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#include <string.h>
#include <pager.h>
#include <vfs.h>
#include <process.h>
#include <frame.h>
#define ENT_FRAME_SHIFT 12
// ========== //
// SWAP PAGER //
// ========== //
static void swap_page_in(pager_t *p, size_t offset, size_t len);
static void swap_page_out(pager_t *p, size_t offset, size_t len);
static void swap_page_release(pager_t *p, size_t offset, size_t len);
static pager_ops_t swap_pager_ops = {
.page_in = swap_page_in,
.page_commit = 0,
.page_out = swap_page_out,
.page_release = swap_page_release,
};
pager_t *new_swap_pager(size_t size) {
pager_t *p = (pager_t*)malloc(sizeof(pager_t));
if (p == 0) return 0;
p->pages = create_hashtbl(id_key_eq_fun, id_hash_fun, 0);
if (p->pages == 0) goto error;
p->ops = &swap_pager_ops;
p->size = size;
p->lock = MUTEX_UNLOCKED;
p->maps = 0;
return p;
error:
if (p) free(p);
return 0;
}
void swap_page_in(pager_t *p, size_t offset, size_t len) {
ASSERT(PAGE_ALIGNED(offset));
size_t npages = PAGE_ALIGN_UP(len) / PAGE_SIZE;
void *region = region_alloc(PAGE_SIZE, "Page zero area", 0);
if (region == 0) return;
for (size_t i = 0; i < npages; i++) {
size_t page = offset + (i * PAGE_SIZE);
if (hashtbl_find(p->pages, (void*)page) == 0) {
uint32_t frame = frame_alloc(1);
if (frame != 0) {
pd_map_page(region, frame, true);
memset(region, 0, PAGE_SIZE);
pd_unmap_page(region);
}
if (!hashtbl_add(p->pages, (void*)page, (void*)(frame << ENT_FRAME_SHIFT))) {
frame_free(frame, 1);
}
}
}
region_free(region);
}
void swap_page_out(pager_t *p, size_t offset, size_t len) {
// later : save to swap file...
}
void swap_page_release(pager_t *p, size_t offset, size_t len) {
ASSERT(PAGE_ALIGNED(offset));
size_t npages = PAGE_ALIGN_UP(len) / PAGE_SIZE;
for (size_t i = 0; i < npages; i++) {
size_t page = offset + (i * PAGE_SIZE);
uint32_t frame = (uint32_t)hashtbl_find(p->pages, (void*)page) >> ENT_FRAME_SHIFT;
if (frame != 0) {
hashtbl_remove(p->pages, (void*)page);
frame_free(frame, 1);
}
}
}
// ======================= //
// GENERIC PAGER FUNCTIONS //
// ======================= //
void delete_pager(pager_t *p) {
ASSERT(p->maps == 0);
pager_commit_dirty(p);
mutex_lock(&p->lock);
p->ops->page_release(p, 0, p->size);
delete_hashtbl(p->pages);
free(p);
}
void pager_access(pager_t *p, size_t offset, size_t len, bool accessed, bool dirty) {
mutex_lock(&p->lock);
ASSERT(PAGE_ALIGNED(offset));
size_t npages = PAGE_ALIGN_UP(len) / PAGE_SIZE;
for (size_t i = 0; i < npages; i++) {
size_t page = offset + (i * PAGE_SIZE);
uint32_t v = (uint32_t)hashtbl_find(p->pages, (void*)page);
if (v != 0) {
hashtbl_change(p->pages, (void*)page,
(void*)(v | (accessed ? PAGE_ACCESSED : 0) | (dirty ? PAGE_DIRTY : 0)));
}
}
mutex_unlock(&p->lock);
}
void pager_commit_dirty(pager_t *p) {
if (!p->ops->page_commit) return;
mutex_lock(&p->lock);
for (size_t i = 0; i < p->size; i += PAGE_SIZE) {
uint32_t v = (uint32_t)hashtbl_find(p->pages, (void*)i);
if (v & PAGE_DIRTY) {
p->ops->page_commit(p, i, PAGE_SIZE);
hashtbl_change(p->pages, (void*)i, (void*)(v & ~PAGE_DIRTY));
}
}
mutex_unlock(&p->lock);
}
int pager_get_frame(pager_t *p, size_t offset) {
mutex_lock(&p->lock);
ASSERT(PAGE_ALIGNED(offset));
uint32_t v = (uint32_t)hashtbl_find(p->pages, (void*)offset);
if (v == 0) {
p->ops->page_in(p, offset, PAGE_SIZE);
}
uint32_t ret = (uint32_t)hashtbl_find(p->pages, (void*)offset) >> ENT_FRAME_SHIFT;
mutex_unlock(&p->lock);
return ret;
}
void pager_add_map(pager_t *p, user_region_t *reg) {
mutex_lock(&p->lock);
reg->next_for_pager = p->maps;
p->maps = reg;
mutex_unlock(&p->lock);
}
void pager_rm_map(pager_t *p, user_region_t *reg) {
mutex_lock(&p->lock);
if (p->maps == reg) {
p->maps = reg->next_for_pager;
} else {
for (user_region_t *it = p->maps; it->next_for_pager != 0; it = it->next_for_pager) {
if (it->next_for_pager == reg) {
it->next_for_pager = reg->next_for_pager;
break;
}
}
}
reg->next_for_pager = 0;
mutex_unlock(&p->lock);
}
/* vim: set ts=4 sw=4 tw=0 noet :*/
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