aboutsummaryrefslogtreecommitdiff
path: root/arch/x86/kernel/setup_percpu.c
blob: 3a97a4cf187245462f3890f08313544762642f28 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/bootmem.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 <asm/sections.h>
#include <asm/processor.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>
#include <asm/stackprotector.h>

#ifdef CONFIG_DEBUG_PER_CPU_MAPS
# define DBG(x...) printk(KERN_DEBUG x)
#else
# define DBG(x...)
#endif

DEFINE_PER_CPU(int, cpu_number);
EXPORT_PER_CPU_SYMBOL(cpu_number);

#ifdef CONFIG_X86_64
#define BOOT_PERCPU_OFFSET ((unsigned long)__per_cpu_load)
#else
#define BOOT_PERCPU_OFFSET 0
#endif

DEFINE_PER_CPU(unsigned long, this_cpu_off) = BOOT_PERCPU_OFFSET;
EXPORT_PER_CPU_SYMBOL(this_cpu_off);

unsigned long __per_cpu_offset[NR_CPUS] __read_mostly = {
	[0 ... NR_CPUS-1] = BOOT_PERCPU_OFFSET,
};
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

/**
 * 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_NEED_MULTIPLE_NODES
	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;
}

/**
 * pcpu_alloc_bootmem - NUMA friendly alloc_bootmem wrapper for percpu
 * @cpu: cpu to allocate for
 * @size: size allocation in bytes
 * @align: alignment
 *
 * Allocate @size bytes aligned at @align for cpu @cpu.  This wrapper
 * does the right thing for NUMA regardless of the current
 * configuration.
 *
 * RETURNS:
 * Pointer to the allocated area on success, NULL on failure.
 */
static void * __init pcpu_alloc_bootmem(unsigned int cpu, unsigned long size,
					unsigned long align)
{
	const unsigned long goal = __pa(MAX_DMA_ADDRESS);
#ifdef CONFIG_NEED_MULTIPLE_NODES
	int node = early_cpu_to_node(cpu);
	void *ptr;

	if (!node_online(node) || !NODE_DATA(node)) {
		ptr = __alloc_bootmem_nopanic(size, align, goal);
		pr_info("cpu %d has no node %d or node-local memory\n",
			cpu, node);
		pr_debug("per cpu data for cpu%d %lu bytes at %016lx\n",
			 cpu, size, __pa(ptr));
	} else {
		ptr = __alloc_bootmem_node_nopanic(NODE_DATA(node),
						   size, align, goal);
		pr_debug("per cpu data for cpu%d %lu bytes on node%d at "
			 "%016lx\n", cpu, size, node, __pa(ptr));
	}
	return ptr;
#else
	return __alloc_bootmem_nopanic(size, align, goal);
#endif
}

/*
 * Remap allocator
 *
 * This allocator uses PMD page as unit.  A PMD page is allocated for
 * each cpu and each is remapped into vmalloc area using PMD mapping.
 * As PMD page is quite large, only part of it is used for the first
 * chunk.  Unused part is returned to the bootmem allocator.
 *
 * So, the PMD pages are mapped twice - once to the physical mapping
 * and to the vmalloc area for the first percpu chunk.  The double
 * mapping does add one more PMD TLB entry pressure but still is much
 * better than only using 4k mappings while still being NUMA friendly.
 */
#ifdef CONFIG_NEED_MULTIPLE_NODES
static size_t pcpur_size __initdata;
static void **pcpur_ptrs __initdata;

static struct page * __init pcpur_get_page(unsigned int cpu, int pageno)
{
	size_t off = (size_t)pageno << PAGE_SHIFT;

	if (off >= pcpur_size)
		return NULL;

	return virt_to_page(pcpur_ptrs[cpu] + off);
}

static ssize_t __init setup_pcpu_remap(size_t static_size)
{
	static struct vm_struct vm;
	size_t ptrs_size, dyn_size;
	unsigned int cpu;
	ssize_t ret;

	/*
	 * If large page isn't supported, there's no benefit in doing
	 * this.  Also, on non-NUMA, embedding is better.
	 */
	if (!cpu_has_pse || !pcpu_need_numa())
		return -EINVAL;

	/*
	 * Currently supports only single page.  Supporting multiple
	 * pages won't be too difficult if it ever becomes necessary.
	 */
	pcpur_size = PFN_ALIGN(static_size + PERCPU_MODULE_RESERVE +
			       PERCPU_DYNAMIC_RESERVE);
	if (pcpur_size > PMD_SIZE) {
		pr_warning("PERCPU: static data is larger than large page, "
			   "can't use large page\n");
		return -EINVAL;
	}
	dyn_size = pcpur_size - static_size - PERCPU_FIRST_CHUNK_RESERVE;

	/* allocate pointer array and alloc large pages */
	ptrs_size = PFN_ALIGN(num_possible_cpus() * sizeof(pcpur_ptrs[0]));
	pcpur_ptrs = alloc_bootmem(ptrs_size);

	for_each_possible_cpu(cpu) {
		pcpur_ptrs[cpu] = pcpu_alloc_bootmem(cpu, PMD_SIZE, PMD_SIZE);
		if (!pcpur_ptrs[cpu])
			goto enomem;

		/*
		 * Only use pcpur_size bytes and give back the rest.
		 *
		 * Ingo: The 2MB up-rounding bootmem is needed to make
		 * sure the partial 2MB page is still fully RAM - it's
		 * not well-specified to have a PAT-incompatible area
		 * (unmapped RAM, device memory, etc.) in that hole.
		 */
		free_bootmem(__pa(pcpur_ptrs[cpu] + pcpur_size),
			     PMD_SIZE - pcpur_size);

		memcpy(pcpur_ptrs[cpu], __per_cpu_load, static_size);
	}

	/* allocate address and map */
	vm.flags = VM_ALLOC;
	vm.size = num_possible_cpus() * PMD_SIZE;
	vm_area_register_early(&vm, PMD_SIZE);

	for_each_possible_cpu(cpu) {
		pmd_t *pmd;

		pmd = populate_extra_pmd((unsigned long)vm.addr
					 + cpu * PMD_SIZE);
		set_pmd(pmd, pfn_pmd(page_to_pfn(virt_to_page(pcpur_ptrs[cpu])),
				     PAGE_KERNEL_LARGE));
	}

	/* we're ready, commit */
	pr_info("PERCPU: Remapped at %p with large pages, static data "
		"%zu bytes\n", vm.addr, static_size);

	ret = pcpu_setup_first_chunk(pcpur_get_page, static_size,
				     PERCPU_FIRST_CHUNK_RESERVE, dyn_size,
				     PMD_SIZE, vm.addr, NULL);
	goto out_free_ar;

enomem:
	for_each_possible_cpu(cpu)
		if (pcpur_ptrs[cpu])
			free_bootmem(__pa(pcpur_ptrs[cpu]), PMD_SIZE);
	ret = -ENOMEM;
out_free_ar:
	free_bootmem(__pa(pcpur_ptrs), ptrs_size);
	return ret;
}
#else
static ssize_t __init setup_pcpu_remap(size_t static_size)
{
	return -EINVAL;
}
#endif

/*
 * Embedding allocator
 *
 * The first chunk is sized to just contain the static area plus
 * module and dynamic reserves and embedded into linear physical
 * mapping so that it can use PMD mapping without additional TLB
 * pressure.
 */
static ssize_t __init setup_pcpu_embed(size_t static_size)
{
	size_t reserve = PERCPU_MODULE_RESERVE + PERCPU_DYNAMIC_RESERVE;

	/*
	 * If large page isn't supported, there's no benefit in doing
	 * this.  Also, embedding allocation doesn't play well with
	 * NUMA.
	 */
	if (!cpu_has_pse || pcpu_need_numa())
		return -EINVAL;

	return pcpu_embed_first_chunk(static_size, PERCPU_FIRST_CHUNK_RESERVE,
				      reserve - PERCPU_FIRST_CHUNK_RESERVE, -1);
}

/*
 * 4k page allocator
 *
 * This is the basic allocator.  Static percpu area is allocated
 * page-by-page and most of initialization is done by the generic
 * setup function.
 */
static struct page **pcpu4k_pages __initdata;
static int pcpu4k_nr_static_pages __initdata;

static struct page * __init pcpu4k_get_page(unsigned int cpu, int pageno)
{
	if (pageno < pcpu4k_nr_static_pages)
		return pcpu4k_pages[cpu * pcpu4k_nr_static_pages + pageno];
	return NULL;
}

static void __init pcpu4k_populate_pte(unsigned long addr)
{
	populate_extra_pte(addr);
}

static ssize_t __init setup_pcpu_4k(size_t static_size)
{
	size_t pages_size;
	unsigned int cpu;
	int i, j;
	ssize_t ret;

	pcpu4k_nr_static_pages = PFN_UP(static_size);

	/* unaligned allocations can't be freed, round up to page size */
	pages_size = PFN_ALIGN(pcpu4k_nr_static_pages * num_possible_cpus()
			       * sizeof(pcpu4k_pages[0]));
	pcpu4k_pages = alloc_bootmem(pages_size);

	/* allocate and copy */
	j = 0;
	for_each_possible_cpu(cpu)
		for (i = 0; i < pcpu4k_nr_static_pages; i++) {
			void *ptr;

			ptr = pcpu_alloc_bootmem(cpu, PAGE_SIZE, PAGE_SIZE);
			if (!ptr)
				goto enomem;

			memcpy(ptr, __per_cpu_load + i * PAGE_SIZE, PAGE_SIZE);
			pcpu4k_pages[j++] = virt_to_page(ptr);
		}

	/* we're ready, commit */
	pr_info("PERCPU: Allocated %d 4k pages, static data %zu bytes\n",
		pcpu4k_nr_static_pages, static_size);

	ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size,
				     PERCPU_FIRST_CHUNK_RESERVE, -1,
				     -1, NULL, pcpu4k_populate_pte);
	goto out_free_ar;

enomem:
	while (--j >= 0)
		free_bootmem(__pa(page_address(pcpu4k_pages[j])), PAGE_SIZE);
	ret = -ENOMEM;
out_free_ar:
	free_bootmem(__pa(pcpu4k_pages), pages_size);
	return ret;
}

static inline void setup_percpu_segment(int cpu)
{
#ifdef CONFIG_X86_32
	struct desc_struct gdt;

	pack_descriptor(&gdt, per_cpu_offset(cpu), 0xFFFFF,
			0x2 | DESCTYPE_S, 0x8);
	gdt.s = 1;
	write_gdt_entry(get_cpu_gdt_table(cpu),
			GDT_ENTRY_PERCPU, &gdt, DESCTYPE_S);
#endif
}

/*
 * Great future plan:
 * Declare PDA itself and support (irqstack,tss,pgd) as per cpu data.
 * Always point %gs to its beginning
 */
void __init setup_per_cpu_areas(void)
{
	size_t static_size = __per_cpu_end - __per_cpu_start;
	unsigned int cpu;
	unsigned long delta;
	size_t pcpu_unit_size;
	ssize_t ret;

	pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%d nr_node_ids:%d\n",
		NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);

	/*
	 * Allocate percpu area.  If PSE is supported, try to make use
	 * of large page mappings.  Please read comments on top of
	 * each allocator for details.
	 */
	ret = setup_pcpu_remap(static_size);
	if (ret < 0)
		ret = setup_pcpu_embed(static_size);
	if (ret < 0)
		ret = setup_pcpu_4k(static_size);
	if (ret < 0)
		panic("cannot allocate static percpu area (%zu bytes, err=%zd)",
		      static_size, ret);

	pcpu_unit_size = ret;

	/* 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 + cpu * pcpu_unit_size;
		per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);
		per_cpu(cpu_number, cpu) = cpu;
		setup_percpu_segment(cpu);
		setup_stack_canary_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_bios_cpu_apicid, cpu) =
			early_per_cpu_map(x86_bios_cpu_apicid, cpu);
#endif
#ifdef CONFIG_X86_64
		per_cpu(irq_stack_ptr, cpu) =
			per_cpu(irq_stack_union.irq_stack, cpu) +
			IRQ_STACK_SIZE - 64;
#ifdef CONFIG_NUMA
		per_cpu(x86_cpu_to_node_map, cpu) =
			early_per_cpu_map(x86_cpu_to_node_map, cpu);
#endif
#endif
		/*
		 * Up to this point, the boot CPU has been using .data.init
		 * area.  Reload any changed state for the boot CPU.
		 */
		if (cpu == boot_cpu_id)
			switch_to_new_gdt(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_bios_cpu_apicid) = NULL;
#endif
#if defined(CONFIG_X86_64) && defined(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();
}