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![Ingo Molnar](/assets/img/avatar_default.png)
Fix ~94 single-word typos in locking code comments, plus a few very obvious grammar mistakes. Link: https://lkml.kernel.org/r/20210322212624.GA1963421@gmail.com Link: https://lore.kernel.org/r/20210322205203.GB1959563@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Cc: Bhaskar Chowdhury <unixbhaskar@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
789 lines
19 KiB
C
789 lines
19 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* High memory handling common code and variables.
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*
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* (C) 1999 Andrea Arcangeli, SuSE GmbH, andrea@suse.de
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* Gerhard Wichert, Siemens AG, Gerhard.Wichert@pdb.siemens.de
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*
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*
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* Redesigned the x86 32-bit VM architecture to deal with
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* 64-bit physical space. With current x86 CPUs this
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* means up to 64 Gigabytes physical RAM.
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*
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* Rewrote high memory support to move the page cache into
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* high memory. Implemented permanent (schedulable) kmaps
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* based on Linus' idea.
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*
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* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
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*/
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#include <linux/mm.h>
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#include <linux/export.h>
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#include <linux/swap.h>
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#include <linux/bio.h>
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#include <linux/pagemap.h>
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#include <linux/mempool.h>
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#include <linux/blkdev.h>
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#include <linux/init.h>
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#include <linux/hash.h>
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#include <linux/highmem.h>
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#include <linux/kgdb.h>
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#include <asm/tlbflush.h>
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#include <linux/vmalloc.h>
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/*
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* Virtual_count is not a pure "count".
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* 0 means that it is not mapped, and has not been mapped
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* since a TLB flush - it is usable.
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* 1 means that there are no users, but it has been mapped
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* since the last TLB flush - so we can't use it.
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* n means that there are (n-1) current users of it.
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*/
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#ifdef CONFIG_HIGHMEM
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/*
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* Architecture with aliasing data cache may define the following family of
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* helper functions in its asm/highmem.h to control cache color of virtual
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* addresses where physical memory pages are mapped by kmap.
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*/
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#ifndef get_pkmap_color
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/*
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* Determine color of virtual address where the page should be mapped.
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*/
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static inline unsigned int get_pkmap_color(struct page *page)
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{
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return 0;
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}
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#define get_pkmap_color get_pkmap_color
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/*
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* Get next index for mapping inside PKMAP region for page with given color.
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*/
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static inline unsigned int get_next_pkmap_nr(unsigned int color)
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{
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static unsigned int last_pkmap_nr;
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last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
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return last_pkmap_nr;
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}
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/*
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* Determine if page index inside PKMAP region (pkmap_nr) of given color
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* has wrapped around PKMAP region end. When this happens an attempt to
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* flush all unused PKMAP slots is made.
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*/
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static inline int no_more_pkmaps(unsigned int pkmap_nr, unsigned int color)
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{
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return pkmap_nr == 0;
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}
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/*
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* Get the number of PKMAP entries of the given color. If no free slot is
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* found after checking that many entries, kmap will sleep waiting for
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* someone to call kunmap and free PKMAP slot.
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*/
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static inline int get_pkmap_entries_count(unsigned int color)
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{
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return LAST_PKMAP;
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}
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/*
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* Get head of a wait queue for PKMAP entries of the given color.
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* Wait queues for different mapping colors should be independent to avoid
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* unnecessary wakeups caused by freeing of slots of other colors.
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*/
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static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color)
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{
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static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
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return &pkmap_map_wait;
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}
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#endif
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atomic_long_t _totalhigh_pages __read_mostly;
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EXPORT_SYMBOL(_totalhigh_pages);
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unsigned int __nr_free_highpages(void)
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{
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struct zone *zone;
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unsigned int pages = 0;
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for_each_populated_zone(zone) {
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if (is_highmem(zone))
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pages += zone_page_state(zone, NR_FREE_PAGES);
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}
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return pages;
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}
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static int pkmap_count[LAST_PKMAP];
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static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock);
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pte_t *pkmap_page_table;
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/*
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* Most architectures have no use for kmap_high_get(), so let's abstract
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* the disabling of IRQ out of the locking in that case to save on a
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* potential useless overhead.
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*/
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#ifdef ARCH_NEEDS_KMAP_HIGH_GET
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#define lock_kmap() spin_lock_irq(&kmap_lock)
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#define unlock_kmap() spin_unlock_irq(&kmap_lock)
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#define lock_kmap_any(flags) spin_lock_irqsave(&kmap_lock, flags)
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#define unlock_kmap_any(flags) spin_unlock_irqrestore(&kmap_lock, flags)
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#else
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#define lock_kmap() spin_lock(&kmap_lock)
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#define unlock_kmap() spin_unlock(&kmap_lock)
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#define lock_kmap_any(flags) \
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do { spin_lock(&kmap_lock); (void)(flags); } while (0)
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#define unlock_kmap_any(flags) \
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do { spin_unlock(&kmap_lock); (void)(flags); } while (0)
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#endif
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struct page *__kmap_to_page(void *vaddr)
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{
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unsigned long addr = (unsigned long)vaddr;
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if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) {
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int i = PKMAP_NR(addr);
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return pte_page(pkmap_page_table[i]);
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}
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return virt_to_page(addr);
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}
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EXPORT_SYMBOL(__kmap_to_page);
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static void flush_all_zero_pkmaps(void)
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{
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int i;
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int need_flush = 0;
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flush_cache_kmaps();
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for (i = 0; i < LAST_PKMAP; i++) {
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struct page *page;
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/*
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* zero means we don't have anything to do,
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* >1 means that it is still in use. Only
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* a count of 1 means that it is free but
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* needs to be unmapped
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*/
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if (pkmap_count[i] != 1)
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continue;
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pkmap_count[i] = 0;
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/* sanity check */
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BUG_ON(pte_none(pkmap_page_table[i]));
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/*
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* Don't need an atomic fetch-and-clear op here;
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* no-one has the page mapped, and cannot get at
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* its virtual address (and hence PTE) without first
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* getting the kmap_lock (which is held here).
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* So no dangers, even with speculative execution.
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*/
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page = pte_page(pkmap_page_table[i]);
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pte_clear(&init_mm, PKMAP_ADDR(i), &pkmap_page_table[i]);
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set_page_address(page, NULL);
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need_flush = 1;
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}
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if (need_flush)
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flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
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}
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void __kmap_flush_unused(void)
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{
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lock_kmap();
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flush_all_zero_pkmaps();
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unlock_kmap();
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}
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static inline unsigned long map_new_virtual(struct page *page)
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{
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unsigned long vaddr;
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int count;
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unsigned int last_pkmap_nr;
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unsigned int color = get_pkmap_color(page);
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start:
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count = get_pkmap_entries_count(color);
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/* Find an empty entry */
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for (;;) {
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last_pkmap_nr = get_next_pkmap_nr(color);
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if (no_more_pkmaps(last_pkmap_nr, color)) {
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flush_all_zero_pkmaps();
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count = get_pkmap_entries_count(color);
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}
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if (!pkmap_count[last_pkmap_nr])
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break; /* Found a usable entry */
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if (--count)
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continue;
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/*
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* Sleep for somebody else to unmap their entries
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*/
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{
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DECLARE_WAITQUEUE(wait, current);
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wait_queue_head_t *pkmap_map_wait =
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get_pkmap_wait_queue_head(color);
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__set_current_state(TASK_UNINTERRUPTIBLE);
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add_wait_queue(pkmap_map_wait, &wait);
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unlock_kmap();
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schedule();
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remove_wait_queue(pkmap_map_wait, &wait);
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lock_kmap();
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/* Somebody else might have mapped it while we slept */
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if (page_address(page))
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return (unsigned long)page_address(page);
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/* Re-start */
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goto start;
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}
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}
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vaddr = PKMAP_ADDR(last_pkmap_nr);
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set_pte_at(&init_mm, vaddr,
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&(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
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pkmap_count[last_pkmap_nr] = 1;
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set_page_address(page, (void *)vaddr);
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return vaddr;
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}
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/**
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* kmap_high - map a highmem page into memory
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* @page: &struct page to map
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*
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* Returns the page's virtual memory address.
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*
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* We cannot call this from interrupts, as it may block.
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*/
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void *kmap_high(struct page *page)
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{
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unsigned long vaddr;
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/*
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* For highmem pages, we can't trust "virtual" until
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* after we have the lock.
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*/
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lock_kmap();
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vaddr = (unsigned long)page_address(page);
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if (!vaddr)
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vaddr = map_new_virtual(page);
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pkmap_count[PKMAP_NR(vaddr)]++;
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BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
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unlock_kmap();
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return (void *) vaddr;
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}
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EXPORT_SYMBOL(kmap_high);
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#ifdef ARCH_NEEDS_KMAP_HIGH_GET
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/**
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* kmap_high_get - pin a highmem page into memory
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* @page: &struct page to pin
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*
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* Returns the page's current virtual memory address, or NULL if no mapping
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* exists. If and only if a non null address is returned then a
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* matching call to kunmap_high() is necessary.
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*
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* This can be called from any context.
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*/
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void *kmap_high_get(struct page *page)
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{
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unsigned long vaddr, flags;
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lock_kmap_any(flags);
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vaddr = (unsigned long)page_address(page);
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if (vaddr) {
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BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1);
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pkmap_count[PKMAP_NR(vaddr)]++;
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}
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unlock_kmap_any(flags);
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return (void *) vaddr;
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}
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#endif
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/**
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* kunmap_high - unmap a highmem page into memory
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* @page: &struct page to unmap
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*
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* If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called
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* only from user context.
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*/
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void kunmap_high(struct page *page)
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{
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unsigned long vaddr;
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unsigned long nr;
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unsigned long flags;
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int need_wakeup;
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unsigned int color = get_pkmap_color(page);
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wait_queue_head_t *pkmap_map_wait;
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lock_kmap_any(flags);
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vaddr = (unsigned long)page_address(page);
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BUG_ON(!vaddr);
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nr = PKMAP_NR(vaddr);
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/*
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* A count must never go down to zero
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* without a TLB flush!
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*/
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need_wakeup = 0;
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switch (--pkmap_count[nr]) {
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case 0:
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BUG();
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case 1:
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/*
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* Avoid an unnecessary wake_up() function call.
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* The common case is pkmap_count[] == 1, but
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* no waiters.
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* The tasks queued in the wait-queue are guarded
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* by both the lock in the wait-queue-head and by
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* the kmap_lock. As the kmap_lock is held here,
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* no need for the wait-queue-head's lock. Simply
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* test if the queue is empty.
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*/
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pkmap_map_wait = get_pkmap_wait_queue_head(color);
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need_wakeup = waitqueue_active(pkmap_map_wait);
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}
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unlock_kmap_any(flags);
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/* do wake-up, if needed, race-free outside of the spin lock */
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if (need_wakeup)
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wake_up(pkmap_map_wait);
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}
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EXPORT_SYMBOL(kunmap_high);
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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void zero_user_segments(struct page *page, unsigned start1, unsigned end1,
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unsigned start2, unsigned end2)
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{
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unsigned int i;
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BUG_ON(end1 > page_size(page) || end2 > page_size(page));
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if (start1 >= end1)
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start1 = end1 = 0;
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if (start2 >= end2)
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start2 = end2 = 0;
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for (i = 0; i < compound_nr(page); i++) {
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void *kaddr = NULL;
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if (start1 >= PAGE_SIZE) {
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start1 -= PAGE_SIZE;
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end1 -= PAGE_SIZE;
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} else {
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unsigned this_end = min_t(unsigned, end1, PAGE_SIZE);
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if (end1 > start1) {
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kaddr = kmap_atomic(page + i);
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memset(kaddr + start1, 0, this_end - start1);
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}
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end1 -= this_end;
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start1 = 0;
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}
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if (start2 >= PAGE_SIZE) {
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start2 -= PAGE_SIZE;
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end2 -= PAGE_SIZE;
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} else {
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unsigned this_end = min_t(unsigned, end2, PAGE_SIZE);
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if (end2 > start2) {
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if (!kaddr)
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kaddr = kmap_atomic(page + i);
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memset(kaddr + start2, 0, this_end - start2);
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}
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end2 -= this_end;
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start2 = 0;
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}
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if (kaddr) {
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kunmap_atomic(kaddr);
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flush_dcache_page(page + i);
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}
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if (!end1 && !end2)
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break;
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}
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BUG_ON((start1 | start2 | end1 | end2) != 0);
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}
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EXPORT_SYMBOL(zero_user_segments);
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#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
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#endif /* CONFIG_HIGHMEM */
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#ifdef CONFIG_KMAP_LOCAL
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#include <asm/kmap_size.h>
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/*
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* With DEBUG_KMAP_LOCAL the stack depth is doubled and every second
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* slot is unused which acts as a guard page
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*/
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#ifdef CONFIG_DEBUG_KMAP_LOCAL
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# define KM_INCR 2
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#else
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# define KM_INCR 1
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#endif
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static inline int kmap_local_idx_push(void)
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{
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WARN_ON_ONCE(in_irq() && !irqs_disabled());
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current->kmap_ctrl.idx += KM_INCR;
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BUG_ON(current->kmap_ctrl.idx >= KM_MAX_IDX);
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return current->kmap_ctrl.idx - 1;
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}
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static inline int kmap_local_idx(void)
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{
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return current->kmap_ctrl.idx - 1;
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}
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static inline void kmap_local_idx_pop(void)
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{
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current->kmap_ctrl.idx -= KM_INCR;
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BUG_ON(current->kmap_ctrl.idx < 0);
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}
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#ifndef arch_kmap_local_post_map
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# define arch_kmap_local_post_map(vaddr, pteval) do { } while (0)
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#endif
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#ifndef arch_kmap_local_pre_unmap
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# define arch_kmap_local_pre_unmap(vaddr) do { } while (0)
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#endif
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#ifndef arch_kmap_local_post_unmap
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# define arch_kmap_local_post_unmap(vaddr) do { } while (0)
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#endif
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#ifndef arch_kmap_local_map_idx
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#define arch_kmap_local_map_idx(idx, pfn) kmap_local_calc_idx(idx)
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#endif
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#ifndef arch_kmap_local_unmap_idx
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#define arch_kmap_local_unmap_idx(idx, vaddr) kmap_local_calc_idx(idx)
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#endif
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#ifndef arch_kmap_local_high_get
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static inline void *arch_kmap_local_high_get(struct page *page)
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{
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return NULL;
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}
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#endif
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#ifndef arch_kmap_local_set_pte
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#define arch_kmap_local_set_pte(mm, vaddr, ptep, ptev) \
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set_pte_at(mm, vaddr, ptep, ptev)
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#endif
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/* Unmap a local mapping which was obtained by kmap_high_get() */
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static inline bool kmap_high_unmap_local(unsigned long vaddr)
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{
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#ifdef ARCH_NEEDS_KMAP_HIGH_GET
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if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
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kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
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return true;
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}
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#endif
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return false;
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}
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static inline int kmap_local_calc_idx(int idx)
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{
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return idx + KM_MAX_IDX * smp_processor_id();
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}
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static pte_t *__kmap_pte;
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static pte_t *kmap_get_pte(void)
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{
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if (!__kmap_pte)
|
|
__kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN));
|
|
return __kmap_pte;
|
|
}
|
|
|
|
void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot)
|
|
{
|
|
pte_t pteval, *kmap_pte = kmap_get_pte();
|
|
unsigned long vaddr;
|
|
int idx;
|
|
|
|
/*
|
|
* Disable migration so resulting virtual address is stable
|
|
* across preemption.
|
|
*/
|
|
migrate_disable();
|
|
preempt_disable();
|
|
idx = arch_kmap_local_map_idx(kmap_local_idx_push(), pfn);
|
|
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
|
|
BUG_ON(!pte_none(*(kmap_pte - idx)));
|
|
pteval = pfn_pte(pfn, prot);
|
|
arch_kmap_local_set_pte(&init_mm, vaddr, kmap_pte - idx, pteval);
|
|
arch_kmap_local_post_map(vaddr, pteval);
|
|
current->kmap_ctrl.pteval[kmap_local_idx()] = pteval;
|
|
preempt_enable();
|
|
|
|
return (void *)vaddr;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__kmap_local_pfn_prot);
|
|
|
|
void *__kmap_local_page_prot(struct page *page, pgprot_t prot)
|
|
{
|
|
void *kmap;
|
|
|
|
/*
|
|
* To broaden the usage of the actual kmap_local() machinery always map
|
|
* pages when debugging is enabled and the architecture has no problems
|
|
* with alias mappings.
|
|
*/
|
|
if (!IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP) && !PageHighMem(page))
|
|
return page_address(page);
|
|
|
|
/* Try kmap_high_get() if architecture has it enabled */
|
|
kmap = arch_kmap_local_high_get(page);
|
|
if (kmap)
|
|
return kmap;
|
|
|
|
return __kmap_local_pfn_prot(page_to_pfn(page), prot);
|
|
}
|
|
EXPORT_SYMBOL(__kmap_local_page_prot);
|
|
|
|
void kunmap_local_indexed(void *vaddr)
|
|
{
|
|
unsigned long addr = (unsigned long) vaddr & PAGE_MASK;
|
|
pte_t *kmap_pte = kmap_get_pte();
|
|
int idx;
|
|
|
|
if (addr < __fix_to_virt(FIX_KMAP_END) ||
|
|
addr > __fix_to_virt(FIX_KMAP_BEGIN)) {
|
|
if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP)) {
|
|
/* This _should_ never happen! See above. */
|
|
WARN_ON_ONCE(1);
|
|
return;
|
|
}
|
|
/*
|
|
* Handle mappings which were obtained by kmap_high_get()
|
|
* first as the virtual address of such mappings is below
|
|
* PAGE_OFFSET. Warn for all other addresses which are in
|
|
* the user space part of the virtual address space.
|
|
*/
|
|
if (!kmap_high_unmap_local(addr))
|
|
WARN_ON_ONCE(addr < PAGE_OFFSET);
|
|
return;
|
|
}
|
|
|
|
preempt_disable();
|
|
idx = arch_kmap_local_unmap_idx(kmap_local_idx(), addr);
|
|
WARN_ON_ONCE(addr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
|
|
|
|
arch_kmap_local_pre_unmap(addr);
|
|
pte_clear(&init_mm, addr, kmap_pte - idx);
|
|
arch_kmap_local_post_unmap(addr);
|
|
current->kmap_ctrl.pteval[kmap_local_idx()] = __pte(0);
|
|
kmap_local_idx_pop();
|
|
preempt_enable();
|
|
migrate_enable();
|
|
}
|
|
EXPORT_SYMBOL(kunmap_local_indexed);
|
|
|
|
/*
|
|
* Invoked before switch_to(). This is safe even when during or after
|
|
* clearing the maps an interrupt which needs a kmap_local happens because
|
|
* the task::kmap_ctrl.idx is not modified by the unmapping code so a
|
|
* nested kmap_local will use the next unused index and restore the index
|
|
* on unmap. The already cleared kmaps of the outgoing task are irrelevant
|
|
* because the interrupt context does not know about them. The same applies
|
|
* when scheduling back in for an interrupt which happens before the
|
|
* restore is complete.
|
|
*/
|
|
void __kmap_local_sched_out(void)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
pte_t *kmap_pte = kmap_get_pte();
|
|
int i;
|
|
|
|
/* Clear kmaps */
|
|
for (i = 0; i < tsk->kmap_ctrl.idx; i++) {
|
|
pte_t pteval = tsk->kmap_ctrl.pteval[i];
|
|
unsigned long addr;
|
|
int idx;
|
|
|
|
/* With debug all even slots are unmapped and act as guard */
|
|
if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) {
|
|
WARN_ON_ONCE(!pte_none(pteval));
|
|
continue;
|
|
}
|
|
if (WARN_ON_ONCE(pte_none(pteval)))
|
|
continue;
|
|
|
|
/*
|
|
* This is a horrible hack for XTENSA to calculate the
|
|
* coloured PTE index. Uses the PFN encoded into the pteval
|
|
* and the map index calculation because the actual mapped
|
|
* virtual address is not stored in task::kmap_ctrl.
|
|
* For any sane architecture this is optimized out.
|
|
*/
|
|
idx = arch_kmap_local_map_idx(i, pte_pfn(pteval));
|
|
|
|
addr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
|
|
arch_kmap_local_pre_unmap(addr);
|
|
pte_clear(&init_mm, addr, kmap_pte - idx);
|
|
arch_kmap_local_post_unmap(addr);
|
|
}
|
|
}
|
|
|
|
void __kmap_local_sched_in(void)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
pte_t *kmap_pte = kmap_get_pte();
|
|
int i;
|
|
|
|
/* Restore kmaps */
|
|
for (i = 0; i < tsk->kmap_ctrl.idx; i++) {
|
|
pte_t pteval = tsk->kmap_ctrl.pteval[i];
|
|
unsigned long addr;
|
|
int idx;
|
|
|
|
/* With debug all even slots are unmapped and act as guard */
|
|
if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) {
|
|
WARN_ON_ONCE(!pte_none(pteval));
|
|
continue;
|
|
}
|
|
if (WARN_ON_ONCE(pte_none(pteval)))
|
|
continue;
|
|
|
|
/* See comment in __kmap_local_sched_out() */
|
|
idx = arch_kmap_local_map_idx(i, pte_pfn(pteval));
|
|
addr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
|
|
set_pte_at(&init_mm, addr, kmap_pte - idx, pteval);
|
|
arch_kmap_local_post_map(addr, pteval);
|
|
}
|
|
}
|
|
|
|
void kmap_local_fork(struct task_struct *tsk)
|
|
{
|
|
if (WARN_ON_ONCE(tsk->kmap_ctrl.idx))
|
|
memset(&tsk->kmap_ctrl, 0, sizeof(tsk->kmap_ctrl));
|
|
}
|
|
|
|
#endif
|
|
|
|
#if defined(HASHED_PAGE_VIRTUAL)
|
|
|
|
#define PA_HASH_ORDER 7
|
|
|
|
/*
|
|
* Describes one page->virtual association
|
|
*/
|
|
struct page_address_map {
|
|
struct page *page;
|
|
void *virtual;
|
|
struct list_head list;
|
|
};
|
|
|
|
static struct page_address_map page_address_maps[LAST_PKMAP];
|
|
|
|
/*
|
|
* Hash table bucket
|
|
*/
|
|
static struct page_address_slot {
|
|
struct list_head lh; /* List of page_address_maps */
|
|
spinlock_t lock; /* Protect this bucket's list */
|
|
} ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER];
|
|
|
|
static struct page_address_slot *page_slot(const struct page *page)
|
|
{
|
|
return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)];
|
|
}
|
|
|
|
/**
|
|
* page_address - get the mapped virtual address of a page
|
|
* @page: &struct page to get the virtual address of
|
|
*
|
|
* Returns the page's virtual address.
|
|
*/
|
|
void *page_address(const struct page *page)
|
|
{
|
|
unsigned long flags;
|
|
void *ret;
|
|
struct page_address_slot *pas;
|
|
|
|
if (!PageHighMem(page))
|
|
return lowmem_page_address(page);
|
|
|
|
pas = page_slot(page);
|
|
ret = NULL;
|
|
spin_lock_irqsave(&pas->lock, flags);
|
|
if (!list_empty(&pas->lh)) {
|
|
struct page_address_map *pam;
|
|
|
|
list_for_each_entry(pam, &pas->lh, list) {
|
|
if (pam->page == page) {
|
|
ret = pam->virtual;
|
|
goto done;
|
|
}
|
|
}
|
|
}
|
|
done:
|
|
spin_unlock_irqrestore(&pas->lock, flags);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(page_address);
|
|
|
|
/**
|
|
* set_page_address - set a page's virtual address
|
|
* @page: &struct page to set
|
|
* @virtual: virtual address to use
|
|
*/
|
|
void set_page_address(struct page *page, void *virtual)
|
|
{
|
|
unsigned long flags;
|
|
struct page_address_slot *pas;
|
|
struct page_address_map *pam;
|
|
|
|
BUG_ON(!PageHighMem(page));
|
|
|
|
pas = page_slot(page);
|
|
if (virtual) { /* Add */
|
|
pam = &page_address_maps[PKMAP_NR((unsigned long)virtual)];
|
|
pam->page = page;
|
|
pam->virtual = virtual;
|
|
|
|
spin_lock_irqsave(&pas->lock, flags);
|
|
list_add_tail(&pam->list, &pas->lh);
|
|
spin_unlock_irqrestore(&pas->lock, flags);
|
|
} else { /* Remove */
|
|
spin_lock_irqsave(&pas->lock, flags);
|
|
list_for_each_entry(pam, &pas->lh, list) {
|
|
if (pam->page == page) {
|
|
list_del(&pam->list);
|
|
spin_unlock_irqrestore(&pas->lock, flags);
|
|
goto done;
|
|
}
|
|
}
|
|
spin_unlock_irqrestore(&pas->lock, flags);
|
|
}
|
|
done:
|
|
return;
|
|
}
|
|
|
|
void __init page_address_init(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) {
|
|
INIT_LIST_HEAD(&page_address_htable[i].lh);
|
|
spin_lock_init(&page_address_htable[i].lock);
|
|
}
|
|
}
|
|
|
|
#endif /* defined(HASHED_PAGE_VIRTUAL) */
|