/*
* 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.
*/
/** @addtogroup kernel_generic_mm
* @{
*/
/**
* @file
* @brief Backend for anonymous memory address space areas.
*
*/
#include <assert.h>
#include <mm/as.h>
#include <mm/page.h>
#include <mm/reserve.h>
#include <genarch/mm/page_pt.h>
#include <genarch/mm/page_ht.h>
#include <mm/frame.h>
#include <mm/slab.h>
#include <mm/km.h>
#include <synch/mutex.h>
#include <adt/list.h>
#include <errno.h>
#include <typedefs.h>
#include <align.h>
#include <memw.h>
#include <arch.h>
static bool anon_create(as_area_t *);
static bool anon_resize(as_area_t *, size_t);
static void anon_share(as_area_t *);
static void anon_destroy(as_area_t *);
static bool anon_is_resizable(as_area_t *);
static bool anon_is_shareable(as_area_t *);
static int anon_page_fault(as_area_t *, uintptr_t, pf_access_t);
static void anon_frame_free(as_area_t *, uintptr_t, uintptr_t);
mem_backend_t anon_backend = {
.create = anon_create,
.resize = anon_resize,
.share = anon_share,
.destroy = anon_destroy,
.is_resizable = anon_is_resizable,
.is_shareable = anon_is_shareable,
.page_fault = anon_page_fault,
.frame_free = anon_frame_free,
.create_shared_data = NULL,
.destroy_shared_data = NULL
};
bool anon_create(as_area_t *area)
{
if (area->flags & AS_AREA_LATE_RESERVE)
return true;
return reserve_try_alloc(area->pages);
}
bool anon_resize(as_area_t *area, size_t new_pages)
{
if (area->flags & AS_AREA_LATE_RESERVE)
return true;
if (new_pages > area->pages)
return reserve_try_alloc(new_pages - area->pages);
else if (new_pages < area->pages)
reserve_free(area->pages - new_pages);
return true;
}
/** Share the anonymous address space area.
*
* Sharing of anonymous area is done by duplicating its entire mapping
* to the pagemap. Page faults will primarily search for frames there.
*
* The address space and address space area must be already locked.
*
* @param area Address space area to be shared.
*/
void anon_share(as_area_t *area)
{
assert(mutex_locked(&area->as->lock));
assert(mutex_locked(&area->lock));
assert(!(area->flags & AS_AREA_LATE_RESERVE));
/*
* Copy used portions of the area to sh_info's page map.
*/
mutex_lock(&area->sh_info->lock);
used_space_ival_t *ival = used_space_first(&area->used_space);
while (ival != NULL) {
uintptr_t base = ival->page;
size_t count = ival->count;
unsigned int j;
for (j = 0; j < count; j++) {
pte_t pte;
bool found;
page_table_lock(area->as, false);
found = page_mapping_find(area->as, base + P2SZ(j),
false, &pte);
(void)found;
assert(found);
assert(PTE_VALID(&pte));
assert(PTE_PRESENT(&pte));
as_pagemap_insert(&area->sh_info->pagemap,
(base + P2SZ(j)) - area->base, PTE_GET_FRAME(&pte));
page_table_unlock(area->as, false);
pfn_t pfn = ADDR2PFN(PTE_GET_FRAME(&pte));
frame_reference_add(pfn);
}
ival = used_space_next(ival);
}
mutex_unlock(&area->sh_info->lock);
}
void anon_destroy(as_area_t *area)
{
if (area->flags & AS_AREA_LATE_RESERVE)
return;
reserve_free(area->pages);
}
bool anon_is_resizable(as_area_t *area)
{
return true;
}
bool anon_is_shareable(as_area_t *area)
{
return !(area->flags & AS_AREA_LATE_RESERVE);
}
/** Service a page fault in the anonymous memory address space area.
*
* The address space area and page tables must be already locked.
*
* @param area Pointer to the address space area.
* @param upage Faulting virtual page.
* @param access Access mode that caused the fault (i.e. read/write/exec).
*
* @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e.
* serviced).
*/
int anon_page_fault(as_area_t *area, uintptr_t upage, pf_access_t access)
{
uintptr_t kpage;
uintptr_t frame;
assert(page_table_locked(AS));
assert(mutex_locked(&area->lock));
assert(IS_ALIGNED(upage, PAGE_SIZE));
if (!as_area_check_access(area, access))
return AS_PF_FAULT;
mutex_lock(&area->sh_info->lock);
if (area->sh_info->shared) {
/*
* The area is shared, chances are that the mapping can be found
* in the pagemap of the address space area share info
* structure.
* In the case that the pagemap does not contain the respective
* mapping, a new frame is allocated and the mapping is created.
*/
errno_t rc = as_pagemap_find(&area->sh_info->pagemap,
upage - area->base, &frame);
if (rc != EOK) {
/* Need to allocate the frame */
kpage = km_temporary_page_get(&frame,
FRAME_NO_RESERVE);
memsetb((void *) kpage, PAGE_SIZE, 0);
km_temporary_page_put(kpage);
/*
* Insert the address of the newly allocated
* frame to the pagemap.
*/
as_pagemap_insert(&area->sh_info->pagemap,
upage - area->base, frame);
}
frame_reference_add(ADDR2PFN(frame));
} else {
/*
* In general, there can be several reasons that
* can have caused this fault.
*
* - non-existent mapping: the area is an anonymous
* area (e.g. heap or stack) and so far has not been
* allocated a frame for the faulting page
*
* - non-present mapping: another possibility,
* currently not implemented, would be frame
* reuse; when this becomes a possibility,
* do not forget to distinguish between
* the different causes
*/
if (area->flags & AS_AREA_LATE_RESERVE) {
/*
* Reserve the memory for this page now.
*/
if (!reserve_try_alloc(1)) {
mutex_unlock(&area->sh_info->lock);
return AS_PF_SILENT;
}
}
kpage = km_temporary_page_get(&frame, FRAME_NO_RESERVE);
memsetb((void *) kpage, PAGE_SIZE, 0);
km_temporary_page_put(kpage);
}
mutex_unlock(&area->sh_info->lock);
/*
* Map 'upage' to 'frame'.
* Note that TLB shootdown is not attempted as only new information is
* being inserted into page tables.
*/
page_mapping_insert(AS, upage, frame, as_area_get_flags(area));
if (!used_space_insert(&area->used_space, upage, 1))
panic("Cannot insert used space.");
return AS_PF_OK;
}
/** Free a frame that is backed by the anonymous memory backend.
*
* The address space area and page tables must be already locked.
*
* @param area Ignored.
* @param page Virtual address of the page corresponding to the frame.
* @param frame Frame to be released.
*/
void anon_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame)
{
assert(page_table_locked(area->as));
assert(mutex_locked(&area->lock));
if (area->flags & AS_AREA_LATE_RESERVE) {
/*
* In case of the late reserve areas, physical memory will not
* be unreserved when the area is destroyed so we need to use
* the normal unreserving frame_free().
*/
frame_free(frame, 1);
} else {
/*
* The reserve will be given back when the area is destroyed or
* resized, so use the frame_free_noreserve() which does not
* manipulate the reserve or it would be given back twice.
*/
frame_free_noreserve(frame, 1);
}
}
/** @}
*/