int pci_mmap_legacy_page_range()

in pci/pci-common.c [303:355]

• 43 lines of code
• 8 McCabe index (conditional complexity)

int pci_mmap_legacy_page_range(struct pci_bus *bus,
			       struct vm_area_struct *vma,
			       enum pci_mmap_state mmap_state)
{
	struct pci_controller *hose = pci_bus_to_host(bus);
	resource_size_t offset =
		((resource_size_t)vma->vm_pgoff) << PAGE_SHIFT;
	resource_size_t size = vma->vm_end - vma->vm_start;
	struct resource *rp;

	pr_debug("pci_mmap_legacy_page_range(%04x:%02x, %s @%llx..%llx)\n",
		 pci_domain_nr(bus), bus->number,
		 mmap_state == pci_mmap_mem ? "MEM" : "IO",
		 (unsigned long long)offset,
		 (unsigned long long)(offset + size - 1));

	if (mmap_state == pci_mmap_mem) {
		/* Hack alert !
		 *
		 * Because X is lame and can fail starting if it gets an error
		 * trying to mmap legacy_mem (instead of just moving on without
		 * legacy memory access) we fake it here by giving it anonymous
		 * memory, effectively behaving just like /dev/zero
		 */
		if ((offset + size) > hose->isa_mem_size) {
			pr_debug("Process %s (pid:%d) mapped non-existing PCI",
				current->comm, current->pid);
			pr_debug("legacy memory for 0%04x:%02x\n",
				pci_domain_nr(bus), bus->number);
			if (vma->vm_flags & VM_SHARED)
				return shmem_zero_setup(vma);
			return 0;
		}
		offset += hose->isa_mem_phys;
	} else {
		unsigned long io_offset = (unsigned long)hose->io_base_virt -
								_IO_BASE;
		unsigned long roffset = offset + io_offset;
		rp = &hose->io_resource;
		if (!(rp->flags & IORESOURCE_IO))
			return -ENXIO;
		if (roffset < rp->start || (roffset + size) > rp->end)
			return -ENXIO;
		offset += hose->io_base_phys;
	}
	pr_debug(" -> mapping phys %llx\n", (unsigned long long)offset);

	vma->vm_pgoff = offset >> PAGE_SHIFT;
	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
	return remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
			       vma->vm_end - vma->vm_start,
			       vma->vm_page_prot);
}