static void __init reserve_crashkernel()

in mm/init.c [780:839]

• 39 lines of code
• 7 McCabe index (conditional complexity)

static void __init reserve_crashkernel(void)
{
	unsigned long long crash_base = 0;
	unsigned long long crash_size = 0;
	unsigned long search_start = memblock_start_of_DRAM();
	unsigned long search_end = memblock_end_of_DRAM();

	int ret = 0;

	/*
	 * Don't reserve a region for a crash kernel on a crash kernel
	 * since it doesn't make much sense and we have limited memory
	 * resources.
	 */
#ifdef CONFIG_CRASH_DUMP
	if (is_kdump_kernel()) {
		pr_info("crashkernel: ignoring reservation request\n");
		return;
	}
#endif

	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
				&crash_size, &crash_base);
	if (ret || !crash_size)
		return;

	crash_size = PAGE_ALIGN(crash_size);

	if (crash_base) {
		search_start = crash_base;
		search_end = crash_base + crash_size;
	}

	/*
	 * Current riscv boot protocol requires 2MB alignment for
	 * RV64 and 4MB alignment for RV32 (hugepage size)
	 *
	 * Try to alloc from 32bit addressible physical memory so that
	 * swiotlb can work on the crash kernel.
	 */
	crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE,
					       search_start,
					       min(search_end, (unsigned long) SZ_4G));
	if (crash_base == 0) {
		/* Try again without restricting region to 32bit addressible memory */
		crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE,
						search_start, search_end);
		if (crash_base == 0) {
			pr_warn("crashkernel: couldn't allocate %lldKB\n",
				crash_size >> 10);
			return;
		}
	}

	pr_info("crashkernel: reserved 0x%016llx - 0x%016llx (%lld MB)\n",
		crash_base, crash_base + crash_size, crash_size >> 20);

	crashk_res.start = crash_base;
	crashk_res.end = crash_base + crash_size - 1;
}