static void __meminit phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end)
{
int i = pud_index(addr);
for (; i < PTRS_PER_PUD; i++, addr = (addr & PUD_MASK) + PUD_SIZE ) {
unsigned long pmd_phys;
pud_t *pud = pud_page + pud_index(addr);
pmd_t *pmd;
if (addr >= end)
break;
if (!after_bootmem && !e820_any_mapped(addr,addr+PUD_SIZE,0)) {
set_pud(pud, __pud(0));
continue;
}
if (pud_val(*pud)) {
phys_pmd_update(pud, addr, end);
continue;
}
pmd = alloc_low_page(&pmd_phys);
spin_lock(&init_mm.page_table_lock);
set_pud(pud, __pud(pmd_phys | _KERNPG_TABLE));
phys_pmd_init(pmd, addr, end);
spin_unlock(&init_mm.page_table_lock);
unmap_low_page(pmd);
}
__flush_tlb();
}
/*
* Create PGD aligned trampoline table to allow real mode initialization
* of additional CPUs. Consume only 1 low memory page.
*/
void __meminit init_trampoline(void)
{
unsigned long paddr, paddr_next;
pgd_t *pgd;
pud_t *pud_page, *pud_page_tramp;
int i;
if (!kaslr_memory_enabled()) {
init_trampoline_default();
return;
}
pud_page_tramp = alloc_low_page();
paddr = 0;
pgd = pgd_offset_k((unsigned long)__va(paddr));
pud_page = (pud_t *) pgd_page_vaddr(*pgd);
for (i = pud_index(paddr); i < PTRS_PER_PUD; i++, paddr = paddr_next) {
pud_t *pud, *pud_tramp;
unsigned long vaddr = (unsigned long)__va(paddr);
pud_tramp = pud_page_tramp + pud_index(paddr);
pud = pud_page + pud_index(vaddr);
paddr_next = (paddr & PUD_MASK) + PUD_SIZE;
*pud_tramp = *pud;
}
set_pgd(&trampoline_pgd_entry,
__pgd(_KERNPG_TABLE | __pa(pud_page_tramp)));
}
static void __meminit init_trampoline_pud(void)
{
pud_t *pud_page_tramp, *pud, *pud_tramp;
p4d_t *p4d_page_tramp, *p4d, *p4d_tramp;
unsigned long paddr, vaddr;
pgd_t *pgd;
pud_page_tramp = alloc_low_page();
/*
* There are two mappings for the low 1MB area, the direct mapping
* and the 1:1 mapping for the real mode trampoline:
*
* Direct mapping: virt_addr = phys_addr + PAGE_OFFSET
* 1:1 mapping: virt_addr = phys_addr
*/
paddr = 0;
vaddr = (unsigned long)__va(paddr);
pgd = pgd_offset_k(vaddr);
p4d = p4d_offset(pgd, vaddr);
pud = pud_offset(p4d, vaddr);
pud_tramp = pud_page_tramp + pud_index(paddr);
*pud_tramp = *pud;
if (pgtable_l5_enabled()) {
p4d_page_tramp = alloc_low_page();
p4d_tramp = p4d_page_tramp + p4d_index(paddr);
set_p4d(p4d_tramp,
__p4d(_KERNPG_TABLE | __pa(pud_page_tramp)));
set_pgd(&trampoline_pgd_entry,
__pgd(_KERNPG_TABLE | __pa(p4d_page_tramp)));
} else {
set_pgd(&trampoline_pgd_entry,
__pgd(_KERNPG_TABLE | __pa(pud_page_tramp)));
}
}
/*
* Create a page table and place a pointer to it in a middle page
* directory entry:
*/
static pte_t * __init one_page_table_init(pmd_t *pmd)
{
if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {
pte_t *page_table = (pte_t *)alloc_low_page();
paravirt_alloc_pte(&init_mm, __pa(page_table) >> PAGE_SHIFT);
#if defined(CONFIG_PAX_PAGEEXEC) || defined(CONFIG_PAX_SEGMEXEC)
set_pmd(pmd, __pmd(__pa(page_table) | _KERNPG_TABLE));
#else
set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
#endif
BUG_ON(page_table != pte_offset_kernel(pmd, 0));
}
/*
* Creates a middle page table and puts a pointer to it in the
* given global directory entry. This only returns the gd entry
* in non-PAE compilation mode, since the middle layer is folded.
*/
static pmd_t * __init one_md_table_init(pgd_t *pgd)
{
pud_t *pud;
pmd_t *pmd_table;
#ifdef CONFIG_X86_PAE
if (!(pgd_val(*pgd) & _PAGE_PRESENT)) {
pmd_table = (pmd_t *)alloc_low_page();
paravirt_alloc_pmd(&init_mm, __pa(pmd_table) >> PAGE_SHIFT);
set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
pud = pud_offset(pgd, 0);
BUG_ON(pmd_table != pmd_offset(pud, 0));
return pmd_table;
}
/*
* Create a page table and place a pointer to it in a middle page
* directory entry:
*/
static pte_t * __init one_page_table_init(pmd_t *pmd)
{
if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {
pte_t *page_table = NULL;
if (after_bootmem) {
#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK)
page_table = (pte_t *) alloc_bootmem_pages(PAGE_SIZE);
#endif
if (!page_table)
page_table =
(pte_t *)alloc_bootmem_pages(PAGE_SIZE);
} else
page_table = (pte_t *)alloc_low_page();
paravirt_alloc_pte(&init_mm, __pa(page_table) >> PAGE_SHIFT);
set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
BUG_ON(page_table != pte_offset_kernel(pmd, 0));
}
/* Setup the direct mapping of the physical memory at PAGE_OFFSET.
This runs before bootmem is initialized and gets pages directly from the
physical memory. To access them they are temporarily mapped. */
void __init_refok init_memory_mapping(unsigned long start, unsigned long end)
{
unsigned long next;
Dprintk("init_memory_mapping\n");
/*
* Find space for the kernel direct mapping tables.
* Later we should allocate these tables in the local node of the memory
* mapped. Unfortunately this is done currently before the nodes are
* discovered.
*/
if (!after_bootmem)
find_early_table_space(end);
start = (unsigned long)__va(start);
end = (unsigned long)__va(end);
for (; start < end; start = next) {
unsigned long pud_phys;
pgd_t *pgd = pgd_offset_k(start);
pud_t *pud;
if (after_bootmem)
pud = pud_offset(pgd, start & PGDIR_MASK);
else
pud = alloc_low_page(&pud_phys);
next = start + PGDIR_SIZE;
if (next > end)
next = end;
phys_pud_init(pud, __pa(start), __pa(next));
if (!after_bootmem)
set_pgd(pgd_offset_k(start), mk_kernel_pgd(pud_phys));
unmap_low_page(pud);
}
if (!after_bootmem)
mmu_cr4_features = read_cr4();
__flush_tlb_all();
}
/*
* Create a page table and place a pointer to it in a middle page
* directory entry:
*/
static pte_t * __init one_page_table_init(pmd_t *pmd)
{
// 判断了pte是不是在内存中
if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {
pte_t *page_table = NULL;
if (after_bootmem) {
#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK)
page_table = (pte_t *) alloc_bootmem_pages(PAGE_SIZE);
#endif
if (!page_table)
page_table =
(pte_t *)alloc_bootmem_pages(PAGE_SIZE);
} else
// 这货按页分配，4k页，1024个指针完全没问题啊....
page_table = (pte_t *)alloc_low_page();
paravirt_alloc_pte(&init_mm, __pa(page_table) >> PAGE_SHIFT);
// __pmd : return (pmd_t) { val };
set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
BUG_ON(page_table != pte_offset_kernel(pmd, 0));
}
/*
* Creates a middle page table and puts a pointer to it in the
* given global directory entry. This only returns the gd entry
* in non-PAE compilation mode, since the middle layer is folded.
*/
static pmd_t * __init one_md_table_init(pgd_t *pgd)
{
pud_t *pud;
pmd_t *pmd_table;
#ifdef CONFIG_X86_PAE
if (!(pgd_val(*pgd) & _PAGE_PRESENT)) {
if (after_bootmem)
pmd_table = (pmd_t *)alloc_bootmem_pages(PAGE_SIZE);
else
pmd_table = (pmd_t *)alloc_low_page();
paravirt_alloc_pmd(&init_mm, __pa(pmd_table) >> PAGE_SHIFT);
set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
pud = pud_offset(pgd, 0);
BUG_ON(pmd_table != pmd_offset(pud, 0));
return pmd_table;
}
#endif
pud = pud_offset(pgd, 0); // 32 nopud, 直接return pud_t,没有取地址过程
pmd_table = pmd_offset(pud, 0); // pmd_index 取得pmd号,加上pud的基址
return pmd_table; // 这么一串下来,pmd_table == pgd的地址....
}
