/*
 *  PowerPC version
 *    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
 *
 *  Dave Engebretsen <engebret@us.ibm.com>
 *      Rework for PPC64 port.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 */

#undef DEBUG

#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/stddef.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/highmem.h>
#include <linux/idr.h>
#include <linux/nodemask.h>
#include <linux/module.h>
#include <linux/poison.h>
#include <linux/memblock.h>
#include <linux/hugetlb.h>
#include <linux/slab.h>
#include <linux/of_fdt.h>
#include <linux/libfdt.h>
#include <linux/memremap.h>

#include <asm/pgalloc.h>
#include <asm/page.h>
#include <asm/prom.h>
#include <asm/rtas.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <linux/uaccess.h>
#include <asm/smp.h>
#include <asm/machdep.h>
#include <asm/tlb.h>
#include <asm/eeh.h>
#include <asm/processor.h>
#include <asm/mmzone.h>
#include <asm/cputable.h>
#include <asm/sections.h>
#include <asm/iommu.h>
#include <asm/vdso.h>

#include "mmu_decl.h"

#ifdef CONFIG_PPC_BOOK3S_64
#if H_PGTABLE_RANGE > USER_VSID_RANGE
#warning Limited user VSID range means pagetable space is wasted
#endif
#endif /* CONFIG_PPC_BOOK3S_64 */

phys_addr_t memstart_addr = ~0;
EXPORT_SYMBOL_GPL(memstart_addr);
phys_addr_t kernstart_addr;
EXPORT_SYMBOL_GPL(kernstart_addr);

#ifdef CONFIG_SPARSEMEM_VMEMMAP
/*
 * Given an address within the vmemmap, determine the pfn of the page that
 * represents the start of the section it is within.  Note that we have to
 * do this by hand as the proffered address may not be correctly aligned.
 * Subtraction of non-aligned pointers produces undefined results.
 */
static unsigned long __meminit vmemmap_section_start(unsigned long page)
{
        unsigned long offset = page - ((unsigned long)(vmemmap));

        /* Return the pfn of the start of the section. */
        return (offset / sizeof(struct page)) & PAGE_SECTION_MASK;
}

/*
 * Check if this vmemmap page is already initialised.  If any section
 * which overlaps this vmemmap page is initialised then this page is
 * initialised already.
 */
static int __meminit vmemmap_populated(unsigned long start, int page_size)
{
        unsigned long end = start + page_size;
        start = (unsigned long)(pfn_to_page(vmemmap_section_start(start)));

        for (; start < end; start += (PAGES_PER_SECTION * sizeof(struct page)))
                if (pfn_valid(page_to_pfn((struct page *)start)))
                        return 1;

        return 0;
}

/*
 * vmemmap virtual address space management does not have a traditonal page
 * table to track which virtual struct pages are backed by physical mapping.
 * The virtual to physical mappings are tracked in a simple linked list
 * format. 'vmemmap_list' maintains the entire vmemmap physical mapping at
 * all times where as the 'next' list maintains the available
 * vmemmap_backing structures which have been deleted from the
 * 'vmemmap_global' list during system runtime (memory hotplug remove
 * operation). The freed 'vmemmap_backing' structures are reused later when
 * new requests come in without allocating fresh memory. This pointer also
 * tracks the allocated 'vmemmap_backing' structures as we allocate one
 * full page memory at a time when we dont have any.
 */
struct vmemmap_backing *vmemmap_list;
static struct vmemmap_backing *next;

/*
 * The same pointer 'next' tracks individual chunks inside the allocated
 * full page during the boot time and again tracks the freeed nodes during
 * runtime. It is racy but it does not happen as they are separated by the
 * boot process. Will create problem if some how we have memory hotplug
 * operation during boot !!
 */
static int num_left;
static int num_freed;

static __meminit struct vmemmap_backing * vmemmap_list_alloc(int node)
{
        struct vmemmap_backing *vmem_back;
        /* get from freed entries first */
        if (num_freed) {
                num_freed--;
                vmem_back = next;
                next = next->list;

                return vmem_back;
        }

        /* allocate a page when required and hand out chunks */
        if (!num_left) {
                next = vmemmap_alloc_block(PAGE_SIZE, node);
                if (unlikely(!next)) {
                        WARN_ON(1);
                        return NULL;
                }
                num_left = PAGE_SIZE / sizeof(struct vmemmap_backing);
        }

        num_left--;

        return next++;
}

static __meminit void vmemmap_list_populate(unsigned long phys,
                                            unsigned long start,
                                            int node)
{
        struct vmemmap_backing *vmem_back;

        vmem_back = vmemmap_list_alloc(node);
        if (unlikely(!vmem_back)) {
                WARN_ON(1);
                return;
        }

        vmem_back->phys = phys;
        vmem_back->virt_addr = start;
        vmem_back->list = vmemmap_list;

        vmemmap_list = vmem_back;
}

int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
                struct vmem_altmap *altmap)
{
        unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;

        /* Align to the page size of the linear mapping. */
        start = _ALIGN_DOWN(start, page_size);

        pr_debug("vmemmap_populate %lx..%lx, node %d\n", start, end, node);

        for (; start < end; start += page_size) {
                void *p;
                int rc;

                if (vmemmap_populated(start, page_size))
                        continue;

                if (altmap)
                        p = altmap_alloc_block_buf(page_size, altmap);
                else
                        p = vmemmap_alloc_block_buf(page_size, node);
                if (!p)
                        return -ENOMEM;

                vmemmap_list_populate(__pa(p), start, node);

                pr_debug("      * %016lx..%016lx allocated at %p\n",
                         start, start + page_size, p);

                rc = vmemmap_create_mapping(start, page_size, __pa(p));
                if (rc < 0) {
                        pr_warn("%s: Unable to create vmemmap mapping: %d\n",
                                __func__, rc);
                        return -EFAULT;
                }
        }

        return 0;
}

#ifdef CONFIG_MEMORY_HOTPLUG
static unsigned long vmemmap_list_free(unsigned long start)
{
        struct vmemmap_backing *vmem_back, *vmem_back_prev;

        vmem_back_prev = vmem_back = vmemmap_list;

        /* look for it with prev pointer recorded */
        for (; vmem_back; vmem_back = vmem_back->list) {
                if (vmem_back->virt_addr == start)
                        break;
                vmem_back_prev = vmem_back;
        }

        if (unlikely(!vmem_back)) {
                WARN_ON(1);
                return 0;
        }

        /* remove it from vmemmap_list */
        if (vmem_back == vmemmap_list) /* remove head */
                vmemmap_list = vmem_back->list;
        else
                vmem_back_prev->list = vmem_back->list;

        /* next point to this freed entry */
        vmem_back->list = next;
        next = vmem_back;
        num_freed++;

        return vmem_back->phys;
}

void __ref vmemmap_free(unsigned long start, unsigned long end,
                struct vmem_altmap *altmap)
{
        unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
        unsigned long page_order = get_order(page_size);

        start = _ALIGN_DOWN(start, page_size);

        pr_debug("vmemmap_free %lx...%lx\n", start, end);

        for (; start < end; start += page_size) {
                unsigned long nr_pages, addr;
                struct page *section_base;
                struct page *page;

                /*
                 * the section has already be marked as invalid, so
                 * vmemmap_populated() true means some other sections still
                 * in this page, so skip it.
                 */
                if (vmemmap_populated(start, page_size))
                        continue;

                addr = vmemmap_list_free(start);
                if (!addr)
                        continue;

                page = pfn_to_page(addr >> PAGE_SHIFT);
                section_base = pfn_to_page(vmemmap_section_start(start));
                nr_pages = 1 << page_order;

                if (altmap) {
                        vmem_altmap_free(altmap, nr_pages);
                } else if (PageReserved(page)) {
                        /* allocated from bootmem */
                        if (page_size < PAGE_SIZE) {
                                /*
                                 * this shouldn't happen, but if it is
                                 * the case, leave the memory there
                                 */
                                WARN_ON_ONCE(1);
                        } else {
                                while (nr_pages--)
                                        free_reserved_page(page++);
                        }
                } else {
                        free_pages((unsigned long)(__va(addr)), page_order);
                }

                vmemmap_remove_mapping(start, page_size);
        }
}
#endif
void register_page_bootmem_memmap(unsigned long section_nr,
                                  struct page *start_page, unsigned long size)
{
}

/*
 * We do not have access to the sparsemem vmemmap, so we fallback to
 * walking the list of sparsemem blocks which we already maintain for
 * the sake of crashdump. In the long run, we might want to maintain
 * a tree if performance of that linear walk becomes a problem.
 *
 * realmode_pfn_to_page functions can fail due to:
 * 1) As real sparsemem blocks do not lay in RAM continously (they
 * are in virtual address space which is not available in the real mode),
 * the requested page struct can be split between blocks so get_page/put_page
 * may fail.
 * 2) When huge pages are used, the get_page/put_page API will fail
 * in real mode as the linked addresses in the page struct are virtual
 * too.
 */
struct page *realmode_pfn_to_page(unsigned long pfn)
{
        struct vmemmap_backing *vmem_back;
        struct page *page;
        unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
        unsigned long pg_va = (unsigned long) pfn_to_page(pfn);

        for (vmem_back = vmemmap_list; vmem_back; vmem_back = vmem_back->list) {
                if (pg_va < vmem_back->virt_addr)
                        continue;

                /* After vmemmap_list entry free is possible, need check all */
                if ((pg_va + sizeof(struct page)) <=
                                (vmem_back->virt_addr + page_size)) {
                        page = (struct page *) (vmem_back->phys + pg_va -
                                vmem_back->virt_addr);
                        return page;
                }
        }

        /* Probably that page struct is split between real pages */
        return NULL;
}
EXPORT_SYMBOL_GPL(realmode_pfn_to_page);

#else

struct page *realmode_pfn_to_page(unsigned long pfn)
{
        struct page *page = pfn_to_page(pfn);
        return page;
}
EXPORT_SYMBOL_GPL(realmode_pfn_to_page);

#endif /* CONFIG_SPARSEMEM_VMEMMAP */

#ifdef CONFIG_PPC_BOOK3S_64
static bool disable_radix = !IS_ENABLED(CONFIG_PPC_RADIX_MMU_DEFAULT);

static int __init parse_disable_radix(char *p)
{
        bool val;

        if (strlen(p) == 0)
                val = true;
        else if (kstrtobool(p, &val))
                return -EINVAL;

        disable_radix = val;

        return 0;
}
early_param("disable_radix", parse_disable_radix);

/*
 * If we're running under a hypervisor, we need to check the contents of
 * /chosen/ibm,architecture-vec-5 to see if the hypervisor is willing to do
 * radix.  If not, we clear the radix feature bit so we fall back to hash.
 */
static void __init early_check_vec5(void)
{
        unsigned long root, chosen;
        int size;
        const u8 *vec5;
        u8 mmu_supported;

        root = of_get_flat_dt_root();
        chosen = of_get_flat_dt_subnode_by_name(root, "chosen");
        if (chosen == -FDT_ERR_NOTFOUND) {
                cur_cpu_spec->mmu_features &= ~MMU_FTR_TYPE_RADIX;
                return;
        }
        vec5 = of_get_flat_dt_prop(chosen, "ibm,architecture-vec-5", &size);
        if (!vec5) {
                cur_cpu_spec->mmu_features &= ~MMU_FTR_TYPE_RADIX;
                return;
        }
        if (size <= OV5_INDX(OV5_MMU_SUPPORT)) {
                cur_cpu_spec->mmu_features &= ~MMU_FTR_TYPE_RADIX;
                return;
        }

        /* Check for supported configuration */
        mmu_supported = vec5[OV5_INDX(OV5_MMU_SUPPORT)] &
                        OV5_FEAT(OV5_MMU_SUPPORT);
        if (mmu_supported == OV5_FEAT(OV5_MMU_RADIX)) {
                /* Hypervisor only supports radix - check enabled && GTSE */
                if (!early_radix_enabled()) {
                        pr_warn("WARNING: Ignoring cmdline option disable_radix\n");
                }
                if (!(vec5[OV5_INDX(OV5_RADIX_GTSE)] &
                                                OV5_FEAT(OV5_RADIX_GTSE))) {
                        pr_warn("WARNING: Hypervisor doesn't support RADIX with GTSE\n");
                }
                /* Do radix anyway - the hypervisor said we had to */
                cur_cpu_spec->mmu_features |= MMU_FTR_TYPE_RADIX;
        } else if (mmu_supported == OV5_FEAT(OV5_MMU_HASH)) {
                /* Hypervisor only supports hash - disable radix */
                cur_cpu_spec->mmu_features &= ~MMU_FTR_TYPE_RADIX;
        }
}

void __init mmu_early_init_devtree(void)
{
        /* Disable radix mode based on kernel command line. */
        if (disable_radix)
                cur_cpu_spec->mmu_features &= ~MMU_FTR_TYPE_RADIX;

        /*
         * Check /chosen/ibm,architecture-vec-5 if running as a guest.
         * When running bare-metal, we can use radix if we like
         * even though the ibm,architecture-vec-5 property created by
         * skiboot doesn't have the necessary bits set.
         */
        if (!(mfmsr() & MSR_HV))
                early_check_vec5();

        if (early_radix_enabled())
                radix__early_init_devtree();
        else
                hash__early_init_devtree();
}
#endif /* CONFIG_PPC_BOOK3S_64 */