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

#include <linux/bootmem.h>
#include <linux/efi.h>
#include <linux/elf.h>
#include <linux/memblock.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 <linux/kexec.h>

#include <asm/dma.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/tlb.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/mca.h>

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

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

void
__ia64_sync_icache_dcache (pte_t pte)
{
        unsigned long addr;
        struct page *page;

        page = pte_page(pte);
        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 << compound_order(page)));
        set_bit(PG_arch_1, &page->flags);       /* mark page as clean */
}

/*
 * Since DMA is i-cache coherent, any (complete) pages that were written via
 * DMA can be marked as "clean" so that lazy_mmu_prot_update() doesn't have to
 * flush them when they get mapped into an executable vm-area.
 */
void
dma_mark_clean(void *addr, size_t size)
{
        unsigned long pg_addr, end;

        pg_addr = PAGE_ALIGN((unsigned long) addr);
        end = (unsigned long) addr + size;
        while (pg_addr + PAGE_SIZE <= end) {
                struct page *page = virt_to_page(pg_addr);
                set_bit(PG_arch_1, &page->flags);
                pg_addr += PAGE_SIZE;
        }
}

inline void
ia64_set_rbs_bot (void)
{
        unsigned long stack_size = rlimit_max(RLIMIT_STACK) & -16;

        if (stack_size > MAX_USER_STACK_SIZE)
                stack_size = MAX_USER_STACK_SIZE;
        current->thread.rbs_bot = PAGE_ALIGN(current->mm->start_stack - 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_zalloc(vm_area_cachep, GFP_KERNEL);
        if (vma) {
                INIT_LIST_HEAD(&vma->anon_vma_chain);
                vma->vm_mm = current->mm;
                vma->vm_start = current->thread.rbs_bot & PAGE_MASK;
                vma->vm_end = vma->vm_start + PAGE_SIZE;
                vma->vm_flags = VM_DATA_DEFAULT_FLAGS|VM_GROWSUP|VM_ACCOUNT;
                vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
                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_zalloc(vm_area_cachep, GFP_KERNEL);
                if (vma) {
                        INIT_LIST_HEAD(&vma->anon_vma_chain);
                        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_DONTEXPAND | VM_DONTDUMP;
                        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)
{
        free_reserved_area(ia64_imva(__init_begin), ia64_imva(__init_end),
                           -1, "unused kernel");
}

void __init
free_initrd_mem (unsigned long start, unsigned long end)
{
        /*
         * 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;
                free_reserved_page(virt_to_page(start));
        }
}

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

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

        {
                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_kernel(pmd, address);
                if (!pte)
                        goto out;
                if (!pte_none(*pte))
                        goto out;
                set_pte(pte, mk_pte(page, pgprot));
        }
  out:
        /* no need for flush_tlb */
        return page;
}

static void __init
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);
        /* Fill in the holes (if any) with read-only zero pages: */
        {
                unsigned long addr;

                for (addr = GATE_ADDR + PAGE_SIZE;
                     addr < GATE_ADDR + PERCPU_PAGE_SIZE;
                     addr += PAGE_SIZE)
                {
                        put_kernel_page(ZERO_PAGE(0), addr,
                                        PAGE_READONLY);
                        put_kernel_page(ZERO_PAGE(0), addr + PERCPU_PAGE_SIZE,
                                        PAGE_READONLY);
                }
        }
#endif
        ia64_patch_gate();
}

static struct vm_area_struct gate_vma;

static int __init gate_vma_init(void)
{
        gate_vma.vm_mm = NULL;
        gate_vma.vm_start = FIXADDR_USER_START;
        gate_vma.vm_end = FIXADDR_USER_END;
        gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
        gate_vma.vm_page_prot = __P101;

        return 0;
}
__initcall(gate_vma_init);

struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
        return &gate_vma;
}

int in_gate_area_no_mm(unsigned long addr)
{
        if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
                return 1;
        return 0;
}

int in_gate_area(struct mm_struct *mm, unsigned long addr)
{
        return in_gate_area_no_mm(addr);
}

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

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

        /*
         * 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);
        /*
         * mapped_space_bits - PAGE_SHIFT is the total number of ptes we need,
         * which must fit into "vmlpt_bits - pte_bits" slots. Second half of
         * the test makes sure that our mapped space doesn't overlap the
         * unimplemented hole in the middle of the region.
         */
        if ((mapped_space_bits - PAGE_SHIFT > vmlpt_bits - pte_bits) ||
            (mapped_space_bits > impl_va_bits - 1))
                panic("Cannot build a big enough virtual-linear page table"
                      " to cover mapped address space.\n"
                      " Try using a smaller page size.\n");


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

        /*
         * 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 vmemmap_find_next_valid_pfn(int node, int i)
{
        unsigned long end_address, hole_next_pfn;
        unsigned long stop_address;
        pg_data_t *pgdat = NODE_DATA(node);

        end_address = (unsigned long) &vmem_map[pgdat->node_start_pfn + i];
        end_address = PAGE_ALIGN(end_address);
        stop_address = (unsigned long) &vmem_map[pgdat_end_pfn(pgdat)];

        do {
                pgd_t *pgd;
                pud_t *pud;
                pmd_t *pmd;
                pte_t *pte;

                pgd = pgd_offset_k(end_address);
                if (pgd_none(*pgd)) {
                        end_address += PGDIR_SIZE;
                        continue;
                }

                pud = pud_offset(pgd, end_address);
                if (pud_none(*pud)) {
                        end_address += PUD_SIZE;
                        continue;
                }

                pmd = pmd_offset(pud, end_address);
                if (pmd_none(*pmd)) {
                        end_address += PMD_SIZE;
                        continue;
                }

                pte = pte_offset_kernel(pmd, end_address);
retry_pte:
                if (pte_none(*pte)) {
                        end_address += PAGE_SIZE;
                        pte++;
                        if ((end_address < stop_address) &&
                            (end_address != ALIGN(end_address, 1UL << PMD_SHIFT)))
                                goto retry_pte;
                        continue;
                }
                /* Found next valid vmem_map page */
                break;
        } while (end_address < stop_address);

        end_address = min(end_address, stop_address);
        end_address = end_address - (unsigned long) vmem_map + sizeof(struct page) - 1;
        hole_next_pfn = end_address / sizeof(struct page);
        return hole_next_pfn - pgdat->node_start_pfn;
}

int __init 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 __meminit
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),
                                 MEMMAP_EARLY);
        return 0;
}

void __meminit
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, MEMMAP_EARLY);
        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 __init 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 */

int __init register_active_ranges(u64 start, u64 len, int nid)
{
        u64 end = start + len;

#ifdef CONFIG_KEXEC
        if (start > crashk_res.start && start < crashk_res.end)
                start = crashk_res.end;
        if (end > crashk_res.start && end < crashk_res.end)
                end = crashk_res.start;
#endif

        if (start < end)
                memblock_add_node(__pa(start), end - start, nid);
        return 0;
}

int
find_max_min_low_pfn (u64 start, u64 end, void *arg)
{
        unsigned long pfn_start, pfn_end;
#ifdef CONFIG_FLATMEM
        pfn_start = (PAGE_ALIGN(__pa(start))) >> PAGE_SHIFT;
        pfn_end = (PAGE_ALIGN(__pa(end - 1))) >> PAGE_SHIFT;
#else
        pfn_start = GRANULEROUNDDOWN(__pa(start)) >> PAGE_SHIFT;
        pfn_end = GRANULEROUNDUP(__pa(end - 1)) >> PAGE_SHIFT;
#endif
        min_low_pfn = min(min_low_pfn, pfn_start);
        max_low_pfn = max(max_low_pfn, pfn_end);
        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 __initdata;

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

__setup("nolwsys", nolwsys_setup);

void __init
mem_init (void)
{
        int i;

        BUG_ON(PTRS_PER_PGD * sizeof(pgd_t) != PAGE_SIZE);
        BUG_ON(PTRS_PER_PMD * sizeof(pmd_t) != PAGE_SIZE);
        BUG_ON(PTRS_PER_PTE * sizeof(pte_t) != PAGE_SIZE);

#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

#ifdef CONFIG_FLATMEM
        BUG_ON(!mem_map);
#endif

        set_max_mapnr(max_low_pfn);
        high_memory = __va(max_low_pfn * PAGE_SIZE);
        free_all_bootmem();
        mem_init_print_info(NULL);

        /*
         * 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_MEMORY_HOTPLUG
int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
{
        pg_data_t *pgdat;
        struct zone *zone;
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long nr_pages = size >> PAGE_SHIFT;
        int ret;

        pgdat = NODE_DATA(nid);

        zone = pgdat->node_zones +
                zone_for_memory(nid, start, size, ZONE_NORMAL, for_device);
        ret = __add_pages(nid, zone, start_pfn, nr_pages);

        if (ret)
                printk("%s: Problem encountered in __add_pages() as ret=%d\n",
                       __func__,  ret);

        return ret;
}

#ifdef CONFIG_MEMORY_HOTREMOVE
int arch_remove_memory(u64 start, u64 size)
{
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long nr_pages = size >> PAGE_SHIFT;
        struct zone *zone;
        int ret;

        zone = page_zone(pfn_to_page(start_pfn));
        ret = __remove_pages(zone, start_pfn, nr_pages);
        if (ret)
                pr_warn("%s: Problem encountered in __remove_pages() as"
                        " ret=%d\n", __func__,  ret);

        return ret;
}
#endif
#endif

/**
 * show_mem - give short summary of memory stats
 *
 * Shows a simple page count of reserved and used pages in the system.
 * For discontig machines, it does this on a per-pgdat basis.
 */
void show_mem(unsigned int filter)
{
        int total_reserved = 0;
        unsigned long total_present = 0;
        pg_data_t *pgdat;

        printk(KERN_INFO "Mem-info:\n");
        show_free_areas(filter);
        printk(KERN_INFO "Node memory in pages:\n");
        for_each_online_pgdat(pgdat) {
                unsigned long present;
                unsigned long flags;
                int reserved = 0;
                int nid = pgdat->node_id;
                int zoneid;

                if (skip_free_areas_node(filter, nid))
                        continue;
                pgdat_resize_lock(pgdat, &flags);

                for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
                        struct zone *zone = &pgdat->node_zones[zoneid];
                        if (!populated_zone(zone))
                                continue;

                        reserved += zone->present_pages - zone->managed_pages;
                }
                present = pgdat->node_present_pages;

                pgdat_resize_unlock(pgdat, &flags);
                total_present += present;
                total_reserved += reserved;
                printk(KERN_INFO "Node %4d:  RAM: %11ld, rsvd: %8d, ",
                       nid, present, reserved);
        }
        printk(KERN_INFO "%ld pages of RAM\n", total_present);
        printk(KERN_INFO "%d reserved pages\n", total_reserved);
        printk(KERN_INFO "Total of %ld pages in page table cache\n",
               quicklist_total_size());
        printk(KERN_INFO "%ld free buffer pages\n", nr_free_buffer_pages());
}