xref: /openbmc/linux/arch/x86/kernel/setup_percpu.c (revision b6dcefde)
1 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
2 
3 #include <linux/kernel.h>
4 #include <linux/module.h>
5 #include <linux/init.h>
6 #include <linux/bootmem.h>
7 #include <linux/percpu.h>
8 #include <linux/kexec.h>
9 #include <linux/crash_dump.h>
10 #include <linux/smp.h>
11 #include <linux/topology.h>
12 #include <linux/pfn.h>
13 #include <asm/sections.h>
14 #include <asm/processor.h>
15 #include <asm/setup.h>
16 #include <asm/mpspec.h>
17 #include <asm/apicdef.h>
18 #include <asm/highmem.h>
19 #include <asm/proto.h>
20 #include <asm/cpumask.h>
21 #include <asm/cpu.h>
22 #include <asm/stackprotector.h>
23 
24 #ifdef CONFIG_DEBUG_PER_CPU_MAPS
25 # define DBG(fmt, ...) pr_dbg(fmt, ##__VA_ARGS__)
26 #else
27 # define DBG(fmt, ...) do { if (0) pr_dbg(fmt, ##__VA_ARGS__); } while (0)
28 #endif
29 
30 DEFINE_PER_CPU(int, cpu_number);
31 EXPORT_PER_CPU_SYMBOL(cpu_number);
32 
33 #ifdef CONFIG_X86_64
34 #define BOOT_PERCPU_OFFSET ((unsigned long)__per_cpu_load)
35 #else
36 #define BOOT_PERCPU_OFFSET 0
37 #endif
38 
39 DEFINE_PER_CPU(unsigned long, this_cpu_off) = BOOT_PERCPU_OFFSET;
40 EXPORT_PER_CPU_SYMBOL(this_cpu_off);
41 
42 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly = {
43 	[0 ... NR_CPUS-1] = BOOT_PERCPU_OFFSET,
44 };
45 EXPORT_SYMBOL(__per_cpu_offset);
46 
47 /*
48  * On x86_64 symbols referenced from code should be reachable using
49  * 32bit relocations.  Reserve space for static percpu variables in
50  * modules so that they are always served from the first chunk which
51  * is located at the percpu segment base.  On x86_32, anything can
52  * address anywhere.  No need to reserve space in the first chunk.
53  */
54 #ifdef CONFIG_X86_64
55 #define PERCPU_FIRST_CHUNK_RESERVE	PERCPU_MODULE_RESERVE
56 #else
57 #define PERCPU_FIRST_CHUNK_RESERVE	0
58 #endif
59 
60 #ifdef CONFIG_X86_32
61 /**
62  * pcpu_need_numa - determine percpu allocation needs to consider NUMA
63  *
64  * If NUMA is not configured or there is only one NUMA node available,
65  * there is no reason to consider NUMA.  This function determines
66  * whether percpu allocation should consider NUMA or not.
67  *
68  * RETURNS:
69  * true if NUMA should be considered; otherwise, false.
70  */
71 static bool __init pcpu_need_numa(void)
72 {
73 #ifdef CONFIG_NEED_MULTIPLE_NODES
74 	pg_data_t *last = NULL;
75 	unsigned int cpu;
76 
77 	for_each_possible_cpu(cpu) {
78 		int node = early_cpu_to_node(cpu);
79 
80 		if (node_online(node) && NODE_DATA(node) &&
81 		    last && last != NODE_DATA(node))
82 			return true;
83 
84 		last = NODE_DATA(node);
85 	}
86 #endif
87 	return false;
88 }
89 #endif
90 
91 /**
92  * pcpu_alloc_bootmem - NUMA friendly alloc_bootmem wrapper for percpu
93  * @cpu: cpu to allocate for
94  * @size: size allocation in bytes
95  * @align: alignment
96  *
97  * Allocate @size bytes aligned at @align for cpu @cpu.  This wrapper
98  * does the right thing for NUMA regardless of the current
99  * configuration.
100  *
101  * RETURNS:
102  * Pointer to the allocated area on success, NULL on failure.
103  */
104 static void * __init pcpu_alloc_bootmem(unsigned int cpu, unsigned long size,
105 					unsigned long align)
106 {
107 	const unsigned long goal = __pa(MAX_DMA_ADDRESS);
108 #ifdef CONFIG_NEED_MULTIPLE_NODES
109 	int node = early_cpu_to_node(cpu);
110 	void *ptr;
111 
112 	if (!node_online(node) || !NODE_DATA(node)) {
113 		ptr = __alloc_bootmem_nopanic(size, align, goal);
114 		pr_info("cpu %d has no node %d or node-local memory\n",
115 			cpu, node);
116 		pr_debug("per cpu data for cpu%d %lu bytes at %016lx\n",
117 			 cpu, size, __pa(ptr));
118 	} else {
119 		ptr = __alloc_bootmem_node_nopanic(NODE_DATA(node),
120 						   size, align, goal);
121 		pr_debug("per cpu data for cpu%d %lu bytes on node%d at %016lx\n",
122 			 cpu, size, node, __pa(ptr));
123 	}
124 	return ptr;
125 #else
126 	return __alloc_bootmem_nopanic(size, align, goal);
127 #endif
128 }
129 
130 /*
131  * Helpers for first chunk memory allocation
132  */
133 static void * __init pcpu_fc_alloc(unsigned int cpu, size_t size, size_t align)
134 {
135 	return pcpu_alloc_bootmem(cpu, size, align);
136 }
137 
138 static void __init pcpu_fc_free(void *ptr, size_t size)
139 {
140 	free_bootmem(__pa(ptr), size);
141 }
142 
143 static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
144 {
145 #ifdef CONFIG_NEED_MULTIPLE_NODES
146 	if (early_cpu_to_node(from) == early_cpu_to_node(to))
147 		return LOCAL_DISTANCE;
148 	else
149 		return REMOTE_DISTANCE;
150 #else
151 	return LOCAL_DISTANCE;
152 #endif
153 }
154 
155 static void __init pcpup_populate_pte(unsigned long addr)
156 {
157 	populate_extra_pte(addr);
158 }
159 
160 static inline void setup_percpu_segment(int cpu)
161 {
162 #ifdef CONFIG_X86_32
163 	struct desc_struct gdt;
164 
165 	pack_descriptor(&gdt, per_cpu_offset(cpu), 0xFFFFF,
166 			0x2 | DESCTYPE_S, 0x8);
167 	gdt.s = 1;
168 	write_gdt_entry(get_cpu_gdt_table(cpu),
169 			GDT_ENTRY_PERCPU, &gdt, DESCTYPE_S);
170 #endif
171 }
172 
173 void __init setup_per_cpu_areas(void)
174 {
175 	unsigned int cpu;
176 	unsigned long delta;
177 	int rc;
178 
179 	pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%d nr_node_ids:%d\n",
180 		NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);
181 
182 	/*
183 	 * Allocate percpu area.  Embedding allocator is our favorite;
184 	 * however, on NUMA configurations, it can result in very
185 	 * sparse unit mapping and vmalloc area isn't spacious enough
186 	 * on 32bit.  Use page in that case.
187 	 */
188 #ifdef CONFIG_X86_32
189 	if (pcpu_chosen_fc == PCPU_FC_AUTO && pcpu_need_numa())
190 		pcpu_chosen_fc = PCPU_FC_PAGE;
191 #endif
192 	rc = -EINVAL;
193 	if (pcpu_chosen_fc != PCPU_FC_PAGE) {
194 		const size_t atom_size = cpu_has_pse ? PMD_SIZE : PAGE_SIZE;
195 		const size_t dyn_size = PERCPU_MODULE_RESERVE +
196 			PERCPU_DYNAMIC_RESERVE - PERCPU_FIRST_CHUNK_RESERVE;
197 
198 		rc = pcpu_embed_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
199 					    dyn_size, atom_size,
200 					    pcpu_cpu_distance,
201 					    pcpu_fc_alloc, pcpu_fc_free);
202 		if (rc < 0)
203 			pr_warning("%s allocator failed (%d), falling back to page size\n",
204 				   pcpu_fc_names[pcpu_chosen_fc], rc);
205 	}
206 	if (rc < 0)
207 		rc = pcpu_page_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
208 					   pcpu_fc_alloc, pcpu_fc_free,
209 					   pcpup_populate_pte);
210 	if (rc < 0)
211 		panic("cannot initialize percpu area (err=%d)", rc);
212 
213 	/* alrighty, percpu areas up and running */
214 	delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
215 	for_each_possible_cpu(cpu) {
216 		per_cpu_offset(cpu) = delta + pcpu_unit_offsets[cpu];
217 		per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);
218 		per_cpu(cpu_number, cpu) = cpu;
219 		setup_percpu_segment(cpu);
220 		setup_stack_canary_segment(cpu);
221 		/*
222 		 * Copy data used in early init routines from the
223 		 * initial arrays to the per cpu data areas.  These
224 		 * arrays then become expendable and the *_early_ptr's
225 		 * are zeroed indicating that the static arrays are
226 		 * gone.
227 		 */
228 #ifdef CONFIG_X86_LOCAL_APIC
229 		per_cpu(x86_cpu_to_apicid, cpu) =
230 			early_per_cpu_map(x86_cpu_to_apicid, cpu);
231 		per_cpu(x86_bios_cpu_apicid, cpu) =
232 			early_per_cpu_map(x86_bios_cpu_apicid, cpu);
233 #endif
234 #ifdef CONFIG_X86_64
235 		per_cpu(irq_stack_ptr, cpu) =
236 			per_cpu(irq_stack_union.irq_stack, cpu) +
237 			IRQ_STACK_SIZE - 64;
238 #ifdef CONFIG_NUMA
239 		per_cpu(x86_cpu_to_node_map, cpu) =
240 			early_per_cpu_map(x86_cpu_to_node_map, cpu);
241 #endif
242 #endif
243 		/*
244 		 * Up to this point, the boot CPU has been using .data.init
245 		 * area.  Reload any changed state for the boot CPU.
246 		 */
247 		if (cpu == boot_cpu_id)
248 			switch_to_new_gdt(cpu);
249 	}
250 
251 	/* indicate the early static arrays will soon be gone */
252 #ifdef CONFIG_X86_LOCAL_APIC
253 	early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
254 	early_per_cpu_ptr(x86_bios_cpu_apicid) = NULL;
255 #endif
256 #if defined(CONFIG_X86_64) && defined(CONFIG_NUMA)
257 	early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
258 #endif
259 
260 #if defined(CONFIG_X86_64) && defined(CONFIG_NUMA)
261 	/*
262 	 * make sure boot cpu node_number is right, when boot cpu is on the
263 	 * node that doesn't have mem installed
264 	 */
265 	per_cpu(node_number, boot_cpu_id) = cpu_to_node(boot_cpu_id);
266 #endif
267 
268 	/* Setup node to cpumask map */
269 	setup_node_to_cpumask_map();
270 
271 	/* Setup cpu initialized, callin, callout masks */
272 	setup_cpu_local_masks();
273 }
274