/*
* Copyright (C) 2006 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* @file page_ht.c
* @brief Virtual Address Translation (VAT) for global page hash table.
*/
#include <genarch/mm/page_ht.h>
#include <mm/page.h>
#include <arch/mm/page.h>
#include <mm/frame.h>
#include <mm/slab.h>
#include <mm/as.h>
#include <arch/mm/asid.h>
#include <arch/types.h>
#include <typedefs.h>
#include <arch/asm.h>
#include <synch/spinlock.h>
#include <arch.h>
#include <debug.h>
#include <memstr.h>
#include <adt/hash_table.h>
#include <align.h>
static index_t hash(__native key[]);
static bool compare(__native key[], count_t keys, link_t *item);
static void remove_callback(link_t *item);
static void ht_mapping_insert(as_t *as, __address page, __address frame, int flags);
static void ht_mapping_remove(as_t *as, __address page);
static pte_t *ht_mapping_find(as_t *as, __address page);
/**
* This lock protects the page hash table. It must be acquired
* after address space lock and after any address space area
* locks.
*/
mutex_t page_ht_lock;
/**
* Page hash table.
* The page hash table may be accessed only when page_ht_lock is held.
*/
hash_table_t page_ht;
/** Hash table operations for page hash table. */
hash_table_operations_t ht_operations = {
.hash = hash,
.compare = compare,
.remove_callback = remove_callback
};
/** Page mapping operations for page hash table architectures. */
page_mapping_operations_t ht_mapping_operations = {
.mapping_insert = ht_mapping_insert,
.mapping_remove = ht_mapping_remove,
.mapping_find = ht_mapping_find
};
/** Compute page hash table index.
*
* @param key Array of two keys (i.e. page and address space).
*
* @return Index into page hash table.
*/
index_t hash(__native key[])
{
as_t *as = (as_t *) key[KEY_AS];
__address page = (__address) key[KEY_PAGE];
index_t index;
/*
* Virtual page addresses have roughly the same probability
* of occurring. Least significant bits of VPN compose the
* hash index.
*/
index = ((page >> PAGE_WIDTH) & (PAGE_HT_ENTRIES-1));
/*
* Address space structures are likely to be allocated from
* similar addresses. Least significant bits compose the
* hash index.
*/
index |= ((__native) as) & (PAGE_HT_ENTRIES-1);
return index;
}
/** Compare page hash table item with page and/or address space.
*
* @param key Array of one or two keys (i.e. page and/or address space).
* @param keys Number of keys passed.
* @param item Item to compare the keys with.
*
* @return true on match, false otherwise.
*/
bool compare(__native key[], count_t keys, link_t *item)
{
pte_t *t;
ASSERT(item);
ASSERT((keys > 0) && (keys <= PAGE_HT_KEYS));
/*
* Convert item to PTE.
*/
t = hash_table_get_instance(item, pte_t, link);
if (keys == PAGE_HT_KEYS) {
return (key[KEY_AS] == (__address) t->as) && (key[KEY_PAGE] == t->page);
} else {
return (key[KEY_AS] == (__address) t->as);
}
}
/** Callback on page hash table item removal.
*
* @param item Page hash table item being removed.
*/
void remove_callback(link_t *item)
{
pte_t *t;
ASSERT(item);
/*
* Convert item to PTE.
*/
t = hash_table_get_instance(item, pte_t, link);
}
/** Map page to frame using page hash table.
*
* Map virtual address page to physical address frame
* using flags.
*
* The page table must be locked and interrupts must be disabled.
*
* @param as Address space to which page belongs.
* @param page Virtual address of the page to be mapped.
* @param frame Physical address of memory frame to which the mapping is done.
* @param flags Flags to be used for mapping.
*/
void ht_mapping_insert(as_t *as, __address page, __address frame, int flags)
{
pte_t *t;
__native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
if (!hash_table_find(&page_ht, key)) {
t
= (pte_t
*) malloc(sizeof(pte_t
), FRAME_ATOMIC
); ASSERT(t != NULL);
t->g = (flags & PAGE_GLOBAL) != 0;
t->x = (flags & PAGE_EXEC) != 0;
t->w = (flags & PAGE_WRITE) != 0;
t->k = !(flags & PAGE_USER);
t->c = (flags & PAGE_CACHEABLE) != 0;
t->p = !(flags & PAGE_NOT_PRESENT);
t->as = as;
t->page = page;
t->frame = frame;
hash_table_insert(&page_ht, key, &t->link);
}
}
/** Remove mapping of page from page hash table.
*
* Remove any mapping of page within address space as.
* TLB shootdown should follow in order to make effects of
* this call visible.
*
* The page table must be locked and interrupts must be disabled.
*
* @param as Address space to wich page belongs.
* @param page Virtual address of the page to be demapped.
*/
void ht_mapping_remove(as_t *as, __address page)
{
__native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
/*
* Note that removed PTE's will be freed
* by remove_callback().
*/
hash_table_remove(&page_ht, key, 2);
}
/** Find mapping for virtual page in page hash table.
*
* Find mapping for virtual page.
*
* The page table must be locked and interrupts must be disabled.
*
* @param as Address space to wich page belongs.
* @param page Virtual page.
*
* @return NULL if there is no such mapping; requested mapping otherwise.
*/
pte_t *ht_mapping_find(as_t *as, __address page)
{
link_t *hlp;
pte_t *t = NULL;
__native key[2] = { (__address) as, page = ALIGN_DOWN(page, PAGE_SIZE) };
hlp = hash_table_find(&page_ht, key);
if (hlp)
t = hash_table_get_instance(hlp, pte_t, link);
return t;
}