LCOV - code coverage report
Current view: top level - arch/x86/kernel - setup_percpu.c (source / functions) Hit Total Coverage
Test: landlock.info Lines: 57 67 85.1 %
Date: 2021-04-22 12:43:58 Functions: 5 6 83.3 %

          Line data    Source code
       1             : // SPDX-License-Identifier: GPL-2.0
       2             : #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
       3             : 
       4             : #include <linux/kernel.h>
       5             : #include <linux/export.h>
       6             : #include <linux/init.h>
       7             : #include <linux/memblock.h>
       8             : #include <linux/percpu.h>
       9             : #include <linux/kexec.h>
      10             : #include <linux/crash_dump.h>
      11             : #include <linux/smp.h>
      12             : #include <linux/topology.h>
      13             : #include <linux/pfn.h>
      14             : #include <asm/sections.h>
      15             : #include <asm/processor.h>
      16             : #include <asm/desc.h>
      17             : #include <asm/setup.h>
      18             : #include <asm/mpspec.h>
      19             : #include <asm/apicdef.h>
      20             : #include <asm/highmem.h>
      21             : #include <asm/proto.h>
      22             : #include <asm/cpumask.h>
      23             : #include <asm/cpu.h>
      24             : #include <asm/stackprotector.h>
      25             : 
      26             : DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number);
      27             : EXPORT_PER_CPU_SYMBOL(cpu_number);
      28             : 
      29             : #ifdef CONFIG_X86_64
      30             : #define BOOT_PERCPU_OFFSET ((unsigned long)__per_cpu_load)
      31             : #else
      32             : #define BOOT_PERCPU_OFFSET 0
      33             : #endif
      34             : 
      35             : DEFINE_PER_CPU_READ_MOSTLY(unsigned long, this_cpu_off) = BOOT_PERCPU_OFFSET;
      36             : EXPORT_PER_CPU_SYMBOL(this_cpu_off);
      37             : 
      38             : unsigned long __per_cpu_offset[NR_CPUS] __ro_after_init = {
      39             :         [0 ... NR_CPUS-1] = BOOT_PERCPU_OFFSET,
      40             : };
      41             : EXPORT_SYMBOL(__per_cpu_offset);
      42             : 
      43             : /*
      44             :  * On x86_64 symbols referenced from code should be reachable using
      45             :  * 32bit relocations.  Reserve space for static percpu variables in
      46             :  * modules so that they are always served from the first chunk which
      47             :  * is located at the percpu segment base.  On x86_32, anything can
      48             :  * address anywhere.  No need to reserve space in the first chunk.
      49             :  */
      50             : #ifdef CONFIG_X86_64
      51             : #define PERCPU_FIRST_CHUNK_RESERVE      PERCPU_MODULE_RESERVE
      52             : #else
      53             : #define PERCPU_FIRST_CHUNK_RESERVE      0
      54             : #endif
      55             : 
      56             : #ifdef CONFIG_X86_32
      57             : /**
      58             :  * pcpu_need_numa - determine percpu allocation needs to consider NUMA
      59             :  *
      60             :  * If NUMA is not configured or there is only one NUMA node available,
      61             :  * there is no reason to consider NUMA.  This function determines
      62             :  * whether percpu allocation should consider NUMA or not.
      63             :  *
      64             :  * RETURNS:
      65             :  * true if NUMA should be considered; otherwise, false.
      66             :  */
      67             : static bool __init pcpu_need_numa(void)
      68             : {
      69             : #ifdef CONFIG_NEED_MULTIPLE_NODES
      70             :         pg_data_t *last = NULL;
      71             :         unsigned int cpu;
      72             : 
      73             :         for_each_possible_cpu(cpu) {
      74             :                 int node = early_cpu_to_node(cpu);
      75             : 
      76             :                 if (node_online(node) && NODE_DATA(node) &&
      77             :                     last && last != NODE_DATA(node))
      78             :                         return true;
      79             : 
      80             :                 last = NODE_DATA(node);
      81             :         }
      82             : #endif
      83             :         return false;
      84             : }
      85             : #endif
      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           1 : static void * __init pcpu_alloc_bootmem(unsigned int cpu, unsigned long size,
     101             :                                         unsigned long align)
     102             : {
     103           1 :         const unsigned long goal = __pa(MAX_DMA_ADDRESS);
     104             : #ifdef CONFIG_NEED_MULTIPLE_NODES
     105           1 :         int node = early_cpu_to_node(cpu);
     106           1 :         void *ptr;
     107             : 
     108           1 :         if (!node_online(node) || !NODE_DATA(node)) {
     109           0 :                 ptr = memblock_alloc_from(size, align, goal);
     110           0 :                 pr_info("cpu %d has no node %d or node-local memory\n",
     111             :                         cpu, node);
     112           0 :                 pr_debug("per cpu data for cpu%d %lu bytes at %016lx\n",
     113             :                          cpu, size, __pa(ptr));
     114             :         } else {
     115           1 :                 ptr = memblock_alloc_try_nid(size, align, goal,
     116             :                                              MEMBLOCK_ALLOC_ACCESSIBLE,
     117             :                                              node);
     118             : 
     119           1 :                 pr_debug("per cpu data for cpu%d %lu bytes on node%d at %016lx\n",
     120             :                          cpu, size, node, __pa(ptr));
     121             :         }
     122           1 :         return ptr;
     123             : #else
     124             :         return memblock_alloc_from(size, align, goal);
     125             : #endif
     126             : }
     127             : 
     128             : /*
     129             :  * Helpers for first chunk memory allocation
     130             :  */
     131           1 : static void * __init pcpu_fc_alloc(unsigned int cpu, size_t size, size_t align)
     132             : {
     133           1 :         return pcpu_alloc_bootmem(cpu, size, align);
     134             : }
     135             : 
     136           4 : static void __init pcpu_fc_free(void *ptr, size_t size)
     137             : {
     138           4 :         memblock_free(__pa(ptr), size);
     139           4 : }
     140             : 
     141           6 : static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
     142             : {
     143             : #ifdef CONFIG_NEED_MULTIPLE_NODES
     144           6 :         if (early_cpu_to_node(from) == early_cpu_to_node(to))
     145             :                 return LOCAL_DISTANCE;
     146             :         else
     147           0 :                 return REMOTE_DISTANCE;
     148             : #else
     149             :         return LOCAL_DISTANCE;
     150             : #endif
     151             : }
     152             : 
     153           0 : static void __init pcpup_populate_pte(unsigned long addr)
     154             : {
     155           0 :         populate_extra_pte(addr);
     156           0 : }
     157             : 
     158           4 : static inline void setup_percpu_segment(int cpu)
     159             : {
     160             : #ifdef CONFIG_X86_32
     161             :         struct desc_struct d = GDT_ENTRY_INIT(0x8092, per_cpu_offset(cpu),
     162             :                                               0xFFFFF);
     163             : 
     164             :         write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_PERCPU, &d, DESCTYPE_S);
     165             : #endif
     166           4 : }
     167             : 
     168           1 : void __init setup_per_cpu_areas(void)
     169             : {
     170           1 :         unsigned int cpu;
     171           1 :         unsigned long delta;
     172           1 :         int rc;
     173             : 
     174           1 :         pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%u nr_node_ids:%u\n",
     175             :                 NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);
     176             : 
     177             :         /*
     178             :          * Allocate percpu area.  Embedding allocator is our favorite;
     179             :          * however, on NUMA configurations, it can result in very
     180             :          * sparse unit mapping and vmalloc area isn't spacious enough
     181             :          * on 32bit.  Use page in that case.
     182             :          */
     183             : #ifdef CONFIG_X86_32
     184             :         if (pcpu_chosen_fc == PCPU_FC_AUTO && pcpu_need_numa())
     185             :                 pcpu_chosen_fc = PCPU_FC_PAGE;
     186             : #endif
     187           1 :         rc = -EINVAL;
     188           1 :         if (pcpu_chosen_fc != PCPU_FC_PAGE) {
     189           1 :                 const size_t dyn_size = PERCPU_MODULE_RESERVE +
     190             :                         PERCPU_DYNAMIC_RESERVE - PERCPU_FIRST_CHUNK_RESERVE;
     191           1 :                 size_t atom_size;
     192             : 
     193             :                 /*
     194             :                  * On 64bit, use PMD_SIZE for atom_size so that embedded
     195             :                  * percpu areas are aligned to PMD.  This, in the future,
     196             :                  * can also allow using PMD mappings in vmalloc area.  Use
     197             :                  * PAGE_SIZE on 32bit as vmalloc space is highly contended
     198             :                  * and large vmalloc area allocs can easily fail.
     199             :                  */
     200             : #ifdef CONFIG_X86_64
     201           1 :                 atom_size = PMD_SIZE;
     202             : #else
     203             :                 atom_size = PAGE_SIZE;
     204             : #endif
     205           1 :                 rc = pcpu_embed_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
     206             :                                             dyn_size, atom_size,
     207             :                                             pcpu_cpu_distance,
     208             :                                             pcpu_fc_alloc, pcpu_fc_free);
     209           1 :                 if (rc < 0)
     210           0 :                         pr_warn("%s allocator failed (%d), falling back to page size\n",
     211             :                                 pcpu_fc_names[pcpu_chosen_fc], rc);
     212             :         }
     213           1 :         if (rc < 0)
     214           0 :                 rc = pcpu_page_first_chunk(PERCPU_FIRST_CHUNK_RESERVE,
     215             :                                            pcpu_fc_alloc, pcpu_fc_free,
     216             :                                            pcpup_populate_pte);
     217           1 :         if (rc < 0)
     218           0 :                 panic("cannot initialize percpu area (err=%d)", rc);
     219             : 
     220             :         /* alrighty, percpu areas up and running */
     221           1 :         delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
     222           6 :         for_each_possible_cpu(cpu) {
     223           4 :                 per_cpu_offset(cpu) = delta + pcpu_unit_offsets[cpu];
     224           4 :                 per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);
     225           4 :                 per_cpu(cpu_number, cpu) = cpu;
     226           4 :                 setup_percpu_segment(cpu);
     227           4 :                 setup_stack_canary_segment(cpu);
     228             :                 /*
     229             :                  * Copy data used in early init routines from the
     230             :                  * initial arrays to the per cpu data areas.  These
     231             :                  * arrays then become expendable and the *_early_ptr's
     232             :                  * are zeroed indicating that the static arrays are
     233             :                  * gone.
     234             :                  */
     235             : #ifdef CONFIG_X86_LOCAL_APIC
     236           4 :                 per_cpu(x86_cpu_to_apicid, cpu) =
     237           4 :                         early_per_cpu_map(x86_cpu_to_apicid, cpu);
     238           4 :                 per_cpu(x86_bios_cpu_apicid, cpu) =
     239           4 :                         early_per_cpu_map(x86_bios_cpu_apicid, cpu);
     240           4 :                 per_cpu(x86_cpu_to_acpiid, cpu) =
     241           4 :                         early_per_cpu_map(x86_cpu_to_acpiid, cpu);
     242             : #endif
     243             : #ifdef CONFIG_X86_32
     244             :                 per_cpu(x86_cpu_to_logical_apicid, cpu) =
     245             :                         early_per_cpu_map(x86_cpu_to_logical_apicid, cpu);
     246             : #endif
     247             : #ifdef CONFIG_NUMA
     248           4 :                 per_cpu(x86_cpu_to_node_map, cpu) =
     249           4 :                         early_per_cpu_map(x86_cpu_to_node_map, cpu);
     250             :                 /*
     251             :                  * Ensure that the boot cpu numa_node is correct when the boot
     252             :                  * cpu is on a node that doesn't have memory installed.
     253             :                  * Also cpu_up() will call cpu_to_node() for APs when
     254             :                  * MEMORY_HOTPLUG is defined, before per_cpu(numa_node) is set
     255             :                  * up later with c_init aka intel_init/amd_init.
     256             :                  * So set them all (boot cpu and all APs).
     257             :                  */
     258           4 :                 set_cpu_numa_node(cpu, early_cpu_to_node(cpu));
     259             : #endif
     260             :                 /*
     261             :                  * Up to this point, the boot CPU has been using .init.data
     262             :                  * area.  Reload any changed state for the boot CPU.
     263             :                  */
     264           4 :                 if (!cpu)
     265           1 :                         switch_to_new_gdt(cpu);
     266             :         }
     267             : 
     268             :         /* indicate the early static arrays will soon be gone */
     269             : #ifdef CONFIG_X86_LOCAL_APIC
     270           1 :         early_per_cpu_ptr(x86_cpu_to_apicid) = NULL;
     271           1 :         early_per_cpu_ptr(x86_bios_cpu_apicid) = NULL;
     272           1 :         early_per_cpu_ptr(x86_cpu_to_acpiid) = NULL;
     273             : #endif
     274             : #ifdef CONFIG_X86_32
     275             :         early_per_cpu_ptr(x86_cpu_to_logical_apicid) = NULL;
     276             : #endif
     277             : #ifdef CONFIG_NUMA
     278           1 :         early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
     279             : #endif
     280             : 
     281             :         /* Setup node to cpumask map */
     282           1 :         setup_node_to_cpumask_map();
     283             : 
     284             :         /* Setup cpu initialized, callin, callout masks */
     285           1 :         setup_cpu_local_masks();
     286             : 
     287             :         /*
     288             :          * Sync back kernel address range again.  We already did this in
     289             :          * setup_arch(), but percpu data also needs to be available in
     290             :          * the smpboot asm and arch_sync_kernel_mappings() doesn't sync to
     291             :          * swapper_pg_dir on 32-bit. The per-cpu mappings need to be available
     292             :          * there too.
     293             :          *
     294             :          * FIXME: Can the later sync in setup_cpu_entry_areas() replace
     295             :          * this call?
     296             :          */
     297           1 :         sync_initial_page_table();
     298           1 : }

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