arch/powerpc/mm/slice.c - kernel/msm-4.9 - Gitiles

 /*
  * 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/module.h>
 #include <asm/mman.h>
 #include <asm/mmu.h>
 #include <asm/spu.h>

 static spinlock_t slice_convert_lock = SPIN_LOCK_UNLOCKED;


 #ifdef DEBUG
 int _slice_debug = 1;

 static void slice_print_mask(const char *label, struct slice_mask mask)
 {
 	char	*p, buf[16 + 3 + 16 + 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 & (1 << 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 = (1u << (GET_HIGH_SLICE_INDEX(end) + 1))
 			- (1u << 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 |= 1u << i;

 	return ret;
 }

 static struct slice_mask slice_mask_for_size(struct mm_struct *mm, int psize)
 {
 	struct slice_mask ret = { 0, 0 };
 	unsigned long i;
 	u64 psizes;

 	psizes = mm->context.low_slices_psize;
 	for (i = 0; i < SLICE_NUM_LOW; i++)
 		if (((psizes >> (i * 4)) & 0xf) == psize)
 			ret.low_slices |= 1u << i;

 	psizes = mm->context.high_slices_psize;
 	for (i = 0; i < SLICE_NUM_HIGH; i++)
 		if (((psizes >> (i * 4)) & 0xf) == psize)
 			ret.high_slices |= 1u << 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)
 {
 	/* Write the new slice psize bits */
 	u64 lpsizes, hpsizes;
 	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));

 	hpsizes = mm->context.high_slices_psize;
 	for (i = 0; i < SLICE_NUM_HIGH; i++)
 		if (mask.high_slices & (1u << i))
 			hpsizes = (hpsizes & ~(0xful << (i * 4))) |
 				(((unsigned long)psize) << (i * 4));

 	mm->context.low_slices_psize = lpsizes;
 	mm->context.high_slices_psize = hpsizes;

 	slice_dbg(" lsps=%lx, hsps=%lx\n",
 		  mm->context.low_slices_psize,
 		  mm->context.high_slices_psize);

 	spin_unlock_irqrestore(&slice_convert_lock, flags);
 	mb();

 	/* XXX this is sub-optimal but will do for now */
 	on_each_cpu(slice_flush_segments, mm, 0, 1);
 #ifdef CONFIG_SPU_BASE
 	spu_flush_all_slbs(mm);
 #endif
 }

 static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
 					      unsigned long len,
 					      struct slice_mask available,
 					      int psize, int use_cache)
 {
 	struct vm_area_struct *vma;
 	unsigned long start_addr, addr;
 	struct slice_mask mask;
 	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);

 	if (use_cache) {
 		if (len <= mm->cached_hole_size) {
 			start_addr = addr = TASK_UNMAPPED_BASE;
 			mm->cached_hole_size = 0;
 		} else
 			start_addr = addr = mm->free_area_cache;
 	} else
 		start_addr = addr = TASK_UNMAPPED_BASE;

 full_search:
 	for (;;) {
 		addr = _ALIGN_UP(addr, 1ul << pshift);
 		if ((TASK_SIZE - len) < addr)
 			break;
 		vma = find_vma(mm, addr);
 		BUG_ON(vma && (addr >= vma->vm_end));

 		mask = slice_range_to_mask(addr, len);
 		if (!slice_check_fit(mask, available)) {
 			if (addr < SLICE_LOW_TOP)
 				addr = _ALIGN_UP(addr + 1,  1ul << SLICE_LOW_SHIFT);
 			else
 				addr = _ALIGN_UP(addr + 1,  1ul << SLICE_HIGH_SHIFT);
 			continue;
 		}
 		if (!vma || addr + len <= vma->vm_start) {
 			/*
 			 * Remember the place where we stopped the search:
 			 */
 			if (use_cache)
 				mm->free_area_cache = addr + len;
 			return addr;
 		}
 		if (use_cache && (addr + mm->cached_hole_size) < vma->vm_start)
 		        mm->cached_hole_size = vma->vm_start - addr;
 		addr = vma->vm_end;
 	}

 	/* Make sure we didn't miss any holes */
 	if (use_cache && start_addr != TASK_UNMAPPED_BASE) {
 		start_addr = addr = TASK_UNMAPPED_BASE;
 		mm->cached_hole_size = 0;
 		goto full_search;
 	}
 	return -ENOMEM;
 }

 static unsigned long slice_find_area_topdown(struct mm_struct *mm,
 					     unsigned long len,
 					     struct slice_mask available,
 					     int psize, int use_cache)
 {
 	struct vm_area_struct *vma;
 	unsigned long addr;
 	struct slice_mask mask;
 	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);

 	/* check if free_area_cache is useful for us */
 	if (use_cache) {
 		if (len <= mm->cached_hole_size) {
 			mm->cached_hole_size = 0;
 			mm->free_area_cache = mm->mmap_base;
 		}

 		/* either no address requested or can't fit in requested
 		 * address hole
 		 */
 		addr = mm->free_area_cache;

 		/* make sure it can fit in the remaining address space */
 		if (addr > len) {
 			addr = _ALIGN_DOWN(addr - len, 1ul << pshift);
 			mask = slice_range_to_mask(addr, len);
 			if (slice_check_fit(mask, available) &&
 			    slice_area_is_free(mm, addr, len))
 					/* remember the address as a hint for
 					 * next time
 					 */
 					return (mm->free_area_cache = addr);
 		}
 	}

 	addr = mm->mmap_base;
 	while (addr > len) {
 		/* Go down by chunk size */
 		addr = _ALIGN_DOWN(addr - len, 1ul << pshift);

 		/* Check for hit with different page size */
 		mask = slice_range_to_mask(addr, len);
 		if (!slice_check_fit(mask, available)) {
 			if (addr < SLICE_LOW_TOP)
 				addr = _ALIGN_DOWN(addr, 1ul << SLICE_LOW_SHIFT);
 			else if (addr < (1ul << SLICE_HIGH_SHIFT))
 				addr = SLICE_LOW_TOP;
 			else
 				addr = _ALIGN_DOWN(addr, 1ul << SLICE_HIGH_SHIFT);
 			continue;
 		}

 		/*
 		 * Lookup failure means no vma is above this address,
 		 * else if new region fits below vma->vm_start,
 		 * return with success:
 		 */
 		vma = find_vma(mm, addr);
 		if (!vma || (addr + len) <= vma->vm_start) {
 			/* remember the address as a hint for next time */
 			if (use_cache)
 				mm->free_area_cache = addr;
 			return addr;
 		}

 		/* remember the largest hole we saw so far */
 		if (use_cache && (addr + mm->cached_hole_size) < vma->vm_start)
 		        mm->cached_hole_size = vma->vm_start - addr;

 		/* try just below the current vma->vm_start */
 		addr = vma->vm_start;
 	}

 	/*
 	 * 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.
 	 */
 	addr = slice_find_area_bottomup(mm, len, available, psize, 0);

 	/*
 	 * Restore the topdown base:
 	 */
 	if (use_cache) {
 		mm->free_area_cache = mm->mmap_base;
 		mm->cached_hole_size = ~0UL;
 	}

 	return addr;
 }


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

 unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
 				      unsigned long flags, unsigned int psize,
 				      int topdown, int use_cache)
 {
 	struct slice_mask mask;
 	struct slice_mask good_mask;
 	struct slice_mask potential_mask = {0,0} /* silence stupid warning */;
 	int pmask_set = 0;
 	int fixed = (flags & MAP_FIXED);
 	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
 	struct mm_struct *mm = current->mm;

 	/* 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, use_cache=%d\n",
 		  addr, len, flags, topdown, use_cache);

 	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 -EINVAL;

 	/* 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);
 	}

 	/* First makeup 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);

 	/* First check hint if it's valid or if we have MAP_FIXED */
 	if ((addr != 0 || fixed) && (mm->task_size - len) >= addr) {

 		/* Don't bother with hint if it overlaps a VMA */
 		if (!fixed && !slice_area_is_free(mm, addr, len))
 			goto search;

 		/* 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;
 		}

 		/* 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);
 		potential_mask.low_slices |= good_mask.low_slices;
 		potential_mask.high_slices |= good_mask.high_slices;
 		pmask_set = 1;
 		slice_print_mask(" potential", potential_mask);
 		if (slice_check_fit(mask, potential_mask)) {
 			slice_dbg(" fits potential !\n");
 			goto convert;
 		}
 	}

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

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

 	/* Now let's see if we can find something in the existing slices
 	 * for that size
 	 */
 	addr = slice_find_area(mm, len, good_mask, psize, topdown, use_cache);
 	if (addr != -ENOMEM) {
 		/* Found within the good mask, we don't have to setup,
 		 * we thus return directly
 		 */
 		slice_dbg(" found area at 0x%lx\n", addr);
 		return addr;
 	}

 	/* Won't fit, check what can be converted */
 	if (!pmask_set) {
 		potential_mask = slice_mask_for_free(mm);
 		potential_mask.low_slices |= good_mask.low_slices;
 		potential_mask.high_slices |= good_mask.high_slices;
 		pmask_set = 1;
 		slice_print_mask(" potential", potential_mask);
 	}

 	/* Now let's see if we can find something in the existing slices
 	 * for that size
 	 */
 	addr = slice_find_area(mm, len, potential_mask, psize, topdown,
 			       use_cache);
 	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:
 	slice_convert(mm, mask, psize);
 	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, 1);
 }

 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, 1);
 }

 unsigned int get_slice_psize(struct mm_struct *mm, unsigned long addr)
 {
 	u64 psizes;
 	int index;

 	if (addr < SLICE_LOW_TOP) {
 		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);
 	}

 	return (psizes >> (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)
 {
 	unsigned long flags, lpsizes, hpsizes;
 	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));

 	hpsizes = mm->context.high_slices_psize;
 	for (i = 0; i < SLICE_NUM_HIGH; i++)
 		if (((hpsizes >> (i * 4)) & 0xf) == old_psize)
 			hpsizes = (hpsizes & ~(0xful << (i * 4))) |
 				(((unsigned long)psize) << (i * 4));

 	mm->context.low_slices_psize = lpsizes;
 	mm->context.high_slices_psize = hpsizes;

 	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);
 }

 /*
  * is_hugepage_only_range() is used by generic code to verify wether
  * 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;

 	mask = slice_range_to_mask(addr, len);
 	available = slice_mask_for_size(mm, mm->context.user_psize);

 #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);
 }
	/*
	* 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/module.h>
	#include <asm/mman.h>
	#include <asm/mmu.h>
	#include <asm/spu.h>

	static spinlock_t slice_convert_lock = SPIN_LOCK_UNLOCKED;


	#ifdef DEBUG
	int _slice_debug = 1;

	static void slice_print_mask(const char *label, struct slice_mask mask)
	{
	char *p, buf[16 + 3 + 16 + 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 & (1 << 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 = (1u << (GET_HIGH_SLICE_INDEX(end) + 1))
	- (1u << 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 \|= 1u << i;

	return ret;
	}

	static struct slice_mask slice_mask_for_size(struct mm_struct *mm, int psize)
	{
	struct slice_mask ret = { 0, 0 };
	unsigned long i;
	u64 psizes;

	psizes = mm->context.low_slices_psize;
	for (i = 0; i < SLICE_NUM_LOW; i++)
	if (((psizes >> (i * 4)) & 0xf) == psize)
	ret.low_slices \|= 1u << i;

	psizes = mm->context.high_slices_psize;
	for (i = 0; i < SLICE_NUM_HIGH; i++)
	if (((psizes >> (i * 4)) & 0xf) == psize)
	ret.high_slices \|= 1u << 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)
	{
	/* Write the new slice psize bits */
	u64 lpsizes, hpsizes;
	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));

	hpsizes = mm->context.high_slices_psize;
	for (i = 0; i < SLICE_NUM_HIGH; i++)
	if (mask.high_slices & (1u << i))
	hpsizes = (hpsizes & ~(0xful << (i * 4))) \|
	(((unsigned long)psize) << (i * 4));

	mm->context.low_slices_psize = lpsizes;
	mm->context.high_slices_psize = hpsizes;

	slice_dbg(" lsps=%lx, hsps=%lx\n",
	mm->context.low_slices_psize,
	mm->context.high_slices_psize);

	spin_unlock_irqrestore(&slice_convert_lock, flags);
	mb();

	/* XXX this is sub-optimal but will do for now */
	on_each_cpu(slice_flush_segments, mm, 0, 1);
	#ifdef CONFIG_SPU_BASE
	spu_flush_all_slbs(mm);
	#endif
	}

	static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
	unsigned long len,
	struct slice_mask available,
	int psize, int use_cache)
	{
	struct vm_area_struct *vma;
	unsigned long start_addr, addr;
	struct slice_mask mask;
	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);

	if (use_cache) {
	if (len <= mm->cached_hole_size) {
	start_addr = addr = TASK_UNMAPPED_BASE;
	mm->cached_hole_size = 0;
	} else
	start_addr = addr = mm->free_area_cache;
	} else
	start_addr = addr = TASK_UNMAPPED_BASE;

	full_search:
	for (;;) {
	addr = _ALIGN_UP(addr, 1ul << pshift);
	if ((TASK_SIZE - len) < addr)
	break;
	vma = find_vma(mm, addr);
	BUG_ON(vma && (addr >= vma->vm_end));

	mask = slice_range_to_mask(addr, len);
	if (!slice_check_fit(mask, available)) {
	if (addr < SLICE_LOW_TOP)
	addr = _ALIGN_UP(addr + 1, 1ul << SLICE_LOW_SHIFT);
	else
	addr = _ALIGN_UP(addr + 1, 1ul << SLICE_HIGH_SHIFT);
	continue;
	}
	if (!vma \|\| addr + len <= vma->vm_start) {
	/*
	* Remember the place where we stopped the search:
	*/
	if (use_cache)
	mm->free_area_cache = addr + len;
	return addr;
	}
	if (use_cache && (addr + mm->cached_hole_size) < vma->vm_start)
	mm->cached_hole_size = vma->vm_start - addr;
	addr = vma->vm_end;
	}

	/* Make sure we didn't miss any holes */
	if (use_cache && start_addr != TASK_UNMAPPED_BASE) {
	start_addr = addr = TASK_UNMAPPED_BASE;
	mm->cached_hole_size = 0;
	goto full_search;
	}
	return -ENOMEM;
	}

	static unsigned long slice_find_area_topdown(struct mm_struct *mm,
	unsigned long len,
	struct slice_mask available,
	int psize, int use_cache)
	{
	struct vm_area_struct *vma;
	unsigned long addr;
	struct slice_mask mask;
	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);

	/* check if free_area_cache is useful for us */
	if (use_cache) {
	if (len <= mm->cached_hole_size) {
	mm->cached_hole_size = 0;
	mm->free_area_cache = mm->mmap_base;
	}

	/* either no address requested or can't fit in requested
	* address hole
	*/
	addr = mm->free_area_cache;

	/* make sure it can fit in the remaining address space */
	if (addr > len) {
	addr = _ALIGN_DOWN(addr - len, 1ul << pshift);
	mask = slice_range_to_mask(addr, len);
	if (slice_check_fit(mask, available) &&
	slice_area_is_free(mm, addr, len))
	/* remember the address as a hint for
	* next time
	*/
	return (mm->free_area_cache = addr);
	}
	}

	addr = mm->mmap_base;
	while (addr > len) {
	/* Go down by chunk size */
	addr = _ALIGN_DOWN(addr - len, 1ul << pshift);

	/* Check for hit with different page size */
	mask = slice_range_to_mask(addr, len);
	if (!slice_check_fit(mask, available)) {
	if (addr < SLICE_LOW_TOP)
	addr = _ALIGN_DOWN(addr, 1ul << SLICE_LOW_SHIFT);
	else if (addr < (1ul << SLICE_HIGH_SHIFT))
	addr = SLICE_LOW_TOP;
	else
	addr = _ALIGN_DOWN(addr, 1ul << SLICE_HIGH_SHIFT);
	continue;
	}

	/*
	* Lookup failure means no vma is above this address,
	* else if new region fits below vma->vm_start,
	* return with success:
	*/
	vma = find_vma(mm, addr);
	if (!vma \|\| (addr + len) <= vma->vm_start) {
	/* remember the address as a hint for next time */
	if (use_cache)
	mm->free_area_cache = addr;
	return addr;
	}

	/* remember the largest hole we saw so far */
	if (use_cache && (addr + mm->cached_hole_size) < vma->vm_start)
	mm->cached_hole_size = vma->vm_start - addr;

	/* try just below the current vma->vm_start */
	addr = vma->vm_start;
	}

	/*
	* 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.
	*/
	addr = slice_find_area_bottomup(mm, len, available, psize, 0);

	/*
	* Restore the topdown base:
	*/
	if (use_cache) {
	mm->free_area_cache = mm->mmap_base;
	mm->cached_hole_size = ~0UL;
	}

	return addr;
	}


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

	unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
	unsigned long flags, unsigned int psize,
	int topdown, int use_cache)
	{
	struct slice_mask mask;
	struct slice_mask good_mask;
	struct slice_mask potential_mask = {0,0} /* silence stupid warning */;
	int pmask_set = 0;
	int fixed = (flags & MAP_FIXED);
	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
	struct mm_struct *mm = current->mm;

	/* 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, use_cache=%d\n",
	addr, len, flags, topdown, use_cache);

	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 -EINVAL;

	/* 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);
	}

	/* First makeup 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);

	/* First check hint if it's valid or if we have MAP_FIXED */
	if ((addr != 0 \|\| fixed) && (mm->task_size - len) >= addr) {

	/* Don't bother with hint if it overlaps a VMA */
	if (!fixed && !slice_area_is_free(mm, addr, len))
	goto search;

	/* 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;
	}

	/* 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);
	potential_mask.low_slices \|= good_mask.low_slices;
	potential_mask.high_slices \|= good_mask.high_slices;
	pmask_set = 1;
	slice_print_mask(" potential", potential_mask);
	if (slice_check_fit(mask, potential_mask)) {
	slice_dbg(" fits potential !\n");
	goto convert;
	}
	}

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

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

	/* Now let's see if we can find something in the existing slices
	* for that size
	*/
	addr = slice_find_area(mm, len, good_mask, psize, topdown, use_cache);
	if (addr != -ENOMEM) {
	/* Found within the good mask, we don't have to setup,
	* we thus return directly
	*/
	slice_dbg(" found area at 0x%lx\n", addr);
	return addr;
	}

	/* Won't fit, check what can be converted */
	if (!pmask_set) {
	potential_mask = slice_mask_for_free(mm);
	potential_mask.low_slices \|= good_mask.low_slices;
	potential_mask.high_slices \|= good_mask.high_slices;
	pmask_set = 1;
	slice_print_mask(" potential", potential_mask);
	}

	/* Now let's see if we can find something in the existing slices
	* for that size
	*/
	addr = slice_find_area(mm, len, potential_mask, psize, topdown,
	use_cache);
	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:
	slice_convert(mm, mask, psize);
	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, 1);
	}

	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, 1);
	}

	unsigned int get_slice_psize(struct mm_struct *mm, unsigned long addr)
	{
	u64 psizes;
	int index;

	if (addr < SLICE_LOW_TOP) {
	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);
	}

	return (psizes >> (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)
	{
	unsigned long flags, lpsizes, hpsizes;
	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));

	hpsizes = mm->context.high_slices_psize;
	for (i = 0; i < SLICE_NUM_HIGH; i++)
	if (((hpsizes >> (i * 4)) & 0xf) == old_psize)
	hpsizes = (hpsizes & ~(0xful << (i * 4))) \|
	(((unsigned long)psize) << (i * 4));

	mm->context.low_slices_psize = lpsizes;
	mm->context.high_slices_psize = hpsizes;

	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);
	}

	/*
	* is_hugepage_only_range() is used by generic code to verify wether
	* 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;

	mask = slice_range_to_mask(addr, len);
	available = slice_mask_for_size(mm, mm->context.user_psize);

	#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);
	}