arch/arm/mm/idmap.c

Source file repositories/reference/linux-study-clean/arch/arm/mm/idmap.c

File Facts

System
Linux kernel
Corpus path
arch/arm/mm/idmap.c
Extension
.c
Size
4316 bytes
Lines
161
Domain
Architecture Layer
Bucket
arch/arm
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 (!pmd) {
			pr_warn("Failed to allocate identity pmd.\n");
			return;
		}
		/*
		 * Copy the original PMD to ensure that the PMD entries for
		 * the kernel image are preserved.
		 */
		if (!pud_none(*pud))
			memcpy(pmd, pmd_offset(pud, 0),
			       PTRS_PER_PMD * sizeof(pmd_t));
		pud_populate(&init_mm, pud, pmd);
		pmd += pmd_index(addr);
	} else
		pmd = pmd_offset(pud, addr);

	do {
		next = pmd_addr_end(addr, end);
		*pmd = __pmd((addr & PMD_MASK) | prot);
		flush_pmd_entry(pmd);
	} while (pmd++, addr = next, addr != end);
}
#else	/* !CONFIG_ARM_LPAE */
static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
	unsigned long prot)
{
	pmd_t *pmd = pmd_offset(pud, addr);

	addr = (addr & PMD_MASK) | prot;
	pmd[0] = __pmd(addr);
	addr += SECTION_SIZE;
	pmd[1] = __pmd(addr);
	flush_pmd_entry(pmd);
}
#endif	/* CONFIG_ARM_LPAE */

static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
	unsigned long prot)
{
	p4d_t *p4d = p4d_offset(pgd, addr);
	pud_t *pud = pud_offset(p4d, addr);
	unsigned long next;

	do {
		next = pud_addr_end(addr, end);
		idmap_add_pmd(pud, addr, next, prot);
	} while (pud++, addr = next, addr != end);
}

static void identity_mapping_add(pgd_t *pgd, const char *text_start,
				 const char *text_end, unsigned long prot)
{
	unsigned long addr, end;
	unsigned long next;

#ifdef CONFIG_XIP_KERNEL
	addr = (phys_addr_t)(text_start) - XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
		+ CONFIG_XIP_PHYS_ADDR;
	end = (phys_addr_t)(text_end) - XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
		+ CONFIG_XIP_PHYS_ADDR;
#else
	addr = virt_to_idmap(text_start);
	end = virt_to_idmap(text_end);
#endif
	pr_info("Setting up static identity map for 0x%lx - 0x%lx\n", addr, end);

	prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;

	if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale_family())
		prot |= PMD_BIT4;

	pgd += pgd_index(addr);
	do {
		next = pgd_addr_end(addr, end);
		idmap_add_pud(pgd, addr, next, prot);
	} while (pgd++, addr = next, addr != end);
}

extern char  __idmap_text_start[], __idmap_text_end[];

static int __init init_static_idmap(void)
{
	idmap_pgd = pgd_alloc(&init_mm);
	if (!idmap_pgd)
		return -ENOMEM;

	identity_mapping_add(idmap_pgd, __idmap_text_start,
			     __idmap_text_end, 0);

	/* Flush L1 for the hardware to see this page table content */

Annotation

Implementation Notes