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)
69 #ifdef CONFIG_NEED_MULTIPLE_NODES
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
);
88 * pcpu_alloc_bootmem - NUMA friendly alloc_bootmem wrapper for percpu
89 * @cpu: cpu to allocate for
90 * @size: size allocation in bytes
93 * Allocate @size bytes aligned at @align for cpu @cpu. This wrapper
94 * does the right thing for NUMA regardless of the current
98 * Pointer to the allocated area on success, NULL on failure.
100 static void * __init
pcpu_alloc_bootmem(unsigned int cpu
, unsigned long size
,
103 const unsigned long goal
= __pa(MAX_DMA_ADDRESS
);
104 #ifdef CONFIG_NEED_MULTIPLE_NODES
105 int node
= early_cpu_to_node(cpu
);
108 if (!node_online(node
) || !NODE_DATA(node
)) {
109 ptr
= memblock_alloc_from(size
, align
, goal
);
110 pr_info("cpu %d has no node %d or node-local memory\n",
112 pr_debug("per cpu data for cpu%d %lu bytes at %016lx\n",
113 cpu
, size
, __pa(ptr
));
115 ptr
= memblock_alloc_try_nid(size
, align
, goal
,
116 MEMBLOCK_ALLOC_ACCESSIBLE
,
119 pr_debug("per cpu data for cpu%d %lu bytes on node%d at %016lx\n",
120 cpu
, size
, node
, __pa(ptr
));
124 return memblock_alloc_from(size
, align
, goal
);
129 * Helpers for first chunk memory allocation
131 static void * __init
pcpu_fc_alloc(unsigned int cpu
, size_t size
, size_t align
)
133 return pcpu_alloc_bootmem(cpu
, size
, align
);
136 static void __init
pcpu_fc_free(void *ptr
, size_t size
)
138 memblock_free(__pa(ptr
), size
);
141 static int __init
pcpu_cpu_distance(unsigned int from
, unsigned int to
)
143 #ifdef CONFIG_NEED_MULTIPLE_NODES
144 if (early_cpu_to_node(from
) == early_cpu_to_node(to
))
145 return LOCAL_DISTANCE
;
147 return REMOTE_DISTANCE
;
149 return LOCAL_DISTANCE
;
153 static void __init
pcpup_populate_pte(unsigned long addr
)
155 populate_extra_pte(addr
);
158 static inline void setup_percpu_segment(int cpu
)
161 struct desc_struct d
= GDT_ENTRY_INIT(0x8092, per_cpu_offset(cpu
),
164 write_gdt_entry(get_cpu_gdt_rw(cpu
), GDT_ENTRY_PERCPU
, &d
, DESCTYPE_S
);
168 void __init
setup_per_cpu_areas(void)
174 pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%u nr_node_ids:%u\n",
175 NR_CPUS
, nr_cpumask_bits
, nr_cpu_ids
, nr_node_ids
);
178 * Allocate percpu area. Embedding allocator is our favorite;
179 * however, on NUMA configurations, it can result in very
180 * sparse unit mapping and vmalloc area isn't spacious enough
181 * on 32bit. Use page in that case.
184 if (pcpu_chosen_fc
== PCPU_FC_AUTO
&& pcpu_need_numa())
185 pcpu_chosen_fc
= PCPU_FC_PAGE
;
188 if (pcpu_chosen_fc
!= PCPU_FC_PAGE
) {
189 const size_t dyn_size
= PERCPU_MODULE_RESERVE
+
190 PERCPU_DYNAMIC_RESERVE
- PERCPU_FIRST_CHUNK_RESERVE
;
194 * On 64bit, use PMD_SIZE for atom_size so that embedded
195 * percpu areas are aligned to PMD. This, in the future,
196 * can also allow using PMD mappings in vmalloc area. Use
197 * PAGE_SIZE on 32bit as vmalloc space is highly contended
198 * and large vmalloc area allocs can easily fail.
201 atom_size
= PMD_SIZE
;
203 atom_size
= PAGE_SIZE
;
205 rc
= pcpu_embed_first_chunk(PERCPU_FIRST_CHUNK_RESERVE
,
208 pcpu_fc_alloc
, pcpu_fc_free
);
210 pr_warn("%s allocator failed (%d), falling back to page size\n",
211 pcpu_fc_names
[pcpu_chosen_fc
], rc
);
214 rc
= pcpu_page_first_chunk(PERCPU_FIRST_CHUNK_RESERVE
,
215 pcpu_fc_alloc
, pcpu_fc_free
,
218 panic("cannot initialize percpu area (err=%d)", rc
);
220 /* alrighty, percpu areas up and running */
221 delta
= (unsigned long)pcpu_base_addr
- (unsigned long)__per_cpu_start
;
222 for_each_possible_cpu(cpu
) {
223 per_cpu_offset(cpu
) = delta
+ pcpu_unit_offsets
[cpu
];
224 per_cpu(this_cpu_off
, cpu
) = per_cpu_offset(cpu
);
225 per_cpu(cpu_number
, cpu
) = cpu
;
226 setup_percpu_segment(cpu
);
227 setup_stack_canary_segment(cpu
);
229 * Copy data used in early init routines from the
230 * initial arrays to the per cpu data areas. These
231 * arrays then become expendable and the *_early_ptr's
232 * are zeroed indicating that the static arrays are
235 #ifdef CONFIG_X86_LOCAL_APIC
236 per_cpu(x86_cpu_to_apicid
, cpu
) =
237 early_per_cpu_map(x86_cpu_to_apicid
, cpu
);
238 per_cpu(x86_bios_cpu_apicid
, cpu
) =
239 early_per_cpu_map(x86_bios_cpu_apicid
, cpu
);
240 per_cpu(x86_cpu_to_acpiid
, cpu
) =
241 early_per_cpu_map(x86_cpu_to_acpiid
, cpu
);
244 per_cpu(x86_cpu_to_logical_apicid
, cpu
) =
245 early_per_cpu_map(x86_cpu_to_logical_apicid
, cpu
);
248 per_cpu(x86_cpu_to_node_map
, cpu
) =
249 early_per_cpu_map(x86_cpu_to_node_map
, cpu
);
251 * Ensure that the boot cpu numa_node is correct when the boot
252 * cpu is on a node that doesn't have memory installed.
253 * Also cpu_up() will call cpu_to_node() for APs when
254 * MEMORY_HOTPLUG is defined, before per_cpu(numa_node) is set
255 * up later with c_init aka intel_init/amd_init.
256 * So set them all (boot cpu and all APs).
258 set_cpu_numa_node(cpu
, early_cpu_to_node(cpu
));
261 * Up to this point, the boot CPU has been using .init.data
262 * area. Reload any changed state for the boot CPU.
265 switch_to_new_gdt(cpu
);
268 /* indicate the early static arrays will soon be gone */
269 #ifdef CONFIG_X86_LOCAL_APIC
270 early_per_cpu_ptr(x86_cpu_to_apicid
) = NULL
;
271 early_per_cpu_ptr(x86_bios_cpu_apicid
) = NULL
;
272 early_per_cpu_ptr(x86_cpu_to_acpiid
) = NULL
;
275 early_per_cpu_ptr(x86_cpu_to_logical_apicid
) = NULL
;
278 early_per_cpu_ptr(x86_cpu_to_node_map
) = NULL
;
281 /* Setup node to cpumask map */
282 setup_node_to_cpumask_map();
284 /* Setup cpu initialized, callin, callout masks */
285 setup_cpu_local_masks();
288 * Sync back kernel address range again. We already did this in
289 * setup_arch(), but percpu data also needs to be available in
290 * the smpboot asm. We can't reliably pick up percpu mappings
291 * using vmalloc_fault(), because exception dispatch needs
294 * FIXME: Can the later sync in setup_cpu_entry_areas() replace
297 sync_initial_page_table();