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          * NOTE: disabled for now.
 165          */
 166         if (true || !cpu_has_pse || !pcpu_need_numa())
 167                 return -EINVAL;
 168
 169         /*
 170          * Currently supports only single page.  Supporting multiple
 171          * pages won't be too difficult if it ever becomes necessary.
 172          */
 173         pcpur_size = PFN_ALIGN(static_size + PERCPU_MODULE_RESERVE +
 174                                PERCPU_DYNAMIC_RESERVE);
 175         if (pcpur_size > PMD_SIZE) {
 176                 pr_warning("PERCPU: static data is larger than large page, "
 177                            "can't use large page\n");
 178                 return -EINVAL;
 179         }
 180         dyn_size = pcpur_size - static_size - PERCPU_FIRST_CHUNK_RESERVE;
 181
 182         /* allocate pointer array and alloc large pages */
 183         ptrs_size = PFN_ALIGN(num_possible_cpus() * sizeof(pcpur_ptrs[0]));
 184         pcpur_ptrs = alloc_bootmem(ptrs_size);
 185
 186         for_each_possible_cpu(cpu) {
 187                 pcpur_ptrs[cpu] = pcpu_alloc_bootmem(cpu, PMD_SIZE, PMD_SIZE);
 188                 if (!pcpur_ptrs[cpu])
 189                         goto enomem;
 190
 191                 /*
 192                  * Only use pcpur_size bytes and give back the rest.
 193                  *
 194                  * Ingo: The 2MB up-rounding bootmem is needed to make
 195                  * sure the partial 2MB page is still fully RAM - it's
 196                  * not well-specified to have a PAT-incompatible area
 197                  * (unmapped RAM, device memory, etc.) in that hole.
 198                  */
 199                 free_bootmem(__pa(pcpur_ptrs[cpu] + pcpur_size),
 200                              PMD_SIZE - pcpur_size);
 201
 202                 memcpy(pcpur_ptrs[cpu], __per_cpu_load, static_size);
 203         }
 204
 205         /* allocate address and map */
 206         vm.flags = VM_ALLOC;
 207         vm.size = num_possible_cpus() * PMD_SIZE;
 208         vm_area_register_early(&vm, PMD_SIZE);
 209
 210         for_each_possible_cpu(cpu) {
 211                 pmd_t *pmd;
 212
 213                 pmd = populate_extra_pmd((unsigned long)vm.addr
 214                                          + cpu * PMD_SIZE);
 215                 set_pmd(pmd, pfn_pmd(page_to_pfn(virt_to_page(pcpur_ptrs[cpu])),
 216                                      PAGE_KERNEL_LARGE));
 217         }
 218
 219         /* we're ready, commit */
 220         pr_info("PERCPU: Remapped at %p with large pages, static data "
 221                 "%zu bytes\n", vm.addr, static_size);
 222
 223         ret = pcpu_setup_first_chunk(pcpur_get_page, static_size,
 224                                      PERCPU_FIRST_CHUNK_RESERVE, dyn_size,
 225                                      PMD_SIZE, vm.addr, NULL);
 226         goto out_free_ar;
 227
 228 enomem:
 229         for_each_possible_cpu(cpu)
 230                 if (pcpur_ptrs[cpu])
 231                         free_bootmem(__pa(pcpur_ptrs[cpu]), PMD_SIZE);
 232         ret = -ENOMEM;
 233 out_free_ar:
 234         free_bootmem(__pa(pcpur_ptrs), ptrs_size);
 235         return ret;
 236 }
 237 #else
 238 static ssize_t __init setup_pcpu_remap(size_t static_size)
 239 {
 240         return -EINVAL;
 241 }
 242 #endif
 243
 244 /*
 245  * Embedding allocator
 246  *
 247  * The first chunk is sized to just contain the static area plus
 248  * module and dynamic reserves and embedded into linear physical
 249  * mapping so that it can use PMD mapping without additional TLB
 250  * pressure.
 251  */
 252 static ssize_t __init setup_pcpu_embed(size_t static_size)
 253 {
 254         size_t reserve = PERCPU_MODULE_RESERVE + PERCPU_DYNAMIC_RESERVE;
 255
 256         /*
 257          * If large page isn't supported, there's no benefit in doing
 258          * this.  Also, embedding allocation doesn't play well with
 259          * NUMA.
 260          */
 261         if (!cpu_has_pse || pcpu_need_numa())
 262                 return -EINVAL;
 263
 264         return pcpu_embed_first_chunk(static_size, PERCPU_FIRST_CHUNK_RESERVE,
 265                                       reserve - PERCPU_FIRST_CHUNK_RESERVE, -1);
 266 }
 267
 268 /*
 269  * 4k page allocator
 270  *
 271  * This is the basic allocator.  Static percpu area is allocated
 272  * page-by-page and most of initialization is done by the generic
 273  * setup function.
 274  */
 275 static struct page **pcpu4k_pages __initdata;
 276 static int pcpu4k_nr_static_pages __initdata;
 277
 278 static struct page * __init pcpu4k_get_page(unsigned int cpu, int pageno)
 279 {
 280         if (pageno < pcpu4k_nr_static_pages)
 281                 return pcpu4k_pages[cpu * pcpu4k_nr_static_pages + pageno];
 282         return NULL;
 283 }
 284
 285 static void __init pcpu4k_populate_pte(unsigned long addr)
 286 {
 287         populate_extra_pte(addr);
 288 }
 289
 290 static ssize_t __init setup_pcpu_4k(size_t static_size)
 291 {
 292         size_t pages_size;
 293         unsigned int cpu;
 294         int i, j;
 295         ssize_t ret;
 296
 297         pcpu4k_nr_static_pages = PFN_UP(static_size);
 298
 299         /* unaligned allocations can't be freed, round up to page size */
 300         pages_size = PFN_ALIGN(pcpu4k_nr_static_pages * num_possible_cpus()
 301                                * sizeof(pcpu4k_pages[0]));
 302         pcpu4k_pages = alloc_bootmem(pages_size);
 303
 304         /* allocate and copy */
 305         j = 0;
 306         for_each_possible_cpu(cpu)
 307                 for (i = 0; i < pcpu4k_nr_static_pages; i++) {
 308                         void *ptr;
 309
 310                         ptr = pcpu_alloc_bootmem(cpu, PAGE_SIZE, PAGE_SIZE);
 311                         if (!ptr)
 312                                 goto enomem;
 313
 314                         memcpy(ptr, __per_cpu_load + i * PAGE_SIZE, PAGE_SIZE);
 315                         pcpu4k_pages[j++] = virt_to_page(ptr);
 316                 }
 317
 318         /* we're ready, commit */
 319         pr_info("PERCPU: Allocated %d 4k pages, static data %zu bytes\n",
 320                 pcpu4k_nr_static_pages, static_size);
 321
 322         ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size,
 323                                      PERCPU_FIRST_CHUNK_RESERVE, -1,
 324                                      -1, NULL, pcpu4k_populate_pte);
 325         goto out_free_ar;
 326
 327 enomem:
 328         while (--j >= 0)
 329                 free_bootmem(__pa(page_address(pcpu4k_pages[j])), PAGE_SIZE);
 330         ret = -ENOMEM;
 331 out_free_ar:
 332         free_bootmem(__pa(pcpu4k_pages), pages_size);
 333         return ret;
 334 }
 335
 336 static inline void setup_percpu_segment(int cpu)
 337 {
 338 #ifdef CONFIG_X86_32
 339         struct desc_struct gdt;
 340
 341         pack_descriptor(&gdt, per_cpu_offset(cpu), 0xFFFFF,
 342                         0x2 | DESCTYPE_S, 0x8);
 343         gdt.s = 1;
 344         write_gdt_entry(get_cpu_gdt_table(cpu),
 345                         GDT_ENTRY_PERCPU, &gdt, DESCTYPE_S);
 346 #endif
 347 }
 348
 349 /*
 350  * Great future plan:
 351  * Declare PDA itself and support (irqstack,tss,pgd) as per cpu data.
 352  * Always point %gs to its beginning
 353  */
 354 void __init setup_per_cpu_areas(void)
 355 {
 356         size_t static_size = __per_cpu_end - __per_cpu_start;
 357         unsigned int cpu;
 358         unsigned long delta;
 359         size_t pcpu_unit_size;
 360         ssize_t ret;
 361
 362         pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%d nr_node_ids:%d\n",
 363                 NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);
 364
 365         /*
 366          * Allocate percpu area.  If PSE is supported, try to make use
 367          * of large page mappings.  Please read comments on top of
 368          * each allocator for details.
 369          */
 370         ret = setup_pcpu_remap(static_size);
 371         if (ret < 0)
 372                 ret = setup_pcpu_embed(static_size);
 373         if (ret < 0)
 374                 ret = setup_pcpu_4k(static_size);
 375         if (ret < 0)
 376                 panic("cannot allocate static percpu area (%zu bytes, err=%zd)",
 377                       static_size, ret);
 378
 379         pcpu_unit_size = ret;
 380
 381         /* alrighty, percpu areas up and running */
 382         delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
 383         for_each_possible_cpu(cpu) {
 384                 per_cpu_offset(cpu) = delta + cpu * pcpu_unit_size;
 385                 per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);
 386                 per_cpu(cpu_number, cpu) = cpu;
 387                 setup_percpu_segment(cpu);
 388                 setup_stack_canary_segment(cpu);
 389                 /*
 390                  * Copy data used in early init routines from the
 391                  * initial arrays to the per cpu data areas.  These
 392                  * arrays then become expendable and the *_early_ptr's
 393                  * are zeroed indicating that the static arrays are
 394                  * gone.
 395                  */
 396 #ifdef CONFIG_X86_LOCAL_APIC
 397                 per_cpu(x86_cpu_to_apicid, cpu) =
 398                         early_per_cpu_map(x86_cpu_to_apicid, cpu);
 399                 per_cpu(x86_bios_cpu_apicid, cpu) =
 400                         early_per_cpu_map(x86_bios_cpu_apicid, cpu);
 401 #endif
 402 #ifdef CONFIG_X86_64
 403                 per_cpu(irq_stack_ptr, cpu) =
 404                         per_cpu(irq_stack_union.irq_stack, cpu) +
 405                         IRQ_STACK_SIZE - 64;
 406 #ifdef CONFIG_NUMA
 407                 per_cpu(x86_cpu_to_node_map, cpu) =
 408                         early_per_cpu_map(x86_cpu_to_node_map, cpu);
 409 #endif
 410 #endif
 411                 /*
 412                  * Up to this point, the boot CPU has been using .data.init
 413                  * area.  Reload any changed state for the boot CPU.
 414                  */
 415                 if (cpu == boot_cpu_id)
 416                         switch_to_new_gdt(cpu);
 417         }
 418
 419         /* indicate the early static arrays will soon be gone */
 420 #ifdef CONFIG_X86_LOCAL_APIC
 421         early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
 422         early_per_cpu_ptr(x86_bios_cpu_apicid) = NULL;
 423 #endif
 424 #if defined(CONFIG_X86_64) && defined(CONFIG_NUMA)
 425         early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
 426 #endif
 427
 428         /* Setup node to cpumask map */
 429         setup_node_to_cpumask_map();
 430
 431         /* Setup cpu initialized, callin, callout masks */
 432         setup_cpu_local_masks();
 433 }