arch/arm/mm/pageattr.c

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

File Facts

System
Linux kernel
Corpus path
arch/arm/mm/pageattr.c
Extension
.c
Size
2656 bytes
Lines
112
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

struct page_change_data {
	pgprot_t set_mask;
	pgprot_t clear_mask;
};

static int change_page_range(pte_t *ptep, unsigned long addr, void *data)
{
	struct page_change_data *cdata = data;
	pte_t pte = *ptep;

	pte = clear_pte_bit(pte, cdata->clear_mask);
	pte = set_pte_bit(pte, cdata->set_mask);

	set_pte_ext(ptep, pte, 0);
	return 0;
}

static bool range_in_range(unsigned long start, unsigned long size,
	unsigned long range_start, unsigned long range_end)
{
	return start >= range_start && start < range_end &&
		size <= range_end - start;
}

/*
 * This function assumes that the range is mapped with PAGE_SIZE pages.
 */
static int __change_memory_common(unsigned long start, unsigned long size,
				pgprot_t set_mask, pgprot_t clear_mask)
{
	struct page_change_data data;
	int ret;

	data.set_mask = set_mask;
	data.clear_mask = clear_mask;

	ret = apply_to_page_range(&init_mm, start, size, change_page_range,
				  &data);

	flush_tlb_kernel_range(start, start + size);
	return ret;
}

static int change_memory_common(unsigned long addr, int numpages,
				pgprot_t set_mask, pgprot_t clear_mask)
{
	unsigned long start = addr & PAGE_MASK;
	unsigned long end = PAGE_ALIGN(addr) + numpages * PAGE_SIZE;
	unsigned long size = end - start;

	WARN_ON_ONCE(start != addr);

	if (!size)
		return 0;

	if (!range_in_range(start, size, MODULES_VADDR, MODULES_END) &&
	    !range_in_range(start, size, VMALLOC_START, VMALLOC_END))
		return -EINVAL;

	return __change_memory_common(start, size, set_mask, clear_mask);
}

int set_memory_ro(unsigned long addr, int numpages)
{
	return change_memory_common(addr, numpages,
					__pgprot(L_PTE_RDONLY),
					__pgprot(0));
}

int set_memory_rw(unsigned long addr, int numpages)
{
	return change_memory_common(addr, numpages,
					__pgprot(0),
					__pgprot(L_PTE_RDONLY));
}

int set_memory_nx(unsigned long addr, int numpages)
{
	return change_memory_common(addr, numpages,
					__pgprot(L_PTE_XN),
					__pgprot(0));
}

int set_memory_x(unsigned long addr, int numpages)
{
	return change_memory_common(addr, numpages,
					__pgprot(0),
					__pgprot(L_PTE_XN));
}

Annotation

Implementation Notes