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rusya
2025-05-10 15:48:10 +03:00
parent 00c9560660
commit 0bf26a6c70
7 changed files with 158 additions and 221 deletions
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src/mm/paging.c
+25 -35
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@@ -7,31 +7,13 @@ uint32_t kernel_page_directory[1024] __attribute__((aligned(4096)));
uint32_t kernel_page_table[1024] __attribute__((aligned(4096)));
uint32_t user_page_table[1024] __attribute__((aligned(4096)));
#define PAGE_OFFSET 0xC0000000
#define PAGE_SIZE 4096
uint32_t *kpage_dir;
#define PAGE_PRESENT 0x1
#define PAGE_RW 0x002 /* Read/Write */
#define PAGE_USER 0x004 /* User */
#define PAGE_NOALLOC 0x200 /* No Page Allocated (OS managed) */
#define PAGE_SHIFT 0x0C
#define PAGE_MASK ~(PAGE_SIZE - 1) /* 0xFFFFF000 */
#define GDT_BASE (0xFFFFFFFF - (PAGE_OFFSET - 1))
#define GET_PGDIR(address) ((unsigned int)((address) >> 22) & 0x3FF)
#define GET_PGTBL(address) ((unsigned int)((address) >> 12) & 0x3FF)
#define PAGE_ALIGN(addr) (((addr) + (PAGE_SIZE - 1)) & PAGE_MASK)
unsigned int *kpage_dir;
unsigned int setup_tmp_pgdir(unsigned int magic, unsigned int info)
uint32_t setup_tmp_pgdir(uint32_t magic, uint32_t info)
{
int n, pd;
unsigned int addr, memksize;
unsigned int *pgtbl;
uint32_t pagedir_address, memksize;
uint32_t *page_table;
struct multiboot_info *mbi;
if(magic != MULTIBOOT_BOOTLOADER_MAGIC) {
@@ -44,33 +26,41 @@ unsigned int setup_tmp_pgdir(unsigned int magic, unsigned int info)
memksize = 4096;
} else {
/* we need to add the first 1MB to memksize */
memksize = (unsigned int)mbi->mem_upper + 1024;
/* CONFIG_VM_SPLIT22 marks the maximum physical memory supported */
memksize = (uint32_t)mbi->mem_upper + 1024;
if(memksize > ((0xFFFFFFFF - PAGE_OFFSET) / 1024)) {
memksize = (0xFFFFFFFF - PAGE_OFFSET) / 1024;
}
}
}
addr = PAGE_OFFSET + (memksize * 1024) - memksize;
addr = PAGE_ALIGN(addr);
/* address becomes PAGE_OFFSET (0xC0000000) plus the size of memory minus the first page */
/* TODO: check if I wrote the comment above correctly*/
pagedir_address = PAGE_OFFSET + (memksize * 1024) - memksize;
pagedir_address = PAGE_ALIGN(pagedir_address);
kpage_dir = (unsigned int *)addr;
/*
memory pages:
0 -> page directory
1 -> page table
*/
kpage_dir = (uint32_t *)pagedir_address;
memset(kpage_dir, 0, PAGE_SIZE);
addr += PAGE_SIZE;
pgtbl = (unsigned int *)addr;
memset(pgtbl, 0, memksize);
pagedir_address += PAGE_SIZE;
page_table = (uint32_t *)pagedir_address;
memset(page_table, 0, memksize);
for(n = 0; n < memksize / sizeof(unsigned int); n++) {
pgtbl[n] = (n << PAGE_SHIFT) | PAGE_PRESENT | PAGE_RW;
/* if we have 4MB assumed earlier, the memksize will be 4096 and this loop will run while n < 1024 */
/* so basically 4MB is 1024 pages */
for(n = 0; n < memksize / sizeof(uint32_t); n++) {
page_table[n] = (n << PAGE_SHIFT) | PAGE_PRESENT | PAGE_RW;
if(!(n % 1024)) {
pd = n / 1024;
kpage_dir[pd] = (unsigned int)(addr + (PAGE_SIZE * pd) + GDT_BASE) | PAGE_PRESENT | PAGE_RW;
kpage_dir[GET_PGDIR(PAGE_OFFSET) + pd] = (unsigned int)(addr + (PAGE_SIZE * pd) + GDT_BASE) | PAGE_PRESENT | PAGE_RW;
kpage_dir[pd] = (uint32_t)(pagedir_address + (PAGE_SIZE * pd) + GDT_BASE) | PAGE_PRESENT | PAGE_RW;
kpage_dir[GET_PGDIR(PAGE_OFFSET) + pd] = (uint32_t)(pagedir_address + (PAGE_SIZE * pd) + GDT_BASE) | PAGE_PRESENT | PAGE_RW;
}
}
return (unsigned int)kpage_dir - PAGE_OFFSET;
return (uint32_t)kpage_dir - PAGE_OFFSET;
}
void enablePaging() {