// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * address space "slices" (meta-segments) support
 *
 * Copyright (C) 2007 Benjamin Herrenschmidt, IBM Corporation.
 *
 * Based on hugetlb implementation
 *
 * Copyright (C) 2003 David Gibson, IBM Corporation.
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/err.h>
#include <linux/spinlock.h>
#include <linux/export.h>
#include <linux/hugetlb.h>
#include <linux/sched/mm.h>
#include <linux/security.h>
#include <asm/mman.h>
#include <asm/mmu.h>
#include <asm/spu.h>
#include <asm/hugetlb.h>
#include <asm/mmu_context.h>

static DEFINE_SPINLOCK(slice_convert_lock);

#ifdef DEBUG
int _slice_debug = 1;

static void slice_print_mask(const char *label, const struct slice_mask *mask)
{
        if (!_slice_debug)
                return;
        pr_devel("%s low_slice: %*pbl\n", label,
                        (int)SLICE_NUM_LOW, &mask->low_slices);
        pr_devel("%s high_slice: %*pbl\n", label,
                        (int)SLICE_NUM_HIGH, mask->high_slices);
}

#define slice_dbg(fmt...) do { if (_slice_debug) pr_devel(fmt); } while (0)

#else

static void slice_print_mask(const char *label, const struct slice_mask *mask) {}
#define slice_dbg(fmt...)

#endif

static inline notrace bool slice_addr_is_low(unsigned long addr)
{
        u64 tmp = (u64)addr;

        return tmp < SLICE_LOW_TOP;
}

static void slice_range_to_mask(unsigned long start, unsigned long len,
                                struct slice_mask *ret)
{
        unsigned long end = start + len - 1;

        ret->low_slices = 0;
        if (SLICE_NUM_HIGH)
                bitmap_zero(ret->high_slices, SLICE_NUM_HIGH);

        if (slice_addr_is_low(start)) {
                unsigned long mend = min(end,
                                         (unsigned long)(SLICE_LOW_TOP - 1));

                ret->low_slices = (1u << (GET_LOW_SLICE_INDEX(mend) + 1))
                        - (1u << GET_LOW_SLICE_INDEX(start));
        }

        if (SLICE_NUM_HIGH && !slice_addr_is_low(end)) {
                unsigned long start_index = GET_HIGH_SLICE_INDEX(start);
                unsigned long align_end = ALIGN(end, (1UL << SLICE_HIGH_SHIFT));
                unsigned long count = GET_HIGH_SLICE_INDEX(align_end) - start_index;

                bitmap_set(ret->high_slices, start_index, count);
        }
}

static int slice_area_is_free(struct mm_struct *mm, unsigned long addr,
                              unsigned long len)
{
        struct vm_area_struct *vma;

        if ((mm_ctx_slb_addr_limit(&mm->context) - len) < addr)
                return 0;
        vma = find_vma(mm, addr);
        return (!vma || (addr + len) <= vm_start_gap(vma));
}

static int slice_low_has_vma(struct mm_struct *mm, unsigned long slice)
{
        return !slice_area_is_free(mm, slice << SLICE_LOW_SHIFT,
                                   1ul << SLICE_LOW_SHIFT);
}

static int slice_high_has_vma(struct mm_struct *mm, unsigned long slice)
{
        unsigned long start = slice << SLICE_HIGH_SHIFT;
        unsigned long end = start + (1ul << SLICE_HIGH_SHIFT);

        /* Hack, so that each addresses is controlled by exactly one
         * of the high or low area bitmaps, the first high area starts
         * at 4GB, not 0 */
        if (start == 0)
                start = (unsigned long)SLICE_LOW_TOP;

        return !slice_area_is_free(mm, start, end - start);
}

static void slice_mask_for_free(struct mm_struct *mm, struct slice_mask *ret,
                                unsigned long high_limit)
{
        unsigned long i;

        ret->low_slices = 0;
        if (SLICE_NUM_HIGH)
                bitmap_zero(ret->high_slices, SLICE_NUM_HIGH);

        for (i = 0; i < SLICE_NUM_LOW; i++)
                if (!slice_low_has_vma(mm, i))
                        ret->low_slices |= 1u << i;

        if (slice_addr_is_low(high_limit - 1))
                return;

        for (i = 0; i < GET_HIGH_SLICE_INDEX(high_limit); i++)
                if (!slice_high_has_vma(mm, i))
                        __set_bit(i, ret->high_slices);
}

static bool slice_check_range_fits(struct mm_struct *mm,
                           const struct slice_mask *available,
                           unsigned long start, unsigned long len)
{
        unsigned long end = start + len - 1;
        u64 low_slices = 0;

        if (slice_addr_is_low(start)) {
                unsigned long mend = min(end,
                                         (unsigned long)(SLICE_LOW_TOP - 1));

                low_slices = (1u << (GET_LOW_SLICE_INDEX(mend) + 1))
                                - (1u << GET_LOW_SLICE_INDEX(start));
        }
        if ((low_slices & available->low_slices) != low_slices)
                return false;

        if (SLICE_NUM_HIGH && !slice_addr_is_low(end)) {
                unsigned long start_index = GET_HIGH_SLICE_INDEX(start);
                unsigned long align_end = ALIGN(end, (1UL << SLICE_HIGH_SHIFT));
                unsigned long count = GET_HIGH_SLICE_INDEX(align_end) - start_index;
                unsigned long i;

                for (i = start_index; i < start_index + count; i++) {
                        if (!test_bit(i, available->high_slices))
                                return false;
                }
        }

        return true;
}

static void slice_flush_segments(void *parm)
{
#ifdef CONFIG_PPC64
        struct mm_struct *mm = parm;
        unsigned long flags;

        if (mm != current->active_mm)
                return;

        copy_mm_to_paca(current->active_mm);

        local_irq_save(flags);
        slb_flush_and_restore_bolted();
        local_irq_restore(flags);
#endif
}

static void slice_convert(struct mm_struct *mm,
                                const struct slice_mask *mask, int psize)
{
        int index, mask_index;
        /* Write the new slice psize bits */
        unsigned char *hpsizes, *lpsizes;
        struct slice_mask *psize_mask, *old_mask;
        unsigned long i, flags;
        int old_psize;

        slice_dbg("slice_convert(mm=%p, psize=%d)\n", mm, psize);
        slice_print_mask(" mask", mask);

        psize_mask = slice_mask_for_size(&mm->context, psize);

        /* We need to use a spinlock here to protect against
         * concurrent 64k -> 4k demotion ...
         */
        spin_lock_irqsave(&slice_convert_lock, flags);

        lpsizes = mm_ctx_low_slices(&mm->context);
        for (i = 0; i < SLICE_NUM_LOW; i++) {
                if (!(mask->low_slices & (1u << i)))
                        continue;

                mask_index = i & 0x1;
                index = i >> 1;

                /* Update the slice_mask */
                old_psize = (lpsizes[index] >> (mask_index * 4)) & 0xf;
                old_mask = slice_mask_for_size(&mm->context, old_psize);
                old_mask->low_slices &= ~(1u << i);
                psize_mask->low_slices |= 1u << i;

                /* Update the sizes array */
                lpsizes[index] = (lpsizes[index] & ~(0xf << (mask_index * 4))) |
                                (((unsigned long)psize) << (mask_index * 4));
        }

        hpsizes = mm_ctx_high_slices(&mm->context);
        for (i = 0; i < GET_HIGH_SLICE_INDEX(mm_ctx_slb_addr_limit(&mm->context)); i++) {
                if (!test_bit(i, mask->high_slices))
                        continue;

                mask_index = i & 0x1;
                index = i >> 1;

                /* Update the slice_mask */
                old_psize = (hpsizes[index] >> (mask_index * 4)) & 0xf;
                old_mask = slice_mask_for_size(&mm->context, old_psize);
                __clear_bit(i, old_mask->high_slices);
                __set_bit(i, psize_mask->high_slices);

                /* Update the sizes array */
                hpsizes[index] = (hpsizes[index] & ~(0xf << (mask_index * 4))) |
                                (((unsigned long)psize) << (mask_index * 4));
        }

        slice_dbg(" lsps=%lx, hsps=%lx\n",
                  (unsigned long)mm_ctx_low_slices(&mm->context),
                  (unsigned long)mm_ctx_high_slices(&mm->context));

        spin_unlock_irqrestore(&slice_convert_lock, flags);

#ifdef CONFIG_SPU_BASE
        spu_flush_all_slbs(mm);
#endif
}

/*
 * Compute which slice addr is part of;
 * set *boundary_addr to the start or end boundary of that slice
 * (depending on 'end' parameter);
 * return boolean indicating if the slice is marked as available in the
 * 'available' slice_mark.
 */
static bool slice_scan_available(unsigned long addr,
                                 const struct slice_mask *available,
                                 int end, unsigned long *boundary_addr)
{
        unsigned long slice;
        if (slice_addr_is_low(addr)) {
                slice = GET_LOW_SLICE_INDEX(addr);
                *boundary_addr = (slice + end) << SLICE_LOW_SHIFT;
                return !!(available->low_slices & (1u << slice));
        } else {
                slice = GET_HIGH_SLICE_INDEX(addr);
                *boundary_addr = (slice + end) ?
                        ((slice + end) << SLICE_HIGH_SHIFT) : SLICE_LOW_TOP;
                return !!test_bit(slice, available->high_slices);
        }
}

static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
                                              unsigned long addr, unsigned long len,
                                              const struct slice_mask *available,
                                              int psize, unsigned long high_limit)
{
        int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
        unsigned long found, next_end;
        struct vm_unmapped_area_info info = {
                .length = len,
                .align_mask = PAGE_MASK & ((1ul << pshift) - 1),
        };
        /*
         * Check till the allow max value for this mmap request
         */
        while (addr < high_limit) {
                info.low_limit = addr;
                if (!slice_scan_available(addr, available, 1, &addr))
                        continue;

 next_slice:
                /*
                 * At this point [info.low_limit; addr) covers
                 * available slices only and ends at a slice boundary.
                 * Check if we need to reduce the range, or if we can
                 * extend it to cover the next available slice.
                 */
                if (addr >= high_limit)
                        addr = high_limit;
                else if (slice_scan_available(addr, available, 1, &next_end)) {
                        addr = next_end;
                        goto next_slice;
                }
                info.high_limit = addr;

                found = vm_unmapped_area(&info);
                if (!(found & ~PAGE_MASK))
                        return found;
        }

        return -ENOMEM;
}

static unsigned long slice_find_area_topdown(struct mm_struct *mm,
                                             unsigned long addr, unsigned long len,
                                             const struct slice_mask *available,
                                             int psize, unsigned long high_limit)
{
        int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
        unsigned long found, prev;
        struct vm_unmapped_area_info info = {
                .flags = VM_UNMAPPED_AREA_TOPDOWN,
                .length = len,
                .align_mask = PAGE_MASK & ((1ul << pshift) - 1),
        };
        unsigned long min_addr = max(PAGE_SIZE, mmap_min_addr);

        /*
         * If we are trying to allocate above DEFAULT_MAP_WINDOW
         * Add the different to the mmap_base.
         * Only for that request for which high_limit is above
         * DEFAULT_MAP_WINDOW we should apply this.
         */
        if (high_limit > DEFAULT_MAP_WINDOW)
                addr += mm_ctx_slb_addr_limit(&mm->context) - DEFAULT_MAP_WINDOW;

        while (addr > min_addr) {
                info.high_limit = addr;
                if (!slice_scan_available(addr - 1, available, 0, &addr))
                        continue;

 prev_slice:
                /*
                 * At this point [addr; info.high_limit) covers
                 * available slices only and starts at a slice boundary.
                 * Check if we need to reduce the range, or if we can
                 * extend it to cover the previous available slice.
                 */
                if (addr < min_addr)
                        addr = min_addr;
                else if (slice_scan_available(addr - 1, available, 0, &prev)) {
                        addr = prev;
                        goto prev_slice;
                }
                info.low_limit = addr;

                found = vm_unmapped_area(&info);
                if (!(found & ~PAGE_MASK))
                        return found;
        }

        /*
         * A failed mmap() very likely causes application failure,
         * so fall back to the bottom-up function here. This scenario
         * can happen with large stack limits and large mmap()
         * allocations.
         */
        return slice_find_area_bottomup(mm, TASK_UNMAPPED_BASE, len, available, psize, high_limit);
}


static unsigned long slice_find_area(struct mm_struct *mm, unsigned long len,
                                     const struct slice_mask *mask, int psize,
                                     int topdown, unsigned long high_limit)
{
        if (topdown)
                return slice_find_area_topdown(mm, mm->mmap_base, len, mask, psize, high_limit);
        else
                return slice_find_area_bottomup(mm, mm->mmap_base, len, mask, psize, high_limit);
}

static inline void slice_copy_mask(struct slice_mask *dst,
                                        const struct slice_mask *src)
{
        dst->low_slices = src->low_slices;
        if (!SLICE_NUM_HIGH)
                return;
        bitmap_copy(dst->high_slices, src->high_slices, SLICE_NUM_HIGH);
}

static inline void slice_or_mask(struct slice_mask *dst,
                                        const struct slice_mask *src1,
                                        const struct slice_mask *src2)
{
        dst->low_slices = src1->low_slices | src2->low_slices;
        if (!SLICE_NUM_HIGH)
                return;
        bitmap_or(dst->high_slices, src1->high_slices, src2->high_slices, SLICE_NUM_HIGH);
}

static inline void slice_andnot_mask(struct slice_mask *dst,
                                        const struct slice_mask *src1,
                                        const struct slice_mask *src2)
{
        dst->low_slices = src1->low_slices & ~src2->low_slices;
        if (!SLICE_NUM_HIGH)
                return;
        bitmap_andnot(dst->high_slices, src1->high_slices, src2->high_slices, SLICE_NUM_HIGH);
}

#ifdef CONFIG_PPC_64K_PAGES
#define MMU_PAGE_BASE   MMU_PAGE_64K
#else
#define MMU_PAGE_BASE   MMU_PAGE_4K
#endif

unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
                                      unsigned long flags, unsigned int psize,
                                      int topdown)
{
        struct slice_mask good_mask;
        struct slice_mask potential_mask;
        const struct slice_mask *maskp;
        const struct slice_mask *compat_maskp = NULL;
        int fixed = (flags & MAP_FIXED);
        int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
        unsigned long page_size = 1UL << pshift;
        struct mm_struct *mm = current->mm;
        unsigned long newaddr;
        unsigned long high_limit;

        high_limit = DEFAULT_MAP_WINDOW;
        if (addr >= high_limit || (fixed && (addr + len > high_limit)))
                high_limit = TASK_SIZE;

        if (len > high_limit)
                return -ENOMEM;
        if (len & (page_size - 1))
                return -EINVAL;
        if (fixed) {
                if (addr & (page_size - 1))
                        return -EINVAL;
                if (addr > high_limit - len)
                        return -ENOMEM;
        }

        if (high_limit > mm_ctx_slb_addr_limit(&mm->context)) {
                /*
                 * Increasing the slb_addr_limit does not require
                 * slice mask cache to be recalculated because it should
                 * be already initialised beyond the old address limit.
                 */
                mm_ctx_set_slb_addr_limit(&mm->context, high_limit);

                on_each_cpu(slice_flush_segments, mm, 1);
        }

        /* Sanity checks */
        BUG_ON(mm->task_size == 0);
        BUG_ON(mm_ctx_slb_addr_limit(&mm->context) == 0);
        VM_BUG_ON(radix_enabled());

        slice_dbg("slice_get_unmapped_area(mm=%p, psize=%d...\n", mm, psize);
        slice_dbg(" addr=%lx, len=%lx, flags=%lx, topdown=%d\n",
                  addr, len, flags, topdown);

        /* If hint, make sure it matches our alignment restrictions */
        if (!fixed && addr) {
                addr = ALIGN(addr, page_size);
                slice_dbg(" aligned addr=%lx\n", addr);
                /* Ignore hint if it's too large or overlaps a VMA */
                if (addr > high_limit - len || addr < mmap_min_addr ||
                    !slice_area_is_free(mm, addr, len))
                        addr = 0;
        }

        /* First make up a "good" mask of slices that have the right size
         * already
         */
        maskp = slice_mask_for_size(&mm->context, psize);

        /*
         * Here "good" means slices that are already the right page size,
         * "compat" means slices that have a compatible page size (i.e.
         * 4k in a 64k pagesize kernel), and "free" means slices without
         * any VMAs.
         *
         * If MAP_FIXED:
         *      check if fits in good | compat => OK
         *      check if fits in good | compat | free => convert free
         *      else bad
         * If have hint:
         *      check if hint fits in good => OK
         *      check if hint fits in good | free => convert free
         * Otherwise:
         *      search in good, found => OK
         *      search in good | free, found => convert free
         *      search in good | compat | free, found => convert free.
         */

        /*
         * If we support combo pages, we can allow 64k pages in 4k slices
         * The mask copies could be avoided in most cases here if we had
         * a pointer to good mask for the next code to use.
         */
        if (IS_ENABLED(CONFIG_PPC_64K_PAGES) && psize == MMU_PAGE_64K) {
                compat_maskp = slice_mask_for_size(&mm->context, MMU_PAGE_4K);
                if (fixed)
                        slice_or_mask(&good_mask, maskp, compat_maskp);
                else
                        slice_copy_mask(&good_mask, maskp);
        } else {
                slice_copy_mask(&good_mask, maskp);
        }

        slice_print_mask(" good_mask", &good_mask);
        if (compat_maskp)
                slice_print_mask(" compat_mask", compat_maskp);

        /* First check hint if it's valid or if we have MAP_FIXED */
        if (addr != 0 || fixed) {
                /* Check if we fit in the good mask. If we do, we just return,
                 * nothing else to do
                 */
                if (slice_check_range_fits(mm, &good_mask, addr, len)) {
                        slice_dbg(" fits good !\n");
                        newaddr = addr;
                        goto return_addr;
                }
        } else {
                /* Now let's see if we can find something in the existing
                 * slices for that size
                 */
                newaddr = slice_find_area(mm, len, &good_mask,
                                          psize, topdown, high_limit);
                if (newaddr != -ENOMEM) {
                        /* Found within the good mask, we don't have to setup,
                         * we thus return directly
                         */
                        slice_dbg(" found area at 0x%lx\n", newaddr);
                        goto return_addr;
                }
        }
        /*
         * We don't fit in the good mask, check what other slices are
         * empty and thus can be converted
         */
        slice_mask_for_free(mm, &potential_mask, high_limit);
        slice_or_mask(&potential_mask, &potential_mask, &good_mask);
        slice_print_mask(" potential", &potential_mask);

        if (addr != 0 || fixed) {
                if (slice_check_range_fits(mm, &potential_mask, addr, len)) {
                        slice_dbg(" fits potential !\n");
                        newaddr = addr;
                        goto convert;
                }
        }

        /* If we have MAP_FIXED and failed the above steps, then error out */
        if (fixed)
                return -EBUSY;

        slice_dbg(" search...\n");

        /* If we had a hint that didn't work out, see if we can fit
         * anywhere in the good area.
         */
        if (addr) {
                newaddr = slice_find_area(mm, len, &good_mask,
                                          psize, topdown, high_limit);
                if (newaddr != -ENOMEM) {
                        slice_dbg(" found area at 0x%lx\n", newaddr);
                        goto return_addr;
                }
        }

        /* Now let's see if we can find something in the existing slices
         * for that size plus free slices
         */
        newaddr = slice_find_area(mm, len, &potential_mask,
                                  psize, topdown, high_limit);

        if (IS_ENABLED(CONFIG_PPC_64K_PAGES) && newaddr == -ENOMEM &&
            psize == MMU_PAGE_64K) {
                /* retry the search with 4k-page slices included */
                slice_or_mask(&potential_mask, &potential_mask, compat_maskp);
                newaddr = slice_find_area(mm, len, &potential_mask,
                                          psize, topdown, high_limit);
        }

        if (newaddr == -ENOMEM)
                return -ENOMEM;

        slice_range_to_mask(newaddr, len, &potential_mask);
        slice_dbg(" found potential area at 0x%lx\n", newaddr);
        slice_print_mask(" mask", &potential_mask);

 convert:
        /*
         * Try to allocate the context before we do slice convert
         * so that we handle the context allocation failure gracefully.
         */
        if (need_extra_context(mm, newaddr)) {
                if (alloc_extended_context(mm, newaddr) < 0)
                        return -ENOMEM;
        }

        slice_andnot_mask(&potential_mask, &potential_mask, &good_mask);
        if (compat_maskp && !fixed)
                slice_andnot_mask(&potential_mask, &potential_mask, compat_maskp);
        if (potential_mask.low_slices ||
                (SLICE_NUM_HIGH &&
                 !bitmap_empty(potential_mask.high_slices, SLICE_NUM_HIGH))) {
                slice_convert(mm, &potential_mask, psize);
                if (psize > MMU_PAGE_BASE)
                        on_each_cpu(slice_flush_segments, mm, 1);
        }
        return newaddr;

return_addr:
        if (need_extra_context(mm, newaddr)) {
                if (alloc_extended_context(mm, newaddr) < 0)
                        return -ENOMEM;
        }
        return newaddr;
}
EXPORT_SYMBOL_GPL(slice_get_unmapped_area);

#ifdef CONFIG_HUGETLB_PAGE
static int file_to_psize(struct file *file)
{
        struct hstate *hstate = hstate_file(file);

        return shift_to_mmu_psize(huge_page_shift(hstate));
}
#else
static int file_to_psize(struct file *file)
{
        return 0;
}
#endif

unsigned long arch_get_unmapped_area(struct file *filp,
                                     unsigned long addr,
                                     unsigned long len,
                                     unsigned long pgoff,
                                     unsigned long flags,
                                     vm_flags_t vm_flags)
{
        unsigned int psize;

        if (radix_enabled())
                return generic_get_unmapped_area(filp, addr, len, pgoff, flags, vm_flags);

        if (filp && is_file_hugepages(filp))
                psize = file_to_psize(filp);
        else
                psize = mm_ctx_user_psize(&current->mm->context);

        return slice_get_unmapped_area(addr, len, flags, psize, 0);
}

unsigned long arch_get_unmapped_area_topdown(struct file *filp,
                                             const unsigned long addr0,
                                             const unsigned long len,
                                             const unsigned long pgoff,
                                             const unsigned long flags,
                                             vm_flags_t vm_flags)
{
        unsigned int psize;

        if (radix_enabled())
                return generic_get_unmapped_area_topdown(filp, addr0, len, pgoff, flags, vm_flags);

        if (filp && is_file_hugepages(filp))
                psize = file_to_psize(filp);
        else
                psize = mm_ctx_user_psize(&current->mm->context);

        return slice_get_unmapped_area(addr0, len, flags, psize, 1);
}

unsigned int notrace get_slice_psize(struct mm_struct *mm, unsigned long addr)
{
        unsigned char *psizes;
        int index, mask_index;

        VM_BUG_ON(radix_enabled());

        if (slice_addr_is_low(addr)) {
                psizes = mm_ctx_low_slices(&mm->context);
                index = GET_LOW_SLICE_INDEX(addr);
        } else {
                psizes = mm_ctx_high_slices(&mm->context);
                index = GET_HIGH_SLICE_INDEX(addr);
        }
        mask_index = index & 0x1;
        return (psizes[index >> 1] >> (mask_index * 4)) & 0xf;
}
EXPORT_SYMBOL_GPL(get_slice_psize);

void slice_init_new_context_exec(struct mm_struct *mm)
{
        unsigned char *hpsizes, *lpsizes;
        struct slice_mask *mask;
        unsigned int psize = mmu_virtual_psize;

        slice_dbg("slice_init_new_context_exec(mm=%p)\n", mm);

        /*
         * In the case of exec, use the default limit. In the
         * case of fork it is just inherited from the mm being
         * duplicated.
         */
        mm_ctx_set_slb_addr_limit(&mm->context, SLB_ADDR_LIMIT_DEFAULT);
        mm_ctx_set_user_psize(&mm->context, psize);

        /*
         * Set all slice psizes to the default.
         */
        lpsizes = mm_ctx_low_slices(&mm->context);
        memset(lpsizes, (psize << 4) | psize, SLICE_NUM_LOW >> 1);

        hpsizes = mm_ctx_high_slices(&mm->context);
        memset(hpsizes, (psize << 4) | psize, SLICE_NUM_HIGH >> 1);

        /*
         * Slice mask cache starts zeroed, fill the default size cache.
         */
        mask = slice_mask_for_size(&mm->context, psize);
        mask->low_slices = ~0UL;
        if (SLICE_NUM_HIGH)
                bitmap_fill(mask->high_slices, SLICE_NUM_HIGH);
}

void slice_setup_new_exec(void)
{
        struct mm_struct *mm = current->mm;

        slice_dbg("slice_setup_new_exec(mm=%p)\n", mm);

        if (!is_32bit_task())
                return;

        mm_ctx_set_slb_addr_limit(&mm->context, DEFAULT_MAP_WINDOW);
}

void slice_set_range_psize(struct mm_struct *mm, unsigned long start,
                           unsigned long len, unsigned int psize)
{
        struct slice_mask mask;

        VM_BUG_ON(radix_enabled());

        slice_range_to_mask(start, len, &mask);
        slice_convert(mm, &mask, psize);
}

#ifdef CONFIG_HUGETLB_PAGE
/*
 * is_hugepage_only_range() is used by generic code to verify whether
 * a normal mmap mapping (non hugetlbfs) is valid on a given area.
 *
 * until the generic code provides a more generic hook and/or starts
 * calling arch get_unmapped_area for MAP_FIXED (which our implementation
 * here knows how to deal with), we hijack it to keep standard mappings
 * away from us.
 *
 * because of that generic code limitation, MAP_FIXED mapping cannot
 * "convert" back a slice with no VMAs to the standard page size, only
 * get_unmapped_area() can. It would be possible to fix it here but I
 * prefer working on fixing the generic code instead.
 *
 * WARNING: This will not work if hugetlbfs isn't enabled since the
 * generic code will redefine that function as 0 in that. This is ok
 * for now as we only use slices with hugetlbfs enabled. This should
 * be fixed as the generic code gets fixed.
 */
int slice_is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
                           unsigned long len)
{
        const struct slice_mask *maskp;
        unsigned int psize = mm_ctx_user_psize(&mm->context);

        VM_BUG_ON(radix_enabled());

        maskp = slice_mask_for_size(&mm->context, psize);

        /* We need to account for 4k slices too */
        if (IS_ENABLED(CONFIG_PPC_64K_PAGES) && psize == MMU_PAGE_64K) {
                const struct slice_mask *compat_maskp;
                struct slice_mask available;

                compat_maskp = slice_mask_for_size(&mm->context, MMU_PAGE_4K);
                slice_or_mask(&available, maskp, compat_maskp);
                return !slice_check_range_fits(mm, &available, addr, len);
        }

        return !slice_check_range_fits(mm, maskp, addr, len);
}

unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
{
        /* With radix we don't use slice, so derive it from vma*/
        if (radix_enabled())
                return vma_kernel_pagesize(vma);

        return 1UL << mmu_psize_to_shift(get_slice_psize(vma->vm_mm, vma->vm_start));
}
#endif