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         size_t ptrs_size, dyn_size;
 157         unsigned int cpu;
 158         ssize_t ret;
 159
 160         /*
 161          * If large page isn't supported, there's no benefit in doing
 162          * this.  Also, on non-NUMA, embedding is better.
 163          */
 164         if (!cpu_has_pse || !pcpu_need_numa())
 165                 return -EINVAL;
 166
 167         /*
 168          * Currently supports only single page.  Supporting multiple
 169          * pages won't be too difficult if it ever becomes necessary.
 170          */
 171         pcpur_size = PFN_ALIGN(static_size + PERCPU_MODULE_RESERVE +
 172                                PERCPU_DYNAMIC_RESERVE);
 173         if (pcpur_size > PMD_SIZE) {
 174                 pr_warning("PERCPU: static data is larger than large page, "
 175                            "can't use large page\n");
 176                 return -EINVAL;
 177         }
 178         dyn_size = pcpur_size - static_size - PERCPU_FIRST_CHUNK_RESERVE;
 179
 180         /* allocate pointer array and alloc large pages */
 181         ptrs_size = PFN_ALIGN(num_possible_cpus() * sizeof(pcpur_ptrs[0]));
 182         pcpur_ptrs = alloc_bootmem(ptrs_size);
 183
 184         for_each_possible_cpu(cpu) {
 185                 pcpur_ptrs[cpu] = pcpu_alloc_bootmem(cpu, PMD_SIZE, PMD_SIZE);
 186                 if (!pcpur_ptrs[cpu])
 187                         goto enomem;
 188
 189                 /*
 190                  * Only use pcpur_size bytes and give back the rest.
 191                  *
 192                  * Ingo: The 2MB up-rounding bootmem is needed to make
 193                  * sure the partial 2MB page is still fully RAM - it's
 194                  * not well-specified to have a PAT-incompatible area
 195                  * (unmapped RAM, device memory, etc.) in that hole.
 196                  */
 197                 free_bootmem(__pa(pcpur_ptrs[cpu] + pcpur_size),
 198                              PMD_SIZE - pcpur_size);
 199
 200                 memcpy(pcpur_ptrs[cpu], __per_cpu_load, static_size);
 201         }
 202
 203         /* allocate address and map */
 204         vm.flags = VM_ALLOC;
 205         vm.size = num_possible_cpus() * PMD_SIZE;
 206         vm_area_register_early(&vm, PMD_SIZE);
 207
 208         for_each_possible_cpu(cpu) {
 209                 pmd_t *pmd;
 210
 211                 pmd = populate_extra_pmd((unsigned long)vm.addr
 212                                          + cpu * PMD_SIZE);
 213                 set_pmd(pmd, pfn_pmd(page_to_pfn(virt_to_page(pcpur_ptrs[cpu])),
 214                                      PAGE_KERNEL_LARGE));
 215         }
 216
 217         /* we're ready, commit */
 218         pr_info("PERCPU: Remapped at %p with large pages, static data "
 219                 "%zu bytes\n", vm.addr, static_size);
 220
 221         ret = pcpu_setup_first_chunk(pcpur_get_page, static_size,
 222                                      PERCPU_FIRST_CHUNK_RESERVE, dyn_size,
 223                                      PMD_SIZE, vm.addr, NULL);
 224         goto out_free_ar;
 225
 226 enomem:
 227         for_each_possible_cpu(cpu)
 228                 if (pcpur_ptrs[cpu])
 229                         free_bootmem(__pa(pcpur_ptrs[cpu]), PMD_SIZE);
 230         ret = -ENOMEM;
 231 out_free_ar:
 232         free_bootmem(__pa(pcpur_ptrs), ptrs_size);
 233         return ret;
 234 }
 235 #else
 236 static ssize_t __init setup_pcpu_remap(size_t static_size)
 237 {
 238         return -EINVAL;
 239 }
 240 #endif
 241
 242 /*
 243  * Embedding allocator
 244  *
 245  * The first chunk is sized to just contain the static area plus
 246  * module and dynamic reserves and embedded into linear physical
 247  * mapping so that it can use PMD mapping without additional TLB
 248  * pressure.
 249  */
 250 static ssize_t __init setup_pcpu_embed(size_t static_size)
 251 {
 252         size_t reserve = PERCPU_MODULE_RESERVE + PERCPU_DYNAMIC_RESERVE;
 253
 254         /*
 255          * If large page isn't supported, there's no benefit in doing
 256          * this.  Also, embedding allocation doesn't play well with
 257          * NUMA.
 258          */
 259         if (!cpu_has_pse || pcpu_need_numa())
 260                 return -EINVAL;
 261
 262         return pcpu_embed_first_chunk(static_size, PERCPU_FIRST_CHUNK_RESERVE,
 263                                       reserve - PERCPU_FIRST_CHUNK_RESERVE, -1);
 264 }
 265
 266 /*
 267  * 4k page allocator
 268  *
 269  * This is the basic allocator.  Static percpu area is allocated
 270  * page-by-page and most of initialization is done by the generic
 271  * setup function.
 272  */
 273 static struct page **pcpu4k_pages __initdata;
 274 static int pcpu4k_nr_static_pages __initdata;
 275
 276 static struct page * __init pcpu4k_get_page(unsigned int cpu, int pageno)
 277 {
 278         if (pageno < pcpu4k_nr_static_pages)
 279                 return pcpu4k_pages[cpu * pcpu4k_nr_static_pages + pageno];
 280         return NULL;
 281 }
 282
 283 static void __init pcpu4k_populate_pte(unsigned long addr)
 284 {
 285         populate_extra_pte(addr);
 286 }
 287
 288 static ssize_t __init setup_pcpu_4k(size_t static_size)
 289 {
 290         size_t pages_size;
 291         unsigned int cpu;
 292         int i, j;
 293         ssize_t ret;
 294
 295         pcpu4k_nr_static_pages = PFN_UP(static_size);
 296
 297         /* unaligned allocations can't be freed, round up to page size */
 298         pages_size = PFN_ALIGN(pcpu4k_nr_static_pages * num_possible_cpus()
 299                                * sizeof(pcpu4k_pages[0]));
 300         pcpu4k_pages = alloc_bootmem(pages_size);
 301
 302         /* allocate and copy */
 303         j = 0;
 304         for_each_possible_cpu(cpu)
 305                 for (i = 0; i < pcpu4k_nr_static_pages; i++) {
 306                         void *ptr;
 307
 308                         ptr = pcpu_alloc_bootmem(cpu, PAGE_SIZE, PAGE_SIZE);
 309                         if (!ptr)
 310                                 goto enomem;
 311
 312                         memcpy(ptr, __per_cpu_load + i * PAGE_SIZE, PAGE_SIZE);
 313                         pcpu4k_pages[j++] = virt_to_page(ptr);
 314                 }
 315
 316         /* we're ready, commit */
 317         pr_info("PERCPU: Allocated %d 4k pages, static data %zu bytes\n",
 318                 pcpu4k_nr_static_pages, static_size);
 319
 320         ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size,
 321                                      PERCPU_FIRST_CHUNK_RESERVE, -1,
 322                                      -1, NULL, pcpu4k_populate_pte);
 323         goto out_free_ar;
 324
 325 enomem:
 326         while (--j >= 0)
 327                 free_bootmem(__pa(page_address(pcpu4k_pages[j])), PAGE_SIZE);
 328         ret = -ENOMEM;
 329 out_free_ar:
 330         free_bootmem(__pa(pcpu4k_pages), pages_size);
 331         return ret;
 332 }
 333
 334 static inline void setup_percpu_segment(int cpu)
 335 {
 336 #ifdef CONFIG_X86_32
 337         struct desc_struct gdt;
 338
 339         pack_descriptor(&gdt, per_cpu_offset(cpu), 0xFFFFF,
 340                         0x2 | DESCTYPE_S, 0x8);
 341         gdt.s = 1;
 342         write_gdt_entry(get_cpu_gdt_table(cpu),
 343                         GDT_ENTRY_PERCPU, &gdt, DESCTYPE_S);
 344 #endif
 345 }
 346
 347 /*
 348  * Great future plan:
 349  * Declare PDA itself and support (irqstack,tss,pgd) as per cpu data.
 350  * Always point %gs to its beginning
 351  */
 352 void __init setup_per_cpu_areas(void)
 353 {
 354         size_t static_size = __per_cpu_end - __per_cpu_start;
 355         unsigned int cpu;
 356         unsigned long delta;
 357         size_t pcpu_unit_size;
 358         ssize_t ret;
 359
 360         pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%d nr_node_ids:%d\n",
 361                 NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);
 362
 363         /*
 364          * Allocate percpu area.  If PSE is supported, try to make use
 365          * of large page mappings.  Please read comments on top of
 366          * each allocator for details.
 367          */
 368         ret = setup_pcpu_remap(static_size);
 369         if (ret < 0)
 370                 ret = setup_pcpu_embed(static_size);
 371         if (ret < 0)
 372                 ret = setup_pcpu_4k(static_size);
 373         if (ret < 0)
 374                 panic("cannot allocate static percpu area (%zu bytes, err=%zd)",
 375                       static_size, ret);
 376
 377         pcpu_unit_size = ret;
 378
 379         /* alrighty, percpu areas up and running */
 380         delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
 381         for_each_possible_cpu(cpu) {
 382                 per_cpu_offset(cpu) = delta + cpu * pcpu_unit_size;
 383                 per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);
 384                 per_cpu(cpu_number, cpu) = cpu;
 385                 setup_percpu_segment(cpu);
 386                 setup_stack_canary_segment(cpu);
 387                 /*
 388                  * Copy data used in early init routines from the
 389                  * initial arrays to the per cpu data areas.  These
 390                  * arrays then become expendable and the *_early_ptr's
 391                  * are zeroed indicating that the static arrays are
 392                  * gone.
 393                  */
 394 #ifdef CONFIG_X86_LOCAL_APIC
 395                 per_cpu(x86_cpu_to_apicid, cpu) =
 396                         early_per_cpu_map(x86_cpu_to_apicid, cpu);
 397                 per_cpu(x86_bios_cpu_apicid, cpu) =
 398                         early_per_cpu_map(x86_bios_cpu_apicid, cpu);
 399 #endif
 400 #ifdef CONFIG_X86_64
 401                 per_cpu(irq_stack_ptr, cpu) =
 402                         per_cpu(irq_stack_union.irq_stack, cpu) +
 403                         IRQ_STACK_SIZE - 64;
 404 #ifdef CONFIG_NUMA
 405                 per_cpu(x86_cpu_to_node_map, cpu) =
 406                         early_per_cpu_map(x86_cpu_to_node_map, cpu);
 407 #endif
 408 #endif
 409                 /*
 410                  * Up to this point, the boot CPU has been using .data.init
 411                  * area.  Reload any changed state for the boot CPU.
 412                  */
 413                 if (cpu == boot_cpu_id)
 414                         switch_to_new_gdt(cpu);
 415         }
 416
 417         /* indicate the early static arrays will soon be gone */
 418 #ifdef CONFIG_X86_LOCAL_APIC
 419         early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
 420         early_per_cpu_ptr(x86_bios_cpu_apicid) = NULL;
 421 #endif
 422 #if defined(CONFIG_X86_64) && defined(CONFIG_NUMA)
 423         early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
 424 #endif
 425
 426         /* Setup node to cpumask map */
 427         setup_node_to_cpumask_map();
 428
 429         /* Setup cpu initialized, callin, callout masks */
 430         setup_cpu_local_masks();
 431 }