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Diffstat (limited to 'arch/x86/kernel/setup_percpu.c')
| -rw-r--r-- | arch/x86/kernel/setup_percpu.c | 234 |
1 files changed, 234 insertions, 0 deletions
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c new file mode 100644 index 0000000000..2c97bf7b56 --- /dev/null +++ b/arch/x86/kernel/setup_percpu.c @@ -0,0 +1,234 @@ +// SPDX-License-Identifier: GPL-2.0 +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/kernel.h> +#include <linux/export.h> +#include <linux/init.h> +#include <linux/memblock.h> +#include <linux/percpu.h> +#include <linux/kexec.h> +#include <linux/crash_dump.h> +#include <linux/smp.h> +#include <linux/topology.h> +#include <linux/pfn.h> +#include <linux/stackprotector.h> +#include <asm/sections.h> +#include <asm/processor.h> +#include <asm/desc.h> +#include <asm/setup.h> +#include <asm/mpspec.h> +#include <asm/apicdef.h> +#include <asm/highmem.h> +#include <asm/proto.h> +#include <asm/cpumask.h> +#include <asm/cpu.h> + +#ifdef CONFIG_X86_64 +#define BOOT_PERCPU_OFFSET ((unsigned long)__per_cpu_load) +#else +#define BOOT_PERCPU_OFFSET 0 +#endif + +DEFINE_PER_CPU_READ_MOSTLY(unsigned long, this_cpu_off) = BOOT_PERCPU_OFFSET; +EXPORT_PER_CPU_SYMBOL(this_cpu_off); + +unsigned long __per_cpu_offset[NR_CPUS] __ro_after_init = { + [0 ... NR_CPUS-1] = BOOT_PERCPU_OFFSET, +}; +EXPORT_SYMBOL(__per_cpu_offset); + +/* + * On x86_64 symbols referenced from code should be reachable using + * 32bit relocations. Reserve space for static percpu variables in + * modules so that they are always served from the first chunk which + * is located at the percpu segment base. On x86_32, anything can + * address anywhere. No need to reserve space in the first chunk. + */ +#ifdef CONFIG_X86_64 +#define PERCPU_FIRST_CHUNK_RESERVE PERCPU_MODULE_RESERVE +#else +#define PERCPU_FIRST_CHUNK_RESERVE 0 +#endif + +#ifdef CONFIG_X86_32 +/** + * pcpu_need_numa - determine percpu allocation needs to consider NUMA + * + * If NUMA is not configured or there is only one NUMA node available, + * there is no reason to consider NUMA. This function determines + * whether percpu allocation should consider NUMA or not. + * + * RETURNS: + * true if NUMA should be considered; otherwise, false. + */ +static bool __init pcpu_need_numa(void) +{ +#ifdef CONFIG_NUMA + pg_data_t *last = NULL; + unsigned int cpu; + + for_each_possible_cpu(cpu) { + int node = early_cpu_to_node(cpu); + + if (node_online(node) && NODE_DATA(node) && + last && last != NODE_DATA(node)) + return true; + + last = NODE_DATA(node); + } +#endif + return false; +} +#endif + +static int __init pcpu_cpu_distance(unsigned int from, unsigned int to) +{ +#ifdef CONFIG_NUMA + if (early_cpu_to_node(from) == early_cpu_to_node(to)) + return LOCAL_DISTANCE; + else + return REMOTE_DISTANCE; +#else + return LOCAL_DISTANCE; +#endif +} + +static int __init pcpu_cpu_to_node(int cpu) +{ + return early_cpu_to_node(cpu); +} + +void __init pcpu_populate_pte(unsigned long addr) +{ + populate_extra_pte(addr); +} + +static inline void setup_percpu_segment(int cpu) +{ +#ifdef CONFIG_X86_32 + struct desc_struct d = GDT_ENTRY_INIT(0x8092, per_cpu_offset(cpu), + 0xFFFFF); + + write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_PERCPU, &d, DESCTYPE_S); +#endif +} + +void __init setup_per_cpu_areas(void) +{ + unsigned int cpu; + unsigned long delta; + int rc; + + pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%u nr_node_ids:%u\n", + NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids); + + /* + * Allocate percpu area. Embedding allocator is our favorite; + * however, on NUMA configurations, it can result in very + * sparse unit mapping and vmalloc area isn't spacious enough + * on 32bit. Use page in that case. + */ +#ifdef CONFIG_X86_32 + if (pcpu_chosen_fc == PCPU_FC_AUTO && pcpu_need_numa()) + pcpu_chosen_fc = PCPU_FC_PAGE; +#endif + rc = -EINVAL; + if (pcpu_chosen_fc != PCPU_FC_PAGE) { + const size_t dyn_size = PERCPU_MODULE_RESERVE + + PERCPU_DYNAMIC_RESERVE - PERCPU_FIRST_CHUNK_RESERVE; + size_t atom_size; + + /* + * On 64bit, use PMD_SIZE for atom_size so that embedded + * percpu areas are aligned to PMD. This, in the future, + * can also allow using PMD mappings in vmalloc area. Use + * PAGE_SIZE on 32bit as vmalloc space is highly contended + * and large vmalloc area allocs can easily fail. + */ +#ifdef CONFIG_X86_64 + atom_size = PMD_SIZE; +#else + atom_size = PAGE_SIZE; +#endif + rc = pcpu_embed_first_chunk(PERCPU_FIRST_CHUNK_RESERVE, + dyn_size, atom_size, + pcpu_cpu_distance, + pcpu_cpu_to_node); + if (rc < 0) + pr_warn("%s allocator failed (%d), falling back to page size\n", + pcpu_fc_names[pcpu_chosen_fc], rc); + } + if (rc < 0) + rc = pcpu_page_first_chunk(PERCPU_FIRST_CHUNK_RESERVE, + pcpu_cpu_to_node); + if (rc < 0) + panic("cannot initialize percpu area (err=%d)", rc); + + /* alrighty, percpu areas up and running */ + delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start; + for_each_possible_cpu(cpu) { + per_cpu_offset(cpu) = delta + pcpu_unit_offsets[cpu]; + per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu); + per_cpu(pcpu_hot.cpu_number, cpu) = cpu; + setup_percpu_segment(cpu); + /* + * Copy data used in early init routines from the + * initial arrays to the per cpu data areas. These + * arrays then become expendable and the *_early_ptr's + * are zeroed indicating that the static arrays are + * gone. + */ +#ifdef CONFIG_X86_LOCAL_APIC + per_cpu(x86_cpu_to_apicid, cpu) = + early_per_cpu_map(x86_cpu_to_apicid, cpu); + per_cpu(x86_cpu_to_acpiid, cpu) = + early_per_cpu_map(x86_cpu_to_acpiid, cpu); +#endif +#ifdef CONFIG_NUMA + per_cpu(x86_cpu_to_node_map, cpu) = + early_per_cpu_map(x86_cpu_to_node_map, cpu); + /* + * Ensure that the boot cpu numa_node is correct when the boot + * cpu is on a node that doesn't have memory installed. + * Also cpu_up() will call cpu_to_node() for APs when + * MEMORY_HOTPLUG is defined, before per_cpu(numa_node) is set + * up later with c_init aka intel_init/amd_init. + * So set them all (boot cpu and all APs). + */ + set_cpu_numa_node(cpu, early_cpu_to_node(cpu)); +#endif + /* + * Up to this point, the boot CPU has been using .init.data + * area. Reload any changed state for the boot CPU. + */ + if (!cpu) + switch_gdt_and_percpu_base(cpu); + } + + /* indicate the early static arrays will soon be gone */ +#ifdef CONFIG_X86_LOCAL_APIC + early_per_cpu_ptr(x86_cpu_to_apicid) = NULL; + early_per_cpu_ptr(x86_cpu_to_acpiid) = NULL; +#endif +#ifdef CONFIG_NUMA + early_per_cpu_ptr(x86_cpu_to_node_map) = NULL; +#endif + + /* Setup node to cpumask map */ + setup_node_to_cpumask_map(); + + /* Setup cpu initialized, callin, callout masks */ + setup_cpu_local_masks(); + + /* + * Sync back kernel address range again. We already did this in + * setup_arch(), but percpu data also needs to be available in + * the smpboot asm and arch_sync_kernel_mappings() doesn't sync to + * swapper_pg_dir on 32-bit. The per-cpu mappings need to be available + * there too. + * + * FIXME: Can the later sync in setup_cpu_entry_areas() replace + * this call? + */ + sync_initial_page_table(); +} |