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page32.c
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/*****************************************************************************/
/* File: page32.c */
/* */
/* Description: Source file for 32 bit page table handling code. */
/* */
/* Author: Shoily O Rahman <[email protected]> */
/* */
/* Date: July 9, 2020 */
/* */
/*****************************************************************************/
#include "page32.h"
#include "system.h"
#include "lock.h"
#include "memory.h"
#include "debug.h"
extern addr_t _kernel_pg_table_0;
extern spinlock spinlock_smp;
extern int smp_bits;
extern int smp_on_hold;
extern pgd_t _master_kernel_pg_dir;
// locks for each GDT entry in kernel space shared among all the CPUs.
spinlock lock_pgd_kernel[(PAGE_SIZE-KERNEL_PGDIR_OFFSET)/sizeof(pgd_t)];
// locks in userspace. One lock per CPU for all GDT entries .
spinlock lock_pgd_user[MAX_NUM_SMPS];
#define LOCK_PGD(cpuid, addr, flags) { \
if (!((flags) & (MAP_USER | MAP_LOCAL_CPU)) && \
(addr) >= (addr_t)KERNEL_VIRT_ADDR) { \
spinlock_lock(&lock_pgd_kernel[((((addr)-KERNEL_VIRT_ADDR) >> PGD_SHIFT) & 0x3ff)]); \
} else { \
spinlock_lock(&lock_pgd_user[(cpuid)]); \
} \
}
#define UNLOCK_PGD(cpuid, addr, flags) { \
if (!((flags) & (MAP_USER | MAP_LOCAL_CPU)) && \
(addr) >= (addr_t)KERNEL_VIRT_ADDR) { \
spinlock_unlock(&lock_pgd_kernel[((((addr)-KERNEL_VIRT_ADDR) >> PGD_SHIFT) & 0x3ff)]); \
} else { \
spinlock_unlock(&lock_pgd_user[(cpuid)]); \
} \
}
void build_pagetable(u32 cpuid, pte_t **pgtable, addr_t phys_addr, addr_t start, u32 length, u32 pgd_flags, u32 pte_flags, u32 map_flags) {
int idx = 0;
bool locked = map_flags & MAP_PGD_LOCKED;
pgd_t *pgdir = (map_flags & (MAP_USER | MAP_LOCAL_CPU)) ? GET_CPU_PGDIR(cpuid) : &_master_kernel_pg_dir;
pgd_t *pgd = pgdir + ((start >> PGD_SHIFT) & 0x3ff);
pte_t *pte = pgtable[idx] + ((start >> PAGE_SHIFT) & 0x3ff);
pte_t *last_pte = (pte_t*)(((long)pte + PAGE_SIZE) & PAGE_MASK);
addr_t end = start + length;
if (!locked)
LOCK_PGD(cpuid, start, map_flags);
if (!*pgd) {
*pgd = ((long)pgtable[idx] - KERNEL_VIRT_ADDR) | pgd_flags;
} else if (((*pgd & PGD_FLAG_MASK) ^ pgd_flags) != 0) {
*pgd |= pgd_flags;
}
if (!locked)
UNLOCK_PGD(cpuid, start, map_flags);
while (start < end) {
if (pte == last_pte) {
idx++;
pte = pgtable[idx];
last_pte = (pte_t*)(((long)pte + PAGE_SIZE) & PAGE_MASK);
pgd++;
if (!locked)
LOCK_PGD(cpuid, start, map_flags);
if (!*pgd) {
*pgd = (((long)pgtable[idx] - KERNEL_VIRT_ADDR) | pgd_flags);
} else if (((*pgd & PGD_FLAG_MASK) ^ pgd_flags) != 0) {
*pgd |= pgd_flags;
}
if (!locked)
UNLOCK_PGD(cpuid, start, map_flags);
}
*pte = (phys_addr | pte_flags);
pte++;
start += PAGE_SIZE;
phys_addr += PAGE_SIZE;
}
}
void unmap_pagetable(u32 cpuid, pte_t **pgtable, addr_t start, u32 length, u32 map_flags) {
int idx = 0;
bool locked = map_flags & MAP_PGD_LOCKED;
pgd_t *pgdir = (map_flags & (MAP_USER | MAP_LOCAL_CPU)) ? GET_CPU_PGDIR(cpuid) : &_master_kernel_pg_dir;
pgd_t *pgd = pgdir + ((start >> PGD_SHIFT) & 0x3ff);
pte_t *pte = pgtable[idx] + ((start >> PAGE_SHIFT) & 0x3ff);
pte_t *last_pte = (pte_t*)(((long)pte + PAGE_SIZE) & PAGE_MASK);
addr_t end = start + length;
if (!locked)
LOCK_PGD(cpuid, start, map_flags);
if (!*pgd) {
start += ((last_pte-pte) << PAGE_SHIFT);
pte = last_pte;
}
if (!locked)
UNLOCK_PGD(cpuid, start, map_flags);
while (start < end) {
if (pte == last_pte) {
idx++;
pte = pgtable[idx];
last_pte = (pte_t*)(((long)pte + PAGE_SIZE) & PAGE_MASK);
pgd++;
if (!locked)
LOCK_PGD(cpuid, start + PAGE_SIZE, map_flags);
if (!*pgd) {
pte = last_pte;
if (!locked)
UNLOCK_PGD(cpuid, start + PAGE_SIZE, map_flags);
start += PGD_SIZE;
continue;
}
if (!locked)
UNLOCK_PGD(cpuid, start + PAGE_SIZE, map_flags);
}
*pte = 0;
pte++;
start += PAGE_SIZE;
}
}
void map_kernel_with_pagetable(addr_t virt_addr, addr_t phys_addr, u32 length, u32 pte_flags, u32 map_flags) {
pte_t *pgtbl[1];
pte_t *pte;
addr_t end_virt_addr;
if ((virt_addr < (addr_t)KERNEL_VIRT_ADDR) || (map_flags & MAP_USER))
return;
end_virt_addr = ALIGN_PAGE(virt_addr + length);
virt_addr = virt_addr & PAGE_MASK;
phys_addr = phys_addr & PAGE_MASK;
pte = (pte_t*)ADDPTRS(&_kernel_pg_table_0, (((VIRT_TO_PHYS_ADDR_LINEAR(virt_addr) >> PGD_SHIFT) & 0x3ff) << PAGE_SHIFT));
pte += (((long)(virt_addr) >> PAGE_SHIFT) & 0x3ff);
while (virt_addr != end_virt_addr) {
pgtbl[0] = (pte_t*)((long)pte & PAGE_MASK);
build_pagetable(CUR_CPU,
pgtbl,
phys_addr,
virt_addr,
PAGE_SIZE,
PGD_PRESENT | PGD_WRITE,
pte_flags | PTE_PRESENT,
map_flags);
virt_addr = ADDPTRS(virt_addr, PAGE_SIZE);
phys_addr = ADDPTRS(phys_addr, PAGE_SIZE);
pte++;
}
}
void unmap_kernel_with_pagetable(addr_t virt_addr, u32 length, u32 map_flags) {
pte_t *pgtbl[1];
pte_t *pte;
addr_t end_virt_addr;
if ((virt_addr < (addr_t)KERNEL_VIRT_ADDR) || (map_flags & MAP_USER))
return;
end_virt_addr = ALIGN_PAGE(virt_addr + length);
virt_addr = virt_addr & PAGE_MASK;
pte = (pte_t*)ADDPTRS(&_kernel_pg_table_0, (((VIRT_TO_PHYS_ADDR_LINEAR(virt_addr) >> PGD_SHIFT) & 0x3ff) << PAGE_SHIFT));
pte += (((long)(virt_addr) >> PAGE_SHIFT) & 0x3ff);
while (virt_addr != end_virt_addr) {
pgtbl[0] = (pte_t*)((long)pte & PAGE_MASK);
unmap_pagetable(CUR_CPU, pgtbl, virt_addr, PAGE_SIZE, map_flags);
virt_addr = ADDPTRS(virt_addr, PAGE_SIZE);
pte++;
}
}
int alloc_user_page(addr_t virt_addr, u32 length, u32 pte_flags) {
u32 pgtbl_idx;
addr_t addr, phys_addr;
struct kpage *page_buf;
struct kpage *page_pgtbl = NULL;
pte_t *pgtbl[1];
pgd_t *pgd;
u32 nr_pgtbls, prev_nr_pgtbls;
u32 pgd_len;
pgd_t *pgdir = GET_CPU_PGDIR(CUR_CPU);
if (!virt_addr)
return ERR_NOT_SUPPORTED;
if (virt_addr & (PAGE_SIZE-1))
return ERR_INVALID;
length = ALIGN_PAGE(length);
if ((virt_addr + length) >= (addr_t)KERNEL_VIRT_ADDR)
return ERR_INVALID;
page_buf = page_alloc(NPAGES_TO_ORDER(length >> PAGE_SHIFT));
if (!page_buf)
return ERR_NOMEM;
prev_nr_pgtbls = 0;
retry_pgtbl_read:
nr_pgtbls = 0;
addr = virt_addr;
pgd_len = ALIGN_PGD(length);
LOCK_PGD(CUR_CPU, 0, MAP_USER | MAP_LOCAL_CPU);
while (pgd_len) {
pgd = pgdir + ((addr >> PGD_SHIFT) & 0x3ff);
if (!*pgd)
nr_pgtbls++;
pgd_len -= PGD_SIZE;
addr = ADDPTRS(addr, PGD_SIZE);
}
if (prev_nr_pgtbls != nr_pgtbls) {
UNLOCK_PGD(CUR_CPU, addr, MAP_USER | MAP_LOCAL_CPU);
if (page_pgtbl) {
page_add_to_slot(page_pgtbl, NULL);
page_pgtbl = NULL;
}
if (nr_pgtbls) {
page_pgtbl = page_alloc(NPAGES_TO_ORDER(nr_pgtbls));
if (!page_pgtbl) {
UNLOCK_PGD(CUR_CPU, addr, MAP_USER | MAP_LOCAL_CPU);
page_add_to_slot(page_buf, NULL);
return ERR_NOMEM;
}
}
prev_nr_pgtbls = nr_pgtbls;
goto retry_pgtbl_read;
}
phys_addr = (addr_t)KPAGE_TO_PHYS_ADDR(page_buf);
pgtbl_idx = 0;
while (length) {
pgd = pgdir + ((virt_addr >> PGD_SHIFT) & 0x3ff);
if (*pgd) {
pgtbl[0] = (pte_t*)ADDPTRS((*pgd & PAGE_MASK), KERNEL_VIRT_ADDR);
} else {
pgtbl[0] = (pte_t*)ADDPTRS(ADDPTRS(KPAGE_TO_PHYS_ADDR(page_pgtbl), pgtbl_idx << PAGE_SHIFT), KERNEL_VIRT_ADDR);
pgtbl_idx++;
}
map_kernel_linear_with_pagetable((addr_t)pgtbl[0],
PAGE_SIZE,
PTE_WRITE,
MAP_LOCAL_CPU | MAP_PGD_LOCKED);
build_pagetable(CUR_CPU,
pgtbl,
phys_addr,
virt_addr,
PAGE_SIZE,
PGD_PRESENT | PGD_USER | ((pte_flags & PTE_WRITE) ? PGD_WRITE : 0),
PTE_PRESENT | PTE_USER | pte_flags,
MAP_USER | MAP_PGD_LOCKED);
unmap_kernel_with_pagetable((addr_t)pgtbl[0],
PAGE_SIZE,
MAP_LOCAL_CPU | MAP_PGD_LOCKED);
virt_addr = ADDPTRS(virt_addr, PAGE_SIZE);
phys_addr = ADDPTRS(phys_addr, PAGE_SIZE);
length -= PAGE_SIZE;
}
UNLOCK_PGD(CUR_CPU, 0, MAP_USER | MAP_LOCAL_CPU);
return 0;
}
pfn_t page_getpfn(void *addr) {
pgd_t *pgd = GET_CURCPU_PGDIR + (((long)(addr) >> PGD_SHIFT) & 0x3ff);
pte_t *pte = ((pte_t*)ADDPTRS(*pgd, KERNEL_VIRT_ADDR)) + (((long)(addr) >> PAGE_SHIFT) & 0x3ff);
return (*pte & PAGE_MASK);
}
void pgd_lock_init() {
u32 i;
for(i = 0; i < (sizeof(lock_pgd_kernel)/sizeof(spinlock)); i++)
INIT_SPIN_LOCK(&lock_pgd_kernel[i]);
for(i = 0; i < MAX_NUM_SMPS; i++)
INIT_SPIN_LOCK(&lock_pgd_user[i]);
}
void pgd_kernel_lock_all() {
u32 i;
for(i=0;i<sizeof(lock_pgd_kernel)/sizeof(spinlock);i++)
spinlock_lock(&lock_pgd_kernel[i]);
}
void pgd_kernel_unlock_all() {
u32 i;
for(i=0;i<sizeof(lock_pgd_kernel)/sizeof(spinlock);i++)
spinlock_unlock(&lock_pgd_kernel[i]);
}
void pagetable_delete_entry(u32 pfn, u32 pages) {
for (u32 i = 0; i < pages; i++, pfn++) {
//clear_tlb(pfn);
}
}