mm, swap: bounds check swap_info array accesses to avoid NULL derefs

[mirror_ubuntu-disco-kernel.git] / mm / cma.c

/*
 * Contiguous Memory Allocator
 *
 * Copyright (c) 2010-2011 by Samsung Electronics.
 * Copyright IBM Corporation, 2013
 * Copyright LG Electronics Inc., 2014
 * Written by:
 *      Marek Szyprowski <m.szyprowski@samsung.com>
 *      Michal Nazarewicz <mina86@mina86.com>
 *      Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
 *      Joonsoo Kim <iamjoonsoo.kim@lge.com>
 *
 * 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 optional) any later version of the license.
 */

#define pr_fmt(fmt) "cma: " fmt

#ifdef CONFIG_CMA_DEBUG
#ifndef DEBUG
#  define DEBUG
#endif
#endif
#define CREATE_TRACE_POINTS

#include <linux/memblock.h>
#include <linux/err.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/log2.h>
#include <linux/cma.h>
#include <linux/highmem.h>
#include <linux/io.h>
#include <linux/kmemleak.h>
#include <trace/events/cma.h>

#include "cma.h"

struct cma cma_areas[MAX_CMA_AREAS];
unsigned cma_area_count;
static DEFINE_MUTEX(cma_mutex);

phys_addr_t cma_get_base(const struct cma *cma)
{
        return PFN_PHYS(cma->base_pfn);
}

unsigned long cma_get_size(const struct cma *cma)
{
        return cma->count << PAGE_SHIFT;
}

const char *cma_get_name(const struct cma *cma)
{
        return cma->name ? cma->name : "(undefined)";
}

static unsigned long cma_bitmap_aligned_mask(const struct cma *cma,
                                             unsigned int align_order)
{
        if (align_order <= cma->order_per_bit)
                return 0;
        return (1UL << (align_order - cma->order_per_bit)) - 1;
}

/*
 * Find the offset of the base PFN from the specified align_order.
 * The value returned is represented in order_per_bits.
 */
static unsigned long cma_bitmap_aligned_offset(const struct cma *cma,
                                               unsigned int align_order)
{
        return (cma->base_pfn & ((1UL << align_order) - 1))
                >> cma->order_per_bit;
}

static unsigned long cma_bitmap_pages_to_bits(const struct cma *cma,
                                              unsigned long pages)
{
        return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit;
}

static void cma_clear_bitmap(struct cma *cma, unsigned long pfn,
                             unsigned int count)
{
        unsigned long bitmap_no, bitmap_count;

        bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit;
        bitmap_count = cma_bitmap_pages_to_bits(cma, count);

        mutex_lock(&cma->lock);
        bitmap_clear(cma->bitmap, bitmap_no, bitmap_count);
        mutex_unlock(&cma->lock);
}

static int __init cma_activate_area(struct cma *cma)
{
        int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long);
        unsigned long base_pfn = cma->base_pfn, pfn = base_pfn;
        unsigned i = cma->count >> pageblock_order;
        struct zone *zone;

        cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);

        if (!cma->bitmap)
                return -ENOMEM;

        WARN_ON_ONCE(!pfn_valid(pfn));
        zone = page_zone(pfn_to_page(pfn));

        do {
                unsigned j;

                base_pfn = pfn;
                for (j = pageblock_nr_pages; j; --j, pfn++) {
                        WARN_ON_ONCE(!pfn_valid(pfn));
                        /*
                         * alloc_contig_range requires the pfn range
                         * specified to be in the same zone. Make this
                         * simple by forcing the entire CMA resv range
                         * to be in the same zone.
                         */
                        if (page_zone(pfn_to_page(pfn)) != zone)
                                goto not_in_zone;
                }
                init_cma_reserved_pageblock(pfn_to_page(base_pfn));
        } while (--i);

        mutex_init(&cma->lock);

#ifdef CONFIG_CMA_DEBUGFS
        INIT_HLIST_HEAD(&cma->mem_head);
        spin_lock_init(&cma->mem_head_lock);
#endif

        return 0;

not_in_zone:
        pr_err("CMA area %s could not be activated\n", cma->name);
        kfree(cma->bitmap);
        cma->count = 0;
        return -EINVAL;
}

static int __init cma_init_reserved_areas(void)
{
        int i;

        for (i = 0; i < cma_area_count; i++) {
                int ret = cma_activate_area(&cma_areas[i]);

                if (ret)
                        return ret;
        }

        return 0;
}
core_initcall(cma_init_reserved_areas);

/**
 * cma_init_reserved_mem() - create custom contiguous area from reserved memory
 * @base: Base address of the reserved area
 * @size: Size of the reserved area (in bytes),
 * @order_per_bit: Order of pages represented by one bit on bitmap.
 * @name: The name of the area. If this parameter is NULL, the name of
 *        the area will be set to "cmaN", where N is a running counter of
 *        used areas.
 * @res_cma: Pointer to store the created cma region.
 *
 * This function creates custom contiguous area from already reserved memory.
 */
int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
                                 unsigned int order_per_bit,
                                 const char *name,
                                 struct cma **res_cma)
{
        struct cma *cma;
        phys_addr_t alignment;

        /* Sanity checks */
        if (cma_area_count == ARRAY_SIZE(cma_areas)) {
                pr_err("Not enough slots for CMA reserved regions!\n");
                return -ENOSPC;
        }

        if (!size || !memblock_is_region_reserved(base, size))
                return -EINVAL;

        /* ensure minimal alignment required by mm core */
        alignment = PAGE_SIZE <<
                        max_t(unsigned long, MAX_ORDER - 1, pageblock_order);

        /* alignment should be aligned with order_per_bit */
        if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
                return -EINVAL;

        if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size)
                return -EINVAL;

        /*
         * Each reserved area must be initialised later, when more kernel
         * subsystems (like slab allocator) are available.
         */
        cma = &cma_areas[cma_area_count];
        if (name) {
                cma->name = name;
        } else {
                cma->name = kasprintf(GFP_KERNEL, "cma%d\n", cma_area_count);
                if (!cma->name)
                        return -ENOMEM;
        }
        cma->base_pfn = PFN_DOWN(base);
        cma->count = size >> PAGE_SHIFT;
        cma->order_per_bit = order_per_bit;
        *res_cma = cma;
        cma_area_count++;
        totalcma_pages += (size / PAGE_SIZE);

        return 0;
}

/**
 * cma_declare_contiguous() - reserve custom contiguous area
 * @base: Base address of the reserved area optional, use 0 for any
 * @size: Size of the reserved area (in bytes),
 * @limit: End address of the reserved memory (optional, 0 for any).
 * @alignment: Alignment for the CMA area, should be power of 2 or zero
 * @order_per_bit: Order of pages represented by one bit on bitmap.
 * @fixed: hint about where to place the reserved area
 * @name: The name of the area. See function cma_init_reserved_mem()
 * @res_cma: Pointer to store the created cma region.
 *
 * This function reserves memory from early allocator. It should be
 * called by arch specific code once the early allocator (memblock or bootmem)
 * has been activated and all other subsystems have already allocated/reserved
 * memory. This function allows to create custom reserved areas.
 *
 * If @fixed is true, reserve contiguous area at exactly @base.  If false,
 * reserve in range from @base to @limit.
 */
int __init cma_declare_contiguous(phys_addr_t base,
                        phys_addr_t size, phys_addr_t limit,
                        phys_addr_t alignment, unsigned int order_per_bit,
                        bool fixed, const char *name, struct cma **res_cma)
{
        phys_addr_t memblock_end = memblock_end_of_DRAM();
        phys_addr_t highmem_start;
        int ret = 0;

        /*
         * We can't use __pa(high_memory) directly, since high_memory
         * isn't a valid direct map VA, and DEBUG_VIRTUAL will (validly)
         * complain. Find the boundary by adding one to the last valid
         * address.
         */
        highmem_start = __pa(high_memory - 1) + 1;
        pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
                __func__, &size, &base, &limit, &alignment);

        if (cma_area_count == ARRAY_SIZE(cma_areas)) {
                pr_err("Not enough slots for CMA reserved regions!\n");
                return -ENOSPC;
        }

        if (!size)
                return -EINVAL;

        if (alignment && !is_power_of_2(alignment))
                return -EINVAL;

        /*
         * Sanitise input arguments.
         * Pages both ends in CMA area could be merged into adjacent unmovable
         * migratetype page by page allocator's buddy algorithm. In the case,
         * you couldn't get a contiguous memory, which is not what we want.
         */
        alignment = max(alignment,  (phys_addr_t)PAGE_SIZE <<
                          max_t(unsigned long, MAX_ORDER - 1, pageblock_order));
        base = ALIGN(base, alignment);
        size = ALIGN(size, alignment);
        limit &= ~(alignment - 1);

        if (!base)
                fixed = false;

        /* size should be aligned with order_per_bit */
        if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
                return -EINVAL;

        /*
         * If allocating at a fixed base the request region must not cross the
         * low/high memory boundary.
         */
        if (fixed && base < highmem_start && base + size > highmem_start) {
                ret = -EINVAL;
                pr_err("Region at %pa defined on low/high memory boundary (%pa)\n",
                        &base, &highmem_start);
                goto err;
        }

        /*
         * If the limit is unspecified or above the memblock end, its effective
         * value will be the memblock end. Set it explicitly to simplify further
         * checks.
         */
        if (limit == 0 || limit > memblock_end)
                limit = memblock_end;

        /* Reserve memory */
        if (fixed) {
                if (memblock_is_region_reserved(base, size) ||
                    memblock_reserve(base, size) < 0) {
                        ret = -EBUSY;
                        goto err;
                }
        } else {
                phys_addr_t addr = 0;

                /*
                 * All pages in the reserved area must come from the same zone.
                 * If the requested region crosses the low/high memory boundary,
                 * try allocating from high memory first and fall back to low
                 * memory in case of failure.
                 */
                if (base < highmem_start && limit > highmem_start) {
                        addr = memblock_alloc_range(size, alignment,
                                                    highmem_start, limit,
                                                    MEMBLOCK_NONE);
                        limit = highmem_start;
                }

                if (!addr) {
                        addr = memblock_alloc_range(size, alignment, base,
                                                    limit,
                                                    MEMBLOCK_NONE);
                        if (!addr) {
                                ret = -ENOMEM;
                                goto err;
                        }
                }

                /*
                 * kmemleak scans/reads tracked objects for pointers to other
                 * objects but this address isn't mapped and accessible
                 */
                kmemleak_ignore_phys(addr);
                base = addr;
        }

        ret = cma_init_reserved_mem(base, size, order_per_bit, name, res_cma);
        if (ret)
                goto free_mem;

        pr_info("Reserved %ld MiB at %pa\n", (unsigned long)size / SZ_1M,
                &base);
        return 0;

free_mem:
        memblock_free(base, size);
err:
        pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
        return ret;
}

#ifdef CONFIG_CMA_DEBUG
static void cma_debug_show_areas(struct cma *cma)
{
        unsigned long next_zero_bit, next_set_bit;
        unsigned long start = 0;
        unsigned int nr_zero, nr_total = 0;

        mutex_lock(&cma->lock);
        pr_info("number of available pages: ");
        for (;;) {
                next_zero_bit = find_next_zero_bit(cma->bitmap, cma->count, start);
                if (next_zero_bit >= cma->count)
                        break;
                next_set_bit = find_next_bit(cma->bitmap, cma->count, next_zero_bit);
                nr_zero = next_set_bit - next_zero_bit;
                pr_cont("%s%u@%lu", nr_total ? "+" : "", nr_zero, next_zero_bit);
                nr_total += nr_zero;
                start = next_zero_bit + nr_zero;
        }
        pr_cont("=> %u free of %lu total pages\n", nr_total, cma->count);
        mutex_unlock(&cma->lock);
}
#else
static inline void cma_debug_show_areas(struct cma *cma) { }
#endif

/**
 * cma_alloc() - allocate pages from contiguous area
 * @cma:   Contiguous memory region for which the allocation is performed.
 * @count: Requested number of pages.
 * @align: Requested alignment of pages (in PAGE_SIZE order).
 * @no_warn: Avoid printing message about failed allocation
 *
 * This function allocates part of contiguous memory on specific
 * contiguous memory area.
 */
struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
                       bool no_warn)
{
        unsigned long mask, offset;
        unsigned long pfn = -1;
        unsigned long start = 0;
        unsigned long bitmap_maxno, bitmap_no, bitmap_count;
        size_t i;
        struct page *page = NULL;
        int ret = -ENOMEM;

        if (!cma || !cma->count)
                return NULL;

        pr_debug("%s(cma %p, count %zu, align %d)\n", __func__, (void *)cma,
                 count, align);

        if (!count)
                return NULL;

        mask = cma_bitmap_aligned_mask(cma, align);
        offset = cma_bitmap_aligned_offset(cma, align);
        bitmap_maxno = cma_bitmap_maxno(cma);
        bitmap_count = cma_bitmap_pages_to_bits(cma, count);

        if (bitmap_count > bitmap_maxno)
                return NULL;

        for (;;) {
                mutex_lock(&cma->lock);
                bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
                                bitmap_maxno, start, bitmap_count, mask,
                                offset);
                if (bitmap_no >= bitmap_maxno) {
                        mutex_unlock(&cma->lock);
                        break;
                }
                bitmap_set(cma->bitmap, bitmap_no, bitmap_count);
                /*
                 * It's safe to drop the lock here. We've marked this region for
                 * our exclusive use. If the migration fails we will take the
                 * lock again and unmark it.
                 */
                mutex_unlock(&cma->lock);

                pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
                mutex_lock(&cma_mutex);
                ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA,
                                     GFP_KERNEL | (no_warn ? __GFP_NOWARN : 0));
                mutex_unlock(&cma_mutex);
                if (ret == 0) {
                        page = pfn_to_page(pfn);
                        break;
                }

                cma_clear_bitmap(cma, pfn, count);
                if (ret != -EBUSY)
                        break;

                pr_debug("%s(): memory range at %p is busy, retrying\n",
                         __func__, pfn_to_page(pfn));
                /* try again with a bit different memory target */
                start = bitmap_no + mask + 1;
        }

        trace_cma_alloc(pfn, page, count, align);

        /*
         * CMA can allocate multiple page blocks, which results in different
         * blocks being marked with different tags. Reset the tags to ignore
         * those page blocks.
         */
        if (page) {
                for (i = 0; i < count; i++)
                        page_kasan_tag_reset(page + i);
        }

        if (ret && !no_warn && printk_ratelimit()) {
                pr_err("%s: alloc failed, req-size: %zu pages, ret: %d\n",
                        __func__, count, ret);
                cma_debug_show_areas(cma);
        }

        pr_debug("%s(): returned %p\n", __func__, page);
        return page;
}

/**
 * cma_release() - release allocated pages
 * @cma:   Contiguous memory region for which the allocation is performed.
 * @pages: Allocated pages.
 * @count: Number of allocated pages.
 *
 * This function releases memory allocated by alloc_cma().
 * It returns false when provided pages do not belong to contiguous area and
 * true otherwise.
 */
bool cma_release(struct cma *cma, const struct page *pages, unsigned int count)
{
        unsigned long pfn;

        if (!cma || !pages)
                return false;

        pr_debug("%s(page %p)\n", __func__, (void *)pages);

        pfn = page_to_pfn(pages);

        if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
                return false;

        VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);

        free_contig_range(pfn, count);
        cma_clear_bitmap(cma, pfn, count);
        trace_cma_release(pfn, pages, count);

        return true;
}

int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data)
{
        int i;

        for (i = 0; i < cma_area_count; i++) {
                int ret = it(&cma_areas[i], data);

                if (ret)
                        return ret;
        }

        return 0;
}