// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * This file contains the routines setting up the linux page tables.
 *  -- paulus
 *
 *  Derived from arch/ppc/mm/init.c:
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
 *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
 *    Copyright (C) 1996 Paul Mackerras
 *
 *  Derived from "arch/i386/mm/init.c"
 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/highmem.h>
#include <linux/memblock.h>
#include <linux/slab.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/fixmap.h>
#include <asm/io.h>
#include <asm/setup.h>
#include <asm/sections.h>

#include <mm/mmu_decl.h>

unsigned long ioremap_bot;
EXPORT_SYMBOL(ioremap_bot);     /* aka VMALLOC_END */

extern char etext[], _stext[], _sinittext[], _einittext[];

void __iomem *
ioremap(phys_addr_t addr, unsigned long size)
{
        pgprot_t prot = pgprot_noncached(PAGE_KERNEL);

        return __ioremap_caller(addr, size, prot, __builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap);

void __iomem *
ioremap_wc(phys_addr_t addr, unsigned long size)
{
        pgprot_t prot = pgprot_noncached_wc(PAGE_KERNEL);

        return __ioremap_caller(addr, size, prot, __builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap_wc);

void __iomem *
ioremap_wt(phys_addr_t addr, unsigned long size)
{
        pgprot_t prot = pgprot_cached_wthru(PAGE_KERNEL);

        return __ioremap_caller(addr, size, prot, __builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap_wt);

void __iomem *
ioremap_coherent(phys_addr_t addr, unsigned long size)
{
        pgprot_t prot = pgprot_cached(PAGE_KERNEL);

        return __ioremap_caller(addr, size, prot, __builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap_coherent);

void __iomem *
ioremap_prot(phys_addr_t addr, unsigned long size, unsigned long flags)
{
        pte_t pte = __pte(flags);

        /* writeable implies dirty for kernel addresses */
        if (pte_write(pte))
                pte = pte_mkdirty(pte);

        /* we don't want to let _PAGE_USER and _PAGE_EXEC leak out */
        pte = pte_exprotect(pte);
        pte = pte_mkprivileged(pte);

        return __ioremap_caller(addr, size, pte_pgprot(pte), __builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap_prot);

void __iomem *
__ioremap(phys_addr_t addr, unsigned long size, unsigned long flags)
{
        return __ioremap_caller(addr, size, __pgprot(flags), __builtin_return_address(0));
}

void __iomem *
__ioremap_caller(phys_addr_t addr, unsigned long size, pgprot_t prot, void *caller)
{
        unsigned long v, i;
        phys_addr_t p;
        int err;

        /*
         * Choose an address to map it to.
         * Once the vmalloc system is running, we use it.
         * Before then, we use space going down from IOREMAP_TOP
         * (ioremap_bot records where we're up to).
         */
        p = addr & PAGE_MASK;
        size = PAGE_ALIGN(addr + size) - p;

        /*
         * If the address lies within the first 16 MB, assume it's in ISA
         * memory space
         */
        if (p < 16*1024*1024)
                p += _ISA_MEM_BASE;

#ifndef CONFIG_CRASH_DUMP
        /*
         * Don't allow anybody to remap normal RAM that we're using.
         * mem_init() sets high_memory so only do the check after that.
         */
        if (slab_is_available() && p <= virt_to_phys(high_memory - 1) &&
            page_is_ram(__phys_to_pfn(p))) {
                printk("__ioremap(): phys addr 0x%llx is RAM lr %ps\n",
                       (unsigned long long)p, __builtin_return_address(0));
                return NULL;
        }
#endif

        if (size == 0)
                return NULL;

        /*
         * Is it already mapped?  Perhaps overlapped by a previous
         * mapping.
         */
        v = p_block_mapped(p);
        if (v)
                goto out;

        if (slab_is_available()) {
                struct vm_struct *area;
                area = get_vm_area_caller(size, VM_IOREMAP, caller);
                if (area == 0)
                        return NULL;
                area->phys_addr = p;
                v = (unsigned long) area->addr;
        } else {
                v = (ioremap_bot -= size);
        }

        /*
         * Should check if it is a candidate for a BAT mapping
         */

        err = 0;
        for (i = 0; i < size && err == 0; i += PAGE_SIZE)
                err = map_kernel_page(v + i, p + i, prot);
        if (err) {
                if (slab_is_available())
                        vunmap((void *)v);
                return NULL;
        }

out:
        return (void __iomem *) (v + ((unsigned long)addr & ~PAGE_MASK));
}
EXPORT_SYMBOL(__ioremap);

void iounmap(volatile void __iomem *addr)
{
        /*
         * If mapped by BATs then there is nothing to do.
         * Calling vfree() generates a benign warning.
         */
        if (v_block_mapped((unsigned long)addr))
                return;

        if (addr > high_memory && (unsigned long) addr < ioremap_bot)
                vunmap((void *) (PAGE_MASK & (unsigned long)addr));
}
EXPORT_SYMBOL(iounmap);

static void __init *early_alloc_pgtable(unsigned long size)
{
        void *ptr = memblock_alloc(size, size);

        if (!ptr)
                panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
                      __func__, size, size);

        return ptr;
}

static pte_t __init *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va)
{
        if (pmd_none(*pmdp)) {
                pte_t *ptep = early_alloc_pgtable(PTE_FRAG_SIZE);

                pmd_populate_kernel(&init_mm, pmdp, ptep);
        }
        return pte_offset_kernel(pmdp, va);
}


int __ref map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
{
        pmd_t *pd;
        pte_t *pg;
        int err = -ENOMEM;

        /* Use upper 10 bits of VA to index the first level map */
        pd = pmd_offset(pud_offset(pgd_offset_k(va), va), va);
        /* Use middle 10 bits of VA to index the second-level map */
        if (likely(slab_is_available()))
                pg = pte_alloc_kernel(pd, va);
        else
                pg = early_pte_alloc_kernel(pd, va);
        if (pg != 0) {
                err = 0;
                /* The PTE should never be already set nor present in the
                 * hash table
                 */
                BUG_ON((pte_present(*pg) | pte_hashpte(*pg)) && pgprot_val(prot));
                set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT, prot));
        }
        smp_wmb();
        return err;
}

/*
 * Map in a chunk of physical memory starting at start.
 */
static void __init __mapin_ram_chunk(unsigned long offset, unsigned long top)
{
        unsigned long v, s;
        phys_addr_t p;
        int ktext;

        s = offset;
        v = PAGE_OFFSET + s;
        p = memstart_addr + s;
        for (; s < top; s += PAGE_SIZE) {
                ktext = ((char *)v >= _stext && (char *)v < etext) ||
                        ((char *)v >= _sinittext && (char *)v < _einittext);
                map_kernel_page(v, p, ktext ? PAGE_KERNEL_TEXT : PAGE_KERNEL);
#ifdef CONFIG_PPC_BOOK3S_32
                if (ktext)
                        hash_preload(&init_mm, v, false, 0x300);
#endif
                v += PAGE_SIZE;
                p += PAGE_SIZE;
        }
}

void __init mapin_ram(void)
{
        struct memblock_region *reg;

        for_each_memblock(memory, reg) {
                phys_addr_t base = reg->base;
                phys_addr_t top = min(base + reg->size, total_lowmem);

                if (base >= top)
                        continue;
                base = mmu_mapin_ram(base, top);
                if (IS_ENABLED(CONFIG_BDI_SWITCH))
                        __mapin_ram_chunk(reg->base, top);
                else
                        __mapin_ram_chunk(base, top);
        }
}

/* Scan the real Linux page tables and return a PTE pointer for
 * a virtual address in a context.
 * Returns true (1) if PTE was found, zero otherwise.  The pointer to
 * the PTE pointer is unmodified if PTE is not found.
 */
static int
get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)
{
        pgd_t   *pgd;
        pud_t   *pud;
        pmd_t   *pmd;
        pte_t   *pte;
        int     retval = 0;

        pgd = pgd_offset(mm, addr & PAGE_MASK);
        if (pgd) {
                pud = pud_offset(pgd, addr & PAGE_MASK);
                if (pud && pud_present(*pud)) {
                        pmd = pmd_offset(pud, addr & PAGE_MASK);
                        if (pmd_present(*pmd)) {
                                pte = pte_offset_map(pmd, addr & PAGE_MASK);
                                if (pte) {
                                        retval = 1;
                                        *ptep = pte;
                                        if (pmdp)
                                                *pmdp = pmd;
                                        /* XXX caller needs to do pte_unmap, yuck */
                                }
                        }
                }
        }
        return(retval);
}

static int __change_page_attr_noflush(struct page *page, pgprot_t prot)
{
        pte_t *kpte;
        pmd_t *kpmd;
        unsigned long address;

        BUG_ON(PageHighMem(page));
        address = (unsigned long)page_address(page);

        if (v_block_mapped(address))
                return 0;
        if (!get_pteptr(&init_mm, address, &kpte, &kpmd))
                return -EINVAL;
        __set_pte_at(&init_mm, address, kpte, mk_pte(page, prot), 0);
        pte_unmap(kpte);

        return 0;
}

/*
 * Change the page attributes of an page in the linear mapping.
 *
 * THIS DOES NOTHING WITH BAT MAPPINGS, DEBUG USE ONLY
 */
static int change_page_attr(struct page *page, int numpages, pgprot_t prot)
{
        int i, err = 0;
        unsigned long flags;
        struct page *start = page;

        local_irq_save(flags);
        for (i = 0; i < numpages; i++, page++) {
                err = __change_page_attr_noflush(page, prot);
                if (err)
                        break;
        }
        wmb();
        local_irq_restore(flags);
        flush_tlb_kernel_range((unsigned long)page_address(start),
                               (unsigned long)page_address(page));
        return err;
}

void mark_initmem_nx(void)
{
        struct page *page = virt_to_page(_sinittext);
        unsigned long numpages = PFN_UP((unsigned long)_einittext) -
                                 PFN_DOWN((unsigned long)_sinittext);

        if (v_block_mapped((unsigned long)_stext + 1))
                mmu_mark_initmem_nx();
        else
                change_page_attr(page, numpages, PAGE_KERNEL);
}

#ifdef CONFIG_STRICT_KERNEL_RWX
void mark_rodata_ro(void)
{
        struct page *page;
        unsigned long numpages;

        if (v_block_mapped((unsigned long)_sinittext)) {
                mmu_mark_rodata_ro();
                return;
        }

        page = virt_to_page(_stext);
        numpages = PFN_UP((unsigned long)_etext) -
                   PFN_DOWN((unsigned long)_stext);

        change_page_attr(page, numpages, PAGE_KERNEL_ROX);
        /*
         * mark .rodata as read only. Use __init_begin rather than __end_rodata
         * to cover NOTES and EXCEPTION_TABLE.
         */
        page = virt_to_page(__start_rodata);
        numpages = PFN_UP((unsigned long)__init_begin) -
                   PFN_DOWN((unsigned long)__start_rodata);

        change_page_attr(page, numpages, PAGE_KERNEL_RO);

        // mark_initmem_nx() should have already run by now
        ptdump_check_wx();
}
#endif

#ifdef CONFIG_DEBUG_PAGEALLOC
void __kernel_map_pages(struct page *page, int numpages, int enable)
{
        if (PageHighMem(page))
                return;

        change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
}
#endif /* CONFIG_DEBUG_PAGEALLOC */