percpu.c

	int rc;

	/*
	 * Always reserve area for module percpu variables.  That's
	 * what the legacy allocator did.
	 */
	rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
				    PERCPU_DYNAMIC_RESERVE, PAGE_SIZE, NULL,
				    pcpu_dfl_fc_alloc, pcpu_dfl_fc_free);
	if (rc < 0)
		panic("Failed to initialize percpu areas.");

	delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
	for_each_possible_cpu(cpu)
		__per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
}
#endif	/* CONFIG_HAVE_SETUP_PER_CPU_AREA */

#else	/* CONFIG_SMP */

/*
 * UP percpu area setup.
 *
 * UP always uses km-based percpu allocator with identity mapping.
 * Static percpu variables are indistinguishable from the usual static
 * variables and don't require any special preparation.
 */
void __init setup_per_cpu_areas(void)
{
	const size_t unit_size =
		roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE,
					 PERCPU_DYNAMIC_RESERVE));
	struct pcpu_alloc_info *ai;
	void *fc;

	ai = pcpu_alloc_alloc_info(1, 1);
	fc = memblock_virt_alloc_from_nopanic(unit_size,
					      PAGE_SIZE,
					      __pa(MAX_DMA_ADDRESS));
	if (!ai || !fc)
		panic("Failed to allocate memory for percpu areas.");
	/* kmemleak tracks the percpu allocations separately */
	kmemleak_free(fc);

	ai->dyn_size = unit_size;
	ai->unit_size = unit_size;
	ai->atom_size = unit_size;
	ai->alloc_size = unit_size;
	ai->groups[0].nr_units = 1;
	ai->groups[0].cpu_map[0] = 0;

	if (pcpu_setup_first_chunk(ai, fc) < 0)
		panic("Failed to initialize percpu areas.");

	pcpu_free_alloc_info(ai);
}

#endif	/* CONFIG_SMP */

/*
 * First and reserved chunks are initialized with temporary allocation
 * map in initdata so that they can be used before slab is online.
 * This function is called after slab is brought up and replaces those
 * with properly allocated maps.
 */
void __init percpu_init_late(void)
{
	struct pcpu_chunk *target_chunks[] =
		{ pcpu_first_chunk, pcpu_reserved_chunk, NULL };
	struct pcpu_chunk *chunk;
	unsigned long flags;
	int i;

	for (i = 0; (chunk = target_chunks[i]); i++) {
		int *map;
		const size_t size = PERCPU_DYNAMIC_EARLY_SLOTS * sizeof(map[0]);

		BUILD_BUG_ON(size > PAGE_SIZE);

		map = pcpu_mem_zalloc(size);
		BUG_ON(!map);

		spin_lock_irqsave(&pcpu_lock, flags);
		memcpy(map, chunk->map, size);
		chunk->map = map;
		spin_unlock_irqrestore(&pcpu_lock, flags);
	}
}