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#include <kernel/arch/amd64/paging.h>
#include <kernel/arch/generic.h>
#include <kernel/mem/alloc.h>
#include <kernel/panic.h>
#include <shared/mem.h>
#include <stdint.h>
static void *addr_extract(pe_generic_t pe) {
return (void*)(uintptr_t)(pe.address << 12);
}
static void *addr_validate(void *addr) {
pe_generic_t pe = {.as_ptr = addr};
assert(addr_extract(pe) == addr);
return addr;
}
static bool addr_canonical(const __user void *addr) {
const int addr_bits = 48;
uintptr_t n = (uintptr_t)addr >> addr_bits;
return (n == 0) || ((~n) << addr_bits == 0);
}
struct pagedir *pagedir_new(void) {
struct pagedir *dir = page_alloc(1);
memset(dir, 0, sizeof *dir);
return dir;
}
void pagedir_free(struct pagedir *dir) {
for (int i = 0; i < 512; i++) {
if (!dir->e[i].present) continue;
assert(!dir->e[i].large);
pe_generic_t *pdpt = addr_extract(dir->e[i]);
for (int j = 0; j < 512; j++) {
if (!pdpt[j].present) continue;
assert(!pdpt[j].large);
pe_generic_t *pd = addr_extract(pdpt[j]);
for (int k = 0; k < 512; k++) {
if (!pd[k].present) continue;
assert(!pd[k].large);
pe_generic_t *pt = addr_extract(pd[k]);
for (int l = 0; l < 512; l++) {
if (!pt[l].present) continue;
if (!pt[l].user) continue;
page_free(addr_extract(pt[l]), 1);
}
page_free(pt, 1);
}
page_free(pd, 1);
}
page_free(pdpt, 1);
}
page_free(dir, 1);
}
static pe_generic_t*
get_entry(struct pagedir *dir, const void __user *virt) {
pe_generic_t *pml4e, *pdpte, *pde, *pte;
const union virt_addr v = {.full = (void __user *)virt};
if (!addr_canonical(virt)) return NULL;
pml4e = &dir->e[v.pml4];
if (!pml4e->present) return NULL;
assert(!pml4e->large);
pdpte = &((pe_generic_t*)addr_extract(*pml4e))[v.pdpt];
if (!pdpte->present) return NULL;
assert(!pdpte->large);
pde = &((pe_generic_t*)addr_extract(*pdpte))[v.pd];
if (!pde->present) return NULL;
assert(!pde->large);
pte = &((pe_generic_t*)addr_extract(*pde))[v.pt];
return pte;
}
void *pagedir_unmap(struct pagedir *dir, void __user *virt) {
pe_generic_t *page = get_entry(dir, virt);
if (!page) return NULL;
page->present = false;
return addr_extract(*page);
}
void pagedir_map(struct pagedir *dir, void __user *virt, void *phys,
bool user, bool writeable)
{
pe_generic_t *pml4e, *pdpte, *pde, *pte;
const union virt_addr v = {.full = virt};
if (!addr_canonical(virt)) return;
pml4e = &dir->e[v.pml4];
if (!pml4e->present) {
pml4e->as_ptr = addr_validate(page_zalloc(1));
pml4e->present = 1;
pml4e->writeable = 1;
pml4e->user = 1;
}
assert(!pml4e->large);
pdpte = &((pe_generic_t*)addr_extract(*pml4e))[v.pdpt];
if (!pdpte->present) {
pdpte->as_ptr = addr_validate(page_zalloc(1));
pdpte->present = 1;
pdpte->writeable = 1;
pdpte->user = 1;
}
assert(!pdpte->large);
pde = &((pe_generic_t*)addr_extract(*pdpte))[v.pd];
if (!pde->present) {
pde->as_ptr = addr_validate(page_zalloc(1));
pde->present = 1;
pde->writeable = 1;
pde->user = 1;
}
assert(!pde->large);
pte = &((pe_generic_t*)addr_extract(*pde))[v.pt];
if (!pte->present) {
pte->address = ((uintptr_t)phys) >> 12;
pte->present = 1;
pte->writeable = writeable;
pte->user = user;
} else {
panic_invalid_state();
}
}
extern void *pagedir_current;
void pagedir_switch(struct pagedir *dir) {
pagedir_current = dir;
}
// creates a new pagedir with exact copies of the user pages
struct pagedir *pagedir_copy(const struct pagedir *pml4_old) {
struct pagedir *pml4_new = page_zalloc(1);
for (int i = 0; i < 512; i++) {
if (!pml4_old->e[i].present) continue;
assert(!pml4_old->e[i].large);
const pe_generic_t *pdpt_old = addr_extract(pml4_old->e[i]);
pe_generic_t *pdpt_new = page_zalloc(1);
pml4_new->e[i] = pml4_old->e[i];
pml4_new->e[i].address = (uintptr_t) pdpt_new >> 12;
for (int j = 0; j < 512; j++) {
if (!pdpt_old[j].present) continue;
assert(!pdpt_old[j].large);
const pe_generic_t *pd_old = addr_extract(pdpt_old[j]);
pe_generic_t *pd_new = page_zalloc(1);
pdpt_new[j] = pdpt_old[j];
pdpt_new[j].address = (uintptr_t) pd_new >> 12;
for (int k = 0; k < 512; k++) {
if (!pd_old[k].present) continue;
assert(!pd_old[k].large);
const pe_generic_t *pt_old = addr_extract(pd_old[k]);
pe_generic_t *pt_new = page_zalloc(1);
pd_new[k] = pd_old[k];
pd_new[k].address = (uintptr_t) pt_new >> 12;
for (int l = 0; l < 512; l++) {
if (!pt_old[l].present) continue;
pt_new[l] = pt_old[l];
if (!pt_old[l].user) continue;
void *page_new = page_alloc(1);
memcpy(page_new, addr_extract(pt_old[l]), PAGE_SIZE);
pt_new[l].address = (uintptr_t) page_new >> 12;
}
}
}
}
return pml4_new;
}
bool pagedir_iskern(struct pagedir *dir, const void __user *virt) {
pe_generic_t *page = get_entry(dir, virt);
return page && page->present && !page->user;
}
void *pagedir_virt2phys(struct pagedir *dir, const void __user *virt,
bool user, bool writeable)
{
pe_generic_t *page = get_entry(dir, virt);
if (!page || !page->present) return NULL;
if (user && !page->user) return NULL;
if (writeable && !page->writeable) return NULL;
return addr_extract(*page) + ((uintptr_t)virt & PAGE_MASK);
}
void __user *pagedir_findfree(struct pagedir *dir, char __user *start, size_t len) {
// TODO dogshit slow
pe_generic_t *page;
char __user *iter;
start = (userptr_t)(((uintptr_t __force)start + PAGE_MASK) & ~PAGE_MASK); // round up to next page
iter = start;
while (iter < (char __user *)0xFFF00000) { // TODO better boundary
page = get_entry(dir, iter);
if (page && page->present) {
start = iter + PAGE_SIZE;
} else {
if ((size_t)(iter + PAGE_SIZE - start) >= len)
return start;
}
iter += PAGE_SIZE;
}
return NULL;
}
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