static void __init map_ram()

in mm/init.c [63:124]

• 47 lines of code
• 9 McCabe index (conditional complexity)

static void __init map_ram(void)
{
	phys_addr_t start, end;
	unsigned long v, p, e;
	pgprot_t prot;
	pgd_t *pge;
	p4d_t *p4e;
	pud_t *pue;
	pmd_t *pme;
	pte_t *pte;
	u64 i;
	/* These mark extents of read-only kernel pages...
	 * ...from vmlinux.lds.S
	 */

	v = PAGE_OFFSET;

	for_each_mem_range(i, &start, &end) {
		p = (u32) start & PAGE_MASK;
		e = (u32) end;

		v = (u32) __va(p);
		pge = pgd_offset_k(v);

		while (p < e) {
			int j;
			p4e = p4d_offset(pge, v);
			pue = pud_offset(p4e, v);
			pme = pmd_offset(pue, v);

			if ((u32) pue != (u32) pge || (u32) pme != (u32) pge) {
				panic("%s: OR1K kernel hardcoded for "
				      "two-level page tables",
				     __func__);
			}

			/* Alloc one page for holding PTE's... */
			pte = memblock_alloc_raw(PAGE_SIZE, PAGE_SIZE);
			if (!pte)
				panic("%s: Failed to allocate page for PTEs\n",
				      __func__);
			set_pmd(pme, __pmd(_KERNPG_TABLE + __pa(pte)));

			/* Fill the newly allocated page with PTE'S */
			for (j = 0; p < e && j < PTRS_PER_PTE;
			     v += PAGE_SIZE, p += PAGE_SIZE, j++, pte++) {
				if (v >= (u32) _e_kernel_ro ||
				    v < (u32) _s_kernel_ro)
					prot = PAGE_KERNEL;
				else
					prot = PAGE_KERNEL_RO;

				set_pte(pte, mk_pte_phys(p, prot));
			}

			pge++;
		}

		printk(KERN_INFO "%s: Memory: 0x%x-0x%x\n", __func__,
		       start, end);
	}
}