/*
 * Initialize MMU support.
 *
 * Copyright (C) 1998-2003 Hewlett-Packard Co
 *      David Mosberger-Tang <davidm@hpl.hp.com>
 */
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/init.h>

#include <linux/bootmem.h>
#include <linux/efi.h>
#include <linux/elf.h>
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/module.h>
#include <linux/personality.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/proc_fs.h>
#include <linux/bitops.h>

#include <asm/a.out.h>
#include <asm/dma.h>
#include <asm/ia32.h>
#include <asm/io.h>
#include <asm/machvec.h>
#include <asm/numa.h>
#include <asm/patch.h>
#include <asm/pgalloc.h>
#include <asm/sal.h>
#include <asm/sections.h>
#include <asm/system.h>
#include <asm/tlb.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/mca.h>

DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);

extern void ia64_tlb_init (void);

unsigned long MAX_DMA_ADDRESS = PAGE_OFFSET + 0x100000000UL;

#ifdef CONFIG_VIRTUAL_MEM_MAP
unsigned long vmalloc_end = VMALLOC_END_INIT;
EXPORT_SYMBOL(vmalloc_end);
struct page *vmem_map;
EXPORT_SYMBOL(vmem_map);
#endif

static int pgt_cache_water[2] = { 25, 50 };

struct page *zero_page_memmap_ptr;              /* map entry for zero page */
EXPORT_SYMBOL(zero_page_memmap_ptr);

void
check_pgt_cache (void)
{
        int low, high;

        low = pgt_cache_water[0];
        high = pgt_cache_water[1];

        preempt_disable();
        if (pgtable_cache_size > (u64) high) {
                do {
                        if (pgd_quicklist)
                                free_page((unsigned long)pgd_alloc_one_fast(NULL));
                        if (pmd_quicklist)
                                free_page((unsigned long)pmd_alloc_one_fast(NULL, 0));
                } while (pgtable_cache_size > (u64) low);
        }
        preempt_enable();
}

void
update_mmu_cache (struct vm_area_struct *vma, unsigned long vaddr, pte_t pte)
{
        unsigned long addr;
        struct page *page;

        if (!pte_exec(pte))
                return;                         /* not an executable page... */

        page = pte_page(pte);
        /* don't use VADDR: it may not be mapped on this CPU (or may have just been flushed): */
        addr = (unsigned long) page_address(page);

        if (test_bit(PG_arch_1, &page->flags))
                return;                         /* i-cache is already coherent with d-cache */

        flush_icache_range(addr, addr + PAGE_SIZE);
        set_bit(PG_arch_1, &page->flags);       /* mark page as clean */
}

inline void
ia64_set_rbs_bot (void)
{
        unsigned long stack_size = current->signal->rlim[RLIMIT_STACK].rlim_max & -16;

        if (stack_size > MAX_USER_STACK_SIZE)
                stack_size = MAX_USER_STACK_SIZE;
        current->thread.rbs_bot = STACK_TOP - stack_size;
}

/*
 * This performs some platform-dependent address space initialization.
 * On IA-64, we want to setup the VM area for the register backing
 * store (which grows upwards) and install the gateway page which is
 * used for signal trampolines, etc.
 */
void
ia64_init_addr_space (void)
{
        struct vm_area_struct *vma;

        ia64_set_rbs_bot();

        /*
         * If we're out of memory and kmem_cache_alloc() returns NULL, we simply ignore
         * the problem.  When the process attempts to write to the register backing store
         * for the first time, it will get a SEGFAULT in this case.
         */
        vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
        if (vma) {
                memset(vma, 0, sizeof(*vma));
                vma->vm_mm = current->mm;
                vma->vm_start = current->thread.rbs_bot & PAGE_MASK;
                vma->vm_end = vma->vm_start + PAGE_SIZE;
                vma->vm_page_prot = protection_map[VM_DATA_DEFAULT_FLAGS & 0x7];
                vma->vm_flags = VM_DATA_DEFAULT_FLAGS | VM_GROWSUP;
                down_write(&current->mm->mmap_sem);
                if (insert_vm_struct(current->mm, vma)) {
                        up_write(&current->mm->mmap_sem);
                        kmem_cache_free(vm_area_cachep, vma);
                        return;
                }
                up_write(&current->mm->mmap_sem);
        }

        /* map NaT-page at address zero to speed up speculative dereferencing of NULL: */
        if (!(current->personality & MMAP_PAGE_ZERO)) {
                vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
                if (vma) {
                        memset(vma, 0, sizeof(*vma));
                        vma->vm_mm = current->mm;
                        vma->vm_end = PAGE_SIZE;
                        vma->vm_page_prot = __pgprot(pgprot_val(PAGE_READONLY) | _PAGE_MA_NAT);
                        vma->vm_flags = VM_READ | VM_MAYREAD | VM_IO | VM_RESERVED;
                        down_write(&current->mm->mmap_sem);
                        if (insert_vm_struct(current->mm, vma)) {
                                up_write(&current->mm->mmap_sem);
                                kmem_cache_free(vm_area_cachep, vma);
                                return;
                        }
                        up_write(&current->mm->mmap_sem);
                }
        }
}

void
free_initmem (void)
{
        unsigned long addr, eaddr;

        addr = (unsigned long) ia64_imva(__init_begin);
        eaddr = (unsigned long) ia64_imva(__init_end);
        while (addr < eaddr) {
                ClearPageReserved(virt_to_page(addr));
                set_page_count(virt_to_page(addr), 1);
                free_page(addr);
                ++totalram_pages;
                addr += PAGE_SIZE;
        }
        printk(KERN_INFO "Freeing unused kernel memory: %ldkB freed\n",
               (__init_end - __init_begin) >> 10);
}

void
free_initrd_mem (unsigned long start, unsigned long end)
{
        struct page *page;
        /*
         * EFI uses 4KB pages while the kernel can use 4KB or bigger.
         * Thus EFI and the kernel may have different page sizes. It is
         * therefore possible to have the initrd share the same page as
         * the end of the kernel (given current setup).
         *
         * To avoid freeing/using the wrong page (kernel sized) we:
         *      - align up the beginning of initrd
         *      - align down the end of initrd
         *
         *  |             |
         *  |=============| a000
         *  |             |
         *  |             |
         *  |             | 9000
         *  |/////////////|
         *  |/////////////|
         *  |=============| 8000
         *  |///INITRD////|
         *  |/////////////|
         *  |/////////////| 7000
         *  |             |
         *  |KKKKKKKKKKKKK|
         *  |=============| 6000
         *  |KKKKKKKKKKKKK|
         *  |KKKKKKKKKKKKK|
         *  K=kernel using 8KB pages
         *
         * In this example, we must free page 8000 ONLY. So we must align up
         * initrd_start and keep initrd_end as is.
         */
        start = PAGE_ALIGN(start);
        end = end & PAGE_MASK;

        if (start < end)
                printk(KERN_INFO "Freeing initrd memory: %ldkB freed\n", (end - start) >> 10);

        for (; start < end; start += PAGE_SIZE) {
                if (!virt_addr_valid(start))
                        continue;
                page = virt_to_page(start);
                ClearPageReserved(page);
                set_page_count(page, 1);
                free_page(start);
                ++totalram_pages;
        }
}

/*
 * This installs a clean page in the kernel's page table.
 */
struct page *
put_kernel_page (struct page *page, unsigned long address, pgprot_t pgprot)
{
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        if (!PageReserved(page))
                printk(KERN_ERR "put_kernel_page: page at 0x%p not in reserved memory\n",
                       page_address(page));

        pgd = pgd_offset_k(address);            /* note: this is NOT pgd_offset()! */

        spin_lock(&init_mm.page_table_lock);
        {
                pud = pud_alloc(&init_mm, pgd, address);
                if (!pud)
                        goto out;

                pmd = pmd_alloc(&init_mm, pud, address);
                if (!pmd)
                        goto out;
                pte = pte_alloc_map(&init_mm, pmd, address);
                if (!pte)
                        goto out;
                if (!pte_none(*pte)) {
                        pte_unmap(pte);
                        goto out;
                }
                set_pte(pte, mk_pte(page, pgprot));
                pte_unmap(pte);
        }
  out:  spin_unlock(&init_mm.page_table_lock);
        /* no need for flush_tlb */
        return page;
}

static void
setup_gate (void)
{
        struct page *page;

        /*
         * Map the gate page twice: once read-only to export the ELF headers etc. and once
         * execute-only page to enable privilege-promotion via "epc":
         */
        page = virt_to_page(ia64_imva(__start_gate_section));
        put_kernel_page(page, GATE_ADDR, PAGE_READONLY);
#ifdef HAVE_BUGGY_SEGREL
        page = virt_to_page(ia64_imva(__start_gate_section + PAGE_SIZE));
        put_kernel_page(page, GATE_ADDR + PAGE_SIZE, PAGE_GATE);
#else
        put_kernel_page(page, GATE_ADDR + PERCPU_PAGE_SIZE, PAGE_GATE);
#endif
        ia64_patch_gate();
}

void __devinit
ia64_mmu_init (void *my_cpu_data)
{
        unsigned long psr, pta, impl_va_bits;
        extern void __devinit tlb_init (void);

#ifdef CONFIG_DISABLE_VHPT
#       define VHPT_ENABLE_BIT  0
#else
#       define VHPT_ENABLE_BIT  1
#endif

        /* Pin mapping for percpu area into TLB */
        psr = ia64_clear_ic();
        ia64_itr(0x2, IA64_TR_PERCPU_DATA, PERCPU_ADDR,
                 pte_val(pfn_pte(__pa(my_cpu_data) >> PAGE_SHIFT, PAGE_KERNEL)),
                 PERCPU_PAGE_SHIFT);

        ia64_set_psr(psr);
        ia64_srlz_i();

        /*
         * Check if the virtually mapped linear page table (VMLPT) overlaps with a mapped
         * address space.  The IA-64 architecture guarantees that at least 50 bits of
         * virtual address space are implemented but if we pick a large enough page size
         * (e.g., 64KB), the mapped address space is big enough that it will overlap with
         * VMLPT.  I assume that once we run on machines big enough to warrant 64KB pages,
         * IMPL_VA_MSB will be significantly bigger, so this is unlikely to become a
         * problem in practice.  Alternatively, we could truncate the top of the mapped
         * address space to not permit mappings that would overlap with the VMLPT.
         * --davidm 00/12/06
         */
#       define pte_bits                 3
#       define mapped_space_bits        (3*(PAGE_SHIFT - pte_bits) + PAGE_SHIFT)
        /*
         * The virtual page table has to cover the entire implemented address space within
         * a region even though not all of this space may be mappable.  The reason for
         * this is that the Access bit and Dirty bit fault handlers perform
         * non-speculative accesses to the virtual page table, so the address range of the
         * virtual page table itself needs to be covered by virtual page table.
         */
#       define vmlpt_bits               (impl_va_bits - PAGE_SHIFT + pte_bits)
#       define POW2(n)                  (1ULL << (n))

        impl_va_bits = ffz(~(local_cpu_data->unimpl_va_mask | (7UL << 61)));

        if (impl_va_bits < 51 || impl_va_bits > 61)
                panic("CPU has bogus IMPL_VA_MSB value of %lu!\n", impl_va_bits - 1);

        /* place the VMLPT at the end of each page-table mapped region: */
        pta = POW2(61) - POW2(vmlpt_bits);

        if (POW2(mapped_space_bits) >= pta)
                panic("mm/init: overlap between virtually mapped linear page table and "
                      "mapped kernel space!");
        /*
         * Set the (virtually mapped linear) page table address.  Bit
         * 8 selects between the short and long format, bits 2-7 the
         * size of the table, and bit 0 whether the VHPT walker is
         * enabled.
         */
        ia64_set_pta(pta | (0 << 8) | (vmlpt_bits << 2) | VHPT_ENABLE_BIT);

        ia64_tlb_init();

#ifdef  CONFIG_HUGETLB_PAGE
        ia64_set_rr(HPAGE_REGION_BASE, HPAGE_SHIFT << 2);
        ia64_srlz_d();
#endif
}

#ifdef CONFIG_VIRTUAL_MEM_MAP

int
create_mem_map_page_table (u64 start, u64 end, void *arg)
{
        unsigned long address, start_page, end_page;
        struct page *map_start, *map_end;
        int node;
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        map_start = vmem_map + (__pa(start) >> PAGE_SHIFT);
        map_end   = vmem_map + (__pa(end) >> PAGE_SHIFT);

        start_page = (unsigned long) map_start & PAGE_MASK;
        end_page = PAGE_ALIGN((unsigned long) map_end);
        node = paddr_to_nid(__pa(start));

        for (address = start_page; address < end_page; address += PAGE_SIZE) {
                pgd = pgd_offset_k(address);
                if (pgd_none(*pgd))
                        pgd_populate(&init_mm, pgd, alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE));
                pud = pud_offset(pgd, address);

                if (pud_none(*pud))
                        pud_populate(&init_mm, pud, alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE));
                pmd = pmd_offset(pud, address);

                if (pmd_none(*pmd))
                        pmd_populate_kernel(&init_mm, pmd, alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE));
                pte = pte_offset_kernel(pmd, address);

                if (pte_none(*pte))
                        set_pte(pte, pfn_pte(__pa(alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE)) >> PAGE_SHIFT,
                                             PAGE_KERNEL));
        }
        return 0;
}

struct memmap_init_callback_data {
        struct page *start;
        struct page *end;
        int nid;
        unsigned long zone;
};

static int
virtual_memmap_init (u64 start, u64 end, void *arg)
{
        struct memmap_init_callback_data *args;
        struct page *map_start, *map_end;

        args = (struct memmap_init_callback_data *) arg;
        map_start = vmem_map + (__pa(start) >> PAGE_SHIFT);
        map_end   = vmem_map + (__pa(end) >> PAGE_SHIFT);

        if (map_start < args->start)
                map_start = args->start;
        if (map_end > args->end)
                map_end = args->end;

        /*
         * We have to initialize "out of bounds" struct page elements that fit completely
         * on the same pages that were allocated for the "in bounds" elements because they
         * may be referenced later (and found to be "reserved").
         */
        map_start -= ((unsigned long) map_start & (PAGE_SIZE - 1)) / sizeof(struct page);
        map_end += ((PAGE_ALIGN((unsigned long) map_end) - (unsigned long) map_end)
                    / sizeof(struct page));

        if (map_start < map_end)
                memmap_init_zone((unsigned long)(map_end - map_start),
                                 args->nid, args->zone, page_to_pfn(map_start));
        return 0;
}

void
memmap_init (unsigned long size, int nid, unsigned long zone,
             unsigned long start_pfn)
{
        if (!vmem_map)
                memmap_init_zone(size, nid, zone, start_pfn);
        else {
                struct page *start;
                struct memmap_init_callback_data args;

                start = pfn_to_page(start_pfn);
                args.start = start;
                args.end = start + size;
                args.nid = nid;
                args.zone = zone;

                efi_memmap_walk(virtual_memmap_init, &args);
        }
}

int
ia64_pfn_valid (unsigned long pfn)
{
        char byte;
        struct page *pg = pfn_to_page(pfn);

        return     (__get_user(byte, (char __user *) pg) == 0)
                && ((((u64)pg & PAGE_MASK) == (((u64)(pg + 1) - 1) & PAGE_MASK))
                        || (__get_user(byte, (char __user *) (pg + 1) - 1) == 0));
}
EXPORT_SYMBOL(ia64_pfn_valid);

int
find_largest_hole (u64 start, u64 end, void *arg)
{
        u64 *max_gap = arg;

        static u64 last_end = PAGE_OFFSET;

        /* NOTE: this algorithm assumes efi memmap table is ordered */

        if (*max_gap < (start - last_end))
                *max_gap = start - last_end;
        last_end = end;
        return 0;
}
#endif /* CONFIG_VIRTUAL_MEM_MAP */

static int
count_reserved_pages (u64 start, u64 end, void *arg)
{
        unsigned long num_reserved = 0;
        unsigned long *count = arg;

        for (; start < end; start += PAGE_SIZE)
                if (PageReserved(virt_to_page(start)))
                        ++num_reserved;
        *count += num_reserved;
        return 0;
}

/*
 * Boot command-line option "nolwsys" can be used to disable the use of any light-weight
 * system call handler.  When this option is in effect, all fsyscalls will end up bubbling
 * down into the kernel and calling the normal (heavy-weight) syscall handler.  This is
 * useful for performance testing, but conceivably could also come in handy for debugging
 * purposes.
 */

static int nolwsys;

static int __init
nolwsys_setup (char *s)
{
        nolwsys = 1;
        return 1;
}

__setup("nolwsys", nolwsys_setup);

void
mem_init (void)
{
        long reserved_pages, codesize, datasize, initsize;
        unsigned long num_pgt_pages;
        pg_data_t *pgdat;
        int i;
        static struct kcore_list kcore_mem, kcore_vmem, kcore_kernel;

#ifdef CONFIG_PCI
        /*
         * This needs to be called _after_ the command line has been parsed but _before_
         * any drivers that may need the PCI DMA interface are initialized or bootmem has
         * been freed.
         */
        platform_dma_init();
#endif

#ifndef CONFIG_DISCONTIGMEM
        if (!mem_map)
                BUG();
        max_mapnr = max_low_pfn;
#endif

        high_memory = __va(max_low_pfn * PAGE_SIZE);

        kclist_add(&kcore_mem, __va(0), max_low_pfn * PAGE_SIZE);
        kclist_add(&kcore_vmem, (void *)VMALLOC_START, VMALLOC_END-VMALLOC_START);
        kclist_add(&kcore_kernel, _stext, _end - _stext);

        for_each_pgdat(pgdat)
                totalram_pages += free_all_bootmem_node(pgdat);

        reserved_pages = 0;
        efi_memmap_walk(count_reserved_pages, &reserved_pages);

        codesize =  (unsigned long) _etext - (unsigned long) _stext;
        datasize =  (unsigned long) _edata - (unsigned long) _etext;
        initsize =  (unsigned long) __init_end - (unsigned long) __init_begin;

        printk(KERN_INFO "Memory: %luk/%luk available (%luk code, %luk reserved, "
               "%luk data, %luk init)\n", (unsigned long) nr_free_pages() << (PAGE_SHIFT - 10),
               num_physpages << (PAGE_SHIFT - 10), codesize >> 10,
               reserved_pages << (PAGE_SHIFT - 10), datasize >> 10, initsize >> 10);

        /*
         * Allow for enough (cached) page table pages so that we can map the entire memory
         * at least once.  Each task also needs a couple of page tables pages, so add in a
         * fudge factor for that (don't use "threads-max" here; that would be wrong!).
         * Don't allow the cache to be more than 10% of total memory, though.
         */
#       define NUM_TASKS        500     /* typical number of tasks */
        num_pgt_pages = nr_free_pages() / PTRS_PER_PGD + NUM_TASKS;
        if (num_pgt_pages > nr_free_pages() / 10)
                num_pgt_pages = nr_free_pages() / 10;
        if (num_pgt_pages > (u64) pgt_cache_water[1])
                pgt_cache_water[1] = num_pgt_pages;

        /*
         * For fsyscall entrpoints with no light-weight handler, use the ordinary
         * (heavy-weight) handler, but mark it by setting bit 0, so the fsyscall entry
         * code can tell them apart.
         */
        for (i = 0; i < NR_syscalls; ++i) {
                extern unsigned long fsyscall_table[NR_syscalls];
                extern unsigned long sys_call_table[NR_syscalls];

                if (!fsyscall_table[i] || nolwsys)
                        fsyscall_table[i] = sys_call_table[i] | 1;
        }
        setup_gate();

#ifdef CONFIG_IA32_SUPPORT
        ia32_mem_init();
#endif
}