Add the rt linux 4.1.3-rt3 as base

Import the rt linux 4.1.3-rt3 as OPNFV kvm base.

It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:

commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Sat Jul 25 12:13:34 2015 +0200

    Prepare v4.1.3-rt3

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.

Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>

1 files changed, 701 insertions, 0 deletions

diff --git a/kernel/arch/powerpc/mm/slice.c b/kernel/arch/powerpc/mm/slice.c
new file mode 100644
index 000000000..0f432a702
--- /dev/null
+++ b/kernel/arch/powerpc/mm/slice.c
@@ -0,0 +1,701 @@
+/*
+ * 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 <asm/mman.h>
+#include <asm/mmu.h>
+#include <asm/copro.h>
+#include <asm/hugetlb.h>
+
+/* some sanity checks */
+#if (PGTABLE_RANGE >> 43) > SLICE_MASK_SIZE
+#error PGTABLE_RANGE exceeds slice_mask high_slices size
+#endif
+
+static DEFINE_SPINLOCK(slice_convert_lock);
+
+
+#ifdef DEBUG
+int _slice_debug = 1;
+
+static void slice_print_mask(const char *label, struct slice_mask mask)
+{
+	char	*p, buf[16 + 3 + 64 + 1];
+	int	i;
+
+	if (!_slice_debug)
+		return;
+	p = buf;
+	for (i = 0; i < SLICE_NUM_LOW; i++)
+		*(p++) = (mask.low_slices & (1 << i)) ? '1' : '0';
+	*(p++) = ' ';
+	*(p++) = '-';
+	*(p++) = ' ';
+	for (i = 0; i < SLICE_NUM_HIGH; i++)
+		*(p++) = (mask.high_slices & (1ul << i)) ? '1' : '0';
+	*(p++) = 0;
+
+	printk(KERN_DEBUG "%s:%s\n", label, buf);
+}
+
+#define slice_dbg(fmt...) do { if (_slice_debug) pr_debug(fmt); } while(0)
+
+#else
+
+static void slice_print_mask(const char *label, struct slice_mask mask) {}
+#define slice_dbg(fmt...)
+
+#endif
+
+static struct slice_mask slice_range_to_mask(unsigned long start,
+					     unsigned long len)
+{
+	unsigned long end = start + len - 1;
+	struct slice_mask ret = { 0, 0 };
+
+	if (start < SLICE_LOW_TOP) {
+		unsigned long mend = min(end, SLICE_LOW_TOP);
+		unsigned long mstart = min(start, SLICE_LOW_TOP);
+
+		ret.low_slices = (1u << (GET_LOW_SLICE_INDEX(mend) + 1))
+			- (1u << GET_LOW_SLICE_INDEX(mstart));
+	}
+
+	if ((start + len) > SLICE_LOW_TOP)
+		ret.high_slices = (1ul << (GET_HIGH_SLICE_INDEX(end) + 1))
+			- (1ul << GET_HIGH_SLICE_INDEX(start));
+
+	return ret;
+}
+
+static int slice_area_is_free(struct mm_struct *mm, unsigned long addr,
+			      unsigned long len)
+{
+	struct vm_area_struct *vma;
+
+	if ((mm->task_size - len) < addr)
+		return 0;
+	vma = find_vma(mm, addr);
+	return (!vma || (addr + len) <= vma->vm_start);
+}
+
+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 = SLICE_LOW_TOP;
+
+	return !slice_area_is_free(mm, start, end - start);
+}
+
+static struct slice_mask slice_mask_for_free(struct mm_struct *mm)
+{
+	struct slice_mask ret = { 0, 0 };
+	unsigned long i;
+
+	for (i = 0; i < SLICE_NUM_LOW; i++)
+		if (!slice_low_has_vma(mm, i))
+			ret.low_slices |= 1u << i;
+
+	if (mm->task_size <= SLICE_LOW_TOP)
+		return ret;
+
+	for (i = 0; i < SLICE_NUM_HIGH; i++)
+		if (!slice_high_has_vma(mm, i))
+			ret.high_slices |= 1ul << i;
+
+	return ret;
+}
+
+static struct slice_mask slice_mask_for_size(struct mm_struct *mm, int psize)
+{
+	unsigned char *hpsizes;
+	int index, mask_index;
+	struct slice_mask ret = { 0, 0 };
+	unsigned long i;
+	u64 lpsizes;
+
+	lpsizes = mm->context.low_slices_psize;
+	for (i = 0; i < SLICE_NUM_LOW; i++)
+		if (((lpsizes >> (i * 4)) & 0xf) == psize)
+			ret.low_slices |= 1u << i;
+
+	hpsizes = mm->context.high_slices_psize;
+	for (i = 0; i < SLICE_NUM_HIGH; i++) {
+		mask_index = i & 0x1;
+		index = i >> 1;
+		if (((hpsizes[index] >> (mask_index * 4)) & 0xf) == psize)
+			ret.high_slices |= 1ul << i;
+	}
+
+	return ret;
+}
+
+static int slice_check_fit(struct slice_mask mask, struct slice_mask available)
+{
+	return (mask.low_slices & available.low_slices) == mask.low_slices &&
+		(mask.high_slices & available.high_slices) == mask.high_slices;
+}
+
+static void slice_flush_segments(void *parm)
+{
+	struct mm_struct *mm = parm;
+	unsigned long flags;
+
+	if (mm != current->active_mm)
+		return;
+
+	/* update the paca copy of the context struct */
+	get_paca()->context = current->active_mm->context;
+
+	local_irq_save(flags);
+	slb_flush_and_rebolt();
+	local_irq_restore(flags);
+}
+
+static void slice_convert(struct mm_struct *mm, struct slice_mask mask, int psize)
+{
+	int index, mask_index;
+	/* Write the new slice psize bits */
+	unsigned char *hpsizes;
+	u64 lpsizes;
+	unsigned long i, flags;
+
+	slice_dbg("slice_convert(mm=%p, psize=%d)\n", mm, psize);
+	slice_print_mask(" mask", mask);
+
+	/* 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))
+			lpsizes = (lpsizes & ~(0xful << (i * 4))) |
+				(((unsigned long)psize) << (i * 4));
+
+	/* Assign the value back */
+	mm->context.low_slices_psize = lpsizes;
+
+	hpsizes = mm->context.high_slices_psize;
+	for (i = 0; i < SLICE_NUM_HIGH; i++) {
+		mask_index = i & 0x1;
+		index = i >> 1;
+		if (mask.high_slices & (1ul << i))
+			hpsizes[index] = (hpsizes[index] &
+					  ~(0xf << (mask_index * 4))) |
+				(((unsigned long)psize) << (mask_index * 4));
+	}
+
+	slice_dbg(" lsps=%lx, hsps=%lx\n",
+		  mm->context.low_slices_psize,
+		  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,
+				 struct slice_mask available,
+				 int end,
+				 unsigned long *boundary_addr)
+{
+	unsigned long slice;
+	if (addr < SLICE_LOW_TOP) {
+		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 !!(available.high_slices & (1ul << slice));
+	}
+}
+
+static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
+					      unsigned long len,
+					      struct slice_mask available,
+					      int psize)
+{
+	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;
+	while (addr < TASK_SIZE) {
+		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 >= TASK_SIZE)
+			addr = TASK_SIZE;
+		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,
+					     struct slice_mask available,
+					     int psize)
+{
+	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
+	unsigned long addr, found, prev;
+	struct vm_unmapped_area_info info;
+
+	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;
+	while (addr > PAGE_SIZE) {
+		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 < PAGE_SIZE)
+			addr = PAGE_SIZE;
+		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);
+}
+
+
+static unsigned long slice_find_area(struct mm_struct *mm, unsigned long len,
+				     struct slice_mask mask, int psize,
+				     int topdown)
+{
+	if (topdown)
+		return slice_find_area_topdown(mm, len, mask, psize);
+	else
+		return slice_find_area_bottomup(mm, len, mask, psize);
+}
+
+#define or_mask(dst, src)	do {			\
+	(dst).low_slices |= (src).low_slices;		\
+	(dst).high_slices |= (src).high_slices;		\
+} while (0)
+
+#define andnot_mask(dst, src)	do {			\
+	(dst).low_slices &= ~(src).low_slices;		\
+	(dst).high_slices &= ~(src).high_slices;	\
+} while (0)
+
+#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 mask = {0, 0};
+	struct slice_mask good_mask;
+	struct slice_mask potential_mask = {0,0} /* silence stupid warning */;
+	struct slice_mask compat_mask = {0, 0};
+	int fixed = (flags & MAP_FIXED);
+	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
+	struct mm_struct *mm = current->mm;
+	unsigned long newaddr;
+
+	/* Sanity checks */
+	BUG_ON(mm->task_size == 0);
+
+	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 (len > mm->task_size)
+		return -ENOMEM;
+	if (len & ((1ul << pshift) - 1))
+		return -EINVAL;
+	if (fixed && (addr & ((1ul << pshift) - 1)))
+		return -EINVAL;
+	if (fixed && addr > (mm->task_size - len))
+		return -ENOMEM;
+
+	/* If hint, make sure it matches our alignment restrictions */
+	if (!fixed && addr) {
+		addr = _ALIGN_UP(addr, 1ul << pshift);
+		slice_dbg(" aligned addr=%lx\n", addr);
+		/* Ignore hint if it's too large or overlaps a VMA */
+		if (addr > mm->task_size - len ||
+		    !slice_area_is_free(mm, addr, len))
+			addr = 0;
+	}
+
+	/* First make up a "good" mask of slices that have the right size
+	 * already
+	 */
+	good_mask = slice_mask_for_size(mm, psize);
+	slice_print_mask(" good_mask", good_mask);
+
+	/*
+	 * 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.
+	 */
+
+#ifdef CONFIG_PPC_64K_PAGES
+	/* If we support combo pages, we can allow 64k pages in 4k slices */
+	if (psize == MMU_PAGE_64K) {
+		compat_mask = slice_mask_for_size(mm, MMU_PAGE_4K);
+		if (fixed)
+			or_mask(good_mask, compat_mask);
+	}
+#endif
+
+	/* First check hint if it's valid or if we have MAP_FIXED */
+	if (addr != 0 || fixed) {
+		/* Build a mask for the requested range */
+		mask = slice_range_to_mask(addr, len);
+		slice_print_mask(" mask", mask);
+
+		/* Check if we fit in the good mask. If we do, we just return,
+		 * nothing else to do
+		 */
+		if (slice_check_fit(mask, good_mask)) {
+			slice_dbg(" fits good !\n");
+			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);
+		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);
+			return newaddr;
+		}
+	}
+
+	/* We don't fit in the good mask, check what other slices are
+	 * empty and thus can be converted
+	 */
+	potential_mask = slice_mask_for_free(mm);
+	or_mask(potential_mask, good_mask);
+	slice_print_mask(" potential", potential_mask);
+
+	if ((addr != 0 || fixed) && slice_check_fit(mask, potential_mask)) {
+		slice_dbg(" fits potential !\n");
+		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) {
+		addr = slice_find_area(mm, len, good_mask, psize, topdown);
+		if (addr != -ENOMEM) {
+			slice_dbg(" found area at 0x%lx\n", addr);
+			return addr;
+		}
+	}
+
+	/* Now let's see if we can find something in the existing slices
+	 * for that size plus free slices
+	 */
+	addr = slice_find_area(mm, len, potential_mask, psize, topdown);
+
+#ifdef CONFIG_PPC_64K_PAGES
+	if (addr == -ENOMEM && psize == MMU_PAGE_64K) {
+		/* retry the search with 4k-page slices included */
+		or_mask(potential_mask, compat_mask);
+		addr = slice_find_area(mm, len, potential_mask, psize,
+				       topdown);
+	}
+#endif
+
+	if (addr == -ENOMEM)
+		return -ENOMEM;
+
+	mask = slice_range_to_mask(addr, len);
+	slice_dbg(" found potential area at 0x%lx\n", addr);
+	slice_print_mask(" mask", mask);
+
+ convert:
+	andnot_mask(mask, good_mask);
+	andnot_mask(mask, compat_mask);
+	if (mask.low_slices || mask.high_slices) {
+		slice_convert(mm, mask, psize);
+		if (psize > MMU_PAGE_BASE)
+			on_each_cpu(slice_flush_segments, mm, 1);
+	}
+	return addr;
+
+}
+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 *hpsizes;
+	int index, mask_index;
+
+	if (addr < SLICE_LOW_TOP) {
+		u64 lpsizes;
+		lpsizes = mm->context.low_slices_psize;
+		index = GET_LOW_SLICE_INDEX(addr);
+		return (lpsizes >> (index * 4)) & 0xf;
+	}
+	hpsizes = mm->context.high_slices_psize;
+	index = GET_HIGH_SLICE_INDEX(addr);
+	mask_index = index & 0x1;
+	return (hpsizes[index >> 1] >> (mask_index * 4)) & 0xf;
+}
+EXPORT_SYMBOL_GPL(get_slice_psize);
+
+/*
+ * This is called by hash_page when it needs to do a lazy conversion of
+ * an address space from real 64K pages to combo 4K pages (typically
+ * when hitting a non cacheable mapping on a processor or hypervisor
+ * that won't allow them for 64K pages).
+ *
+ * This is also called in init_new_context() to change back the user
+ * psize from whatever the parent context had it set to
+ * N.B. This may be called before mm->context.id has been set.
+ *
+ * This function will only change the content of the {low,high)_slice_psize
+ * masks, it will not flush SLBs as this shall be handled lazily by the
+ * caller.
+ */
+void slice_set_user_psize(struct mm_struct *mm, unsigned int psize)
+{
+	int index, mask_index;
+	unsigned char *hpsizes;
+	unsigned long flags, lpsizes;
+	unsigned int old_psize;
+	int i;
+
+	slice_dbg("slice_set_user_psize(mm=%p, psize=%d)\n", mm, psize);
+
+	spin_lock_irqsave(&slice_convert_lock, flags);
+
+	old_psize = mm->context.user_psize;
+	slice_dbg(" old_psize=%d\n", old_psize);
+	if (old_psize == psize)
+		goto bail;
+
+	mm->context.user_psize = psize;
+	wmb();
+
+	lpsizes = mm->context.low_slices_psize;
+	for (i = 0; i < SLICE_NUM_LOW; i++)
+		if (((lpsizes >> (i * 4)) & 0xf) == old_psize)
+			lpsizes = (lpsizes & ~(0xful << (i * 4))) |
+				(((unsigned long)psize) << (i * 4));
+	/* Assign the value back */
+	mm->context.low_slices_psize = lpsizes;
+
+	hpsizes = mm->context.high_slices_psize;
+	for (i = 0; i < SLICE_NUM_HIGH; i++) {
+		mask_index = i & 0x1;
+		index = i >> 1;
+		if (((hpsizes[index] >> (mask_index * 4)) & 0xf) == old_psize)
+			hpsizes[index] = (hpsizes[index] &
+					  ~(0xf << (mask_index * 4))) |
+				(((unsigned long)psize) << (mask_index * 4));
+	}
+
+
+
+
+	slice_dbg(" lsps=%lx, hsps=%lx\n",
+		  mm->context.low_slices_psize,
+		  mm->context.high_slices_psize);
+
+ bail:
+	spin_unlock_irqrestore(&slice_convert_lock, flags);
+}
+
+void slice_set_range_psize(struct mm_struct *mm, unsigned long start,
+			   unsigned long len, unsigned int psize)
+{
+	struct slice_mask mask = slice_range_to_mask(start, len);
+
+	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 is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
+			   unsigned long len)
+{
+	struct slice_mask mask, available;
+	unsigned int psize = mm->context.user_psize;
+
+	mask = slice_range_to_mask(addr, len);
+	available = slice_mask_for_size(mm, psize);
+#ifdef CONFIG_PPC_64K_PAGES
+	/* We need to account for 4k slices too */
+	if (psize == MMU_PAGE_64K) {
+		struct slice_mask compat_mask;
+		compat_mask = slice_mask_for_size(mm, MMU_PAGE_4K);
+		or_mask(available, compat_mask);
+	}
+#endif
+
+#if 0 /* too verbose */
+	slice_dbg("is_hugepage_only_range(mm=%p, addr=%lx, len=%lx)\n",
+		 mm, addr, len);
+	slice_print_mask(" mask", mask);
+	slice_print_mask(" available", available);
+#endif
+	return !slice_check_fit(mask, available);
+}
+#endif