1 // SPDX-License-Identifier: GPL-2.0
2 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
3 
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 <linux/stackprotector.h>
15 #include <asm/sections.h>
16 #include <asm/processor.h>
17 #include <asm/desc.h>
18 #include <asm/setup.h>
19 #include <asm/mpspec.h>
20 #include <asm/apicdef.h>
21 #include <asm/highmem.h>
22 #include <asm/proto.h>
23 #include <asm/cpumask.h>
24 #include <asm/cpu.h>
25 
26 DEFINE_PER_CPU_CACHE_HOT(int, cpu_number);
27 EXPORT_PER_CPU_SYMBOL(cpu_number);
28 
29 DEFINE_PER_CPU_CACHE_HOT(unsigned long, this_cpu_off);
30 EXPORT_PER_CPU_SYMBOL(this_cpu_off);
31 
32 unsigned long __per_cpu_offset[NR_CPUS] __ro_after_init;
33 EXPORT_SYMBOL(__per_cpu_offset);
34 
35 /*
36  * On x86_64 symbols referenced from code should be reachable using
37  * 32bit relocations.  Reserve space for static percpu variables in
38  * modules so that they are always served from the first chunk which
39  * is located at the percpu segment base.  On x86_32, anything can
40  * address anywhere.  No need to reserve space in the first chunk.
41  */
42 #ifdef CONFIG_X86_64
43 #define PERCPU_FIRST_CHUNK_RESERVE	PERCPU_MODULE_RESERVE
44 #else
45 #define PERCPU_FIRST_CHUNK_RESERVE	0
46 #endif
47 
48 #ifdef CONFIG_X86_32
49 /**
50  * pcpu_need_numa - determine percpu allocation needs to consider NUMA
51  *
52  * If NUMA is not configured or there is only one NUMA node available,
53  * there is no reason to consider NUMA.  This function determines
54  * whether percpu allocation should consider NUMA or not.
55  *
56  * RETURNS:
57  * true if NUMA should be considered; otherwise, false.
58  */
pcpu_need_numa(void)59 static bool __init pcpu_need_numa(void)
60 {
61 #ifdef CONFIG_NUMA
62 	pg_data_t *last = NULL;
63 	unsigned int cpu;
64 
65 	for_each_possible_cpu(cpu) {
66 		int node = early_cpu_to_node(cpu);
67 
68 		if (node_online(node) && NODE_DATA(node) &&
69 		    last && last != NODE_DATA(node))
70 			return true;
71 
72 		last = NODE_DATA(node);
73 	}
74 #endif
75 	return false;
76 }
77 #endif
78 
pcpu_cpu_distance(unsigned int from,unsigned int to)79 static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
80 {
81 #ifdef CONFIG_NUMA
82 	if (early_cpu_to_node(from) == early_cpu_to_node(to))
83 		return LOCAL_DISTANCE;
84 	else
85 		return REMOTE_DISTANCE;
86 #else
87 	return LOCAL_DISTANCE;
88 #endif
89 }
90 
pcpu_cpu_to_node(int cpu)91 static int __init pcpu_cpu_to_node(int cpu)
92 {
93 	return early_cpu_to_node(cpu);
94 }
95 
pcpu_populate_pte(unsigned long addr)96 void __init pcpu_populate_pte(unsigned long addr)
97 {
98 	populate_extra_pte(addr);
99 }
100 
setup_percpu_segment(int cpu)101 static inline void setup_percpu_segment(int cpu)
102 {
103 #ifdef CONFIG_X86_32
104 	struct desc_struct d = GDT_ENTRY_INIT(DESC_DATA32,
105 					      per_cpu_offset(cpu), 0xFFFFF);
106 
107 	write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_PERCPU, &d, DESCTYPE_S);
108 #endif
109 }
110 
setup_per_cpu_areas(void)111 void __init setup_per_cpu_areas(void)
112 {
113 	unsigned int cpu;
114 	unsigned long delta;
115 	int rc;
116 
117 	pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%u nr_node_ids:%u\n",
118 		NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);
119 
120 	/*
121 	 * Allocate percpu area.  Embedding allocator is our favorite;
122 	 * however, on NUMA configurations, it can result in very
123 	 * sparse unit mapping and vmalloc area isn't spacious enough
124 	 * on 32bit.  Use page in that case.
125 	 */
126 #ifdef CONFIG_X86_32
127 	if (pcpu_chosen_fc == PCPU_FC_AUTO && pcpu_need_numa())
128 		pcpu_chosen_fc = PCPU_FC_PAGE;
129 #endif
130 	rc = -EINVAL;
131 	if (pcpu_chosen_fc != PCPU_FC_PAGE) {
132 		const size_t dyn_size = PERCPU_MODULE_RESERVE +
133 			PERCPU_DYNAMIC_RESERVE - PERCPU_FIRST_CHUNK_RESERVE;
134 		size_t atom_size;
135 
136 		/*
137 		 * On 64bit, use PMD_SIZE for atom_size so that embedded
138 		 * percpu areas are aligned to PMD.  This, in the future,
139 		 * can also allow using PMD mappings in vmalloc area.  Use
140 		 * PAGE_SIZE on 32bit as vmalloc space is highly contended
141 		 * and large vmalloc area allocs can easily fail.
142 		 */
143 #ifdef CONFIG_X86_64
144 		atom_size = PMD_SIZE;
145 #else
146 		atom_size = PAGE_SIZE;
147 #endif
148 		rc = pcpu_embed_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
149 					    dyn_size, atom_size,
150 					    pcpu_cpu_distance,
151 					    pcpu_cpu_to_node);
152 		if (rc < 0)
153 			pr_warn("%s allocator failed (%d), falling back to page size\n",
154 				pcpu_fc_names[pcpu_chosen_fc], rc);
155 	}
156 	if (rc < 0)
157 		rc = pcpu_page_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
158 					   pcpu_cpu_to_node);
159 	if (rc < 0)
160 		panic("cannot initialize percpu area (err=%d)", rc);
161 
162 	/* alrighty, percpu areas up and running */
163 	delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
164 	for_each_possible_cpu(cpu) {
165 		per_cpu_offset(cpu) = delta + pcpu_unit_offsets[cpu];
166 		per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);
167 		per_cpu(cpu_number, cpu) = cpu;
168 		setup_percpu_segment(cpu);
169 		/*
170 		 * Copy data used in early init routines from the
171 		 * initial arrays to the per cpu data areas.  These
172 		 * arrays then become expendable and the *_early_ptr's
173 		 * are zeroed indicating that the static arrays are
174 		 * gone.
175 		 */
176 #ifdef CONFIG_X86_LOCAL_APIC
177 		per_cpu(x86_cpu_to_apicid, cpu) =
178 			early_per_cpu_map(x86_cpu_to_apicid, cpu);
179 		per_cpu(x86_cpu_to_acpiid, cpu) =
180 			early_per_cpu_map(x86_cpu_to_acpiid, cpu);
181 #endif
182 #ifdef CONFIG_NUMA
183 		per_cpu(x86_cpu_to_node_map, cpu) =
184 			early_per_cpu_map(x86_cpu_to_node_map, cpu);
185 		/*
186 		 * Ensure that the boot cpu numa_node is correct when the boot
187 		 * cpu is on a node that doesn't have memory installed.
188 		 * Also cpu_up() will call cpu_to_node() for APs when
189 		 * MEMORY_HOTPLUG is defined, before per_cpu(numa_node) is set
190 		 * up later with c_init aka intel_init/amd_init.
191 		 * So set them all (boot cpu and all APs).
192 		 */
193 		set_cpu_numa_node(cpu, early_cpu_to_node(cpu));
194 #endif
195 		/*
196 		 * Up to this point, the boot CPU has been using .init.data
197 		 * area.  Reload any changed state for the boot CPU.
198 		 */
199 		if (!cpu)
200 			switch_gdt_and_percpu_base(cpu);
201 	}
202 
203 	/* indicate the early static arrays will soon be gone */
204 #ifdef CONFIG_X86_LOCAL_APIC
205 	early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
206 	early_per_cpu_ptr(x86_cpu_to_acpiid) = NULL;
207 #endif
208 #ifdef CONFIG_NUMA
209 	early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
210 #endif
211 
212 	/* Setup node to cpumask map */
213 	setup_node_to_cpumask_map();
214 
215 	/* Setup cpu initialized, callin, callout masks */
216 	setup_cpu_local_masks();
217 
218 	/*
219 	 * Sync back kernel address range again.  We already did this in
220 	 * setup_arch(), but percpu data also needs to be available in
221 	 * the smpboot asm and arch_sync_kernel_mappings() doesn't sync to
222 	 * swapper_pg_dir on 32-bit. The per-cpu mappings need to be available
223 	 * there too.
224 	 *
225 	 * FIXME: Can the later sync in setup_cpu_entry_areas() replace
226 	 * this call?
227 	 */
228 	sync_initial_page_table();
229 }
230