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Initial implementation of lab 2.

This commit is contained in:
Danila Fedorin 2019-04-19 01:14:51 -07:00
parent d7a96eb60f
commit ca51596893
1 changed files with 106 additions and 19 deletions
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125
kern/pmap.c
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@ -102,8 +102,10 @@ boot_alloc(uint32_t n)
// to a multiple of PGSIZE.
//
// LAB 2: Your code here.
result = nextfree;
nextfree = ROUNDUP(nextfree + n, PGSIZE);
return NULL;
return result;
}
// Set up a two-level page table:
@ -124,9 +126,6 @@ mem_init(void)
// Find out how much memory the machine has (npages & npages_basemem).
i386_detect_memory();
// Remove this line when you're ready to test this function.
panic("mem_init: This function is not finished\n");
//////////////////////////////////////////////////////////////////////
// create initial page directory.
kern_pgdir = (pde_t *) boot_alloc(PGSIZE);
@ -148,7 +147,9 @@ mem_init(void)
// array. 'npages' is the number of physical pages in memory. Use memset
// to initialize all fields of each struct PageInfo to 0.
// Your code goes here:
size_t pages_size = sizeof(struct PageInfo) * npages;
pages = boot_alloc(pages_size);
memset(pages, 0, pages_size);
//////////////////////////////////////////////////////////////////////
// Now that we've allocated the initial kernel data structures, we set
@ -172,6 +173,11 @@ mem_init(void)
// (ie. perm = PTE_U | PTE_P)
// - pages itself -- kernel RW, user NONE
// Your code goes here:
boot_map_region(kern_pgdir,
UPAGES, ROUNDUP(pages_size, PGSIZE),
PADDR(pages), PTE_W);
kern_pgdir[PDX(UPAGES)] |= PTE_U | PTE_P;
kern_pgdir[PDX(UPAGES)] &= ~PTE_W;
//////////////////////////////////////////////////////////////////////
// Use the physical memory that 'bootstack' refers to as the kernel
@ -184,6 +190,11 @@ mem_init(void)
// overwrite memory. Known as a "guard page".
// Permissions: kernel RW, user NONE
// Your code goes here:
boot_map_region(kern_pgdir,
KSTACKTOP-KSTKSIZE, KSTKSIZE,
PADDR(bootstack), PTE_W);
kern_pgdir[PDX(KSTACKTOP-KSTKSIZE)] |= PTE_W | PTE_P;
kern_pgdir[PDX(KSTACKTOP-KSTKSIZE)] &= ~PTE_U;
//////////////////////////////////////////////////////////////////////
// Map all of physical memory at KERNBASE.
@ -193,6 +204,12 @@ mem_init(void)
// we just set up the mapping anyway.
// Permissions: kernel RW, user NONE
// Your code goes here:
boot_map_region(kern_pgdir,
KERNBASE, 0x100000000 - KERNBASE,
0, PTE_W);
kern_pgdir[PDX(KERNBASE)] |= PTE_W | PTE_P;
kern_pgdir[PDX(KERNBASE)] &= ~PTE_U;
// Check that the initial page directory has been set up correctly.
check_kern_pgdir();
@ -224,6 +241,14 @@ mem_init(void)
// The 'pages' array has one 'struct PageInfo' entry per physical page.
// Pages are reference counted, and free pages are kept on a linked list.
// --------------------------------------------------------------
bool
is_reserved(size_t pagenum) {
if(pagenum == 0) return true;
if(pagenum >= PGNUM(IOPHYSMEM) &&
pagenum < PGNUM(PADDR(boot_alloc(0)))) return true;
return false;
}
//
// Initialize page structure and memory free list.
@ -253,9 +278,13 @@ page_init(void)
// free pages!
size_t i;
for (i = 0; i < npages; i++) {
pages[i].pp_ref = 0;
pages[i].pp_link = page_free_list;
page_free_list = &pages[i];
if(is_reserved(i)) {
pages[i].pp_ref = 1;
} else {
pages[i].pp_ref = 0;
pages[i].pp_link = page_free_list;
page_free_list = &pages[i];
}
}
}
@ -274,8 +303,17 @@ page_init(void)
struct PageInfo *
page_alloc(int alloc_flags)
{
// Fill this function in
return 0;
struct PageInfo* to_return = page_free_list;
if(to_return == 0) return NULL;
page_free_list = to_return->pp_link;
to_return->pp_link = NULL;
if(alloc_flags & ALLOC_ZERO) {
memset(page2kva(to_return), 0, PGSIZE);
}
return to_return;
}
//
@ -285,9 +323,10 @@ page_alloc(int alloc_flags)
void
page_free(struct PageInfo *pp)
{
// Fill this function in
// Hint: You may want to panic if pp->pp_ref is nonzero or
// pp->pp_link is not NULL.
if(pp->pp_ref || pp->pp_link != NULL)
panic("Freeing page with nonzero reference count!");
pp->pp_link = page_free_list;
page_free_list = pp;
}
//
@ -326,8 +365,25 @@ page_decref(struct PageInfo* pp)
pte_t *
pgdir_walk(pde_t *pgdir, const void *va, int create)
{
pte_t* base_table = NULL;
if(pgdir[PDX(va)] & PTE_P) {
// We have a valid page table; awesome!
base_table = KADDR(PTE_ADDR(pgdir[PDX(va)]));
} else {
if(!create) return NULL;
struct PageInfo* page = page_alloc(ALLOC_ZERO);
if(!page) return NULL;
page->pp_ref++;
physaddr_t ppa = page2pa(page);
pgdir[PDX(va)] = ppa | PTE_P | PTE_U | PTE_W;
base_table = KADDR(ppa);
}
// Fill this function in
return NULL;
return &base_table[PTX(va)];
}
//
@ -344,7 +400,16 @@ pgdir_walk(pde_t *pgdir, const void *va, int create)
static void
boot_map_region(pde_t *pgdir, uintptr_t va, size_t size, physaddr_t pa, int perm)
{
// Fill this function in
size_t count = size / PGSIZE;
uintptr_t start_va = va;
physaddr_t start_pa = pa;
while(count-- && start_va <= va && start_pa <= pa) {
pte_t* pte = pgdir_walk(pgdir, (void*) va, true);
*pte = pa | perm | PTE_P;
va += PGSIZE;
pa += PGSIZE;
}
}
//
@ -375,7 +440,14 @@ boot_map_region(pde_t *pgdir, uintptr_t va, size_t size, physaddr_t pa, int perm
int
page_insert(pde_t *pgdir, struct PageInfo *pp, void *va, int perm)
{
// Fill this function in
pte_t* pte;
if(!(pte = pgdir_walk(pgdir, va, true))) return -E_NO_MEM;
pp->pp_ref++;
if(*pte & PTE_P) page_remove(pgdir, va);
*pte = page2pa(pp) | PTE_P | perm;
tlb_invalidate(pgdir, va);
return 0;
}
@ -393,8 +465,15 @@ page_insert(pde_t *pgdir, struct PageInfo *pp, void *va, int perm)
struct PageInfo *
page_lookup(pde_t *pgdir, void *va, pte_t **pte_store)
{
// Fill this function in
return NULL;
pte_t* pte;
if(!(pte = pgdir_walk(pgdir, va, false))) {
if(pte_store) *pte_store = NULL;
return NULL;
}
struct PageInfo* pp = pa2page(PTE_ADDR(*pte));
if(pte_store) *pte_store = pte;
return pp;
}
//
@ -415,7 +494,15 @@ page_lookup(pde_t *pgdir, void *va, pte_t **pte_store)
void
page_remove(pde_t *pgdir, void *va)
{
// Fill this function in
pte_t* pte;
struct PageInfo* pp;
pp = page_lookup(pgdir, va, &pte);
if(!(*pte & PTE_P)) return;
if(!(--(pp->pp_ref))) page_free(pp);
*pte = 0;
tlb_invalidate(pgdir, va);
}
//