arch/x86/kernel/setup_percpu.c

   1 #include <linux/kernel.h>
   2 #include <linux/module.h>
   3 #include <linux/init.h>
   4 #include <linux/bootmem.h>
   5 #include <linux/percpu.h>
   6 #include <linux/kexec.h>
   7 #include <linux/crash_dump.h>
   8 #include <linux/smp.h>
   9 #include <linux/topology.h>
  10 #include <linux/pfn.h>
  11 #include <asm/sections.h>
  12 #include <asm/processor.h>
  13 #include <asm/setup.h>
  14 #include <asm/mpspec.h>
  15 #include <asm/apicdef.h>
  16 #include <asm/highmem.h>
  17 #include <asm/proto.h>
  18 #include <asm/cpumask.h>
  19 #include <asm/cpu.h>
  20 #include <asm/stackprotector.h>
  21
  22 #ifdef CONFIG_DEBUG_PER_CPU_MAPS
  23 # define DBG(x...) printk(KERN_DEBUG x)
  24 #else
  25 # define DBG(x...)
  26 #endif
  27
  28 DEFINE_PER_CPU(int, cpu_number);
  29 EXPORT_PER_CPU_SYMBOL(cpu_number);
  30
  31 #ifdef CONFIG_X86_64
  32 #define BOOT_PERCPU_OFFSET ((unsigned long)__per_cpu_load)
  33 #else
  34 #define BOOT_PERCPU_OFFSET 0
  35 #endif
  36
  37 DEFINE_PER_CPU(unsigned long, this_cpu_off) = BOOT_PERCPU_OFFSET;
  38 EXPORT_PER_CPU_SYMBOL(this_cpu_off);
  39
  40 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly = {
  41         [0 ... NR_CPUS-1] = BOOT_PERCPU_OFFSET,
  42 };
  43 EXPORT_SYMBOL(__per_cpu_offset);
  44
  45 /*
  46  * On x86_64 symbols referenced from code should be reachable using
  47  * 32bit relocations.  Reserve space for static percpu variables in
  48  * modules so that they are always served from the first chunk which
  49  * is located at the percpu segment base.  On x86_32, anything can
  50  * address anywhere.  No need to reserve space in the first chunk.
  51  */
  52 #ifdef CONFIG_X86_64
  53 #define PERCPU_FIRST_CHUNK_RESERVE      PERCPU_MODULE_RESERVE
  54 #else
  55 #define PERCPU_FIRST_CHUNK_RESERVE      0
  56 #endif
  57
  58 /**
  59  * pcpu_need_numa - determine percpu allocation needs to consider NUMA
  60  *
  61  * If NUMA is not configured or there is only one NUMA node available,
  62  * there is no reason to consider NUMA.  This function determines
  63  * whether percpu allocation should consider NUMA or not.
  64  *
  65  * RETURNS:
  66  * true if NUMA should be considered; otherwise, false.
  67  */
  68 static bool __init pcpu_need_numa(void)
  69 {
  70 #ifdef CONFIG_NEED_MULTIPLE_NODES
  71         pg_data_t *last = NULL;
  72         unsigned int cpu;
  73
  74         for_each_possible_cpu(cpu) {
  75                 int node = early_cpu_to_node(cpu);
  76
  77                 if (node_online(node) && NODE_DATA(node) &&
  78                     last && last != NODE_DATA(node))
  79                         return true;
  80
  81                 last = NODE_DATA(node);
  82         }
  83 #endif
  84         return false;
  85 }
  86
  87 /**
  88  * pcpu_alloc_bootmem - NUMA friendly alloc_bootmem wrapper for percpu
  89  * @cpu: cpu to allocate for
  90  * @size: size allocation in bytes
  91  * @align: alignment
  92  *
  93  * Allocate @size bytes aligned at @align for cpu @cpu.  This wrapper
  94  * does the right thing for NUMA regardless of the current
  95  * configuration.
  96  *
  97  * RETURNS:
  98  * Pointer to the allocated area on success, NULL on failure.
  99  */
 100 static void * __init pcpu_alloc_bootmem(unsigned int cpu, unsigned long size,
 101                                         unsigned long align)
 102 {
 103         const unsigned long goal = __pa(MAX_DMA_ADDRESS);
 104 #ifdef CONFIG_NEED_MULTIPLE_NODES
 105         int node = early_cpu_to_node(cpu);
 106         void *ptr;
 107
 108         if (!node_online(node) || !NODE_DATA(node)) {
 109                 ptr = __alloc_bootmem_nopanic(size, align, goal);
 110                 pr_info("cpu %d has no node %d or node-local memory\n",
 111                         cpu, node);
 112                 pr_debug("per cpu data for cpu%d %lu bytes at %016lx\n",
 113                          cpu, size, __pa(ptr));
 114         } else {
 115                 ptr = __alloc_bootmem_node_nopanic(NODE_DATA(node),
 116                                                    size, align, goal);
 117                 pr_debug("per cpu data for cpu%d %lu bytes on node%d at "
 118                          "%016lx\n", cpu, size, node, __pa(ptr));
 119         }
 120         return ptr;
 121 #else
 122         return __alloc_bootmem_nopanic(size, align, goal);
 123 #endif
 124 }
 125
 126 /*
 127  * Remap allocator
 128  *
 129  * This allocator uses PMD page as unit.  A PMD page is allocated for
 130  * each cpu and each is remapped into vmalloc area using PMD mapping.
 131  * As PMD page is quite large, only part of it is used for the first
 132  * chunk.  Unused part is returned to the bootmem allocator.
 133  *
 134  * So, the PMD pages are mapped twice - once to the physical mapping
 135  * and to the vmalloc area for the first percpu chunk.  The double
 136  * mapping does add one more PMD TLB entry pressure but still is much
 137  * better than only using 4k mappings while still being NUMA friendly.
 138  */
 139 #ifdef CONFIG_NEED_MULTIPLE_NODES
 140 static size_t pcpur_size __initdata;
 141 static void **pcpur_ptrs __initdata;
 142
 143 static struct page * __init pcpur_get_page(unsigned int cpu, int pageno)
 144 {
 145         size_t off = (size_t)pageno << PAGE_SHIFT;
 146
 147         if (off >= pcpur_size)
 148                 return NULL;
 149
 150         return virt_to_page(pcpur_ptrs[cpu] + off);
 151 }
 152
 153 static ssize_t __init setup_pcpu_remap(size_t static_size)
 154 {
 155         static struct vm_struct vm;
 156         pg_data_t *last;
 157         size_t ptrs_size, dyn_size;
 158         unsigned int cpu;
 159         ssize_t ret;
 160
 161         /*
 162          * If large page isn't supported, there's no benefit in doing
 163          * this.  Also, on non-NUMA, embedding is better.
 164          */
 165         if (!cpu_has_pse || pcpu_need_numa())
 166                 return -EINVAL;
 167
 168         last = NULL;
 169         for_each_possible_cpu(cpu) {
 170                 int node = early_cpu_to_node(cpu);
 171
 172                 if (node_online(node) && NODE_DATA(node) &&
 173                     last && last != NODE_DATA(node))
 174                         goto proceed;
 175
 176                 last = NODE_DATA(node);
 177         }
 178         return -EINVAL;
 179
 180 proceed:
 181         /*
 182          * Currently supports only single page.  Supporting multiple
 183          * pages won't be too difficult if it ever becomes necessary.
 184          */
 185         pcpur_size = PFN_ALIGN(static_size + PERCPU_MODULE_RESERVE +
 186                                PERCPU_DYNAMIC_RESERVE);
 187         if (pcpur_size > PMD_SIZE) {
 188                 pr_warning("PERCPU: static data is larger than large page, "
 189                            "can't use large page\n");
 190                 return -EINVAL;
 191         }
 192         dyn_size = pcpur_size - static_size - PERCPU_FIRST_CHUNK_RESERVE;
 193
 194         /* allocate pointer array and alloc large pages */
 195         ptrs_size = PFN_ALIGN(num_possible_cpus() * sizeof(pcpur_ptrs[0]));
 196         pcpur_ptrs = alloc_bootmem(ptrs_size);
 197
 198         for_each_possible_cpu(cpu) {
 199                 pcpur_ptrs[cpu] = pcpu_alloc_bootmem(cpu, PMD_SIZE, PMD_SIZE);
 200                 if (!pcpur_ptrs[cpu])
 201                         goto enomem;
 202
 203                 /*
 204                  * Only use pcpur_size bytes and give back the rest.
 205                  *
 206                  * Ingo: The 2MB up-rounding bootmem is needed to make
 207                  * sure the partial 2MB page is still fully RAM - it's
 208                  * not well-specified to have a PAT-incompatible area
 209                  * (unmapped RAM, device memory, etc.) in that hole.
 210                  */
 211                 free_bootmem(__pa(pcpur_ptrs[cpu] + pcpur_size),
 212                              PMD_SIZE - pcpur_size);
 213
 214                 memcpy(pcpur_ptrs[cpu], __per_cpu_load, static_size);
 215         }
 216
 217         /* allocate address and map */
 218         vm.flags = VM_ALLOC;
 219         vm.size = num_possible_cpus() * PMD_SIZE;
 220         vm_area_register_early(&vm, PMD_SIZE);
 221
 222         for_each_possible_cpu(cpu) {
 223                 pmd_t *pmd;
 224
 225                 pmd = populate_extra_pmd((unsigned long)vm.addr
 226                                          + cpu * PMD_SIZE);
 227                 set_pmd(pmd, pfn_pmd(page_to_pfn(virt_to_page(pcpur_ptrs[cpu])),
 228                                      PAGE_KERNEL_LARGE));
 229         }
 230
 231         /* we're ready, commit */
 232         pr_info("PERCPU: Remapped at %p with large pages, static data "
 233                 "%zu bytes\n", vm.addr, static_size);
 234
 235         ret = pcpu_setup_first_chunk(pcpur_get_page, static_size,
 236                                      PERCPU_FIRST_CHUNK_RESERVE,
 237                                      PMD_SIZE, dyn_size, vm.addr, NULL);
 238         goto out_free_ar;
 239
 240 enomem:
 241         for_each_possible_cpu(cpu)
 242                 if (pcpur_ptrs[cpu])
 243                         free_bootmem(__pa(pcpur_ptrs[cpu]), PMD_SIZE);
 244         ret = -ENOMEM;
 245 out_free_ar:
 246         free_bootmem(__pa(pcpur_ptrs), ptrs_size);
 247         return ret;
 248 }
 249 #else
 250 static ssize_t __init setup_pcpu_remap(size_t static_size)
 251 {
 252         return -EINVAL;
 253 }
 254 #endif
 255
 256 /*
 257  * Embedding allocator
 258  *
 259  * The first chunk is sized to just contain the static area plus
 260  * module and dynamic reserves, and allocated as a contiguous area
 261  * using bootmem allocator and used as-is without being mapped into
 262  * vmalloc area.  This enables the first chunk to piggy back on the
 263  * linear physical PMD mapping and doesn't add any additional pressure
 264  * to TLB.  Note that if the needed size is smaller than the minimum
 265  * unit size, the leftover is returned to the bootmem allocator.
 266  */
 267 static void *pcpue_ptr __initdata;
 268 static size_t pcpue_size __initdata;
 269 static size_t pcpue_unit_size __initdata;
 270
 271 static struct page * __init pcpue_get_page(unsigned int cpu, int pageno)
 272 {
 273         size_t off = (size_t)pageno << PAGE_SHIFT;
 274
 275         if (off >= pcpue_size)
 276                 return NULL;
 277
 278         return virt_to_page(pcpue_ptr + cpu * pcpue_unit_size + off);
 279 }
 280
 281 static ssize_t __init setup_pcpu_embed(size_t static_size)
 282 {
 283         unsigned int cpu;
 284         size_t dyn_size;
 285
 286         /*
 287          * If large page isn't supported, there's no benefit in doing
 288          * this.  Also, embedding allocation doesn't play well with
 289          * NUMA.
 290          */
 291         if (!cpu_has_pse || pcpu_need_numa())
 292                 return -EINVAL;
 293
 294         /* allocate and copy */
 295         pcpue_size = PFN_ALIGN(static_size + PERCPU_MODULE_RESERVE +
 296                                PERCPU_DYNAMIC_RESERVE);
 297         pcpue_unit_size = max_t(size_t, pcpue_size, PCPU_MIN_UNIT_SIZE);
 298         dyn_size = pcpue_size - static_size - PERCPU_FIRST_CHUNK_RESERVE;
 299
 300         pcpue_ptr = pcpu_alloc_bootmem(0, num_possible_cpus() * pcpue_unit_size,
 301                                        PAGE_SIZE);
 302         if (!pcpue_ptr)
 303                 return -ENOMEM;
 304
 305         for_each_possible_cpu(cpu) {
 306                 void *ptr = pcpue_ptr + cpu * pcpue_unit_size;
 307
 308                 free_bootmem(__pa(ptr + pcpue_size),
 309                              pcpue_unit_size - pcpue_size);
 310                 memcpy(ptr, __per_cpu_load, static_size);
 311         }
 312
 313         /* we're ready, commit */
 314         pr_info("PERCPU: Embedded %zu pages at %p, static data %zu bytes\n",
 315                 pcpue_size >> PAGE_SHIFT, pcpue_ptr, static_size);
 316
 317         return pcpu_setup_first_chunk(pcpue_get_page, static_size,
 318                                       PERCPU_FIRST_CHUNK_RESERVE,
 319                                       pcpue_unit_size, dyn_size,
 320                                       pcpue_ptr, NULL);
 321 }
 322
 323 /*
 324  * 4k page allocator
 325  *
 326  * This is the basic allocator.  Static percpu area is allocated
 327  * page-by-page and most of initialization is done by the generic
 328  * setup function.
 329  */
 330 static struct page **pcpu4k_pages __initdata;
 331 static int pcpu4k_nr_static_pages __initdata;
 332
 333 static struct page * __init pcpu4k_get_page(unsigned int cpu, int pageno)
 334 {
 335         if (pageno < pcpu4k_nr_static_pages)
 336                 return pcpu4k_pages[cpu * pcpu4k_nr_static_pages + pageno];
 337         return NULL;
 338 }
 339
 340 static void __init pcpu4k_populate_pte(unsigned long addr)
 341 {
 342         populate_extra_pte(addr);
 343 }
 344
 345 static ssize_t __init setup_pcpu_4k(size_t static_size)
 346 {
 347         size_t pages_size;
 348         unsigned int cpu;
 349         int i, j;
 350         ssize_t ret;
 351
 352         pcpu4k_nr_static_pages = PFN_UP(static_size);
 353
 354         /* unaligned allocations can't be freed, round up to page size */
 355         pages_size = PFN_ALIGN(pcpu4k_nr_static_pages * num_possible_cpus()
 356                                * sizeof(pcpu4k_pages[0]));
 357         pcpu4k_pages = alloc_bootmem(pages_size);
 358
 359         /* allocate and copy */
 360         j = 0;
 361         for_each_possible_cpu(cpu)
 362                 for (i = 0; i < pcpu4k_nr_static_pages; i++) {
 363                         void *ptr;
 364
 365                         ptr = pcpu_alloc_bootmem(cpu, PAGE_SIZE, PAGE_SIZE);
 366                         if (!ptr)
 367                                 goto enomem;
 368
 369                         memcpy(ptr, __per_cpu_load + i * PAGE_SIZE, PAGE_SIZE);
 370                         pcpu4k_pages[j++] = virt_to_page(ptr);
 371                 }
 372
 373         /* we're ready, commit */
 374         pr_info("PERCPU: Allocated %d 4k pages, static data %zu bytes\n",
 375                 pcpu4k_nr_static_pages, static_size);
 376
 377         ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size,
 378                                      PERCPU_FIRST_CHUNK_RESERVE, -1, -1, NULL,
 379                                      pcpu4k_populate_pte);
 380         goto out_free_ar;
 381
 382 enomem:
 383         while (--j >= 0)
 384                 free_bootmem(__pa(page_address(pcpu4k_pages[j])), PAGE_SIZE);
 385         ret = -ENOMEM;
 386 out_free_ar:
 387         free_bootmem(__pa(pcpu4k_pages), pages_size);
 388         return ret;
 389 }
 390
 391 static inline void setup_percpu_segment(int cpu)
 392 {
 393 #ifdef CONFIG_X86_32
 394         struct desc_struct gdt;
 395
 396         pack_descriptor(&gdt, per_cpu_offset(cpu), 0xFFFFF,
 397                         0x2 | DESCTYPE_S, 0x8);
 398         gdt.s = 1;
 399         write_gdt_entry(get_cpu_gdt_table(cpu),
 400                         GDT_ENTRY_PERCPU, &gdt, DESCTYPE_S);
 401 #endif
 402 }
 403
 404 /*
 405  * Great future plan:
 406  * Declare PDA itself and support (irqstack,tss,pgd) as per cpu data.
 407  * Always point %gs to its beginning
 408  */
 409 void __init setup_per_cpu_areas(void)
 410 {
 411         size_t static_size = __per_cpu_end - __per_cpu_start;
 412         unsigned int cpu;
 413         unsigned long delta;
 414         size_t pcpu_unit_size;
 415         ssize_t ret;
 416
 417         pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%d nr_node_ids:%d\n",
 418                 NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);
 419
 420         /*
 421          * Allocate percpu area.  If PSE is supported, try to make use
 422          * of large page mappings.  Please read comments on top of
 423          * each allocator for details.
 424          */
 425         ret = setup_pcpu_remap(static_size);
 426         if (ret < 0)
 427                 ret = setup_pcpu_embed(static_size);
 428         if (ret < 0)
 429                 ret = setup_pcpu_4k(static_size);
 430         if (ret < 0)
 431                 panic("cannot allocate static percpu area (%zu bytes, err=%zd)",
 432                       static_size, ret);
 433
 434         pcpu_unit_size = ret;
 435
 436         /* alrighty, percpu areas up and running */
 437         delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
 438         for_each_possible_cpu(cpu) {
 439                 per_cpu_offset(cpu) = delta + cpu * pcpu_unit_size;
 440                 per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);
 441                 per_cpu(cpu_number, cpu) = cpu;
 442                 setup_percpu_segment(cpu);
 443                 setup_stack_canary_segment(cpu);
 444                 /*
 445                  * Copy data used in early init routines from the
 446                  * initial arrays to the per cpu data areas.  These
 447                  * arrays then become expendable and the *_early_ptr's
 448                  * are zeroed indicating that the static arrays are
 449                  * gone.
 450                  */
 451 #ifdef CONFIG_X86_LOCAL_APIC
 452                 per_cpu(x86_cpu_to_apicid, cpu) =
 453                         early_per_cpu_map(x86_cpu_to_apicid, cpu);
 454                 per_cpu(x86_bios_cpu_apicid, cpu) =
 455                         early_per_cpu_map(x86_bios_cpu_apicid, cpu);
 456 #endif
 457 #ifdef CONFIG_X86_64
 458                 per_cpu(irq_stack_ptr, cpu) =
 459                         per_cpu(irq_stack_union.irq_stack, cpu) +
 460                         IRQ_STACK_SIZE - 64;
 461 #ifdef CONFIG_NUMA
 462                 per_cpu(x86_cpu_to_node_map, cpu) =
 463                         early_per_cpu_map(x86_cpu_to_node_map, cpu);
 464 #endif
 465 #endif
 466                 /*
 467                  * Up to this point, the boot CPU has been using .data.init
 468                  * area.  Reload any changed state for the boot CPU.
 469                  */
 470                 if (cpu == boot_cpu_id)
 471                         switch_to_new_gdt(cpu);
 472         }
 473
 474         /* indicate the early static arrays will soon be gone */
 475 #ifdef CONFIG_X86_LOCAL_APIC
 476         early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
 477         early_per_cpu_ptr(x86_bios_cpu_apicid) = NULL;
 478 #endif
 479 #if defined(CONFIG_X86_64) && defined(CONFIG_NUMA)
 480         early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
 481 #endif
 482
 483         /* Setup node to cpumask map */
 484         setup_node_to_cpumask_map();
 485
 486         /* Setup cpu initialized, callin, callout masks */
 487         setup_cpu_local_masks();
 488 }