arch/x86/kernel/setup_percpu.c

   1 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   2
   3 #include <linux/kernel.h>
   4 #include <linux/module.h>
   5 #include <linux/init.h>
   6 #include <linux/bootmem.h>
   7 #include <linux/percpu.h>
   8 #include <linux/kexec.h>
   9 #include <linux/crash_dump.h>
  10 #include <linux/smp.h>
  11 #include <linux/topology.h>
  12 #include <linux/pfn.h>
  13 #include <asm/sections.h>
  14 #include <asm/processor.h>
  15 #include <asm/setup.h>
  16 #include <asm/mpspec.h>
  17 #include <asm/apicdef.h>
  18 #include <asm/highmem.h>
  19 #include <asm/proto.h>
  20 #include <asm/cpumask.h>
  21 #include <asm/cpu.h>
  22 #include <asm/stackprotector.h>
  23
  24 DEFINE_PER_CPU(int, cpu_number);
  25 EXPORT_PER_CPU_SYMBOL(cpu_number);
  26
  27 #ifdef CONFIG_X86_64
  28 #define BOOT_PERCPU_OFFSET ((unsigned long)__per_cpu_load)
  29 #else
  30 #define BOOT_PERCPU_OFFSET 0
  31 #endif
  32
  33 DEFINE_PER_CPU(unsigned long, this_cpu_off) = BOOT_PERCPU_OFFSET;
  34 EXPORT_PER_CPU_SYMBOL(this_cpu_off);
  35
  36 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly = {
  37         [0 ... NR_CPUS-1] = BOOT_PERCPU_OFFSET,
  38 };
  39 EXPORT_SYMBOL(__per_cpu_offset);
  40
  41 /*
  42  * On x86_64 symbols referenced from code should be reachable using
  43  * 32bit relocations.  Reserve space for static percpu variables in
  44  * modules so that they are always served from the first chunk which
  45  * is located at the percpu segment base.  On x86_32, anything can
  46  * address anywhere.  No need to reserve space in the first chunk.
  47  */
  48 #ifdef CONFIG_X86_64
  49 #define PERCPU_FIRST_CHUNK_RESERVE      PERCPU_MODULE_RESERVE
  50 #else
  51 #define PERCPU_FIRST_CHUNK_RESERVE      0
  52 #endif
  53
  54 #ifdef CONFIG_X86_32
  55 /**
  56  * pcpu_need_numa - determine percpu allocation needs to consider NUMA
  57  *
  58  * If NUMA is not configured or there is only one NUMA node available,
  59  * there is no reason to consider NUMA.  This function determines
  60  * whether percpu allocation should consider NUMA or not.
  61  *
  62  * RETURNS:
  63  * true if NUMA should be considered; otherwise, false.
  64  */
  65 static bool __init pcpu_need_numa(void)
  66 {
  67 #ifdef CONFIG_NEED_MULTIPLE_NODES
  68         pg_data_t *last = NULL;
  69         unsigned int cpu;
  70
  71         for_each_possible_cpu(cpu) {
  72                 int node = early_cpu_to_node(cpu);
  73
  74                 if (node_online(node) && NODE_DATA(node) &&
  75                     last && last != NODE_DATA(node))
  76                         return true;
  77
  78                 last = NODE_DATA(node);
  79         }
  80 #endif
  81         return false;
  82 }
  83 #endif
  84
  85 /**
  86  * pcpu_alloc_bootmem - NUMA friendly alloc_bootmem wrapper for percpu
  87  * @cpu: cpu to allocate for
  88  * @size: size allocation in bytes
  89  * @align: alignment
  90  *
  91  * Allocate @size bytes aligned at @align for cpu @cpu.  This wrapper
  92  * does the right thing for NUMA regardless of the current
  93  * configuration.
  94  *
  95  * RETURNS:
  96  * Pointer to the allocated area on success, NULL on failure.
  97  */
  98 static void * __init pcpu_alloc_bootmem(unsigned int cpu, unsigned long size,
  99                                         unsigned long align)
 100 {
 101         const unsigned long goal = __pa(MAX_DMA_ADDRESS);
 102 #ifdef CONFIG_NEED_MULTIPLE_NODES
 103         int node = early_cpu_to_node(cpu);
 104         void *ptr;
 105
 106         if (!node_online(node) || !NODE_DATA(node)) {
 107                 ptr = __alloc_bootmem_nopanic(size, align, goal);
 108                 pr_info("cpu %d has no node %d or node-local memory\n",
 109                         cpu, node);
 110                 pr_debug("per cpu data for cpu%d %lu bytes at %016lx\n",
 111                          cpu, size, __pa(ptr));
 112         } else {
 113                 ptr = __alloc_bootmem_node_nopanic(NODE_DATA(node),
 114                                                    size, align, goal);
 115                 pr_debug("per cpu data for cpu%d %lu bytes on node%d at %016lx\n",
 116                          cpu, size, node, __pa(ptr));
 117         }
 118         return ptr;
 119 #else
 120         return __alloc_bootmem_nopanic(size, align, goal);
 121 #endif
 122 }
 123
 124 /*
 125  * Helpers for first chunk memory allocation
 126  */
 127 static void * __init pcpu_fc_alloc(unsigned int cpu, size_t size, size_t align)
 128 {
 129         return pcpu_alloc_bootmem(cpu, size, align);
 130 }
 131
 132 static void __init pcpu_fc_free(void *ptr, size_t size)
 133 {
 134 #ifdef CONFIG_NO_BOOTMEM
 135         u64 start = __pa(ptr);
 136         u64 end = start + size;
 137         free_early_partial(start, end);
 138 #else
 139         free_bootmem(__pa(ptr), size);
 140 #endif
 141 }
 142
 143 static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
 144 {
 145 #ifdef CONFIG_NEED_MULTIPLE_NODES
 146         if (early_cpu_to_node(from) == early_cpu_to_node(to))
 147                 return LOCAL_DISTANCE;
 148         else
 149                 return REMOTE_DISTANCE;
 150 #else
 151         return LOCAL_DISTANCE;
 152 #endif
 153 }
 154
 155 static void __init pcpup_populate_pte(unsigned long addr)
 156 {
 157         populate_extra_pte(addr);
 158 }
 159
 160 static inline void setup_percpu_segment(int cpu)
 161 {
 162 #ifdef CONFIG_X86_32
 163         struct desc_struct gdt;
 164
 165         pack_descriptor(&gdt, per_cpu_offset(cpu), 0xFFFFF,
 166                         0x2 | DESCTYPE_S, 0x8);
 167         gdt.s = 1;
 168         write_gdt_entry(get_cpu_gdt_table(cpu),
 169                         GDT_ENTRY_PERCPU, &gdt, DESCTYPE_S);
 170 #endif
 171 }
 172
 173 void __init setup_per_cpu_areas(void)
 174 {
 175         unsigned int cpu;
 176         unsigned long delta;
 177         int rc;
 178
 179         pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%d nr_node_ids:%d\n",
 180                 NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);
 181
 182         /*
 183          * Allocate percpu area.  Embedding allocator is our favorite;
 184          * however, on NUMA configurations, it can result in very
 185          * sparse unit mapping and vmalloc area isn't spacious enough
 186          * on 32bit.  Use page in that case.
 187          */
 188 #ifdef CONFIG_X86_32
 189         if (pcpu_chosen_fc == PCPU_FC_AUTO && pcpu_need_numa())
 190                 pcpu_chosen_fc = PCPU_FC_PAGE;
 191 #endif
 192         rc = -EINVAL;
 193         if (pcpu_chosen_fc != PCPU_FC_PAGE) {
 194                 const size_t atom_size = cpu_has_pse ? PMD_SIZE : PAGE_SIZE;
 195                 const size_t dyn_size = PERCPU_MODULE_RESERVE +
 196                         PERCPU_DYNAMIC_RESERVE - PERCPU_FIRST_CHUNK_RESERVE;
 197
 198                 rc = pcpu_embed_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
 199                                             dyn_size, atom_size,
 200                                             pcpu_cpu_distance,
 201                                             pcpu_fc_alloc, pcpu_fc_free);
 202                 if (rc < 0)
 203                         pr_warning("%s allocator failed (%d), falling back to page size\n",
 204                                    pcpu_fc_names[pcpu_chosen_fc], rc);
 205         }
 206         if (rc < 0)
 207                 rc = pcpu_page_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
 208                                            pcpu_fc_alloc, pcpu_fc_free,
 209                                            pcpup_populate_pte);
 210         if (rc < 0)
 211                 panic("cannot initialize percpu area (err=%d)", rc);
 212
 213         /* alrighty, percpu areas up and running */
 214         delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
 215         for_each_possible_cpu(cpu) {
 216                 per_cpu_offset(cpu) = delta + pcpu_unit_offsets[cpu];
 217                 per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);
 218                 per_cpu(cpu_number, cpu) = cpu;
 219                 setup_percpu_segment(cpu);
 220                 setup_stack_canary_segment(cpu);
 221                 /*
 222                  * Copy data used in early init routines from the
 223                  * initial arrays to the per cpu data areas.  These
 224                  * arrays then become expendable and the *_early_ptr's
 225                  * are zeroed indicating that the static arrays are
 226                  * gone.
 227                  */
 228 #ifdef CONFIG_X86_LOCAL_APIC
 229                 per_cpu(x86_cpu_to_apicid, cpu) =
 230                         early_per_cpu_map(x86_cpu_to_apicid, cpu);
 231                 per_cpu(x86_bios_cpu_apicid, cpu) =
 232                         early_per_cpu_map(x86_bios_cpu_apicid, cpu);
 233 #endif
 234 #ifdef CONFIG_X86_64
 235                 per_cpu(irq_stack_ptr, cpu) =
 236                         per_cpu(irq_stack_union.irq_stack, cpu) +
 237                         IRQ_STACK_SIZE - 64;
 238 #ifdef CONFIG_NUMA
 239                 per_cpu(x86_cpu_to_node_map, cpu) =
 240                         early_per_cpu_map(x86_cpu_to_node_map, cpu);
 241 #endif
 242 #endif
 243                 /*
 244                  * Up to this point, the boot CPU has been using .init.data
 245                  * area.  Reload any changed state for the boot CPU.
 246                  */
 247                 if (cpu == boot_cpu_id)
 248                         switch_to_new_gdt(cpu);
 249         }
 250
 251         /* indicate the early static arrays will soon be gone */
 252 #ifdef CONFIG_X86_LOCAL_APIC
 253         early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
 254         early_per_cpu_ptr(x86_bios_cpu_apicid) = NULL;
 255 #endif
 256 #if defined(CONFIG_X86_64) && defined(CONFIG_NUMA)
 257         early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
 258 #endif
 259
 260 #if defined(CONFIG_X86_64) && defined(CONFIG_NUMA)
 261         /*
 262          * make sure boot cpu numa_node is right, when boot cpu is on the
 263          * node that doesn't have mem installed
 264          */
 265         set_cpu_numa_node(boot_cpu_id, early_cpu_to_node(boot_cpu_id));
 266 #endif
 267
 268         /* Setup node to cpumask map */
 269         setup_node_to_cpumask_map();
 270
 271         /* Setup cpu initialized, callin, callout masks */
 272         setup_cpu_local_masks();
 273 }