static void
default_free_pages(struct Page *base, size_t n) {
assert(n > 0);
list_entry_t *le = &free_list;
struct Page * p;
while (p <= base && (le = list_next(le)) != &free_list)
p = le2page(le, page_link);
for(p=base;p<base+n;p++)
{
list_add_before(le, &(p->page_link));
p->flags = 0;
set_page_ref(p, 0);
}
base->flags = 0;
set_page_ref(base, 0);
ClearPageProperty(base);
SetPageProperty(base);
base->property = n;
while (1)
{
p = le2page(le, page_link);
if (base->page_link.next != &free_list && base+base->property==p)
{
base->property += p->property;
p->property = 0;
}
else break;
}
le = list_prev(&(base->page_link));
p = le2page(le, page_link);
if(le != &free_list && p == base-1)
{
while (1)
{
if (p->property)
{
p->property += base->property;
base->property = 0;
break;
}
if (le != &free_list)
{
le = list_prev(le);
p = le2page(le,page_link);
}
else break;
}
}
nr_free += n;
}
pmd_t *
get_pmd(pgd_t *pgdir, uintptr_t la, bool create) {
#if PMXSHIFT == PUXSHIFT
return get_pud(pgdir, la, create);
#else /* PMXSHIFT == PUXSHIFT */
pud_t *pudp;
if ((pudp = get_pud(pgdir, la, create)) == NULL) {
return NULL;
}
if (! ptep_present(pudp)) {
struct Page *page;
if (!create || (page = alloc_page()) == NULL) {
return NULL;
}
set_page_ref(page, 1);
uintptr_t pa = page2pa(page);
memset(KADDR(pa), 0, PGSIZE);
ptep_map(pudp, pa);
ptep_set_u_write(pudp);
ptep_set_accessed(pudp);
ptep_set_dirty(pudp);
}
return &((pmd_t *)KADDR(PUD_ADDR(*pudp)))[PMX(la)];
#endif /* PMXSHIFT == PUXSHIFT */
}
pte_t *
get_pte(pgd_t *pgdir, uintptr_t la, bool create) {
#if PTXSHIFT == PMXSHIFT
return get_pmd(pgdir, la, create);
#else /* PTXSHIFT == PMXSHIFT */
pmd_t *pmdp;
if ((pmdp = get_pmd(pgdir, la, create)) == NULL) {
return NULL;
}
if (! ptep_present(pmdp)) {
struct Page *page;
if (!create || (page = alloc_page()) == NULL) {
return NULL;
}
set_page_ref(page, 1);
uintptr_t pa = page2pa(page);
memset(KADDR(pa), 0, PGSIZE);
#ifdef ARCH_ARM
pdep_map(pmdp, pa);
#else
ptep_map(pmdp, pa);
#endif
#ifndef ARCH_ARM
ptep_set_u_write(pmdp);
ptep_set_accessed(pmdp);
ptep_set_dirty(pmdp);
#else
#warning ARM9 PDE does not have access field
#endif
}
return &((pte_t *)KADDR(PMD_ADDR(*pmdp)))[PTX(la)];
#endif /* PTXSHIFT == PMXSHIFT */
}
static void default_free_pages(struct Page *base, size_t n) {
assert(n > 0);
struct Page *p = base;
for (; p != base + n; p++) {
assert(!PageReserved(p) && !PageProperty(p));
p->flags = 0;
set_page_ref(p, 0);
}
base->property = n;
SetPageProperty(base);
list_entry_t *le = list_next(&free_list);
while (le != &free_list) {
p = le2page(le, page_link);
le = list_next(le);
if (base + base->property == p) {
base->property += p->property;
ClearPageProperty(p);
list_del(&(p->page_link));
} else if (p + p->property == base) {
p->property += base->property;
ClearPageProperty(base);
base = p;
list_del(&(p->page_link));
}
}
nr_free += n;
le = &free_list;
while ((le = list_next(le)) != &free_list) {
if (le2page(le, page_link) > base) {
break;
}
}
list_add_before(le, &(base->page_link));
}
static void
default_init_memmap(struct Page *base, size_t n) {
// Given Code
// assert(n > 0);
// struct Page *p = base;
// for (; p != base + n; p ++) {
// assert(PageReserved(p));
// p->flags = p->property = 0;
// set_page_ref(p, 0);
// }
// base->property = n;
// SetPageProperty(base);
// nr_free += n;
// list_add(&free_list, &(base->page_link));
assert(n > 0);
struct Page *p = base;
for (; p != base + n; p ++) {
assert(PageReserved(p));
p->flags = p->property = 0;
ClearPageProperty(p);
set_page_ref(p, 0);
}
base->property = n;
SetPageProperty(base);
nr_free += n;
list_add(&free_list, &(base->page_link));
}
//buddy_init_memmap - build free_list for Page base follow n continuing pages.
static void buddy_init_memmap(struct numa_mem_zone *zone)
{
static int zone_num = 0;
size_t n = zone->n;
assert(n > 0 && zone_num < MAX_NUMA_MEM_ZONES);
zone_num ++;
struct Page *base = zone->page;
struct Page *p = base;
for (; p != base + n; p++) {
assert(PageReserved(p));
p->flags = p->property = 0;
p->zone_num = zone->id;
set_page_ref(p, 0);
}
//p = zones[zone_num++].mem_base = base;
p = base;
size_t order = MAX_ORDER, order_size = (1 << order);
uint32_t numa_id = zone->node->id;
assert(numa_id < sysconf.lnuma_count);
while (n != 0) {
while (n >= order_size) {
p->property = order;
SetPageProperty(p);
list_add(&free_list(numa_id, order), &(p->page_link));
n -= order_size, p += order_size;
nr_free(numa_id, order)++;
}
order--;
order_size >>= 1;
}
}
//buddy_init_memmap - build free_list for Page base follow n continuous pages.
static void
buddy_init_memmap(struct Page *base, size_t n) {
static int zone_num = 0;
assert(n > 0 && zone_num < MAX_ZONE_NUM);
struct Page *p = base;
for (; p != base + n; p ++) {
assert(PageReserved(p));
p->flags = p->property = 0;
p->zone_num = zone_num;
set_page_ref(p, 0);
}
p = zones[zone_num ++].mem_base = base;
size_t order = MAX_ORDER, order_size = (1 << order);
while (n != 0) {
while (n >= order_size) {
p->property = order;
SetPageProperty(p);
list_add(&free_list(order), &(p->page_link));
n -= order_size, p += order_size;
nr_free(order) ++;
}
order --;
order_size >>= 1;
}
}
//get_pte - get pte and return the kernel virtual address of this pte for la
// - if the PT contians this pte didn't exist, alloc a page for PT
// parameter:
// pgdir: the kernel virtual base address of PDT
// la: the linear address need to map
// create: a logical value to decide if alloc a page for PT
// return vaule: the kernel virtual address of this pte
pte_t *
get_pte(pde_t *pgdir, uintptr_t la, bool create) {
/* LAB2 EXERCISE 2: YOUR CODE
*
* If you need to visit a physical address, please use KADDR()
* please read pmm.h for useful macros
*
* Maybe you want help comment, BELOW comments can help you finish the code
*
* Some Useful MACROs and DEFINEs, you can use them in below implementation.
* MACROs or Functions:
* PDX(la) = the index of page directory entry of VIRTUAL ADDRESS la.
* KADDR(pa) : takes a physical address and returns the corresponding kernel virtual address.
* set_page_ref(page,1) : means the page be referenced by one time
* page2pa(page): get the physical address of memory which this (struct Page *) page manages
* struct Page * alloc_page() : allocation a page
* memset(void *s, char c, size_t n) : sets the first n bytes of the memory area pointed by s
* to the specified value c.
* DEFINEs:
* PTE_V 0x001 // page table/directory entry flags bit : Present
* PTE_W 0x002 // page table/directory entry flags bit : Writeable
* PTE_U 0x004 // page table/directory entry flags bit : User can access
*/
#if 0
pde_t *pdep = NULL; // (1) find page directory entry
if (0) { // (2) check if entry is not present
// (3) check if creating is needed, then alloc page for page table
// CAUTION: this page is used for page table, not for common data page
// (4) set page reference
uintptr_t pa = 0; // (5) get linear address of page
// (6) clear page content using memset
// (7) set page directory entry's permission
}
return NULL; // (8) return page table entry
#endif
pde_t *pdep = &pgdir[PDX(la)]; //right!!!
// if(la==0x50000000)
// cprintf("pdep=%08x\n",pdep);
if (!(*pdep & PTE_V)) {
struct Page *page;
// cprintf("haha\n");
// cprintf("create=%d\n",create);
if (!create || (page = alloc_page()) == NULL) {
return NULL;
}
//cprintf("hahapaget_pte\n");
set_page_ref(page, 1);
uintptr_t pa = page2pa(page);
memset(KADDR(pa), 0, PGSIZE);
*pdep = pa | PTE_TYPE_TABLE | PTE_V | PTE_R;
}
//cprintf("%08x\n",&((pte_t *)KADDR(PDE_ADDR(*pdep)))[PTX(la)]);
// if(la==0x50000000)
// cprintf("get_pte return=%08x\n",&((pte_t *)KADDR(PDE_ADDR(*pdep)))[PTX(la)]);
return &((pte_t *)KADDR(PDE_ADDR(*pdep)))[PTX(la)];
}
static void
default_free_pages(struct Page *base, size_t n) {
assert(n > 0);
struct Page *p = base;
for (; p != base + n; p ++) {
assert(!PageReserved(p) && !PageProperty(p));
p->flags = 0;
set_page_ref(p, 0);
}
base->property = n;
SetPageProperty(base);
list_entry_t *le = list_next(&free_list);
// Given Code
// while (le != &free_list) {
// p = le2page(le, page_link);
// le = list_next(le);
// if (base + base->property == p) {
// base->property += p->property;
// ClearPageProperty(p);
// list_del(&(p->page_link));
// }
// else if (p + p->property == base) {
// p->property += base->property;
// ClearPageProperty(base);
// base = p;
// list_del(&(p->page_link));
// }
// }
// nr_free += n;
// list_add(&free_list, &(base->page_link));
while (le != &free_list) {
p = le2page(le, page_link);
if (base + base->property < p) //已经遍历到第一个地址大于base且无法合并的块，跳出循环
break;
le = list_next(le);
if (p + p->property == base) { //检查是否是base之前的能合并的块
p->property += base->property;
base->flags = base->property = 0;
ClearPageProperty(base);
base = p;
list_del(&(p->page_link));
}
else if (base + base->property == p) { //检查是否是base之后能合并的块
base->property += p->property;
p->flags = p->property = 0;
ClearPageProperty(p);
list_del(&(p->page_link));
}
}
nr_free += n; //空闲空间增加
SetPageProperty(base); //property = 1
list_add_before(le, &(base->page_link)); //插入在第一个第一个地址大于base且无法合并的块之前
}
static void
default_free_pages(struct Page *base, size_t n) {
assert(n > 0);
struct Page *p = base;
for (; p != base + n; p ++) {
assert(!PageReserved(p) && !PageProperty(p));
p->flags = 0;
set_page_ref(p, 0);
}
base->property = n;
SetPageProperty(base);
list_entry_t *le = &free_list;
while (1) {
//TODO: set reserve bits and could be faster
le = list_next(le);
p = le2page(le, page_link);
if (le == &free_list || p > base) {
list_add_before(&(p->page_link), &(base->page_link));
break;
}
}
int flag = 1;
//cprintf("Now check merge\n");
while (flag == 1)
{
flag = 0;
p = le2page((base->page_link.next), page_link);
//cprintf("base = %08x p = %08x size = %d\n", base, p, base->property);
//cprintf(" plus = %08x\n", base + base->property);
if (base->page_link.next != &free_list && base+base->property==p) {
base->property += p->property;
//cprintf("merge on the back: %d\n", p->property);
ClearPageProperty(p);
list_del(&(p->page_link));
//cprintf("flag = %d %d\n", base->flags, p->flags);
flag = 1;
}
p = le2page((base->page_link.prev), page_link);
//cprintf("base = %08x p = %08x size = %d\n", base, p, base->property);
if (base->page_link.prev != &free_list && p+p->property==base) {
p->property += base->property;
//cprintf("merge on the front: %d\n", p->property);
ClearPageProperty(base);
list_del(&(base->page_link));
//cprintf("flag = %d %d\n", base->flags, p->flags);
base = p;
flag = 1;
}
}
nr_free += n;
//list_add(&free_list, &(base->page_link));
}
static void default_init_memmap(struct Page *base, size_t n) {
assert(n > 0);
struct Page *p = base;
for (; p != base + n; p++) {
assert(PageReserved(p));
p->flags = p->property = 0;
set_page_ref(p, 0);
}
base->property = n;
SetPageProperty(base);
nr_free += n;
list_add(&free_list, &(base->page_link));
}
//static void
default_free_pages(struct Page *base, size_t n) {
assert(n > 0);
assert(PageReserved(base));
//遍历空闲块链表，找到合适的位置插入回收的地址块
list_entry_t *le = &free_list;
struct Page *page = NULL;
//寻找第一个空闲块
while ((le = list_next(le)) != &free_list) {
page = le2page(le, page_link);
if (page > base) {
break;
}
}
//插入回收的空闲块：按页插入
for (page=base; page<(base+n); page++) {
list_add_before(le, &(page->page_link));
}
//重置该块的字段
base->flags = 0;
base->property = n;
set_page_ref(base, 0);
ClearPageProperty(base);
SetPageProperty(base);
//尝试合并地址相连的空闲地址块
//先查看后一个空闲块
page = le2page(le, page_link); //得到后一个空闲块起始地址
if ((base+n) == page) {
base->property += page->property;
page->property = 0;
}
//后查看前一个空闲块
le = list_prev(&(base->page_link));
page = le2page(le, page_link); //此时并不是前一个空闲块，而是前一个page
if ((le!= &free_list) && page == (base-1)) {
while (le!= &free_list) {
if (page->property > 0) {
page->property += base->property;
base->property =0;
break;
}
le = list_prev(le);
page = le2page(le, page_link);
}
}
nr_free += n;
return;
}
static void
default_init_memmap(struct Page *base, size_t n) {
assert(n > 0);
struct Page *p = base;
for (; p != base + n; p ++) {
assert(PageReserved(p));
p->flags = 0; // init p->flags as 0
SetPageProperty(p); // p->flags should be set bit PG_property
p->property = 0; // p->property should be set to 0
set_page_ref(p, 0); // p->ref should be 0, because now p is free and no reference
list_add_before(&free_list, &(p->page_link)); // link this page to free_list
}
base->property = n; // for the first page of free block, its property should be set to total num of block
nr_free += n; // sum the number of free mem block
}
static void
default_init_memmap(struct Page *base, size_t n) {
assert(n > 0);
struct Page *p = base +1;
for (; p < base + n; ++ p) {
assert(PageReserved(p));
ClearPageReserved(p);
ClearPageProperty(p);
p->property = 0;
set_page_ref(p, 0);
list_init(&(p->page_link));
}
assert(PageReserved(base));
ClearPageReserved(base);
SetPageProperty(base);
base->property = n;
set_page_ref(base, 0);
list_add_before(&free_list, &(base -> page_link));
nr_free += n;
}
static void
default_init_memmap(struct Page *base, size_t n) {
assert(n > 0);
struct Page *p = base;
for (; p != base + n; p ++) {
assert(PageReserved(p));
p->flags = 0; // Clears the flags.
p->property = 0; // Not the first page of free block.
set_page_ref(p, 0); // Free and no reference.
}
SetPageProperty(base); // Valid page.
list_add(&free_list, &(base->page_link)); // Links this page to free_list
base->property = n; // First page of n free blocks.
nr_free += n;
}
static void
default_free_pages(struct Page *base, size_t n) {
assert(n > 0);
assert(PageReserved(base));
list_entry_t *le = &free_list;
struct Page * p;
while((le=list_next(le)) != &free_list) {
p = le2page(le, page_link);
if(p>base){
break;
}
}
// 每个page都加入freelist
for(p=base;p<base+n;p++){
list_add_before(le, &(p->page_link));
}
// 首个page进行设置
base->flags = 0;
set_page_ref(base, 0);
ClearPageProperty(base);
SetPageProperty(base);
base->property = n;
p = le2page(le,page_link);
// 如果后面需要合并
if( base+n == p ){
base->property += p->property;
p->property = 0;
}
le = list_prev(&(base->page_link));
p = le2page(le, page_link);
// 如果前面需要合并
if(le!=&free_list && p==base-1){
while(le!=&free_list){
if(p->property){
p->property += base->property;
base->property = 0;
break;
}
le = list_prev(le);
p = le2page(le,page_link);
}
}
nr_free += n;
return ;
}
static void
default_free_pages(struct Page *base, size_t n) {
// 用于释放页
// 我们来仔细看一下释放page的函数吧！
assert(n > 0);
assert(PageReserved(base));
list_entry_t *le = &free_list; // le指向空闲段链表的头部
struct Page *p;
while ((le = list_next(le)) != &free_list) { // 开始遍历
p = le2page(le, page_link);
if (p > base) { // free_list里面的数据都是按照地址从小到大排列的吧！
break;
}
}
// le现在指向一个恰好在base页面之后的page
for (p = base; p < base + n; p++) { // 不断地在前面插入
list_add_before(le, &(p->page_link));
}
base->flags = 0;
set_page_ref(base, 0); // 引用计数变为了0
ClearPageProperty(base); //
SetPageProperty(base); // 只需要这句就行了吧！
base->property = n;
p = le2page(le, page_link);
if (base + n == p) { // 也就是说，前后可以连接起来
base->property += p->property;
p->property = 0;
}
le = list_prev(&(base->page_link));
p = le2page(le, page_link); // 找到free_list中base之前的那个free page
if (le != &free_list && p == base - 1) { // 如果两个也可以连起来
while (le != &free_list) {
if (p->property) {
p->property += base->property;
base->property = 0;
break;
}
le = list_prev(le);
p = le2page(le, page_link);
}
}
nr_free += n; // 空闲页的计数加n
return;
}
static void
default_init_memmap(struct Page *base, size_t n) {
assert(n > 0);
struct Page *p = base;
for (; p != base + n; p ++) {
assert(PageReserved(p));
p->flags = 0;
SetPageProperty(p);
p->property = 0;
set_page_ref(p, 0);
list_add_before(&free_list, &(p->page_link));
}
nr_free += n;
//first block
base->property = n;
}
static void
default_free_pages(struct Page *base, size_t n) {
assert(n > 0);
struct Page *p = base;
for (; p != base + n; p ++) {
assert(!PageReserved(p) && !PageProperty(p));
p->flags = 0;
set_page_ref(p, 0);
}
base->property = n;
SetPageProperty(base);
list_entry_t *le = list_next(&free_list);
while (le != &free_list) {
p = le2page(le, page_link);
le = list_next(le);
if (base + base->property == p) {
base->property += p->property;
ClearPageProperty(p);
list_del(&(p->page_link));
}
else if (p + p->property == base) {
p->property += base->property;
ClearPageProperty(base);
base = p;
list_del(&(p->page_link));
}else{
if(base + base->property < p && p->page_link.prev == &free_list){
list_add(&free_list , &base->page_link);
nr_free += n;
return ;
}else if(le == &free_list && p+p->property < base){
list_add_before(&free_list , &base->page_link);
nr_free += n;
return ;
}else {
struct Page *page_next = le2page(le , page_link);
if(p+p->property < base && base+base->property<page_next){
list_add(p , &base->page_link);
nr_free += n;
return ;
}
}
}
}
nr_free += n;
list_add(&free_list, &(base->page_link));
}
static void
default_free_pages(struct Page *base, size_t n) {
assert(n > 0);
assert(PageReserved(base));
list_entry_t *le = &free_list; //获取空闲内存页的起始地址
struct Page *p;
while((le = list_next(le))!= &free_list){
p = le2page(le, page_link);
if( p > base){
//说明base应该接到p的前面,也就是le的前面
break;
}
}
for( p = base; p<base+n; p++){
list_add_before(le, &(p->page_link));
}
base->flags = 0;
set_page_ref(base, 0);
ClearPageProperty(base);
SetPageProperty(base);
base->property = n;
//下面是块的合并
//向后
p = le2page(le, page_link);
if(base+n == p){
base->property += p->property;
p->property = 0;
}
//向前
le = list_prev(&(base->page_link));
p = le2page(le, page_link);
if(le!=&free_list && p == base-1){
while(le!=&free_list){
if(p->property){
p->property += base->property;
base->property = 0;
break;
}
le = list_prev(le);
p = le2page(le, page_link);
}
}
nr_free += n;
return ;
}
static void
default_free_pages(struct Page *base, size_t n) {
assert(n > 0);
struct Page *p = base;
for (; p != base + n; p ++) {
assert(!PageReserved(p) && !PageProperty(p));
p->flags = 0;
set_page_ref(p, 0);
}
base->property = n;
SetPageProperty(base);
list_entry_t *le = list_next(&free_list);
while(1) {
p = le2page(le, page_link);
if (le == &free_list || p >= base) {
list_add_before(le, &(base->page_link));
break;
}
le = list_next(le);
}
// Search Next
le = list_next(&(base->page_link));
if(le != &free_list) {
p = le2page(le, page_link);
if(base + n == p) {
// Link them
base->property += p->property;
ClearPageProperty(p);
list_del(&(p->page_link));
}
}
// Search Prev
le = list_prev(&(base->page_link));
if(le != &free_list) {
p = le2page(le, page_link);
if(p + p->property == base) {
// Link them
p->property += base->property;
ClearPageProperty(base);
list_del(&(base->page_link));
}
}
nr_free += n;
}
static void
default_free_pages(struct Page *base, size_t n) {
assert(n > 0);
// (5.1)
list_entry_t *le = &free_list;
while ((le = list_next(le)) != &free_list) {
if (le2page(le, page_link) > base) { // the first position higher than base
break;
}
}
struct Page *p;
for (p = base; p < base + n; p++) { // insert these pages
p->property = 0;
list_add_before(le, &(p->page_link));
}
// (5.2) mark base as free page
base->flags = 0;
SetPageProperty(base);
base->property = n;
set_page_ref(base, 0);
// (5.3)
p = le2page(le, page_link);
if (p == base + n) { // merge forward
base->property += p->property; // merge p into base
p->property = 0;
}
le = list_prev(&(base->page_link));
p = le2page(le, page_link); // prev of base
if (p == base - 1) { // merge backward
for (; le != &free_list; le = list_prev(le)) {
p = le2page(le, page_link);
if (p->property > 0) { // find property, merge base into p
p->property += base->property;
base->property = 0;
break;
}
}
}
nr_free += n;
}
static void
default_free_pages(struct Page *base, size_t n) {
assert(n > 0);
assert(PageReserved(base));
struct Page *p = base;
struct Page * q = NULL;
list_entry_t * le = &free_list;
while((le = list_next(le)) != &free_list)
{
q = le2page(le,page_link);
if(q > base)
break;
}
//struct Page * q =
for(;p < base + n;p++){
list_add_before(le,&(p -> page_link));
}
base -> flags = 0;
set_page_ref(base,0);
ClearPageProperty(base);
SetPageProperty(base);
base->property = n;
if(q == base + n){
base -> property += q -> property;
q -> property = 0;
}
le = list_prev(&(base -> page_link));
q = le2page(le,page_link);
if(le != &free_list && q == base -1)
{
while(le != &free_list){
if(q -> property)
{
q -> property += base -> property;
base -> property = 0;
break;
}
le = list_prev(le);
q = le2page(le,page_link);
}
}
nr_free += n;
return;
}
static void
default_free_pages(struct Page *base, size_t n) {
assert(n > 0);
list_entry_t *le = &free_list;
list_entry_t *bef;
struct Page* p;
while ((le = list_next(le)) != &free_list){
p = le2page(le, page_link);
if (p > base) break;
}
for (p = base; p< base+n; p++){
list_add_before(le, &(p->page_link));
}
base ->flags = 0;
set_page_ref(base, 0);
ClearPageReserved(base); //
SetPageProperty(base);
base->property = n;
p = le2page(le, page_link);
if (base + n == p){
base->property += p->property;
p->property = 0;
}
bef = list_prev(&(base->page_link));
p = le2page(bef, page_link);
if (bef != &free_list && p == base-1){
while (bef != &free_list){
if (p -> property != 0){
p->property += base->property;
base->property = 0;
break;
}
bef = list_prev(bef);
p = le2page(bef, page_link);
}
}
nr_free += n;
return;
}
static void
default_init_memmap(struct Page *base, size_t n) {
assert(n > 0);
//首先需要初始化该空闲块中的每个页
struct Page *p = base;
for (; p != base + n; p++) {
assert(PageReserved(p));
p->flags = 0;
SetPageProperty(p); //设置p->flags
p->property = 0; //设置p->property
set_page_ref(p, 0); //设置 p->ref
list_add_before(&free_list, &(p->page_link));
}
//base是该空闲块中的第一个page，并且是free的，故property赋值为n
base->property = n;
//最后更新nf_free的值
nr_free += n;
}
static void
default_free_pages(struct Page *base, size_t n) {
assert(n > 0);
// Frees the pages;
base->flags = 0; // Clears the flags.
base->property = 0; // Not the first page of free block.
set_page_ref(base, 0); // Free and no reference.
SetPageProperty(base);
base->property = n; // First page of n free blocks.
// Finds the insertion position.
list_entry_t *le = &free_list;
struct Page *prev_page = NULL;
struct Page *next_page = NULL;
while ((le = list_next(le)) != &free_list) {
next_page = le2page(le, page_link);
if (next_page > base) {
break;
}
prev_page = next_page;
}
// Adds freed space to list.
list_add_before(le, &(base->page_link));
// If next_p is adjacent, combine them.
if (next_page && base + base->property == next_page) {
base->property += next_page->property;
ClearPageProperty(next_page);
next_page->property = 0;
list_del(&(next_page->page_link));
}
// If prev_page is adjacent, combine them.
if (prev_page && prev_page + prev_page->property == base) {
prev_page->property += base->property;
ClearPageProperty(base);
base->property = 0;
list_del(&(base->page_link));
}
nr_free += n;
}
static void
default_init_memmap(struct Page *base, size_t n) {
assert(n > 0);
struct Page *p = base;
for (; p != base + n; p ++) {
assert(PageReserved(p));
p->flags = p->property = 0;
set_page_ref(p, 0);
}
base->property = n;
SetPageProperty(base);
nr_free += n;
list_add(&free_list, &(base->page_link));
list_entry_t *le = &free_list;
while ((le = list_next(le)) != &free_list) {
struct Page *p = le2page(le, page_link);
cprintf("iiiiiiii %d \n",p->flags);
}
}
static void
default_init_memmap(struct Page *base, size_t n) {
assert(n > 0);
// n是页数
struct Page *p = base;
for (; p != base + n; p ++) {
assert(PageReserved(p));
p->flags = p->property = 0;
SetPageProperty(p);
set_page_ref(p, 0); // 引用计数设置为0
// 也就是在free_list的前面插入，不过考虑到这是一个双向链表，所以实际的意思是，插到链表的尾部
list_add_before(&free_list, &(p->page_link));
}
// 因为base是头表
// property这个玩意只有在free block首地址对应的Page有用，其余都被设置为了0
// 用于指示这个free block一共有多少个free page
base->property = n; // 可用的页面数是n
SetPageProperty(base); // base所在的页面为头表
nr_free += n; // 空闲的页面数目增加了n
//list_add(&free_list, &(base->page_link)); // 添加到free_list的头部
}
pmd_t *
get_pmd(pgd_t *pgdir, uintptr_t la, bool create) {
#if PMXSHIFT == PUXSHIFT
return get_pud(pgdir, la, create);
#else /* PMXSHIFT == PUXSHIFT */
pud_t *pudp;
if ((pudp = get_pud(pgdir, la, create)) == NULL) {
return NULL;
}
if (!(*pudp & PTE_P)) {
struct Page *page;
if (!create || (page = alloc_page()) == NULL) {
return NULL;
}
set_page_ref(page, 1);
uintptr_t pa = page2pa(page);
memset(VADDR_DIRECT(pa), 0, PGSIZE);
*pudp = pa | PTE_U | PTE_W | PTE_P;
}
return &((pmd_t *)VADDR_DIRECT(PUD_ADDR(*pudp)))[PMX(la)];
#endif /* PMXSHIFT == PUXSHIFT */
}
static void default_free_pages(struct Page* base, size_t n) {
assert(0 < n);
struct Page* p = base;
for (; p != base + n; ++p) {
assert(!PageReserved(p) && !PageProperty(p));
p->flags = 0;
set_page_ref(p, 0);
}
base->property = n;
SetPageProperty(base);
list_entry_t* le = list_next(&free_list);
// Find insertion position
while (le2page(le, page_link) < base && le != &free_list) {
le = list_next(le);
}
le = list_prev(le);
// Insert into list
list_add(le, &(base->page_link));
// Merge previous one
p = le2page(le, page_link);
if (p + p->property == base) {
p->property += base->property;
ClearPageProperty(base);
base->property = 0;
list_del(&(base->page_link));
base = p;
}
// Merge next one
if (list_next(&(base->page_link)) != &free_list) {
p = le2page(list_next(&(base->page_link)), page_link);
if (base + base->property == p) {
base->property += p->property;
ClearPageProperty(p);
p->property = 0;
list_del(&(p->page_link));
}
}
nr_free += n;
}
