void kernel_set_cachemode()

in mm/kmap.c [315:390]

• 69 lines of code
• 15 McCabe index (conditional complexity)

void kernel_set_cachemode(void *addr, unsigned long size, int cmode)
{
	unsigned long virtaddr = (unsigned long)addr;
	pgd_t *pgd_dir;
	p4d_t *p4d_dir;
	pud_t *pud_dir;
	pmd_t *pmd_dir;
	pte_t *pte_dir;

	if (CPU_IS_040_OR_060) {
		switch (cmode) {
		case IOMAP_FULL_CACHING:
			cmode = _PAGE_CACHE040;
			break;
		case IOMAP_NOCACHE_SER:
		default:
			cmode = _PAGE_NOCACHE_S;
			break;
		case IOMAP_NOCACHE_NONSER:
			cmode = _PAGE_NOCACHE;
			break;
		case IOMAP_WRITETHROUGH:
			cmode = _PAGE_CACHE040W;
			break;
		}
	} else {
		switch (cmode) {
		case IOMAP_NOCACHE_SER:
		case IOMAP_NOCACHE_NONSER:
		default:
			cmode = _PAGE_NOCACHE030;
			break;
		case IOMAP_FULL_CACHING:
		case IOMAP_WRITETHROUGH:
			cmode = 0;
		}
	}

	while ((long)size > 0) {
		pgd_dir = pgd_offset_k(virtaddr);
		p4d_dir = p4d_offset(pgd_dir, virtaddr);
		pud_dir = pud_offset(p4d_dir, virtaddr);
		if (pud_bad(*pud_dir)) {
			printk("iocachemode: bad pud(%08lx)\n", pud_val(*pud_dir));
			pud_clear(pud_dir);
			return;
		}
		pmd_dir = pmd_offset(pud_dir, virtaddr);

#if CONFIG_PGTABLE_LEVELS == 3
		if (CPU_IS_020_OR_030) {
			unsigned long pmd = pmd_val(*pmd_dir);

			if ((pmd & _DESCTYPE_MASK) == _PAGE_PRESENT) {
				*pmd_dir = __pmd((pmd & _CACHEMASK040) | cmode);
				virtaddr += PMD_SIZE;
				size -= PMD_SIZE;
				continue;
			}
		}
#endif

		if (pmd_bad(*pmd_dir)) {
			printk("iocachemode: bad pmd (%08lx)\n", pmd_val(*pmd_dir));
			pmd_clear(pmd_dir);
			return;
		}
		pte_dir = pte_offset_kernel(pmd_dir, virtaddr);

		pte_val(*pte_dir) = (pte_val(*pte_dir) & _CACHEMASK040) | cmode;
		virtaddr += PAGE_SIZE;
		size -= PAGE_SIZE;
	}

	flush_tlb_all();
}