arch/x86/mm/ident_map.c

Source file repositories/reference/linux-study-clean/arch/x86/mm/ident_map.c

File Facts

System
Linux kernel
Corpus path
arch/x86/mm/ident_map.c
Extension
.c
Size
5015 bytes
Lines
226
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

if (use_gbpage) {
			pud_t pudval;

			pudval = __pud((addr - info->offset) | info->page_flag);
			set_pud(pud, pudval);
			continue;
		}

		if (pud_present(*pud)) {
			pmd = pmd_offset(pud, 0);
			ident_pmd_init(info, pmd, addr, next);
			continue;
		}
		pmd = (pmd_t *)info->alloc_pgt_page(info->context);
		if (!pmd)
			return -ENOMEM;
		ident_pmd_init(info, pmd, addr, next);
		set_pud(pud, __pud(__pa(pmd) | info->kernpg_flag));
	}

	return 0;
}

static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page,
			  unsigned long addr, unsigned long end)
{
	unsigned long next;
	int result;

	for (; addr < end; addr = next) {
		p4d_t *p4d = p4d_page + p4d_index(addr);
		pud_t *pud;

		next = p4d_addr_end(addr, end);
		if (p4d_present(*p4d)) {
			pud = pud_offset(p4d, 0);
			result = ident_pud_init(info, pud, addr, next);
			if (result)
				return result;

			continue;
		}
		pud = (pud_t *)info->alloc_pgt_page(info->context);
		if (!pud)
			return -ENOMEM;

		result = ident_pud_init(info, pud, addr, next);
		if (result)
			return result;

		set_p4d(p4d, __p4d(__pa(pud) | info->kernpg_flag | _PAGE_NOPTISHADOW));
	}

	return 0;
}

int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
			      unsigned long pstart, unsigned long pend)
{
	unsigned long addr = pstart + info->offset;
	unsigned long end = pend + info->offset;
	unsigned long next;
	int result;

	/* Set the default pagetable flags if not supplied */
	if (!info->kernpg_flag)
		info->kernpg_flag = _KERNPG_TABLE;

	/* Filter out unsupported __PAGE_KERNEL_* bits: */
	info->kernpg_flag &= __default_kernel_pte_mask;

	for (; addr < end; addr = next) {
		pgd_t *pgd = pgd_page + pgd_index(addr);
		p4d_t *p4d;

		next = pgd_addr_end(addr, end);
		if (pgd_present(*pgd)) {
			p4d = p4d_offset(pgd, 0);
			result = ident_p4d_init(info, p4d, addr, next);
			if (result)
				return result;
			continue;
		}

		p4d = (p4d_t *)info->alloc_pgt_page(info->context);
		if (!p4d)
			return -ENOMEM;
		result = ident_p4d_init(info, p4d, addr, next);
		if (result)
			return result;

Annotation

Implementation Notes