// SPDX-License-Identifier: GPL-2.0
/*
 *    Copyright IBM Corp. 2006
 */

#include <linux/memory_hotplug.h>
#include <linux/bootmem_info.h>
#include <linux/cpufeature.h>
#include <linux/memblock.h>
#include <linux/pfn.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/hugetlb.h>
#include <linux/slab.h>
#include <linux/sort.h>
#include <asm/page-states.h>
#include <asm/abs_lowcore.h>
#include <asm/cacheflush.h>
#include <asm/maccess.h>
#include <asm/nospec-branch.h>
#include <asm/ctlreg.h>
#include <asm/pgalloc.h>
#include <asm/setup.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
#include <asm/set_memory.h>
#include <asm/physmem_info.h>

static DEFINE_MUTEX(vmem_mutex);

static void __ref *vmem_alloc_pages(unsigned int order)
{
        unsigned long size = PAGE_SIZE << order;

        if (slab_is_available())
                return (void *)__get_free_pages(GFP_KERNEL, order);
        return memblock_alloc(size, size);
}

static void vmem_free_pages(unsigned long addr, int order, struct vmem_altmap *altmap)
{
        unsigned int nr_pages = 1 << order;
        struct page *page;

        if (altmap) {
                vmem_altmap_free(altmap, 1 << order);
                return;
        }
        page = virt_to_page((void *)addr);
        if (PageReserved(page)) {
                /* allocated from memblock */
                while (nr_pages--)
                        free_bootmem_page(page++);
        } else {
                free_pages(addr, order);
        }
}

void *vmem_crst_alloc(unsigned long val)
{
        unsigned long *table;

        table = vmem_alloc_pages(CRST_ALLOC_ORDER);
        if (!table)
                return NULL;
        crst_table_init(table, val);
        __arch_set_page_dat(table, 1UL << CRST_ALLOC_ORDER);
        return table;
}

pte_t __ref *vmem_pte_alloc(void)
{
        pte_t *pte;

        if (slab_is_available())
                pte = (pte_t *)page_table_alloc(&init_mm);
        else
                pte = (pte_t *)memblock_alloc(PAGE_SIZE, PAGE_SIZE);
        if (!pte)
                return NULL;
        memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE);
        __arch_set_page_dat(pte, 1);
        return pte;
}

static void vmem_pte_free(unsigned long *table)
{
        page_table_free(&init_mm, table);
}

#define PAGE_UNUSED 0xFD

/*
 * The unused vmemmap range, which was not yet memset(PAGE_UNUSED) ranges
 * from unused_sub_pmd_start to next PMD_SIZE boundary.
 */
static unsigned long unused_sub_pmd_start;

static void vmemmap_flush_unused_sub_pmd(void)
{
        if (!unused_sub_pmd_start)
                return;
        memset((void *)unused_sub_pmd_start, PAGE_UNUSED,
               ALIGN(unused_sub_pmd_start, PMD_SIZE) - unused_sub_pmd_start);
        unused_sub_pmd_start = 0;
}

static void vmemmap_mark_sub_pmd_used(unsigned long start, unsigned long end)
{
        /*
         * As we expect to add in the same granularity as we remove, it's
         * sufficient to mark only some piece used to block the memmap page from
         * getting removed (just in case the memmap never gets initialized,
         * e.g., because the memory block never gets onlined).
         */
        memset((void *)start, 0, sizeof(struct page));
}

static void vmemmap_use_sub_pmd(unsigned long start, unsigned long end)
{
        /*
         * We only optimize if the new used range directly follows the
         * previously unused range (esp., when populating consecutive sections).
         */
        if (unused_sub_pmd_start == start) {
                unused_sub_pmd_start = end;
                if (likely(IS_ALIGNED(unused_sub_pmd_start, PMD_SIZE)))
                        unused_sub_pmd_start = 0;
                return;
        }
        vmemmap_flush_unused_sub_pmd();
        vmemmap_mark_sub_pmd_used(start, end);
}

static void vmemmap_use_new_sub_pmd(unsigned long start, unsigned long end)
{
        unsigned long page = ALIGN_DOWN(start, PMD_SIZE);

        vmemmap_flush_unused_sub_pmd();

        /* Could be our memmap page is filled with PAGE_UNUSED already ... */
        vmemmap_mark_sub_pmd_used(start, end);

        /* Mark the unused parts of the new memmap page PAGE_UNUSED. */
        if (!IS_ALIGNED(start, PMD_SIZE))
                memset((void *)page, PAGE_UNUSED, start - page);
        /*
         * We want to avoid memset(PAGE_UNUSED) when populating the vmemmap of
         * consecutive sections. Remember for the last added PMD the last
         * unused range in the populated PMD.
         */
        if (!IS_ALIGNED(end, PMD_SIZE))
                unused_sub_pmd_start = end;
}

/* Returns true if the PMD is completely unused and can be freed. */
static bool vmemmap_unuse_sub_pmd(unsigned long start, unsigned long end)
{
        unsigned long page = ALIGN_DOWN(start, PMD_SIZE);

        vmemmap_flush_unused_sub_pmd();
        memset((void *)start, PAGE_UNUSED, end - start);
        return !memchr_inv((void *)page, PAGE_UNUSED, PMD_SIZE);
}

/* __ref: we'll only call vmemmap_alloc_block() via vmemmap_populate() */
static int __ref modify_pte_table(pmd_t *pmd, unsigned long addr,
                                  unsigned long end, bool add, bool direct,
                                  struct vmem_altmap *altmap)
{
        unsigned long prot, pages = 0;
        int ret = -ENOMEM;
        pte_t *pte;

        prot = pgprot_val(PAGE_KERNEL);
        pte = pte_offset_kernel(pmd, addr);
        for (; addr < end; addr += PAGE_SIZE, pte++) {
                if (!add) {
                        if (pte_none(*pte))
                                continue;
                        if (!direct)
                                vmem_free_pages((unsigned long)pfn_to_virt(pte_pfn(*pte)), get_order(PAGE_SIZE), altmap);
                        pte_clear(&init_mm, addr, pte);
                } else if (pte_none(*pte)) {
                        if (!direct) {
                                void *new_page = vmemmap_alloc_block_buf(PAGE_SIZE, NUMA_NO_NODE, altmap);

                                if (!new_page)
                                        goto out;
                                set_pte(pte, __pte(__pa(new_page) | prot));
                        } else {
                                set_pte(pte, __pte(__pa(addr) | prot));
                        }
                } else {
                        continue;
                }
                pages++;
        }
        ret = 0;
out:
        if (direct)
                update_page_count(PG_DIRECT_MAP_4K, add ? pages : -pages);
        return ret;
}

static void try_free_pte_table(pmd_t *pmd, unsigned long start)
{
        pte_t *pte;
        int i;

        /* We can safely assume this is fully in 1:1 mapping & vmemmap area */
        pte = pte_offset_kernel(pmd, start);
        for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
                if (!pte_none(*pte))
                        return;
        }
        vmem_pte_free((unsigned long *) pmd_deref(*pmd));
        pmd_clear(pmd);
}

/* __ref: we'll only call vmemmap_alloc_block() via vmemmap_populate() */
static int __ref modify_pmd_table(pud_t *pud, unsigned long addr,
                                  unsigned long end, bool add, bool direct,
                                  struct vmem_altmap *altmap)
{
        unsigned long next, prot, pages = 0;
        int ret = -ENOMEM;
        pmd_t *pmd;
        pte_t *pte;

        prot = pgprot_val(SEGMENT_KERNEL);
        pmd = pmd_offset(pud, addr);
        for (; addr < end; addr = next, pmd++) {
                next = pmd_addr_end(addr, end);
                if (!add) {
                        if (pmd_none(*pmd))
                                continue;
                        if (pmd_leaf(*pmd)) {
                                if (IS_ALIGNED(addr, PMD_SIZE) &&
                                    IS_ALIGNED(next, PMD_SIZE)) {
                                        if (!direct)
                                                vmem_free_pages(pmd_deref(*pmd), get_order(PMD_SIZE), altmap);
                                        pmd_clear(pmd);
                                        pages++;
                                } else if (!direct && vmemmap_unuse_sub_pmd(addr, next)) {
                                        vmem_free_pages(pmd_deref(*pmd), get_order(PMD_SIZE), altmap);
                                        pmd_clear(pmd);
                                }
                                continue;
                        }
                } else if (pmd_none(*pmd)) {
                        if (IS_ALIGNED(addr, PMD_SIZE) &&
                            IS_ALIGNED(next, PMD_SIZE) &&
                            cpu_has_edat1() && direct &&
                            !debug_pagealloc_enabled()) {
                                set_pmd(pmd, __pmd(__pa(addr) | prot));
                                pages++;
                                continue;
                        } else if (!direct && cpu_has_edat1()) {
                                void *new_page;

                                /*
                                 * Use 1MB frames for vmemmap if available. We
                                 * always use large frames even if they are only
                                 * partially used. Otherwise we would have also
                                 * page tables since vmemmap_populate gets
                                 * called for each section separately.
                                 */
                                new_page = vmemmap_alloc_block_buf(PMD_SIZE, NUMA_NO_NODE, altmap);
                                if (new_page) {
                                        set_pmd(pmd, __pmd(__pa(new_page) | prot));
                                        if (!IS_ALIGNED(addr, PMD_SIZE) ||
                                            !IS_ALIGNED(next, PMD_SIZE)) {
                                                vmemmap_use_new_sub_pmd(addr, next);
                                        }
                                        continue;
                                }
                        }
                        pte = vmem_pte_alloc();
                        if (!pte)
                                goto out;
                        pmd_populate(&init_mm, pmd, pte);
                } else if (pmd_leaf(*pmd)) {
                        if (!direct)
                                vmemmap_use_sub_pmd(addr, next);
                        continue;
                }
                ret = modify_pte_table(pmd, addr, next, add, direct, altmap);
                if (ret)
                        goto out;
                if (!add)
                        try_free_pte_table(pmd, addr & PMD_MASK);
        }
        ret = 0;
out:
        if (direct)
                update_page_count(PG_DIRECT_MAP_1M, add ? pages : -pages);
        return ret;
}

static void try_free_pmd_table(pud_t *pud, unsigned long start)
{
        pmd_t *pmd;
        int i;

        pmd = pmd_offset(pud, start);
        for (i = 0; i < PTRS_PER_PMD; i++, pmd++)
                if (!pmd_none(*pmd))
                        return;
        vmem_free_pages(pud_deref(*pud), CRST_ALLOC_ORDER, NULL);
        pud_clear(pud);
}

static int modify_pud_table(p4d_t *p4d, unsigned long addr, unsigned long end,
                            bool add, bool direct, struct vmem_altmap *altmap)
{
        unsigned long next, prot, pages = 0;
        int ret = -ENOMEM;
        pud_t *pud;
        pmd_t *pmd;

        prot = pgprot_val(REGION3_KERNEL);
        pud = pud_offset(p4d, addr);
        for (; addr < end; addr = next, pud++) {
                next = pud_addr_end(addr, end);
                if (!add) {
                        if (pud_none(*pud))
                                continue;
                        if (pud_leaf(*pud)) {
                                if (IS_ALIGNED(addr, PUD_SIZE) &&
                                    IS_ALIGNED(next, PUD_SIZE)) {
                                        if (!direct)
                                                vmem_free_pages(pud_deref(*pud), get_order(PUD_SIZE), altmap);
                                        pud_clear(pud);
                                        pages++;
                                        continue;
                                } else {
                                        split_pud_page(pud, addr & PUD_MASK);
                                }
                        }
                } else if (pud_none(*pud)) {
                        if (IS_ALIGNED(addr, PUD_SIZE) &&
                            IS_ALIGNED(next, PUD_SIZE) &&
                            cpu_has_edat2() && direct &&
                            !debug_pagealloc_enabled()) {
                                set_pud(pud, __pud(__pa(addr) | prot));
                                pages++;
                                continue;
                        }
                        pmd = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
                        if (!pmd)
                                goto out;
                        pud_populate(&init_mm, pud, pmd);
                } else if (pud_leaf(*pud)) {
                        continue;
                }
                ret = modify_pmd_table(pud, addr, next, add, direct, altmap);
                if (ret)
                        goto out;
                if (!add)
                        try_free_pmd_table(pud, addr & PUD_MASK);
        }
        ret = 0;
out:
        if (direct)
                update_page_count(PG_DIRECT_MAP_2G, add ? pages : -pages);
        return ret;
}

static void try_free_pud_table(p4d_t *p4d, unsigned long start)
{
        pud_t *pud;
        int i;

        pud = pud_offset(p4d, start);
        for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
                if (!pud_none(*pud))
                        return;
        }
        vmem_free_pages(p4d_deref(*p4d), CRST_ALLOC_ORDER, NULL);
        p4d_clear(p4d);
}

static int modify_p4d_table(pgd_t *pgd, unsigned long addr, unsigned long end,
                            bool add, bool direct, struct vmem_altmap *altmap)
{
        unsigned long next;
        int ret = -ENOMEM;
        p4d_t *p4d;
        pud_t *pud;

        p4d = p4d_offset(pgd, addr);
        for (; addr < end; addr = next, p4d++) {
                next = p4d_addr_end(addr, end);
                if (!add) {
                        if (p4d_none(*p4d))
                                continue;
                } else if (p4d_none(*p4d)) {
                        pud = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
                        if (!pud)
                                goto out;
                        p4d_populate(&init_mm, p4d, pud);
                }
                ret = modify_pud_table(p4d, addr, next, add, direct, altmap);
                if (ret)
                        goto out;
                if (!add)
                        try_free_pud_table(p4d, addr & P4D_MASK);
        }
        ret = 0;
out:
        return ret;
}

static void try_free_p4d_table(pgd_t *pgd, unsigned long start)
{
        p4d_t *p4d;
        int i;

        p4d = p4d_offset(pgd, start);
        for (i = 0; i < PTRS_PER_P4D; i++, p4d++) {
                if (!p4d_none(*p4d))
                        return;
        }
        vmem_free_pages(pgd_deref(*pgd), CRST_ALLOC_ORDER, NULL);
        pgd_clear(pgd);
}

static int modify_pagetable(unsigned long start, unsigned long end, bool add,
                            bool direct, struct vmem_altmap *altmap)
{
        unsigned long addr, next;
        int ret = -ENOMEM;
        pgd_t *pgd;
        p4d_t *p4d;

        if (WARN_ON_ONCE(!PAGE_ALIGNED(start | end)))
                return -EINVAL;
        /* Don't mess with any tables not fully in 1:1 mapping, vmemmap & kasan area */
#ifdef CONFIG_KASAN
        if (WARN_ON_ONCE(!(start >= KASAN_SHADOW_START && end <= KASAN_SHADOW_END) &&
                         end > __abs_lowcore))
                return -EINVAL;
#else
        if (WARN_ON_ONCE(end > __abs_lowcore))
                return -EINVAL;
#endif
        for (addr = start; addr < end; addr = next) {
                next = pgd_addr_end(addr, end);
                pgd = pgd_offset_k(addr);

                if (!add) {
                        if (pgd_none(*pgd))
                                continue;
                } else if (pgd_none(*pgd)) {
                        p4d = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
                        if (!p4d)
                                goto out;
                        pgd_populate(&init_mm, pgd, p4d);
                }
                ret = modify_p4d_table(pgd, addr, next, add, direct, altmap);
                if (ret)
                        goto out;
                if (!add)
                        try_free_p4d_table(pgd, addr & PGDIR_MASK);
        }
        ret = 0;
out:
        if (!add)
                flush_tlb_kernel_range(start, end);
        return ret;
}

static int add_pagetable(unsigned long start, unsigned long end, bool direct,
                         struct vmem_altmap *altmap)
{
        return modify_pagetable(start, end, true, direct, altmap);
}

static int remove_pagetable(unsigned long start, unsigned long end, bool direct,
                            struct vmem_altmap *altmap)
{
        return modify_pagetable(start, end, false, direct, altmap);
}

/*
 * Add a physical memory range to the 1:1 mapping.
 */
static int vmem_add_range(unsigned long start, unsigned long size)
{
        start = (unsigned long)__va(start);
        return add_pagetable(start, start + size, true, NULL);
}

/*
 * Remove a physical memory range from the 1:1 mapping.
 */
static void vmem_remove_range(unsigned long start, unsigned long size)
{
        start = (unsigned long)__va(start);
        remove_pagetable(start, start + size, true, NULL);
}

/*
 * Add a backed mem_map array to the virtual mem_map array.
 */
int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
                               struct vmem_altmap *altmap)
{
        int ret;

        mutex_lock(&vmem_mutex);
        /* We don't care about the node, just use NUMA_NO_NODE on allocations */
        ret = add_pagetable(start, end, false, altmap);
        if (ret)
                remove_pagetable(start, end, false, altmap);
        mutex_unlock(&vmem_mutex);
        return ret;
}

#ifdef CONFIG_MEMORY_HOTPLUG

void vmemmap_free(unsigned long start, unsigned long end,
                  struct vmem_altmap *altmap)
{
        mutex_lock(&vmem_mutex);
        remove_pagetable(start, end, false, altmap);
        mutex_unlock(&vmem_mutex);
}

#endif

void vmem_remove_mapping(unsigned long start, unsigned long size)
{
        mutex_lock(&vmem_mutex);
        vmem_remove_range(start, size);
        mutex_unlock(&vmem_mutex);
}

struct range arch_get_mappable_range(void)
{
        struct range mhp_range;

        mhp_range.start = 0;
        mhp_range.end = max_mappable - 1;
        return mhp_range;
}

int vmem_add_mapping(unsigned long start, unsigned long size)
{
        struct range range = arch_get_mappable_range();
        int ret;

        if (start < range.start ||
            start + size > range.end + 1 ||
            start + size < start)
                return -ERANGE;

        mutex_lock(&vmem_mutex);
        ret = vmem_add_range(start, size);
        if (ret)
                vmem_remove_range(start, size);
        mutex_unlock(&vmem_mutex);
        return ret;
}

/*
 * Allocate new or return existing page-table entry, but do not map it
 * to any physical address. If missing, allocate segment- and region-
 * table entries along. Meeting a large segment- or region-table entry
 * while traversing is an error, since the function is expected to be
 * called against virtual regions reserved for 4KB mappings only.
 */
pte_t *vmem_get_alloc_pte(unsigned long addr, bool alloc)
{
        pte_t *ptep = NULL;
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        pgd = pgd_offset_k(addr);
        if (pgd_none(*pgd)) {
                if (!alloc)
                        goto out;
                p4d = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
                if (!p4d)
                        goto out;
                pgd_populate(&init_mm, pgd, p4d);
        }
        p4d = p4d_offset(pgd, addr);
        if (p4d_none(*p4d)) {
                if (!alloc)
                        goto out;
                pud = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
                if (!pud)
                        goto out;
                p4d_populate(&init_mm, p4d, pud);
        }
        pud = pud_offset(p4d, addr);
        if (pud_none(*pud)) {
                if (!alloc)
                        goto out;
                pmd = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
                if (!pmd)
                        goto out;
                pud_populate(&init_mm, pud, pmd);
        } else if (WARN_ON_ONCE(pud_leaf(*pud))) {
                goto out;
        }
        pmd = pmd_offset(pud, addr);
        if (pmd_none(*pmd)) {
                if (!alloc)
                        goto out;
                pte = vmem_pte_alloc();
                if (!pte)
                        goto out;
                pmd_populate(&init_mm, pmd, pte);
        } else if (WARN_ON_ONCE(pmd_leaf(*pmd))) {
                goto out;
        }
        ptep = pte_offset_kernel(pmd, addr);
out:
        return ptep;
}

int __vmem_map_4k_page(unsigned long addr, unsigned long phys, pgprot_t prot, bool alloc)
{
        pte_t *ptep, pte;

        if (!IS_ALIGNED(addr, PAGE_SIZE))
                return -EINVAL;
        ptep = vmem_get_alloc_pte(addr, alloc);
        if (!ptep)
                return -ENOMEM;
        __ptep_ipte(addr, ptep, 0, 0, IPTE_GLOBAL);
        pte = mk_pte_phys(phys, prot);
        set_pte(ptep, pte);
        return 0;
}

int vmem_map_4k_page(unsigned long addr, unsigned long phys, pgprot_t prot)
{
        int rc;

        mutex_lock(&vmem_mutex);
        rc = __vmem_map_4k_page(addr, phys, prot, true);
        mutex_unlock(&vmem_mutex);
        return rc;
}

void vmem_unmap_4k_page(unsigned long addr)
{
        pte_t *ptep;

        mutex_lock(&vmem_mutex);
        ptep = virt_to_kpte(addr);
        __ptep_ipte(addr, ptep, 0, 0, IPTE_GLOBAL);
        pte_clear(&init_mm, addr, ptep);
        mutex_unlock(&vmem_mutex);
}

void __init vmem_map_init(void)
{
        __set_memory_rox(_stext, _etext);
        __set_memory_ro(_etext, __end_rodata);
        __set_memory_rox(__stext_amode31, __etext_amode31);
        /*
         * If the BEAR-enhancement facility is not installed the first
         * prefix page is used to return to the previous context with
         * an LPSWE instruction and therefore must be executable.
         */
        if (!cpu_has_bear())
                set_memory_x(0, 1);
        if (debug_pagealloc_enabled())
                __set_memory_4k(__va(0), absolute_pointer(__va(0)) + ident_map_size);
        pr_info("Write protected kernel read-only data: %luk\n",
                (unsigned long)(__end_rodata - _stext) >> 10);
}