RISC-V: Remove any memblock representing unusable memory area

void __init setup_bootmem(void)

{

	phys_addr_t mem_size = 0;

	phys_addr_t total_mem = 0;

	phys_addr_t mem_start, start, end = 0;

	phys_addr_t mem_start = 0;

	phys_addr_t start, end = 0;

	phys_addr_t vmlinux_end = __pa_symbol(&_end);

	phys_addr_t vmlinux_start = __pa_symbol(&_start);

	u64 i;

	/* Find the memory region containing the kernel */

	for_each_mem_range(i, &start, &end) {

		phys_addr_t size = end - start;

		if (!total_mem)

		if (!mem_start)

			mem_start = start;

		if (start <= vmlinux_start && vmlinux_end <= end)

			BUG_ON(size == 0);

		total_mem = total_mem + size;

	}

	/*

	 * Remove memblock from the end of usable area to the

	 * end of region

	 * The maximal physical memory size is -PAGE_OFFSET.

	 * Make sure that any memory beyond mem_start + (-PAGE_OFFSET) is removed

	 * as it is unusable by kernel.

	 */

	mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);

	if (mem_start + mem_size < end)

		memblock_remove(mem_start + mem_size,

				end - mem_start - mem_size);

	memblock_enforce_memory_limit(mem_start - PAGE_OFFSET);

	/* Reserve from the start of the kernel to the end of the kernel */

	memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);