arch/mips/kernel/vdso.c

Source file repositories/reference/linux-study-clean/arch/mips/kernel/vdso.c

File Facts

System
Linux kernel
Corpus path
arch/mips/kernel/vdso.c
Extension
.c
Size
4697 bytes
Lines
187
Domain
Architecture Layer
Bucket
arch/mips
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration 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

base = do_mmap(NULL, STACK_TOP, PAGE_SIZE, PROT_READ | PROT_EXEC,
			       MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, 0, 0, &unused,
			       NULL);
		if (IS_ERR_VALUE(base)) {
			ret = base;
			goto out;
		}
	}

	/*
	 * Determine total area size. This includes the VDSO data itself, the
	 * data page, and the GIC user page if present. Always create a mapping
	 * for the GIC user area if the GIC is present regardless of whether it
	 * is the current clocksource, in case it comes into use later on. We
	 * only map a page even though the total area is 64K, as we only need
	 * the counter registers at the start.
	 */
	gic_size = mips_gic_present() ? PAGE_SIZE : 0;
	size = gic_size + VDSO_NR_PAGES * PAGE_SIZE + image->size;

	/*
	 * Find a region that's large enough for us to perform the
	 * colour-matching alignment below.
	 */
	if (cpu_has_dc_aliases)
		size += shm_align_mask + 1;

	base = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
	if (IS_ERR_VALUE(base)) {
		ret = base;
		goto out;
	}

	/*
	 * If we suffer from dcache aliasing, ensure that the VDSO data page
	 * mapping is coloured the same as the kernel's mapping of that memory.
	 * This ensures that when the kernel updates the VDSO data userland
	 * will observe it without requiring cache invalidations.
	 */
	if (cpu_has_dc_aliases && IS_ENABLED(CONFIG_HAVE_GENERIC_VDSO)) {
		base = __ALIGN_MASK(base, shm_align_mask);
		base += ((unsigned long)vdso_k_time_data - gic_size) & shm_align_mask;
	}

	data_addr = base + gic_size;
	vdso_addr = data_addr + VDSO_NR_PAGES * PAGE_SIZE;

	if (IS_ENABLED(CONFIG_HAVE_GENERIC_VDSO)) {
		vma = vdso_install_vvar_mapping(mm, data_addr);
		if (IS_ERR(vma)) {
			ret = PTR_ERR(vma);
			goto out;
		}
	}

	/* Map GIC user page. */
	if (gic_size) {
		gic_base = (unsigned long)mips_gic_base + MIPS_GIC_USER_OFS;
		gic_pfn = PFN_DOWN(__pa(gic_base));
		static const struct vm_special_mapping gic_mapping = {
			.name	= "[gic]",
			.pages	= (struct page **) { NULL },
		};

		vma = _install_special_mapping(mm, base, gic_size, VM_READ | VM_MAYREAD,
					       &gic_mapping);
		if (IS_ERR(vma)) {
			ret = PTR_ERR(vma);
			goto out;
		}

		ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size,
					 pgprot_noncached(vma->vm_page_prot));
		if (ret)
			goto out;
	}

	/* Map VDSO image. */
	vma = _install_special_mapping(mm, vdso_addr, image->size,
				       VM_READ | VM_EXEC |
				       VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
				       &image->mapping);
	if (IS_ERR(vma)) {
		ret = PTR_ERR(vma);
		goto out;
	}

	mm->context.vdso = (void *)vdso_addr;
	ret = 0;

Annotation

Implementation Notes