crypto: s5p-sss - remove unnecessary alignmask for ahashes

[thirdparty/kernel/linux.git] / mm / hugetlb_vmemmap.c

// SPDX-License-Identifier: GPL-2.0
/*
 * HugeTLB Vmemmap Optimization (HVO)
 *
 * Copyright (c) 2020, ByteDance. All rights reserved.
 *
 *     Author: Muchun Song <songmuchun@bytedance.com>
 *
 * See Documentation/mm/vmemmap_dedup.rst
 */
#define pr_fmt(fmt)     "HugeTLB: " fmt

#include <linux/pgtable.h>
#include <linux/moduleparam.h>
#include <linux/bootmem_info.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include "hugetlb_vmemmap.h"

/**
 * struct vmemmap_remap_walk - walk vmemmap page table
 *
 * @remap_pte:          called for each lowest-level entry (PTE).
 * @nr_walked:          the number of walked pte.
 * @reuse_page:         the page which is reused for the tail vmemmap pages.
 * @reuse_addr:         the virtual address of the @reuse_page page.
 * @vmemmap_pages:      the list head of the vmemmap pages that can be freed
 *                      or is mapped from.
 */
struct vmemmap_remap_walk {
        void                    (*remap_pte)(pte_t *pte, unsigned long addr,
                                             struct vmemmap_remap_walk *walk);
        unsigned long           nr_walked;
        struct page             *reuse_page;
        unsigned long           reuse_addr;
        struct list_head        *vmemmap_pages;
};

static int split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start)
{
        pmd_t __pmd;
        int i;
        unsigned long addr = start;
        struct page *head;
        pte_t *pgtable;

        spin_lock(&init_mm.page_table_lock);
        head = pmd_leaf(*pmd) ? pmd_page(*pmd) : NULL;
        spin_unlock(&init_mm.page_table_lock);

        if (!head)
                return 0;

        pgtable = pte_alloc_one_kernel(&init_mm);
        if (!pgtable)
                return -ENOMEM;

        pmd_populate_kernel(&init_mm, &__pmd, pgtable);

        for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
                pte_t entry, *pte;
                pgprot_t pgprot = PAGE_KERNEL;

                entry = mk_pte(head + i, pgprot);
                pte = pte_offset_kernel(&__pmd, addr);
                set_pte_at(&init_mm, addr, pte, entry);
        }

        spin_lock(&init_mm.page_table_lock);
        if (likely(pmd_leaf(*pmd))) {
                /*
                 * Higher order allocations from buddy allocator must be able to
                 * be treated as indepdenent small pages (as they can be freed
                 * individually).
                 */
                if (!PageReserved(head))
                        split_page(head, get_order(PMD_SIZE));

                /* Make pte visible before pmd. See comment in pmd_install(). */
                smp_wmb();
                pmd_populate_kernel(&init_mm, pmd, pgtable);
                flush_tlb_kernel_range(start, start + PMD_SIZE);
        } else {
                pte_free_kernel(&init_mm, pgtable);
        }
        spin_unlock(&init_mm.page_table_lock);

        return 0;
}

static void vmemmap_pte_range(pmd_t *pmd, unsigned long addr,
                              unsigned long end,
                              struct vmemmap_remap_walk *walk)
{
        pte_t *pte = pte_offset_kernel(pmd, addr);

        /*
         * The reuse_page is found 'first' in table walk before we start
         * remapping (which is calling @walk->remap_pte).
         */
        if (!walk->reuse_page) {
                walk->reuse_page = pte_page(ptep_get(pte));
                /*
                 * Because the reuse address is part of the range that we are
                 * walking, skip the reuse address range.
                 */
                addr += PAGE_SIZE;
                pte++;
                walk->nr_walked++;
        }

        for (; addr != end; addr += PAGE_SIZE, pte++) {
                walk->remap_pte(pte, addr, walk);
                walk->nr_walked++;
        }
}

static int vmemmap_pmd_range(pud_t *pud, unsigned long addr,
                             unsigned long end,
                             struct vmemmap_remap_walk *walk)
{
        pmd_t *pmd;
        unsigned long next;

        pmd = pmd_offset(pud, addr);
        do {
                int ret;

                ret = split_vmemmap_huge_pmd(pmd, addr & PMD_MASK);
                if (ret)
                        return ret;

                next = pmd_addr_end(addr, end);
                vmemmap_pte_range(pmd, addr, next, walk);
        } while (pmd++, addr = next, addr != end);

        return 0;
}

static int vmemmap_pud_range(p4d_t *p4d, unsigned long addr,
                             unsigned long end,
                             struct vmemmap_remap_walk *walk)
{
        pud_t *pud;
        unsigned long next;

        pud = pud_offset(p4d, addr);
        do {
                int ret;

                next = pud_addr_end(addr, end);
                ret = vmemmap_pmd_range(pud, addr, next, walk);
                if (ret)
                        return ret;
        } while (pud++, addr = next, addr != end);

        return 0;
}

static int vmemmap_p4d_range(pgd_t *pgd, unsigned long addr,
                             unsigned long end,
                             struct vmemmap_remap_walk *walk)
{
        p4d_t *p4d;
        unsigned long next;

        p4d = p4d_offset(pgd, addr);
        do {
                int ret;

                next = p4d_addr_end(addr, end);
                ret = vmemmap_pud_range(p4d, addr, next, walk);
                if (ret)
                        return ret;
        } while (p4d++, addr = next, addr != end);

        return 0;
}

static int vmemmap_remap_range(unsigned long start, unsigned long end,
                               struct vmemmap_remap_walk *walk)
{
        unsigned long addr = start;
        unsigned long next;
        pgd_t *pgd;

        VM_BUG_ON(!PAGE_ALIGNED(start));
        VM_BUG_ON(!PAGE_ALIGNED(end));

        pgd = pgd_offset_k(addr);
        do {
                int ret;

                next = pgd_addr_end(addr, end);
                ret = vmemmap_p4d_range(pgd, addr, next, walk);
                if (ret)
                        return ret;
        } while (pgd++, addr = next, addr != end);

        flush_tlb_kernel_range(start, end);

        return 0;
}

/*
 * Free a vmemmap page. A vmemmap page can be allocated from the memblock
 * allocator or buddy allocator. If the PG_reserved flag is set, it means
 * that it allocated from the memblock allocator, just free it via the
 * free_bootmem_page(). Otherwise, use __free_page().
 */
static inline void free_vmemmap_page(struct page *page)
{
        if (PageReserved(page))
                free_bootmem_page(page);
        else
                __free_page(page);
}

/* Free a list of the vmemmap pages */
static void free_vmemmap_page_list(struct list_head *list)
{
        struct page *page, *next;

        list_for_each_entry_safe(page, next, list, lru)
                free_vmemmap_page(page);
}

static void vmemmap_remap_pte(pte_t *pte, unsigned long addr,
                              struct vmemmap_remap_walk *walk)
{
        /*
         * Remap the tail pages as read-only to catch illegal write operation
         * to the tail pages.
         */
        pgprot_t pgprot = PAGE_KERNEL_RO;
        struct page *page = pte_page(ptep_get(pte));
        pte_t entry;

        /* Remapping the head page requires r/w */
        if (unlikely(addr == walk->reuse_addr)) {
                pgprot = PAGE_KERNEL;
                list_del(&walk->reuse_page->lru);

                /*
                 * Makes sure that preceding stores to the page contents from
                 * vmemmap_remap_free() become visible before the set_pte_at()
                 * write.
                 */
                smp_wmb();
        }

        entry = mk_pte(walk->reuse_page, pgprot);
        list_add_tail(&page->lru, walk->vmemmap_pages);
        set_pte_at(&init_mm, addr, pte, entry);
}

/*
 * How many struct page structs need to be reset. When we reuse the head
 * struct page, the special metadata (e.g. page->flags or page->mapping)
 * cannot copy to the tail struct page structs. The invalid value will be
 * checked in the free_tail_page_prepare(). In order to avoid the message
 * of "corrupted mapping in tail page". We need to reset at least 3 (one
 * head struct page struct and two tail struct page structs) struct page
 * structs.
 */
#define NR_RESET_STRUCT_PAGE            3

static inline void reset_struct_pages(struct page *start)
{
        struct page *from = start + NR_RESET_STRUCT_PAGE;

        BUILD_BUG_ON(NR_RESET_STRUCT_PAGE * 2 > PAGE_SIZE / sizeof(struct page));
        memcpy(start, from, sizeof(*from) * NR_RESET_STRUCT_PAGE);
}

static void vmemmap_restore_pte(pte_t *pte, unsigned long addr,
                                struct vmemmap_remap_walk *walk)
{
        pgprot_t pgprot = PAGE_KERNEL;
        struct page *page;
        void *to;

        BUG_ON(pte_page(ptep_get(pte)) != walk->reuse_page);

        page = list_first_entry(walk->vmemmap_pages, struct page, lru);
        list_del(&page->lru);
        to = page_to_virt(page);
        copy_page(to, (void *)walk->reuse_addr);
        reset_struct_pages(to);

        /*
         * Makes sure that preceding stores to the page contents become visible
         * before the set_pte_at() write.
         */
        smp_wmb();
        set_pte_at(&init_mm, addr, pte, mk_pte(page, pgprot));
}

/**
 * vmemmap_remap_free - remap the vmemmap virtual address range [@start, @end)
 *                      to the page which @reuse is mapped to, then free vmemmap
 *                      which the range are mapped to.
 * @start:      start address of the vmemmap virtual address range that we want
 *              to remap.
 * @end:        end address of the vmemmap virtual address range that we want to
 *              remap.
 * @reuse:      reuse address.
 *
 * Return: %0 on success, negative error code otherwise.
 */
static int vmemmap_remap_free(unsigned long start, unsigned long end,
                              unsigned long reuse)
{
        int ret;
        LIST_HEAD(vmemmap_pages);
        struct vmemmap_remap_walk walk = {
                .remap_pte      = vmemmap_remap_pte,
                .reuse_addr     = reuse,
                .vmemmap_pages  = &vmemmap_pages,
        };
        int nid = page_to_nid((struct page *)start);
        gfp_t gfp_mask = GFP_KERNEL | __GFP_THISNODE | __GFP_NORETRY |
                        __GFP_NOWARN;

        /*
         * Allocate a new head vmemmap page to avoid breaking a contiguous
         * block of struct page memory when freeing it back to page allocator
         * in free_vmemmap_page_list(). This will allow the likely contiguous
         * struct page backing memory to be kept contiguous and allowing for
         * more allocations of hugepages. Fallback to the currently
         * mapped head page in case should it fail to allocate.
         */
        walk.reuse_page = alloc_pages_node(nid, gfp_mask, 0);
        if (walk.reuse_page) {
                copy_page(page_to_virt(walk.reuse_page),
                          (void *)walk.reuse_addr);
                list_add(&walk.reuse_page->lru, &vmemmap_pages);
        }

        /*
         * In order to make remapping routine most efficient for the huge pages,
         * the routine of vmemmap page table walking has the following rules
         * (see more details from the vmemmap_pte_range()):
         *
         * - The range [@start, @end) and the range [@reuse, @reuse + PAGE_SIZE)
         *   should be continuous.
         * - The @reuse address is part of the range [@reuse, @end) that we are
         *   walking which is passed to vmemmap_remap_range().
         * - The @reuse address is the first in the complete range.
         *
         * So we need to make sure that @start and @reuse meet the above rules.
         */
        BUG_ON(start - reuse != PAGE_SIZE);

        mmap_read_lock(&init_mm);
        ret = vmemmap_remap_range(reuse, end, &walk);
        if (ret && walk.nr_walked) {
                end = reuse + walk.nr_walked * PAGE_SIZE;
                /*
                 * vmemmap_pages contains pages from the previous
                 * vmemmap_remap_range call which failed.  These
                 * are pages which were removed from the vmemmap.
                 * They will be restored in the following call.
                 */
                walk = (struct vmemmap_remap_walk) {
                        .remap_pte      = vmemmap_restore_pte,
                        .reuse_addr     = reuse,
                        .vmemmap_pages  = &vmemmap_pages,
                };

                vmemmap_remap_range(reuse, end, &walk);
        }
        mmap_read_unlock(&init_mm);

        free_vmemmap_page_list(&vmemmap_pages);

        return ret;
}

static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
                                   struct list_head *list)
{
        gfp_t gfp_mask = GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_THISNODE;
        unsigned long nr_pages = (end - start) >> PAGE_SHIFT;
        int nid = page_to_nid((struct page *)start);
        struct page *page, *next;

        while (nr_pages--) {
                page = alloc_pages_node(nid, gfp_mask, 0);
                if (!page)
                        goto out;
                list_add_tail(&page->lru, list);
        }

        return 0;
out:
        list_for_each_entry_safe(page, next, list, lru)
                __free_page(page);
        return -ENOMEM;
}

/**
 * vmemmap_remap_alloc - remap the vmemmap virtual address range [@start, end)
 *                       to the page which is from the @vmemmap_pages
 *                       respectively.
 * @start:      start address of the vmemmap virtual address range that we want
 *              to remap.
 * @end:        end address of the vmemmap virtual address range that we want to
 *              remap.
 * @reuse:      reuse address.
 *
 * Return: %0 on success, negative error code otherwise.
 */
static int vmemmap_remap_alloc(unsigned long start, unsigned long end,
                               unsigned long reuse)
{
        LIST_HEAD(vmemmap_pages);
        struct vmemmap_remap_walk walk = {
                .remap_pte      = vmemmap_restore_pte,
                .reuse_addr     = reuse,
                .vmemmap_pages  = &vmemmap_pages,
        };

        /* See the comment in the vmemmap_remap_free(). */
        BUG_ON(start - reuse != PAGE_SIZE);

        if (alloc_vmemmap_page_list(start, end, &vmemmap_pages))
                return -ENOMEM;

        mmap_read_lock(&init_mm);
        vmemmap_remap_range(reuse, end, &walk);
        mmap_read_unlock(&init_mm);

        return 0;
}

DEFINE_STATIC_KEY_FALSE(hugetlb_optimize_vmemmap_key);
EXPORT_SYMBOL(hugetlb_optimize_vmemmap_key);

static bool vmemmap_optimize_enabled = IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON);
core_param(hugetlb_free_vmemmap, vmemmap_optimize_enabled, bool, 0);

/**
 * hugetlb_vmemmap_restore - restore previously optimized (by
 *                           hugetlb_vmemmap_optimize()) vmemmap pages which
 *                           will be reallocated and remapped.
 * @h:          struct hstate.
 * @head:       the head page whose vmemmap pages will be restored.
 *
 * Return: %0 if @head's vmemmap pages have been reallocated and remapped,
 * negative error code otherwise.
 */
int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head)
{
        int ret;
        unsigned long vmemmap_start = (unsigned long)head, vmemmap_end;
        unsigned long vmemmap_reuse;

        if (!HPageVmemmapOptimized(head))
                return 0;

        vmemmap_end     = vmemmap_start + hugetlb_vmemmap_size(h);
        vmemmap_reuse   = vmemmap_start;
        vmemmap_start   += HUGETLB_VMEMMAP_RESERVE_SIZE;

        /*
         * The pages which the vmemmap virtual address range [@vmemmap_start,
         * @vmemmap_end) are mapped to are freed to the buddy allocator, and
         * the range is mapped to the page which @vmemmap_reuse is mapped to.
         * When a HugeTLB page is freed to the buddy allocator, previously
         * discarded vmemmap pages must be allocated and remapping.
         */
        ret = vmemmap_remap_alloc(vmemmap_start, vmemmap_end, vmemmap_reuse);
        if (!ret) {
                ClearHPageVmemmapOptimized(head);
                static_branch_dec(&hugetlb_optimize_vmemmap_key);
        }

        return ret;
}

/* Return true iff a HugeTLB whose vmemmap should and can be optimized. */
static bool vmemmap_should_optimize(const struct hstate *h, const struct page *head)
{
        if (!READ_ONCE(vmemmap_optimize_enabled))
                return false;

        if (!hugetlb_vmemmap_optimizable(h))
                return false;

        if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) {
                pmd_t *pmdp, pmd;
                struct page *vmemmap_page;
                unsigned long vaddr = (unsigned long)head;

                /*
                 * Only the vmemmap page's vmemmap page can be self-hosted.
                 * Walking the page tables to find the backing page of the
                 * vmemmap page.
                 */
                pmdp = pmd_off_k(vaddr);
                /*
                 * The READ_ONCE() is used to stabilize *pmdp in a register or
                 * on the stack so that it will stop changing under the code.
                 * The only concurrent operation where it can be changed is
                 * split_vmemmap_huge_pmd() (*pmdp will be stable after this
                 * operation).
                 */
                pmd = READ_ONCE(*pmdp);
                if (pmd_leaf(pmd))
                        vmemmap_page = pmd_page(pmd) + pte_index(vaddr);
                else
                        vmemmap_page = pte_page(*pte_offset_kernel(pmdp, vaddr));
                /*
                 * Due to HugeTLB alignment requirements and the vmemmap pages
                 * being at the start of the hotplugged memory region in
                 * memory_hotplug.memmap_on_memory case. Checking any vmemmap
                 * page's vmemmap page if it is marked as VmemmapSelfHosted is
                 * sufficient.
                 *
                 * [                  hotplugged memory                  ]
                 * [        section        ][...][        section        ]
                 * [ vmemmap ][              usable memory               ]
                 *   ^   |     |                                        |
                 *   +---+     |                                        |
                 *     ^       |                                        |
                 *     +-------+                                        |
                 *          ^                                           |
                 *          +-------------------------------------------+
                 */
                if (PageVmemmapSelfHosted(vmemmap_page))
                        return false;
        }

        return true;
}

/**
 * hugetlb_vmemmap_optimize - optimize @head page's vmemmap pages.
 * @h:          struct hstate.
 * @head:       the head page whose vmemmap pages will be optimized.
 *
 * This function only tries to optimize @head's vmemmap pages and does not
 * guarantee that the optimization will succeed after it returns. The caller
 * can use HPageVmemmapOptimized(@head) to detect if @head's vmemmap pages
 * have been optimized.
 */
void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head)
{
        unsigned long vmemmap_start = (unsigned long)head, vmemmap_end;
        unsigned long vmemmap_reuse;

        if (!vmemmap_should_optimize(h, head))
                return;

        static_branch_inc(&hugetlb_optimize_vmemmap_key);

        vmemmap_end     = vmemmap_start + hugetlb_vmemmap_size(h);
        vmemmap_reuse   = vmemmap_start;
        vmemmap_start   += HUGETLB_VMEMMAP_RESERVE_SIZE;

        /*
         * Remap the vmemmap virtual address range [@vmemmap_start, @vmemmap_end)
         * to the page which @vmemmap_reuse is mapped to, then free the pages
         * which the range [@vmemmap_start, @vmemmap_end] is mapped to.
         */
        if (vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse))
                static_branch_dec(&hugetlb_optimize_vmemmap_key);
        else
                SetHPageVmemmapOptimized(head);
}

static struct ctl_table hugetlb_vmemmap_sysctls[] = {
        {
                .procname       = "hugetlb_optimize_vmemmap",
                .data           = &vmemmap_optimize_enabled,
                .maxlen         = sizeof(vmemmap_optimize_enabled),
                .mode           = 0644,
                .proc_handler   = proc_dobool,
        },
        { }
};

static int __init hugetlb_vmemmap_init(void)
{
        const struct hstate *h;

        /* HUGETLB_VMEMMAP_RESERVE_SIZE should cover all used struct pages */
        BUILD_BUG_ON(__NR_USED_SUBPAGE * sizeof(struct page) > HUGETLB_VMEMMAP_RESERVE_SIZE);

        for_each_hstate(h) {
                if (hugetlb_vmemmap_optimizable(h)) {
                        register_sysctl_init("vm", hugetlb_vmemmap_sysctls);
                        break;
                }
        }
        return 0;
}
late_initcall(hugetlb_vmemmap_init);