vmem.c

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/*
 *    Copyright IBM Corp. 2006
 *    Author(s): Heiko Carstens <[email protected]>
 */

#include <linux/bootmem.h>
#include <linux/pfn.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/hugetlb.h>
#include <linux/slab.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/setup.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>

static DEFINE_MUTEX(vmem_mutex);

struct memory_segment {
    struct list_head list;
    unsigned long start;
    unsigned long size;
};

static LIST_HEAD(mem_segs);

static void __ref *vmem_alloc_pages(unsigned int order)
{
    if (slab_is_available())
        return (void *)__get_free_pages(GFP_KERNEL, order);
    return alloc_bootmem_pages((1 << order) * PAGE_SIZE);
}

static inline pud_t *vmem_pud_alloc(void)
{
    pud_t *pud = NULL;

#ifdef CONFIG_64BIT
    pud = vmem_alloc_pages(2);
    if (!pud)
        return NULL;
    clear_table((unsigned long *) pud, _REGION3_ENTRY_EMPTY, PAGE_SIZE * 4);
#endif
    return pud;
}

static inline pmd_t *vmem_pmd_alloc(void)
{
    pmd_t *pmd = NULL;

#ifdef CONFIG_64BIT
    pmd = vmem_alloc_pages(2);
    if (!pmd)
        return NULL;
    clear_table((unsigned long *) pmd, _SEGMENT_ENTRY_EMPTY, PAGE_SIZE * 4);
#endif
    return pmd;
}

static pte_t __ref *vmem_pte_alloc(unsigned long address)
{
    pte_t *pte;

    if (slab_is_available())
        pte = (pte_t *) page_table_alloc(&init_mm, address);
    else
        pte = alloc_bootmem(PTRS_PER_PTE * sizeof(pte_t));
    if (!pte)
        return NULL;
    clear_table((unsigned long *) pte, _PAGE_TYPE_EMPTY,
            PTRS_PER_PTE * sizeof(pte_t));
    return pte;
}

/*
 * Add a physical memory range to the 1:1 mapping.
 */
static int vmem_add_mem(unsigned long start, unsigned long size, int ro)
{
    unsigned long end = start + size;
    unsigned long address = start;
    pgd_t *pg_dir;
    pud_t *pu_dir;
    pmd_t *pm_dir;
    pte_t *pt_dir;
    pte_t  pte;
    int ret = -ENOMEM;

    while (address < end) {
        pg_dir = pgd_offset_k(address);
        if (pgd_none(*pg_dir)) {
            pu_dir = vmem_pud_alloc();
            if (!pu_dir)
                goto out;
            pgd_populate(&init_mm, pg_dir, pu_dir);
        }

        pu_dir = pud_offset(pg_dir, address);
        if (pud_none(*pu_dir)) {
            pm_dir = vmem_pmd_alloc();
            if (!pm_dir)
                goto out;
            pud_populate(&init_mm, pu_dir, pm_dir);
        }

        pte = mk_pte_phys(address, __pgprot(ro ? _PAGE_RO : 0));
        pm_dir = pmd_offset(pu_dir, address);

#if defined(CONFIG_64BIT) && !defined(CONFIG_DEBUG_PAGEALLOC)
        if (MACHINE_HAS_EDAT1 && pmd_none(*pm_dir) && address &&
            !(address & ~PMD_MASK) && (address + PMD_SIZE <= end)) {
            pte_val(pte) |= _SEGMENT_ENTRY_LARGE;
            pmd_val(*pm_dir) = pte_val(pte);
            address += PMD_SIZE;
            continue;
        }
#endif
        if (pmd_none(*pm_dir)) {
            pt_dir = vmem_pte_alloc(address);
            if (!pt_dir)
                goto out;
            pmd_populate(&init_mm, pm_dir, pt_dir);
        }

        pt_dir = pte_offset_kernel(pm_dir, address);
        *pt_dir = pte;
        address += PAGE_SIZE;
    }
    ret = 0;
out:
    flush_tlb_kernel_range(start, end);
    return ret;
}

/*
 * Remove a physical memory range from the 1:1 mapping.
 * Currently only invalidates page table entries.
 */
static void vmem_remove_range(unsigned long start, unsigned long size)
{
    unsigned long end = start + size;
    unsigned long address = start;
    pgd_t *pg_dir;
    pud_t *pu_dir;
    pmd_t *pm_dir;
    pte_t *pt_dir;
    pte_t  pte;

    pte_val(pte) = _PAGE_TYPE_EMPTY;
    while (address < end) {
        pg_dir = pgd_offset_k(address);
        if (pgd_none(*pg_dir)) {
            address += PGDIR_SIZE;
            continue;
        }
        pu_dir = pud_offset(pg_dir, address);
        if (pud_none(*pu_dir)) {
            address += PUD_SIZE;
            continue;
        }
        pm_dir = pmd_offset(pu_dir, address);
        if (pmd_none(*pm_dir)) {
            address += PMD_SIZE;
            continue;
        }
        if (pmd_large(*pm_dir)) {
            pmd_clear(pm_dir);
            address += PMD_SIZE;
            continue;
        }
        pt_dir = pte_offset_kernel(pm_dir, address);
        *pt_dir = pte;
        address += PAGE_SIZE;
    }
    flush_tlb_kernel_range(start, end);
}

/*
 * Add a backed mem_map array to the virtual mem_map array.
 */
int __meminit vmemmap_populate(struct page *start, unsigned long nr, int node)
{
    unsigned long address, start_addr, end_addr;
    pgd_t *pg_dir;
    pud_t *pu_dir;
    pmd_t *pm_dir;
    pte_t *pt_dir;
    pte_t  pte;
    int ret = -ENOMEM;

    start_addr = (unsigned long) start;
    end_addr = (unsigned long) (start + nr);

    for (address = start_addr; address < end_addr; address += PAGE_SIZE) {
        pg_dir = pgd_offset_k(address);
        if (pgd_none(*pg_dir)) {
            pu_dir = vmem_pud_alloc();
            if (!pu_dir)
                goto out;
            pgd_populate(&init_mm, pg_dir, pu_dir);
        }

        pu_dir = pud_offset(pg_dir, address);
        if (pud_none(*pu_dir)) {
            pm_dir = vmem_pmd_alloc();
            if (!pm_dir)
                goto out;
            pud_populate(&init_mm, pu_dir, pm_dir);
        }

        pm_dir = pmd_offset(pu_dir, address);
        if (pmd_none(*pm_dir)) {
            pt_dir = vmem_pte_alloc(address);
            if (!pt_dir)
                goto out;
            pmd_populate(&init_mm, pm_dir, pt_dir);
        }

        pt_dir = pte_offset_kernel(pm_dir, address);
        if (pte_none(*pt_dir)) {
            unsigned long new_page;

            new_page =__pa(vmem_alloc_pages(0));
            if (!new_page)
                goto out;
            pte = pfn_pte(new_page >> PAGE_SHIFT, PAGE_KERNEL);
            *pt_dir = pte;
        }
    }
    memset(start, 0, nr * sizeof(struct page));
    ret = 0;
out:
    flush_tlb_kernel_range(start_addr, end_addr);
    return ret;
}

/*
 * Add memory segment to the segment list if it doesn't overlap with
 * an already present segment.
 */
static int insert_memory_segment(struct memory_segment *seg)
{
    struct memory_segment *tmp;

    if (seg->start + seg->size > VMEM_MAX_PHYS ||
        seg->start + seg->size < seg->start)
        return -ERANGE;

    list_for_each_entry(tmp, &mem_segs, list) {
        if (seg->start >= tmp->start + tmp->size)
            continue;
        if (seg->start + seg->size <= tmp->start)
            continue;
        return -ENOSPC;
    }
    list_add(&seg->list, &mem_segs);
    return 0;
}

/*
 * Remove memory segment from the segment list.
 */
static void remove_memory_segment(struct memory_segment *seg)
{
    list_del(&seg->list);
}

static void __remove_shared_memory(struct memory_segment *seg)
{
    remove_memory_segment(seg);
    vmem_remove_range(seg->start, seg->size);
}

int vmem_remove_mapping(unsigned long start, unsigned long size)
{
    struct memory_segment *seg;
    int ret;

    mutex_lock(&vmem_mutex);

    ret = -ENOENT;
    list_for_each_entry(seg, &mem_segs, list) {
        if (seg->start == start && seg->size == size)
            break;
    }

    if (seg->start != start || seg->size != size)
        goto out;

    ret = 0;
    __remove_shared_memory(seg);
    kfree(seg);
out:
    mutex_unlock(&vmem_mutex);
    return ret;
}

int vmem_add_mapping(unsigned long start, unsigned long size)
{
    struct memory_segment *seg;
    int ret;

    mutex_lock(&vmem_mutex);
    ret = -ENOMEM;
    seg = kzalloc(sizeof(*seg), GFP_KERNEL);
    if (!seg)
        goto out;
    seg->start = start;
    seg->size = size;

    ret = insert_memory_segment(seg);
    if (ret)
        goto out_free;

    ret = vmem_add_mem(start, size, 0);
    if (ret)
        goto out_remove;
    goto out;

out_remove:
    __remove_shared_memory(seg);
out_free:
    kfree(seg);
out:
    mutex_unlock(&vmem_mutex);
    return ret;
}

/*
 * map whole physical memory to virtual memory (identity mapping)
 * we reserve enough space in the vmalloc area for vmemmap to hotplug
 * additional memory segments.
 */
void __init vmem_map_init(void)
{
    unsigned long ro_start, ro_end;
    unsigned long start, end;
    int i;

    ro_start = PFN_ALIGN((unsigned long)&_stext);
    ro_end = (unsigned long)&_eshared & PAGE_MASK;
    for (i = 0; i < MEMORY_CHUNKS && memory_chunk[i].size > 0; i++) {
        if (memory_chunk[i].type == CHUNK_CRASHK ||
            memory_chunk[i].type == CHUNK_OLDMEM)
            continue;
        start = memory_chunk[i].addr;
        end = memory_chunk[i].addr + memory_chunk[i].size;
        if (start >= ro_end || end <= ro_start)
            vmem_add_mem(start, end - start, 0);
        else if (start >= ro_start && end <= ro_end)
            vmem_add_mem(start, end - start, 1);
        else if (start >= ro_start) {
            vmem_add_mem(start, ro_end - start, 1);
            vmem_add_mem(ro_end, end - ro_end, 0);
        } else if (end < ro_end) {
            vmem_add_mem(start, ro_start - start, 0);
            vmem_add_mem(ro_start, end - ro_start, 1);
        } else {
            vmem_add_mem(start, ro_start - start, 0);
            vmem_add_mem(ro_start, ro_end - ro_start, 1);
            vmem_add_mem(ro_end, end - ro_end, 0);
        }
    }
}

/*
 * Convert memory chunk array to a memory segment list so there is a single
 * list that contains both r/w memory and shared memory segments.
 */
static int __init vmem_convert_memory_chunk(void)
{
    struct memory_segment *seg;
    int i;

    mutex_lock(&vmem_mutex);
    for (i = 0; i < MEMORY_CHUNKS; i++) {
        if (!memory_chunk[i].size)
            continue;
        if (memory_chunk[i].type == CHUNK_CRASHK ||
            memory_chunk[i].type == CHUNK_OLDMEM)
            continue;
        seg = kzalloc(sizeof(*seg), GFP_KERNEL);
        if (!seg)
            panic("Out of memory...\n");
        seg->start = memory_chunk[i].addr;
        seg->size = memory_chunk[i].size;
        insert_memory_segment(seg);
    }
    mutex_unlock(&vmem_mutex);
    return 0;
}

core_initcall(vmem_convert_memory_chunk);