// 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>

DEFINE_PER_CPU_CACHE_HOT(int, cpu_number);
EXPORT_PER_CPU_SYMBOL(cpu_number);

DEFINE_PER_CPU_CACHE_HOT(unsigned long, this_cpu_off);
EXPORT_PER_CPU_SYMBOL(this_cpu_off);

unsigned long __per_cpu_offset[NR_CPUS] __ro_after_init;
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(DESC_DATA32,
                                              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(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();
}