor_id();37}38 39#ifndef arch_kmap_local_map_idx40#define arch_kmap_local_map_idx(idx, pfn) kmap_local_calc_idx(idx)41#endif42#endif /* CONFIG_KMAP_LOCAL */43 44/*45 * Virtual_count is not a pure "count".46 * 0 means that it is not mapped, and has not been mapped47 * since a TLB flush - it is usable.48 * 1 means that there are no users, but it has been mapped49 * since the last TLB flush - so we can't use it.50 * n means that there are (n-1) current users of it.51 */52#ifdef CONFIG_HIGHMEM53 54/*55 * Architecture with aliasing data cache may define the following family of56 * helper functions in its asm/highmem.h to control cache color of virtual57 * addresses where physical memory pages are mapped by kmap.58 */59#ifndef get_pkmap_color60 61/*62 * Determine color of virtual address where the page should be mapped.63 */64static inline unsigned int get_pkmap_color(struct page *page)65{66 return 0;67}68#define get_pkmap_color get_pkmap_color69 70/*71 * Get next index for mapping inside PKMAP region for page with given color.72 */73static inline unsigned int get_next_pkmap_nr(unsigned int color)74{75 static unsigned int last_pkmap_nr;76 77 last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;78 return last_pkmap_nr;79}80 81/*82 * Determine if page index inside PKMAP region (pkmap_nr) of given color83 * has wrapped around PKMAP region end. When this happens an attempt to84 * flush all unused PKMAP slots is made.85 */86static inline int no_more_pkmaps(unsigned int pkmap_nr, unsigned int color)87{88 return pkmap_nr == 0;89}90 91/*92 * Get the number of PKMAP entries of the given color. If no free slot is93 * found after checking that many entries, kmap will sleep waiting for94 * someone to call kunmap and free PKMAP slot.95 */96static inline int get_pkmap_entries_count(unsigned int color)97{98 return LAST_PKMAP;99}100 101/*102 * Get head of a wait queue for PKMAP entries of the given color.103 * Wait queues for different mapping colors should be independent to avoid104 * unnecessary wakeups caused by freeing of slots of other colors.105 */106static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color)107{108 static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);109 110 return &pkmap_map_wait;111}112#endif113 114unsigned long __nr_free_highpages(void)115{116 unsigned long pages = 0;117 struct zone *zone;118 119 for_each_populated_zone(zone) {120 if (is_highmem(zone))121 pages += zone_page_state(zone, NR_FREE_PAGES);122 }123 124 return pages;125}126 127unsigned long __totalhigh_pages(void)128{129 unsigned long pages = 0;130 struct zone *zone;131 132 for_each_populated_zone(zone) {133 if (is_highmem(zone))134 pages += zone_managed_pages(zone);135 }136 137 return pages;138}139EXPORT_SYMBOL(__totalhigh_pages);140 141static int pkmap_count[LAST_PKMAP];142static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);143 144pte_t *pkmap_page_table;145 146/*147 * Most architectures have no use for kmap_high_get(), so let's abstract148 * the disabling of IRQ out of the locking in that case to save on a149 * potential useless overhead.150 */151#ifdef ARCH_NEEDS_KMAP_HIGH_GET152#define lock_kmap() spin_lock_irq(&kmap_lock)153#define unlock_kmap() spin_unlock_irq(&kmap_lock)154#define lock_kmap_any(flags) spin_lock_irqsave(&kmap_lock, flags)155#define unlock_kmap_any(flags) spin_unlock_irqrestore(&kmap_lock, flags)156#else157#define lock_kmap() spin_lock(&kmap_lock)158#define unlock_kmap() spin_unlock(&kmap_lock)159#define lock_kmap_any(flags) \160 do { spin_lock(&kmap_lock); (void)(flags); } while (0)161#define unlock_kmap_any(flags) \162 do { spin_unlock(&kmap_lock); (void)(flags); } while (0)163#endif164 165struct page *__kmap_to_page(void *vaddr)166{167 unsigned long base = (unsigned long) vaddr & PAGE_MASK;168 struct kmap_ctrl *kctrl = ¤t->kmap_ctrl;169 unsigned long addr = (unsigned long)vaddr;170 int i;171 172 /* kmap() mappings */173 if (WARN_ON_ONCE(addr >= PKMAP_ADDR(0) &&174 addr < PKMAP_ADDR(LAST_PKMAP)))175 return pte_page(ptep_get(&pkmap_page_table[PKMAP_NR(addr)]));176 177 /* kmap_local_page() mappings */178 if (WARN_ON_ONCE(base >= __fix_to_virt(FIX_KMAP_END) &&179 base < __fix_to_virt(FIX_KMAP_BEGIN))) {180 for (i = 0; i < kctrl->idx; i++) {181 unsigned long base_addr;182 int idx;183 184 idx = arch_kmap_local_map_idx(i, pte_pfn(pteval));185 base_addr = __fix_to_virt(FIX_KMAP_BEGIN + idx);186 187 if (base_addr == base)188 return pte_page(kctrl->pteval[i]);189 }190 }191 192 return virt_to_page(vaddr);193}194EXPORT_SYMBOL(__kmap_to_page);195 196static void flush_all_zero_pkmaps(void)197{198 int i;199 int need_flush = 0;200 201 flush_cache_kmaps();202 203 for (i = 0; i < LAST_PKMAP; i++) {204 struct page *page;205 pte_t ptent;206 207 /*208 * zero means we don't have anything to do,209 * >1 means that it is still in use. Only210 * a count of 1 means that it is free but211 * needs to be unmapped212 */213 if (pkmap_count[i] != 1)214 continue;215 pkmap_count[i] = 0;216 217 /* sanity check */218 ptent = ptep_get(&pkmap_page_table[i]);219 BUG_ON(pte_none(ptent));220 221 /*222 * Don't need an atomic fetch-and-clear op here;223 * no-one has the page mapped, and cannot get at224 * its virtual address (and hence PTE) without first225 * getting the kmap_lock (which is held here).226 * So no dangers, even with speculative execution.227 */228 page = pte_page(ptent);229 pte_clear(&init_mm, PKMAP_ADDR(i), &pkmap_page_table[i]);230 231 set_page_address(page, NULL);232 need_flush = 1;233 }234 if (need_flush)235 flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));236}237 238void __kmap_flush_unused(void)239{240 lock_kmap();241 flush_all_zero_pkmaps();242 unlock_kmap();243}244 245static inline unsigned long map_new_virtual(struct page *page)246{247 unsigned long vaddr;248 int count;249 unsigned int last_pkmap_nr;250 unsigned int color = get_pkmap_color(page);251 252start:253 count = get_pkmap_entries_count(color);254 /* Find an empty entry */255 for (;;) {256 last_pkmap_nr = get_next_pkmap_nr(color);257 if (no_more_pkmaps(last_pkmap_nr, color)) {258 flush_all_zero_pkmaps();259 count = get_pkmap_entries_count(color);260 }261 if (!pkmap_count[last_pkmap_nr])262 break; /* Found a usable entry */263 if (--count)264 continue;265 266 /*267 * Sleep for somebody else to unmap their entries268 */269 {270 DECLARE_WAITQUEUE(wait, current);271 wait_queue_head_t *pkmap_map_wait =272 get_pkmap_wait_queue_head(color);273 274 __set_current_state(TASK_UNINTERRUPTIBLE);275 add_wait_queue(pkmap_map_wait, &wait);276 unlock_kmap();277 schedule();278 remove_wait_queue(pkmap_map_wait, &wait);279 lock_kmap();280 281 /* Somebody else might have mapped it while we slept */282 if (page_address(page))283 return (unsigned long)page_address(page);284 285 /* Re-start */286 goto start;287 }288 }289 vaddr = PKMAP_ADDR(last_pkmap_nr);290 set_pte_at(&init_mm, vaddr,291 &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));292 293 pkmap_count[last_pkmap_nr] = 1;294 set_page_address(page, (void *)vaddr);295 296 return vaddr;297}298 299/**300 * kmap_high - map a highmem page into memory301 * @page: &struct page to map302 *303 * Returns the page's virtual memory address.304 *305 * We cannot call this from interrupts, as it may block.306 */307void *kmap_high(struct page *page)308{309 unsigned long vaddr;310 311 /*312 * For highmem pages, we can't trust "virtual" until313 * after we have the lock.314 */315 lock_kmap();316 vaddr = (unsigned long)page_address(page);317 if (!vaddr)318 vaddr = map_new_virtual(page);319 pkmap_count[PKMAP_NR(vaddr)]++;320 BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);321 unlock_kmap();322 return (void *) vaddr;323}324EXPORT_SYMBOL(kmap_high);325 326#ifdef ARCH_NEEDS_KMAP_HIGH_GET327/**328 * kmap_high_get - pin a highmem page into memory329 * @page: &struct page to pin330 *331 * Returns the page's current virtual memory address, or NULL if no mapping332 * exists. If and only if a non null address is returned then a333 * matching call to kunmap_high() is necessary.334 *335 * This can be called from any context.336 */337void *kmap_high_get(struct page *page)338{339 unsigned long vaddr, flags;340 341 lock_kmap_any(flags);342 vaddr = (unsigned long)page_address(page);343 if (vaddr) {344 BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1);345 pkmap_count[PKMAP_NR(vaddr)]++;346 }347 unlock_kmap_any(flags);348 return (void *) vaddr;349}350#endif351 352/**353 * kunmap_high - unmap a highmem page into memory354 * @page: &struct page to unmap355 *356 * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called357 * only from user context.358 */359void kunmap_high(struct page *page)360{361 unsigned long vaddr;362 unsigned long nr;363 unsigned long flags;364 int need_wakeup;365 unsigned int color = get_pkmap_color(page);366 wait_queue_head_t *pkmap_map_wait;367 368 lock_kmap_any(flags);369 vaddr = (unsigned long)page_address(page);370 BUG_ON(!vaddr);371 nr = PKMAP_NR(vaddr);372 373 /*374 * A count must never go down to zero375 * without a TLB flush!376 */377 need_wakeup = 0;378 switch (--pkmap_count[nr]) {379 case 0:380 BUG();381 case 1:382 /*383 * Avoid an unnecessary wake_up() function call.384 * The common case is pkmap_count[] == 1, but385 * no waiters.386 * The tasks queued in the wait-queue are guarded387 * by both the lock in the wait-queue-head and by388 * the kmap_lock. As the kmap_lock is held here,389 * no need for the wait-queue-head's lock. Simply390 * test if the queue is empty.391 */392 pkmap_map_wait = get_pkmap_wait_queue_head(color);393 need_wakeup = waitqueue_active(pkmap_map_wait);394 }395 unlock_kmap_any(flags);396 397 /* do wake-up, if needed, race-free outside of the spin lock */398 if (need_wakeup)399 wake_up(pkmap_map_wait);400}401EXPORT_SYMBOL(kunmap_high);402 403void zero_user_segments(struct page *page, unsigned start1, unsigned end1,404 unsigned start2, unsigned end2)405{406 unsigned int i;407 408 BUG_ON(end1 > page_size(page) || end2 > page_size(page));409 410 if (start1 >= end1)411 start1 = end1 = 0;412 if (start2 >= end2)413 start2 = end2 = 0;414 415 for (i = 0; i < compound_nr(page); i++) {416 void *kaddr = NULL;417 418 if (start1 >= PAGE_SIZE) {419 start1 -= PAGE_SIZE;420 end1 -= PAGE_SIZE;421 } else {422 unsigned this_end = min_t(unsigned, end1, PAGE_SIZE);423 424 if (end1 > start1) {425 kaddr = kmap_local_page(page + i);426 memset(kaddr + start1, 0, this_end - start1);427 }428 end1 -= this_end;429 start1 = 0;430 }431 432 if (start2 >= PAGE_SIZE) {433 start2 -= PAGE_SIZE;434 end2 -= PAGE_SIZE;435 } else {436 unsigned this_end = min_t(unsigned, end2, PAGE_SIZE);437 438 if (end2 > start2) {439 if (!kaddr)440 kaddr = kmap_local_page(page + i);441 memset(kaddr + start2, 0, this_end - start2);442 }443 end2 -= this_end;444 start2 = 0;445 }446 447 if (kaddr) {448 kunmap_local(kaddr);449 flush_dcache_page(page + i);450 }451 452 if (!end1 && !end2)453 break;454 }455 456 BUG_ON((start1 | start2 | end1 | end2) != 0);457}458EXPORT_SYMBOL(zero_user_segments);459#endif /* CONFIG_HIGHMEM */460 461#ifdef CONFIG_KMAP_LOCAL462 463#include <asm/kmap_size.h>464 465/*466 * With DEBUG_KMAP_LOCAL the stack depth is doubled and every second467 * slot is unused which acts as a guard page468 */469#ifdef CONFIG_DEBUG_KMAP_LOCAL470# define KM_INCR 2471#else472# define KM_INCR 1473#endif474 475static inline int kmap_local_idx_push(void)476{477 WARN_ON_ONCE(in_hardirq() && !irqs_disabled());478 current->kmap_ctrl.idx += KM_INCR;479 BUG_ON(current->kmap_ctrl.idx >= KM_MAX_IDX);480 return current->kmap_ctrl.idx - 1;481}482 483static inline int kmap_local_idx(void)484{485 return current->kmap_ctrl.idx - 1;486}487 488static inline void kmap_local_idx_pop(void)489{490 current->kmap_ctrl.idx -= KM_INCR;491 BUG_ON(current->kmap_ctrl.idx < 0);492}493 494#ifndef arch_kmap_local_post_map495# define arch_kmap_local_post_map(vaddr, pteval) do { } while (0)496#endif497 498#ifndef arch_kmap_local_pre_unmap499# define arch_kmap_local_pre_unmap(vaddr) do { } while (0)500#endif501 502#ifndef arch_kmap_local_post_unmap503# define arch_kmap_local_post_unmap(vaddr) do { } while (0)504#endif505 506#ifndef arch_kmap_local_unmap_idx507#define arch_kmap_local_unmap_idx(idx, vaddr) kmap_local_calc_idx(idx)508#endif509 510#ifndef arch_kmap_local_high_get511static inline void *arch_kmap_local_high_get(struct page *page)512{513 return NULL;514}515#endif516 517#ifndef arch_kmap_local_set_pte518#define arch_kmap_local_set_pte(mm, vaddr, ptep, ptev) \519 set_pte_at(mm, vaddr, ptep, ptev)520#endif521 522/* Unmap a local mapping which was obtained by kmap_high_get() */523static inline bool kmap_high_unmap_local(unsigned long vaddr)524{525#ifdef ARCH_NEEDS_KMAP_HIGH_GET526 if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {527 kunmap_high(pte_page(ptep_get(&pkmap_page_table[PKMAP_NR(vaddr)])));528 return true;529 }530#endif531 return false;532}533 534static pte_t *__kmap_pte;535 536static pte_t *kmap_get_pte(unsigned long vaddr, int idx)537{538 if (IS_ENABLED(CONFIG_KMAP_LOCAL_NON_LINEAR_PTE_ARRAY))539 /*540 * Set by the arch if __kmap_pte[-idx] does not produce541 * the correct entry.542 */543 return virt_to_kpte(vaddr);544 if (!__kmap_pte)545 __kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN));546 return &__kmap_pte[-idx];547}548 549void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot)550{551 pte_t pteval, *kmap_pte;552 unsigned long vaddr;553 int idx;554 555 /*556 * Disable migration so resulting virtual address is stable557 * across preemption.558 */559 migrate_disable();560 preempt_disable();561 idx = arch_kmap_local_map_idx(kmap_local_idx_push(), pfn);562 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);563 kmap_pte = kmap_get_pte(vaddr, idx);564 BUG_ON(!pte_none(ptep_get(kmap_pte)));565 pteval = pfn_pte(pfn, prot);566 arch_kmap_local_set_pte(&init_mm, vaddr, kmap_pte, pteval);567 arch_kmap_local_post_map(vaddr, pteval);568 current->kmap_ctrl.pteval[kmap_local_idx()] = pteval;569 preempt_enable();570 571 return (void *)vaddr;572}573EXPORT_SYMBOL_GPL(__kmap_local_pfn_prot);574 575void *__kmap_local_page_prot(struct page *page, pgprot_t prot)576{577 void *kmap;578 579 /*580 * To broaden the usage of the actual kmap_local() machinery always map581 * pages when debugging is enabled and the architecture has no problems582 * with alias mappings.583 */584 if (!IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP) && !PageHighMem(page))585 return page_address(page);586 587 /* Try kmap_high_get() if architecture has it enabled */588 kmap = arch_kmap_local_high_get(page);589 if (kmap)590 return kmap;591 592 return __kmap_local_pfn_prot(page_to_pfn(page), prot);593}594EXPORT_SYMBOL(__kmap_local_page_prot);595 596void kunmap_local_indexed(const void *vaddr)597{598 unsigned long addr = (unsigned long) vaddr & PAGE_MASK;599 pte_t *kmap_pte;600 int idx;601 602 if (addr < __fix_to_virt(FIX_KMAP_END) ||603 addr > __fix_to_virt(FIX_KMAP_BEGIN)) {604 if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP)) {605 /* This _should_ never happen! See above. */606 WARN_ON_ONCE(1);607 return;608 }609 /*610 * Handle mappings which were obtained by kmap_high_get()611 * first as the virtual address of such mappings is below612 * PAGE_OFFSET. Warn for all other addresses which are in613 * the user space part of the virtual address space.614 */615 if (!kmap_high_unmap_local(addr))616 WARN_ON_ONCE(addr < PAGE_OFFSET);617 return;618 }619 620 preempt_disable();621 idx = arch_kmap_local_unmap_idx(kmap_local_idx(), addr);622 WARN_ON_ONCE(addr != __fix_to_virt(FIX_KMAP_BEGIN + idx));623 624 kmap_pte = kmap_get_pte(addr, idx);625 arch_kmap_local_pre_unmap(addr);626 pte_clear(&init_mm, addr, kmap_pte);627 arch_kmap_local_post_unmap(addr);628 current->kmap_ctrl.pteval[kmap_local_idx()] = __pte(0);629 kmap_local_idx_pop();630 preempt_enable();631 migrate_enable();632}633EXPORT_SYMBOL(kunmap_local_indexed);634 635/*636 * Invoked before switch_to(). This is safe even when during or after637 * clearing the maps an interrupt which needs a kmap_local happens because638 * the task::kmap_ctrl.idx is not modified by the unmapping code so a639 * nested kmap_local will use the next unused index and restore the index640 * on unmap. The already cleared kmaps of the outgoing task are irrelevant641 * because the interrupt context does not know about them. The same applies642 * when scheduling back in for an interrupt which happens before the643 * restore is complete.644 */645void __kmap_local_sched_out(void)646{647 struct task_struct *tsk = current;648 pte_t *kmap_pte;649 int i;650 651 /* Clear kmaps */652 for (i = 0; i < tsk->kmap_ctrl.idx; i++) {653 pte_t pteval = tsk->kmap_ctrl.pteval[i];654 unsigned long addr;655 int idx;656 657 /* With debug all even slots are unmapped and act as guard */658 if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) {659 WARN_ON_ONCE(pte_val(pteval) != 0);660 continue;661 }662 if (WARN_ON_ONCE(pte_none(pteval)))663 continue;664 665 /*666 * This is a horrible hack for XTENSA to calculate the667 * coloured PTE index. Uses the PFN encoded into the pteval668 * and the map index calculation because the actual mapped669 * virtual address is not stored in task::kmap_ctrl.670 * For any sane architecture this is optimized out.671 */672 idx = arch_kmap_local_map_idx(i, pte_pfn(pteval));673 674 addr = __fix_to_virt(FIX_KMAP_BEGIN + idx);675 kmap_pte = kmap_get_pte(addr, idx);676 arch_kmap_local_pre_unmap(addr);677 pte_clear(&init_mm, addr, kmap_pte);678 arch_kmap_local_post_unmap(addr);679 }680}681 682void __kmap_local_sched_in(void)683{684 struct task_struct *tsk = current;685 pte_t *kmap_pte;686 int i;687 688 /* Restore kmaps */689 for (i = 0; i < tsk->kmap_ctrl.idx; i++) {690 pte_t pteval = tsk->kmap_ctrl.pteval[i];691 unsigned long addr;692 int idx;693 694 /* With debug all even slots are unmapped and act as guard */695 if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) {696 WARN_ON_ONCE(pte_val(pteval) != 0);697 continue;698 }699 if (WARN_ON_ONCE(pte_none(pteval)))700 continue;701 702 /* See comment in __kmap_local_sched_out() */703 idx = arch_kmap_local_map_idx(i, pte_pfn(pteval));704 addr = __fix_to_virt(FIX_KMAP_BEGIN + idx);705 kmap_pte = kmap_get_pte(addr, idx);706 set_pte_at(&init_mm, addr, kmap_pte, pteval);707 arch_kmap_local_post_map(addr, pteval);708 }709}710 711void kmap_local_fork(struct task_struct *tsk)712{713 if (WARN_ON_ONCE(tsk->kmap_ctrl.idx))714 memset(&tsk->kmap_ctrl, 0, sizeof(tsk->kmap_ctrl));715}716 717#endif718 719#if defined(HASHED_PAGE_VIRTUAL)720 721#define PA_HASH_ORDER 7722 723/*724 * Describes one page->virtual association725 */726struct page_address_map {727 struct page *page;728 void *virtual;729 struct list_head list;730};731 732static struct page_address_map page_address_maps[LAST_PKMAP];733 734/*735 * Hash table bucket736 */737static struct page_address_slot {738 struct list_head lh; /* List of page_address_maps */739 spinlock_t lock; /* Protect this bucket's list */740} ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER];741 742static struct page_address_slot *page_slot(const struct page *page)743{744 return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];745}746 747/**748 * page_address - get the mapped virtual address of a page749 * @page: &struct page to get the virtual address of750 *751 * Returns the page's virtual address.752 */753void *page_address(const struct page *page)754{755 unsigned long flags;756 void *ret;757 struct page_address_slot *pas;758 759 if (!PageHighMem(page))760 return lowmem_page_address(page);761 762 pas = page_slot(page);763 ret = NULL;764 spin_lock_irqsave(&pas->lock, flags);765 if (!list_empty(&pas->lh)) {766 struct page_address_map *pam;767 768 list_for_each_entry(pam, &pas->lh, list) {769 if (pam->page == page) {770 ret = pam->virtual;771 break;772 }773 }774 }775 776 spin_unlock_irqrestore(&pas->lock, flags);777 return ret;778}779EXPORT_SYMBOL(page_address);780 781/**782 * set_page_address - set a page's virtual address783 * @page: &struct page to set784 * @virtual: virtual address to use785 */786void set_page_address(struct page *page, void *virtual)787{788 unsigned long flags;789 struct page_address_slot *pas;790 struct page_address_map *pam;791 792 BUG_ON(!PageHighMem(page));793 794 pas = page_slot(page);795 if (virtual) { /* Add */796 pam = &page_address_maps[PKMAP_NR((unsigned long)virtual)];797 pam->page = page;798 pam->virtual = virtual;799 800 spin_lock_irqsave(&pas->lock, flags);801 list_add_tail(&pam->list, &pas->lh);802 spin_unlock_irqrestore(&pas->lock, flags);803 } else { /* Remove */804 spin_lock_irqsave(&pas->lock, flags);805 list_for_each_entry(pam, &pas->lh, list) {806 if (pam->page == page) {807 list_del(&pam->list);808 break;809 }810 }811 spin_unlock_irqrestore(&pas->lock, flags);812 }813}814 815void __init page_address_init(void)816{817 int i;818 819 for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) {820 INIT_LIST_HEAD(&page_address_htable[i].lh);821 spin_lock_init(&page_address_htable[i].lock);822 }823}824 825#endif /* defined(HASHED_PAGE_VIRTUAL) */826