// SPDX-License-Identifier: GPL-2.0#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/kernel.h>#include <linux/export.h>#include <linux/init.h>#include <linux/memblock.h>#include <linux/percpu.h>#include <linux/kexec.h>#include <linux/crash_dump.h>#include <linux/smp.h>#include <linux/topology.h>#include <linux/pfn.h>#include <linux/stackprotector.h>#include <asm/sections.h>#include <asm/processor.h>#include <asm/desc.h>#include <asm/setup.h>#include <asm/mpspec.h>#include <asm/apicdef.h>#include <asm/highmem.h>#include <asm/proto.h>#include <asm/cpumask.h>#include <asm/cpu.h> DEFINE_PER_CPU_CACHE_HOT(int, cpu_number);EXPORT_PER_CPU_SYMBOL(cpu_number); DEFINE_PER_CPU_CACHE_HOT(unsigned long, this_cpu_off);EXPORT_PER_CPU_SYMBOL(this_cpu_off); unsigned long __per_cpu_offset[NR_CPUS] __ro_after_init;EXPORT_SYMBOL(__per_cpu_offset); /* * On x86_64 symbols referenced from code should be reachable using * 32bit relocations.  Reserve space for static percpu variables in * modules so that they are always served from the first chunk which * is located at the percpu segment base.  On x86_32, anything can * address anywhere.  No need to reserve space in the first chunk. */#ifdef CONFIG_X86_64#define PERCPU_FIRST_CHUNK_RESERVE	PERCPU_MODULE_RESERVE#else#define PERCPU_FIRST_CHUNK_RESERVE	0#endif #ifdef CONFIG_X86_32/** * pcpu_need_numa - determine percpu allocation needs to consider NUMA * * If NUMA is not configured or there is only one NUMA node available, * there is no reason to consider NUMA.  This function determines * whether percpu allocation should consider NUMA or not. * * RETURNS: * true if NUMA should be considered; otherwise, false. */static bool __init pcpu_need_numa(void){#ifdef CONFIG_NUMA	pg_data_t *last = NULL;	unsigned int cpu; 	for_each_possible_cpu(cpu) {		int node = early_cpu_to_node(cpu); 		if (node_online(node) && NODE_DATA(node) &&		    last && last != NODE_DATA(node))			return true; 		last = NODE_DATA(node);	}#endif	return false;}#endif static int __init pcpu_cpu_distance(unsigned int from, unsigned int to){#ifdef CONFIG_NUMA	if (early_cpu_to_node(from) == early_cpu_to_node(to))		return LOCAL_DISTANCE;	else		return REMOTE_DISTANCE;#else	return LOCAL_DISTANCE;#endif} static int __init pcpu_cpu_to_node(int cpu){	return early_cpu_to_node(cpu);} void __init pcpu_populate_pte(unsigned long addr){	populate_extra_pte(addr);} static inline void setup_percpu_segment(int cpu){#ifdef CONFIG_X86_32	struct desc_struct d = GDT_ENTRY_INIT(DESC_DATA32,					      per_cpu_offset(cpu), 0xFFFFF); 	write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_PERCPU, &d, DESCTYPE_S);#endif} void __init setup_per_cpu_areas(void){	unsigned int cpu;	unsigned long delta;	int rc; 	pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%u nr_node_ids:%u\n",		NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids); 	/*	 * Allocate percpu area.  Embedding allocator is our favorite;	 * however, on NUMA configurations, it can result in very	 * sparse unit mapping and vmalloc area isn't spacious enough	 * on 32bit.  Use page in that case.	 */#ifdef CONFIG_X86_32	if (pcpu_chosen_fc == PCPU_FC_AUTO && pcpu_need_numa())		pcpu_chosen_fc = PCPU_FC_PAGE;#endif	rc = -EINVAL;	if (pcpu_chosen_fc != PCPU_FC_PAGE) {		const size_t dyn_size = PERCPU_MODULE_RESERVE +			PERCPU_DYNAMIC_RESERVE - PERCPU_FIRST_CHUNK_RESERVE;		size_t atom_size; 		/*		 * On 64bit, use PMD_SIZE for atom_size so that embedded		 * percpu areas are aligned to PMD.  This, in the future,		 * can also allow using PMD mappings in vmalloc area.  Use		 * PAGE_SIZE on 32bit as vmalloc space is highly contended		 * and large vmalloc area allocs can easily fail.		 */#ifdef CONFIG_X86_64		atom_size = PMD_SIZE;#else		atom_size = PAGE_SIZE;#endif		rc = pcpu_embed_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,					    dyn_size, atom_size,					    pcpu_cpu_distance,					    pcpu_cpu_to_node);		if (rc < 0)			pr_warn("%s allocator failed (%d), falling back to page size\n",				pcpu_fc_names[pcpu_chosen_fc], rc);	}	if (rc < 0)		rc = pcpu_page_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,					   pcpu_cpu_to_node);	if (rc < 0)		panic("cannot initialize percpu area (err=%d)", rc); 	/* alrighty, percpu areas up and running */	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];		per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);		per_cpu(cpu_number, cpu) = cpu;		setup_percpu_segment(cpu);		/*		 * Copy data used in early init routines from the		 * initial arrays to the per cpu data areas.  These		 * arrays then become expendable and the *_early_ptr's		 * are zeroed indicating that the static arrays are		 * gone.		 */#ifdef CONFIG_X86_LOCAL_APIC		per_cpu(x86_cpu_to_apicid, cpu) =			early_per_cpu_map(x86_cpu_to_apicid, cpu);		per_cpu(x86_cpu_to_acpiid, cpu) =			early_per_cpu_map(x86_cpu_to_acpiid, cpu);#endif#ifdef CONFIG_NUMA		per_cpu(x86_cpu_to_node_map, cpu) =			early_per_cpu_map(x86_cpu_to_node_map, cpu);		/*		 * Ensure that the boot cpu numa_node is correct when the boot		 * cpu is on a node that doesn't have memory installed.		 * Also cpu_up() will call cpu_to_node() for APs when		 * MEMORY_HOTPLUG is defined, before per_cpu(numa_node) is set		 * up later with c_init aka intel_init/amd_init.		 * So set them all (boot cpu and all APs).		 */		set_cpu_numa_node(cpu, early_cpu_to_node(cpu));#endif		/*		 * Up to this point, the boot CPU has been using .init.data		 * area.  Reload any changed state for the boot CPU.		 */		if (!cpu)			switch_gdt_and_percpu_base(cpu);	} 	/* indicate the early static arrays will soon be gone */#ifdef CONFIG_X86_LOCAL_APIC	early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;	early_per_cpu_ptr(x86_cpu_to_acpiid) = NULL;#endif#ifdef CONFIG_NUMA	early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;#endif 	/* Setup node to cpumask map */	setup_node_to_cpumask_map(); 	/* Setup cpu initialized, callin, callout masks */	setup_cpu_local_masks(); 	/*	 * Sync back kernel address range again.  We already did this in	 * setup_arch(), but percpu data also needs to be available in	 * the smpboot asm and arch_sync_kernel_mappings() doesn't sync to	 * swapper_pg_dir on 32-bit. The per-cpu mappings need to be available	 * there too.	 *	 * FIXME: Can the later sync in setup_cpu_entry_areas() replace	 * this call?	 */	sync_initial_page_table();}