Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 823 insertions, 0 deletions

diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
new file mode 100644
index 000000000..53e9b58e8
--- /dev/null
+++ b/arch/powerpc/mm/slice.c
@@ -0,0 +1,823 @@
+/*
+ * address space "slices" (meta-segments) support
+ *
+ * Copyright (C) 2007 Benjamin Herrenschmidt, IBM Corporation.
+ *
+ * Based on hugetlb implementation
+ *
+ * Copyright (C) 2003 David Gibson, IBM Corporation.
+ *
+ * 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 option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#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/security.h>
+#include <asm/mman.h>
+#include <asm/mmu.h>
+#include <asm/copro.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 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->context.slb_addr_limit - 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);
+
+#ifdef CONFIG_PPC64
+	/* 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 = SLICE_LOW_TOP;
+#endif
+
+	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);
+}
+
+#ifdef CONFIG_PPC_BOOK3S_64
+static struct slice_mask *slice_mask_for_size(struct mm_struct *mm, int psize)
+{
+#ifdef CONFIG_PPC_64K_PAGES
+	if (psize == MMU_PAGE_64K)
+		return &mm->context.mask_64k;
+#endif
+	if (psize == MMU_PAGE_4K)
+		return &mm->context.mask_4k;
+#ifdef CONFIG_HUGETLB_PAGE
+	if (psize == MMU_PAGE_16M)
+		return &mm->context.mask_16m;
+	if (psize == MMU_PAGE_16G)
+		return &mm->context.mask_16g;
+#endif
+	BUG();
+}
+#elif defined(CONFIG_PPC_8xx)
+static struct slice_mask *slice_mask_for_size(struct mm_struct *mm, int psize)
+{
+	if (psize == mmu_virtual_psize)
+		return &mm->context.mask_base_psize;
+#ifdef CONFIG_HUGETLB_PAGE
+	if (psize == MMU_PAGE_512K)
+		return &mm->context.mask_512k;
+	if (psize == MMU_PAGE_8M)
+		return &mm->context.mask_8m;
+#endif
+	BUG();
+}
+#else
+#error "Must define the slice masks for page sizes supported by the platform"
+#endif
+
+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_rebolt();
+	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, psize);
+
+	/* We need to use a spinlock here to protect against
+	 * concurrent 64k -> 4k demotion ...
+	 */
+	spin_lock_irqsave(&slice_convert_lock, flags);
+
+	lpsizes = mm->context.low_slices_psize;
+	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, 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->context.high_slices_psize;
+	for (i = 0; i < GET_HIGH_SLICE_INDEX(mm->context.slb_addr_limit); 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, 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->context.low_slices_psize,
+		  (unsigned long)mm->context.high_slices_psize);
+
+	spin_unlock_irqrestore(&slice_convert_lock, flags);
+
+	copro_flush_all_slbs(mm);
+}
+
+/*
+ * 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 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 addr, found, next_end;
+	struct vm_unmapped_area_info info;
+
+	info.flags = 0;
+	info.length = len;
+	info.align_mask = PAGE_MASK & ((1ul << pshift) - 1);
+	info.align_offset = 0;
+
+	addr = TASK_UNMAPPED_BASE;
+	/*
+	 * 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 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 addr, found, prev;
+	struct vm_unmapped_area_info info;
+	unsigned long min_addr = max(PAGE_SIZE, mmap_min_addr);
+
+	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+	info.length = len;
+	info.align_mask = PAGE_MASK & ((1ul << pshift) - 1);
+	info.align_offset = 0;
+
+	addr = mm->mmap_base;
+	/*
+	 * 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->context.slb_addr_limit - 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, 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, len, mask, psize, high_limit);
+	else
+		return slice_find_area_bottomup(mm, 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->context.slb_addr_limit) {
+		/*
+		 * 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->context.slb_addr_limit = high_limit;
+
+		on_each_cpu(slice_flush_segments, mm, 1);
+	}
+
+	/* Sanity checks */
+	BUG_ON(mm->task_size == 0);
+	BUG_ON(mm->context.slb_addr_limit == 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_UP(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, 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, 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);
+
+#ifdef CONFIG_PPC_64K_PAGES
+	if (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);
+	}
+#endif
+
+	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);
+
+unsigned long arch_get_unmapped_area(struct file *filp,
+				     unsigned long addr,
+				     unsigned long len,
+				     unsigned long pgoff,
+				     unsigned long flags)
+{
+	return slice_get_unmapped_area(addr, len, flags,
+				       current->mm->context.user_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)
+{
+	return slice_get_unmapped_area(addr0, len, flags,
+				       current->mm->context.user_psize, 1);
+}
+
+unsigned int 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->context.low_slices_psize;
+		index = GET_LOW_SLICE_INDEX(addr);
+	} else {
+		psizes = mm->context.high_slices_psize;
+		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.
+	 */
+#ifdef CONFIG_PPC64
+	mm->context.slb_addr_limit = DEFAULT_MAP_WINDOW_USER64;
+#else
+	mm->context.slb_addr_limit = DEFAULT_MAP_WINDOW;
+#endif
+
+	mm->context.user_psize = psize;
+
+	/*
+	 * Set all slice psizes to the default.
+	 */
+	lpsizes = mm->context.low_slices_psize;
+	memset(lpsizes, (psize << 4) | psize, SLICE_NUM_LOW >> 1);
+
+	hpsizes = mm->context.high_slices_psize;
+	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, psize);
+	mask->low_slices = ~0UL;
+	if (SLICE_NUM_HIGH)
+		bitmap_fill(mask->high_slices, SLICE_NUM_HIGH);
+}
+
+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->context.user_psize;
+
+	VM_BUG_ON(radix_enabled());
+
+	maskp = slice_mask_for_size(mm, psize);
+#ifdef CONFIG_PPC_64K_PAGES
+	/* We need to account for 4k slices too */
+	if (psize == MMU_PAGE_64K) {
+		const struct slice_mask *compat_maskp;
+		struct slice_mask available;
+
+		compat_maskp = slice_mask_for_size(mm, MMU_PAGE_4K);
+		slice_or_mask(&available, maskp, compat_maskp);
+		return !slice_check_range_fits(mm, &available, addr, len);
+	}
+#endif
+
+	return !slice_check_range_fits(mm, maskp, addr, len);
+}
+#endif