x86, percpu: setup reserved percpu area for x86_64

[deliverable/linux.git] / arch / x86 / kernel / setup_percpu.c

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/bootmem.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 <asm/sections.h>
#include <asm/processor.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>
#include <asm/stackprotector.h>

#ifdef CONFIG_DEBUG_PER_CPU_MAPS
# define DBG(x...) printk(KERN_DEBUG x)
#else
# define DBG(x...)
#endif

DEFINE_PER_CPU(int, cpu_number);
EXPORT_PER_CPU_SYMBOL(cpu_number);

#ifdef CONFIG_X86_64
#define BOOT_PERCPU_OFFSET ((unsigned long)__per_cpu_load)
#else
#define BOOT_PERCPU_OFFSET 0
#endif

DEFINE_PER_CPU(unsigned long, this_cpu_off) = BOOT_PERCPU_OFFSET;
EXPORT_PER_CPU_SYMBOL(this_cpu_off);

unsigned long __per_cpu_offset[NR_CPUS] __read_mostly = {
        [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

/**
 * 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_NEED_MULTIPLE_NODES
        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;
}

/**
 * pcpu_alloc_bootmem - NUMA friendly alloc_bootmem wrapper for percpu
 * @cpu: cpu to allocate for
 * @size: size allocation in bytes
 * @align: alignment
 *
 * Allocate @size bytes aligned at @align for cpu @cpu.  This wrapper
 * does the right thing for NUMA regardless of the current
 * configuration.
 *
 * RETURNS:
 * Pointer to the allocated area on success, NULL on failure.
 */
static void * __init pcpu_alloc_bootmem(unsigned int cpu, unsigned long size,
                                        unsigned long align)
{
        const unsigned long goal = __pa(MAX_DMA_ADDRESS);
#ifdef CONFIG_NEED_MULTIPLE_NODES
        int node = early_cpu_to_node(cpu);
        void *ptr;

        if (!node_online(node) || !NODE_DATA(node)) {
                ptr = __alloc_bootmem_nopanic(size, align, goal);
                pr_info("cpu %d has no node %d or node-local memory\n",
                        cpu, node);
                pr_debug("per cpu data for cpu%d %lu bytes at %016lx\n",
                         cpu, size, __pa(ptr));
        } else {
                ptr = __alloc_bootmem_node_nopanic(NODE_DATA(node),
                                                   size, align, goal);
                pr_debug("per cpu data for cpu%d %lu bytes on node%d at "
                         "%016lx\n", cpu, size, node, __pa(ptr));
        }
        return ptr;
#else
        return __alloc_bootmem_nopanic(size, align, goal);
#endif
}

/*
 * Remap allocator
 *
 * This allocator uses PMD page as unit.  A PMD page is allocated for
 * each cpu and each is remapped into vmalloc area using PMD mapping.
 * As PMD page is quite large, only part of it is used for the first
 * chunk.  Unused part is returned to the bootmem allocator.
 *
 * So, the PMD pages are mapped twice - once to the physical mapping
 * and to the vmalloc area for the first percpu chunk.  The double
 * mapping does add one more PMD TLB entry pressure but still is much
 * better than only using 4k mappings while still being NUMA friendly.
 */
#ifdef CONFIG_NEED_MULTIPLE_NODES
static size_t pcpur_size __initdata;
static void **pcpur_ptrs __initdata;

static struct page * __init pcpur_get_page(unsigned int cpu, int pageno)
{
        size_t off = (size_t)pageno << PAGE_SHIFT;

        if (off >= pcpur_size)
                return NULL;

        return virt_to_page(pcpur_ptrs[cpu] + off);
}

static ssize_t __init setup_pcpu_remap(size_t static_size)
{
        static struct vm_struct vm;
        pg_data_t *last;
        size_t ptrs_size, dyn_size;
        unsigned int cpu;
        ssize_t ret;

        /*
         * If large page isn't supported, there's no benefit in doing
         * this.  Also, on non-NUMA, embedding is better.
         */
        if (!cpu_has_pse || pcpu_need_numa())
                return -EINVAL;

        last = NULL;
        for_each_possible_cpu(cpu) {
                int node = early_cpu_to_node(cpu);

                if (node_online(node) && NODE_DATA(node) &&
                    last && last != NODE_DATA(node))
                        goto proceed;

                last = NODE_DATA(node);
        }
        return -EINVAL;

proceed:
        /*
         * Currently supports only single page.  Supporting multiple
         * pages won't be too difficult if it ever becomes necessary.
         */
        pcpur_size = PFN_ALIGN(static_size + PERCPU_MODULE_RESERVE +
                               PERCPU_DYNAMIC_RESERVE);
        if (pcpur_size > PMD_SIZE) {
                pr_warning("PERCPU: static data is larger than large page, "
                           "can't use large page\n");
                return -EINVAL;
        }
        dyn_size = pcpur_size - static_size - PERCPU_FIRST_CHUNK_RESERVE;

        /* allocate pointer array and alloc large pages */
        ptrs_size = PFN_ALIGN(num_possible_cpus() * sizeof(pcpur_ptrs[0]));
        pcpur_ptrs = alloc_bootmem(ptrs_size);

        for_each_possible_cpu(cpu) {
                pcpur_ptrs[cpu] = pcpu_alloc_bootmem(cpu, PMD_SIZE, PMD_SIZE);
                if (!pcpur_ptrs[cpu])
                        goto enomem;

                /*
                 * Only use pcpur_size bytes and give back the rest.
                 *
                 * Ingo: The 2MB up-rounding bootmem is needed to make
                 * sure the partial 2MB page is still fully RAM - it's
                 * not well-specified to have a PAT-incompatible area
                 * (unmapped RAM, device memory, etc.) in that hole.
                 */
                free_bootmem(__pa(pcpur_ptrs[cpu] + pcpur_size),
                             PMD_SIZE - pcpur_size);

                memcpy(pcpur_ptrs[cpu], __per_cpu_load, static_size);
        }

        /* allocate address and map */
        vm.flags = VM_ALLOC;
        vm.size = num_possible_cpus() * PMD_SIZE;
        vm_area_register_early(&vm, PMD_SIZE);

        for_each_possible_cpu(cpu) {
                pmd_t *pmd;

                pmd = populate_extra_pmd((unsigned long)vm.addr
                                         + cpu * PMD_SIZE);
                set_pmd(pmd, pfn_pmd(page_to_pfn(virt_to_page(pcpur_ptrs[cpu])),
                                     PAGE_KERNEL_LARGE));
        }

        /* we're ready, commit */
        pr_info("PERCPU: Remapped at %p with large pages, static data "
                "%zu bytes\n", vm.addr, static_size);

        ret = pcpu_setup_first_chunk(pcpur_get_page, static_size,
                                     PERCPU_FIRST_CHUNK_RESERVE,
                                     PMD_SIZE, dyn_size, vm.addr, NULL);
        goto out_free_ar;

enomem:
        for_each_possible_cpu(cpu)
                if (pcpur_ptrs[cpu])
                        free_bootmem(__pa(pcpur_ptrs[cpu]), PMD_SIZE);
        ret = -ENOMEM;
out_free_ar:
        free_bootmem(__pa(pcpur_ptrs), ptrs_size);
        return ret;
}
#else
static ssize_t __init setup_pcpu_remap(size_t static_size)
{
        return -EINVAL;
}
#endif

/*
 * Embedding allocator
 *
 * The first chunk is sized to just contain the static area plus
 * module and dynamic reserves, and allocated as a contiguous area
 * using bootmem allocator and used as-is without being mapped into
 * vmalloc area.  This enables the first chunk to piggy back on the
 * linear physical PMD mapping and doesn't add any additional pressure
 * to TLB.  Note that if the needed size is smaller than the minimum
 * unit size, the leftover is returned to the bootmem allocator.
 */
static void *pcpue_ptr __initdata;
static size_t pcpue_size __initdata;
static size_t pcpue_unit_size __initdata;

static struct page * __init pcpue_get_page(unsigned int cpu, int pageno)
{
        size_t off = (size_t)pageno << PAGE_SHIFT;

        if (off >= pcpue_size)
                return NULL;

        return virt_to_page(pcpue_ptr + cpu * pcpue_unit_size + off);
}

static ssize_t __init setup_pcpu_embed(size_t static_size)
{
        unsigned int cpu;
        size_t dyn_size;

        /*
         * If large page isn't supported, there's no benefit in doing
         * this.  Also, embedding allocation doesn't play well with
         * NUMA.
         */
        if (!cpu_has_pse || pcpu_need_numa())
                return -EINVAL;

        /* allocate and copy */
        pcpue_size = PFN_ALIGN(static_size + PERCPU_MODULE_RESERVE +
                               PERCPU_DYNAMIC_RESERVE);
        pcpue_unit_size = max_t(size_t, pcpue_size, PCPU_MIN_UNIT_SIZE);
        dyn_size = pcpue_size - static_size - PERCPU_FIRST_CHUNK_RESERVE;

        pcpue_ptr = pcpu_alloc_bootmem(0, num_possible_cpus() * pcpue_unit_size,
                                       PAGE_SIZE);
        if (!pcpue_ptr)
                return -ENOMEM;

        for_each_possible_cpu(cpu) {
                void *ptr = pcpue_ptr + cpu * pcpue_unit_size;

                free_bootmem(__pa(ptr + pcpue_size),
                             pcpue_unit_size - pcpue_size);
                memcpy(ptr, __per_cpu_load, static_size);
        }

        /* we're ready, commit */
        pr_info("PERCPU: Embedded %zu pages at %p, static data %zu bytes\n",
                pcpue_size >> PAGE_SHIFT, pcpue_ptr, static_size);

        return pcpu_setup_first_chunk(pcpue_get_page, static_size,
                                      PERCPU_FIRST_CHUNK_RESERVE,
                                      pcpue_unit_size, dyn_size,
                                      pcpue_ptr, NULL);
}

/*
 * 4k page allocator
 *
 * This is the basic allocator.  Static percpu area is allocated
 * page-by-page and most of initialization is done by the generic
 * setup function.
 */
static struct page **pcpu4k_pages __initdata;
static int pcpu4k_nr_static_pages __initdata;

static struct page * __init pcpu4k_get_page(unsigned int cpu, int pageno)
{
        if (pageno < pcpu4k_nr_static_pages)
                return pcpu4k_pages[cpu * pcpu4k_nr_static_pages + pageno];
        return NULL;
}

static void __init pcpu4k_populate_pte(unsigned long addr)
{
        populate_extra_pte(addr);
}

static ssize_t __init setup_pcpu_4k(size_t static_size)
{
        size_t pages_size;
        unsigned int cpu;
        int i, j;
        ssize_t ret;

        pcpu4k_nr_static_pages = PFN_UP(static_size);

        /* unaligned allocations can't be freed, round up to page size */
        pages_size = PFN_ALIGN(pcpu4k_nr_static_pages * num_possible_cpus()
                               * sizeof(pcpu4k_pages[0]));
        pcpu4k_pages = alloc_bootmem(pages_size);

        /* allocate and copy */
        j = 0;
        for_each_possible_cpu(cpu)
                for (i = 0; i < pcpu4k_nr_static_pages; i++) {
                        void *ptr;

                        ptr = pcpu_alloc_bootmem(cpu, PAGE_SIZE, PAGE_SIZE);
                        if (!ptr)
                                goto enomem;

                        memcpy(ptr, __per_cpu_load + i * PAGE_SIZE, PAGE_SIZE);
                        pcpu4k_pages[j++] = virt_to_page(ptr);
                }

        /* we're ready, commit */
        pr_info("PERCPU: Allocated %d 4k pages, static data %zu bytes\n",
                pcpu4k_nr_static_pages, static_size);

        ret = pcpu_setup_first_chunk(pcpu4k_get_page, static_size,
                                     PERCPU_FIRST_CHUNK_RESERVE, -1, -1, NULL,
                                     pcpu4k_populate_pte);
        goto out_free_ar;

enomem:
        while (--j >= 0)
                free_bootmem(__pa(page_address(pcpu4k_pages[j])), PAGE_SIZE);
        ret = -ENOMEM;
out_free_ar:
        free_bootmem(__pa(pcpu4k_pages), pages_size);
        return ret;
}

static inline void setup_percpu_segment(int cpu)
{
#ifdef CONFIG_X86_32
        struct desc_struct gdt;

        pack_descriptor(&gdt, per_cpu_offset(cpu), 0xFFFFF,
                        0x2 | DESCTYPE_S, 0x8);
        gdt.s = 1;
        write_gdt_entry(get_cpu_gdt_table(cpu),
                        GDT_ENTRY_PERCPU, &gdt, DESCTYPE_S);
#endif
}

/*
 * Great future plan:
 * Declare PDA itself and support (irqstack,tss,pgd) as per cpu data.
 * Always point %gs to its beginning
 */
void __init setup_per_cpu_areas(void)
{
        size_t static_size = __per_cpu_end - __per_cpu_start;
        unsigned int cpu;
        unsigned long delta;
        size_t pcpu_unit_size;
        ssize_t ret;

        pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%d nr_node_ids:%d\n",
                NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);

        /*
         * Allocate percpu area.  If PSE is supported, try to make use
         * of large page mappings.  Please read comments on top of
         * each allocator for details.
         */
        ret = setup_pcpu_remap(static_size);
        if (ret < 0)
                ret = setup_pcpu_embed(static_size);
        if (ret < 0)
                ret = setup_pcpu_4k(static_size);
        if (ret < 0)
                panic("cannot allocate static percpu area (%zu bytes, err=%zd)",
                      static_size, ret);

        pcpu_unit_size = ret;

        /* 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 + cpu * pcpu_unit_size;
                per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu);
                per_cpu(cpu_number, cpu) = cpu;
                setup_percpu_segment(cpu);
                setup_stack_canary_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_bios_cpu_apicid, cpu) =
                        early_per_cpu_map(x86_bios_cpu_apicid, cpu);
#endif
#ifdef CONFIG_X86_64
                per_cpu(irq_stack_ptr, cpu) =
                        per_cpu(irq_stack_union.irq_stack, cpu) +
                        IRQ_STACK_SIZE - 64;
#ifdef CONFIG_NUMA
                per_cpu(x86_cpu_to_node_map, cpu) =
                        early_per_cpu_map(x86_cpu_to_node_map, cpu);
#endif
#endif
                /*
                 * Up to this point, the boot CPU has been using .data.init
                 * area.  Reload any changed state for the boot CPU.
                 */
                if (cpu == boot_cpu_id)
                        switch_to_new_gdt(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_bios_cpu_apicid) = NULL;
#endif
#if defined(CONFIG_X86_64) && defined(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();
}