static inline unsigned long low_free_pages(void)
{
return nr_free_pages() - nr_free_highpages();
}
/* SunOS is completely broken... it returns 0 on success, otherwise
* ENOMEM. For sys_sbrk() it wants the old brk value as a return
* on success and ENOMEM as before on failure.
*/
asmlinkage int sunos_brk(unsigned long brk)
{
int freepages, retval = -ENOMEM;
unsigned long rlim;
unsigned long newbrk, oldbrk;
down_write(¤t->mm->mmap_sem);
if (ARCH_SUN4C_SUN4) {
if (brk >= 0x20000000 && brk < 0xe0000000) {
goto out;
}
}
if (brk < current->mm->end_code)
goto out;
newbrk = PAGE_ALIGN(brk);
oldbrk = PAGE_ALIGN(current->mm->brk);
retval = 0;
if (oldbrk == newbrk) {
current->mm->brk = brk;
goto out;
}
/*
* Always allow shrinking brk
*/
if (brk <= current->mm->brk) {
current->mm->brk = brk;
do_munmap(current->mm, newbrk, oldbrk-newbrk);
goto out;
}
/*
* Check against rlimit and stack..
*/
retval = -ENOMEM;
rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
if (rlim >= RLIM_INFINITY)
rlim = ~0;
if (brk - current->mm->end_code > rlim)
goto out;
/*
* Check against existing mmap mappings.
*/
if (find_vma_intersection(current->mm, oldbrk, newbrk+PAGE_SIZE))
goto out;
/*
* stupid algorithm to decide if we have enough memory: while
* simple, it hopefully works in most obvious cases.. Easy to
* fool it, but this should catch most mistakes.
*/
freepages = global_page_state(NR_FILE_PAGES);
freepages >>= 1;
freepages += nr_free_pages();
freepages += nr_swap_pages;
freepages -= num_physpages >> 4;
freepages -= (newbrk-oldbrk) >> PAGE_SHIFT;
if (freepages < 0)
goto out;
/*
* Ok, we have probably got enough memory - let it rip.
*/
current->mm->brk = brk;
do_brk(oldbrk, newbrk-oldbrk);
retval = 0;
out:
up_write(¤t->mm->mmap_sem);
return retval;
}
// LAB2: below code is used to check the first fit allocation algorithm (your EXERCISE 1)
// NOTICE: You SHOULD NOT CHANGE basic_check, default_check functions!
static void
default_check(void) {
int count = 0, total = 0;
list_entry_t *le = &free_list;
while ((le = list_next(le)) != &free_list) {
struct Page *p = le2page(le, page_link);
assert(PageProperty(p));
count ++, total += p->property;
}
assert(total == nr_free_pages());
basic_check();
struct Page *p0 = alloc_pages(5), *p1, *p2;
assert(p0 != NULL);
assert(!PageProperty(p0));
list_entry_t free_list_store = free_list;
list_init(&free_list);
assert(list_empty(&free_list));
assert(alloc_page() == NULL);
unsigned int nr_free_store = nr_free;
nr_free = 0;
free_pages(p0 + 2, 3);
assert(alloc_pages(4) == NULL);
assert(PageProperty(p0 + 2) && p0[2].property == 3);
assert((p1 = alloc_pages(3)) != NULL);
assert(alloc_page() == NULL);
assert(p0 + 2 == p1);
p2 = p0 + 1;
free_page(p0);
free_pages(p1, 3);
assert(PageProperty(p0) && p0->property == 1);
assert(PageProperty(p1) && p1->property == 3);
assert((p0 = alloc_page()) == p2 - 1);
free_page(p0);
assert((p0 = alloc_pages(2)) == p2 + 1);
free_pages(p0, 2);
free_page(p2);
assert((p0 = alloc_pages(5)) != NULL);
assert(alloc_page() == NULL);
assert(nr_free == 0);
nr_free = nr_free_store;
free_list = free_list_store;
free_pages(p0, 5);
le = &free_list;
while ((le = list_next(le)) != &free_list) {
struct Page *p = le2page(le, page_link);
count --, total -= p->property;
}
assert(count == 0);
assert(total == 0);
}
static void
check_vma_struct(void) {
size_t nr_free_pages_store = nr_free_pages();
struct mm_struct *mm = mm_create();
assert(mm != NULL);
int step1 = 10, step2 = step1 * 10;
int i;
for (i = step1; i >= 1; i --) {
struct vma_struct *vma = vma_create(i * 5, i * 5 + 2, 0);
assert(vma != NULL);
insert_vma_struct(mm, vma);
}
for (i = step1 + 1; i <= step2; i ++) {
struct vma_struct *vma = vma_create(i * 5, i * 5 + 2, 0);
assert(vma != NULL);
insert_vma_struct(mm, vma);
}
list_entry_t *le = list_next(&(mm->mmap_list));
for (i = 1; i <= step2; i ++) {
assert(le != &(mm->mmap_list));
struct vma_struct *mmap = le2vma(le, list_link);
assert(mmap->vm_start == i * 5 && mmap->vm_end == i * 5 + 2);
le = list_next(le);
}
for (i = 5; i <= 5 * step2; i +=5) {
struct vma_struct *vma1 = find_vma(mm, i);
assert(vma1 != NULL);
struct vma_struct *vma2 = find_vma(mm, i+1);
assert(vma2 != NULL);
struct vma_struct *vma3 = find_vma(mm, i+2);
assert(vma3 == NULL);
struct vma_struct *vma4 = find_vma(mm, i+3);
assert(vma4 == NULL);
struct vma_struct *vma5 = find_vma(mm, i+4);
assert(vma5 == NULL);
assert(vma1->vm_start == i && vma1->vm_end == i + 2);
assert(vma2->vm_start == i && vma2->vm_end == i + 2);
}
for (i =4; i>=0; i--) {
struct vma_struct *vma_below_5= find_vma(mm,i);
if (vma_below_5 != NULL ) {
cprintf("vma_below_5: i %x, start %x, end %x\n",i, vma_below_5->vm_start, vma_below_5->vm_end);
}
assert(vma_below_5 == NULL);
}
mm_destroy(mm);
assert(nr_free_pages_store == nr_free_pages());
cprintf("check_vma_struct() succeeded!\n");
}
