static void
context_switch(struct task_struct *prev,
struct task_struct *next)
{
switch_pgd(next->mm.pgd, next->pid);
switch_to(prev, next);
}
void vmm_init(void)
{
// 注册页错误中断的处理函数
register_interrupt_handler(INT_PAGE_FAULT, &do_page_fault);
// 页表数组指针
pte_t (*pte_kern)[PTE_SIZE] = (pte_t (*)[PTE_SIZE])pte_addr;
// 构造页目录(MMU需要的是物理地址，此处需要减去偏移)
uint32_t pgd_idx = PGD_INDEX(PAGE_OFFSET);
for (uint32_t i = pgd_idx; i < pgd_idx + PTE_COUNT; ++i) {
pgd_kern[i] = ((uint32_t)ka_to_pa(pte_kern[i])) | PAGE_PRESENT | PAGE_WRITE;
}
// 构造页表映射，内核 0xC0000000～0xF8000000 映射到 物理 0x00000000～0x38000000 (物理内存前896MB)
uint32_t *pte_start = (uint32_t *)(pte_addr + PTE_SIZE * pgd_idx);
for (uint32_t i = 0; i < PTE_SIZE * PTE_COUNT; ++i) {
pte_start[i] = (i << 12) | PAGE_PRESENT | PAGE_WRITE;
}
switch_pgd((uint32_t)ka_to_pa(pgd_kern));
}
