1 // SPDX-License-Identifier: GPL-2.0
2 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
4 #include <linux/kernel.h>
5 #include <linux/export.h>
6 #include <linux/init.h>
7 #include <linux/memblock.h>
8 #include <linux/percpu.h>
9 #include <linux/kexec.h>
10 #include <linux/crash_dump.h>
11 #include <linux/smp.h>
12 #include <linux/topology.h>
13 #include <linux/pfn.h>
14 #include <asm/sections.h>
15 #include <asm/processor.h>
17 #include <asm/setup.h>
18 #include <asm/mpspec.h>
19 #include <asm/apicdef.h>
20 #include <asm/highmem.h>
21 #include <asm/proto.h>
22 #include <asm/cpumask.h>
24 #include <asm/stackprotector.h>
26 DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number);
27 EXPORT_PER_CPU_SYMBOL(cpu_number);
30 #define BOOT_PERCPU_OFFSET ((unsigned long)__per_cpu_load)
32 #define BOOT_PERCPU_OFFSET 0
35 DEFINE_PER_CPU_READ_MOSTLY(unsigned long, this_cpu_off) = BOOT_PERCPU_OFFSET;
36 EXPORT_PER_CPU_SYMBOL(this_cpu_off);
38 unsigned long __per_cpu_offset[NR_CPUS] __ro_after_init = {
39 [0 ... NR_CPUS-1] = BOOT_PERCPU_OFFSET,
41 EXPORT_SYMBOL(__per_cpu_offset);
44 * On x86_64 symbols referenced from code should be reachable using
45 * 32bit relocations. Reserve space for static percpu variables in
46 * modules so that they are always served from the first chunk which
47 * is located at the percpu segment base. On x86_32, anything can
48 * address anywhere. No need to reserve space in the first chunk.
51 #define PERCPU_FIRST_CHUNK_RESERVE PERCPU_MODULE_RESERVE
53 #define PERCPU_FIRST_CHUNK_RESERVE 0
58 * pcpu_need_numa - determine percpu allocation needs to consider NUMA
60 * If NUMA is not configured or there is only one NUMA node available,
61 * there is no reason to consider NUMA. This function determines
62 * whether percpu allocation should consider NUMA or not.
65 * true if NUMA should be considered; otherwise, false.
67 static bool __init pcpu_need_numa(void)
70 pg_data_t *last = NULL;
73 for_each_possible_cpu(cpu) {
74 int node = early_cpu_to_node(cpu);
76 if (node_online(node) && NODE_DATA(node) &&
77 last && last != NODE_DATA(node))
80 last = NODE_DATA(node);
87 static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
90 if (early_cpu_to_node(from) == early_cpu_to_node(to))
91 return LOCAL_DISTANCE;
93 return REMOTE_DISTANCE;
95 return LOCAL_DISTANCE;
99 static int __init pcpu_cpu_to_node(int cpu)
101 return early_cpu_to_node(cpu);
104 void __init pcpu_populate_pte(unsigned long addr)
106 populate_extra_pte(addr);
109 static inline void setup_percpu_segment(int cpu)
112 struct desc_struct d = GDT_ENTRY_INIT(0x8092, per_cpu_offset(cpu),
115 write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_PERCPU, &d, DESCTYPE_S);
119 void __init setup_per_cpu_areas(void)
125 pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%u nr_node_ids:%u\n",
126 NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);
129 * Allocate percpu area. Embedding allocator is our favorite;
130 * however, on NUMA configurations, it can result in very
131 * sparse unit mapping and vmalloc area isn't spacious enough
132 * on 32bit. Use page in that case.
135 if (pcpu_chosen_fc == PCPU_FC_AUTO && pcpu_need_numa())
136 pcpu_chosen_fc = PCPU_FC_PAGE;
139 if (pcpu_chosen_fc != PCPU_FC_PAGE) {
140 const size_t dyn_size = PERCPU_MODULE_RESERVE +
141 PERCPU_DYNAMIC_RESERVE - PERCPU_FIRST_CHUNK_RESERVE;
145 * On 64bit, use PMD_SIZE for atom_size so that embedded
146 * percpu areas are aligned to PMD. This, in the future,
147 * can also allow using PMD mappings in vmalloc area. Use
148 * PAGE_SIZE on 32bit as vmalloc space is highly contended
149 * and large vmalloc area allocs can easily fail.
152 atom_size = PMD_SIZE;
154 atom_size = PAGE_SIZE;
156 rc = pcpu_embed_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
161 pr_warn("%s allocator failed (%d), falling back to page size\n",
162 pcpu_fc_names[pcpu_chosen_fc], rc);
165 rc = pcpu_page_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
168 panic("cannot initialize percpu area (err=%d)", rc);
170 /* alrighty, percpu areas up and running */
171 delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
172 for_each_possible_cpu(cpu) {
173 per_cpu_offset(cpu) = delta + pcpu_unit_offsets[cpu];
174 per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);
175 per_cpu(cpu_number, cpu) = cpu;
176 setup_percpu_segment(cpu);
178 * Copy data used in early init routines from the
179 * initial arrays to the per cpu data areas. These
180 * arrays then become expendable and the *_early_ptr's
181 * are zeroed indicating that the static arrays are
184 #ifdef CONFIG_X86_LOCAL_APIC
185 per_cpu(x86_cpu_to_apicid, cpu) =
186 early_per_cpu_map(x86_cpu_to_apicid, cpu);
187 per_cpu(x86_bios_cpu_apicid, cpu) =
188 early_per_cpu_map(x86_bios_cpu_apicid, cpu);
189 per_cpu(x86_cpu_to_acpiid, cpu) =
190 early_per_cpu_map(x86_cpu_to_acpiid, cpu);
193 per_cpu(x86_cpu_to_logical_apicid, cpu) =
194 early_per_cpu_map(x86_cpu_to_logical_apicid, cpu);
197 per_cpu(x86_cpu_to_node_map, cpu) =
198 early_per_cpu_map(x86_cpu_to_node_map, cpu);
200 * Ensure that the boot cpu numa_node is correct when the boot
201 * cpu is on a node that doesn't have memory installed.
202 * Also cpu_up() will call cpu_to_node() for APs when
203 * MEMORY_HOTPLUG is defined, before per_cpu(numa_node) is set
204 * up later with c_init aka intel_init/amd_init.
205 * So set them all (boot cpu and all APs).
207 set_cpu_numa_node(cpu, early_cpu_to_node(cpu));
210 * Up to this point, the boot CPU has been using .init.data
211 * area. Reload any changed state for the boot CPU.
214 switch_to_new_gdt(cpu);
217 /* indicate the early static arrays will soon be gone */
218 #ifdef CONFIG_X86_LOCAL_APIC
219 early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
220 early_per_cpu_ptr(x86_bios_cpu_apicid) = NULL;
221 early_per_cpu_ptr(x86_cpu_to_acpiid) = NULL;
224 early_per_cpu_ptr(x86_cpu_to_logical_apicid) = NULL;
227 early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
230 /* Setup node to cpumask map */
231 setup_node_to_cpumask_map();
233 /* Setup cpu initialized, callin, callout masks */
234 setup_cpu_local_masks();
237 * Sync back kernel address range again. We already did this in
238 * setup_arch(), but percpu data also needs to be available in
239 * the smpboot asm and arch_sync_kernel_mappings() doesn't sync to
240 * swapper_pg_dir on 32-bit. The per-cpu mappings need to be available
243 * FIXME: Can the later sync in setup_cpu_entry_areas() replace
246 sync_initial_page_table();