static void __init setup_bootmem()

in mm/init.c [162:229]

• 36 lines of code
• 5 McCabe index (conditional complexity)

static void __init setup_bootmem(void)
{
	phys_addr_t vmlinux_end = __pa_symbol(&_end);
	phys_addr_t vmlinux_start = __pa_symbol(&_start);
	phys_addr_t __maybe_unused max_mapped_addr;
	phys_addr_t phys_ram_end;

#ifdef CONFIG_XIP_KERNEL
	vmlinux_start = __pa_symbol(&_sdata);
#endif

	memblock_enforce_memory_limit(memory_limit);

	/*
	 * Reserve from the start of the kernel to the end of the kernel
	 */
#if defined(CONFIG_64BIT) && defined(CONFIG_STRICT_KERNEL_RWX)
	/*
	 * Make sure we align the reservation on PMD_SIZE since we will
	 * map the kernel in the linear mapping as read-only: we do not want
	 * any allocation to happen between _end and the next pmd aligned page.
	 */
	vmlinux_end = (vmlinux_end + PMD_SIZE - 1) & PMD_MASK;
#endif
	memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);


	phys_ram_end = memblock_end_of_DRAM();
#ifndef CONFIG_XIP_KERNEL
	phys_ram_base = memblock_start_of_DRAM();
#endif
#ifndef CONFIG_64BIT
	/*
	 * memblock allocator is not aware of the fact that last 4K bytes of
	 * the addressable memory can not be mapped because of IS_ERR_VALUE
	 * macro. Make sure that last 4k bytes are not usable by memblock
	 * if end of dram is equal to maximum addressable memory.  For 64-bit
	 * kernel, this problem can't happen here as the end of the virtual
	 * address space is occupied by the kernel mapping then this check must
	 * be done as soon as the kernel mapping base address is determined.
	 */
	max_mapped_addr = __pa(~(ulong)0);
	if (max_mapped_addr == (phys_ram_end - 1))
		memblock_set_current_limit(max_mapped_addr - 4096);
#endif

	min_low_pfn = PFN_UP(phys_ram_base);
	max_low_pfn = max_pfn = PFN_DOWN(phys_ram_end);

	dma32_phys_limit = min(4UL * SZ_1G, (unsigned long)PFN_PHYS(max_low_pfn));
	set_max_mapnr(max_low_pfn - ARCH_PFN_OFFSET);

	reserve_initrd_mem();
	/*
	 * If DTB is built in, no need to reserve its memblock.
	 * Otherwise, do reserve it but avoid using
	 * early_init_fdt_reserve_self() since __pa() does
	 * not work for DTB pointers that are fixmap addresses
	 */
	if (!IS_ENABLED(CONFIG_BUILTIN_DTB))
		memblock_reserve(dtb_early_pa, fdt_totalsize(dtb_early_va));

	early_init_fdt_scan_reserved_mem();
	dma_contiguous_reserve(dma32_phys_limit);
	if (IS_ENABLED(CONFIG_64BIT))
		hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT);
	memblock_allow_resize();
}