text: /*
   * Handle caching attributes in page tables (PAT)
   *
   * Authors: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
   *          Suresh B Siddha <suresh.b.siddha@intel.com>
   *
   * Loosely based on earlier PAT patchset from Eric Biederman and Andi Kleen.
   */
  
  #include <linux/seq_file.h>
  #include <linux/bootmem.h>
  #include <linux/debugfs.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/mm.h>
  #include <linux/fs.h>
  #include <linux/rbtree.h>
  
  #include <asm/cacheflush.h>
  #include <asm/processor.h>
  #include <asm/tlbflush.h>
  #include <asm/x86_init.h>
  #include <asm/pgtable.h>
  #include <asm/fcntl.h>
  #include <asm/e820.h>
  #include <asm/mtrr.h>
  #include <asm/page.h>
  #include <asm/msr.h>
  #include <asm/pat.h>
  #include <asm/io.h>
  
  #include "pat_internal.h"
  #include "mm_internal.h"
  
  #ifdef CONFIG_X86_PAT
  int __read_mostly pat_enabled = 1;
  
  static inline void pat_disable(const char *reason)
  {
  	pat_enabled = 0;
  	printk(KERN_INFO "%s\n", reason);
  }
  
  static int __init nopat(char *str)
  {
  	pat_disable("PAT support disabled.");
  	return 0;
  }
  early_param("nopat", nopat);
  #else
  static inline void pat_disable(const char *reason)
  {
  	(void)reason;
  }
  #endif
  
  
  int pat_debug_enable;
  
  static int __init pat_debug_setup(char *str)
  {
  	pat_debug_enable = 1;
  	return 0;
  }
  __setup("debugpat", pat_debug_setup);
  
  static u64 __read_mostly boot_pat_state;
  
  #ifdef CONFIG_X86_PAT
  /*
   * X86 PAT uses page flags WC and Uncached together to keep track of
   * memory type of pages that have backing page struct. X86 PAT supports 3
   * different memory types, _PAGE_CACHE_MODE_WB, _PAGE_CACHE_MODE_WC and
   * _PAGE_CACHE_MODE_UC_MINUS and fourth state where page's memory type has not
   * been changed from its default (value of -1 used to denote this).
   * Note we do not support _PAGE_CACHE_MODE_UC here.
   */
  
  #define _PGMT_DEFAULT		0
  #define _PGMT_WC		(1UL << PG_arch_1)
  #define _PGMT_UC_MINUS		(1UL << PG_uncached)
  #define _PGMT_WB		(1UL << PG_uncached | 1UL << PG_arch_1)
  #define _PGMT_MASK		(1UL << PG_uncached | 1UL << PG_arch_1)
  #define _PGMT_CLEAR_MASK	(~_PGMT_MASK)
  
  static inline enum page_cache_mode get_page_memtype(struct page *pg)
  {
  	unsigned long pg_flags = pg->flags & _PGMT_MASK;
  
  	if (pg_flags == _PGMT_DEFAULT)
  		return -1;
  	else if (pg_flags == _PGMT_WC)
  		return _PAGE_CACHE_MODE_WC;
  	else if (pg_flags == _PGMT_UC_MINUS)
  		return _PAGE_CACHE_MODE_UC_MINUS;
  	else
  		return _PAGE_CACHE_MODE_WB;
  }
  
  static inline void set_page_memtype(struct page *pg,
  				    enum page_cache_mode memtype)
  {
  	unsigned long memtype_flags;
  	unsigned long old_flags;
  	unsigned long new_flags;
  
  	switch (memtype) {
  	case _PAGE_CACHE_MODE_WC:
  		memtype_flags = _PGMT_WC;
  		break;
  	case _PAGE_CACHE_MODE_UC_MINUS:
  		memtype_flags = _PGMT_UC_MINUS;
  		break;
  	case _PAGE_CACHE_MODE_WB:
  		memtype_flags = _PGMT_WB;
  		break;
  	default:
  		memtype_flags = _PGMT_DEFAULT;
  		break;
  	}
  
  	do {
  		old_flags = pg->flags;
  		new_flags = (old_flags & _PGMT_CLEAR_MASK) | memtype_flags;
  	} while (cmpxchg(&pg->flags, old_flags, new_flags) != old_flags);
  }
  #else
  static inline enum page_cache_mode get_page_memtype(struct page *pg)
  {
  	return -1;
  }
  static inline void set_page_memtype(struct page *pg,
  				    enum page_cache_mode memtype)
  {
  }
  #endif
  
  enum {
  	PAT_UC = 0,		/* uncached */
  	PAT_WC = 1,		/* Write combining */
  	PAT_WT = 4,		/* Write Through */
  	PAT_WP = 5,		/* Write Protected */
  	PAT_WB = 6,		/* Write Back (default) */
  	PAT_UC_MINUS = 7,	/* UC, but can be overriden by MTRR */
  };
  
  #define CM(c) (_PAGE_CACHE_MODE_ ## c)
  
  static enum page_cache_mode pat_get_cache_mode(unsigned pat_val, char *msg)
  {
  	enum page_cache_mode cache;
  	char *cache_mode;
  
  	switch (pat_val) {
  	case PAT_UC:       cache = CM(UC);       cache_mode = "UC  "; break;
  	case PAT_WC:       cache = CM(WC);       cache_mode = "WC  "; break;
  	case PAT_WT:       cache = CM(WT);       cache_mode = "WT  "; break;
  	case PAT_WP:       cache = CM(WP);       cache_mode = "WP  "; break;
  	case PAT_WB:       cache = CM(WB);       cache_mode = "WB  "; break;
  	case PAT_UC_MINUS: cache = CM(UC_MINUS); cache_mode = "UC- "; break;
  	default:           cache = CM(WB);       cache_mode = "WB  "; break;
  	}
  
  	memcpy(msg, cache_mode, 4);
  
  	return cache;
  }
  
  #undef CM
  
  /*
   * Update the cache mode to pgprot translation tables according to PAT
   * configuration.
   * Using lower indices is preferred, so we start with highest index.
   */
  void pat_init_cache_modes(void)
  {
  	int i;
  	enum page_cache_mode cache;
  	char pat_msg[33];
  	u64 pat;
  
  	rdmsrl(MSR_IA32_CR_PAT, pat);
  	pat_msg[32] = 0;
  	for (i = 7; i >= 0; i--) {
  		cache = pat_get_cache_mode((pat >> (i * 8)) & 7,
  					   pat_msg + 4 * i);
  		update_cache_mode_entry(i, cache);
  	}
  	pr_info("PAT configuration [0-7]: %s\n", pat_msg);
  }
  
  #define PAT(x, y)	((u64)PAT_ ## y << ((x)*8))
  
  void pat_init(void)
  {
  	u64 pat;
  	bool boot_cpu = !boot_pat_state;
  
  	if (!pat_enabled)
  		return;
  
  	if (!cpu_has_pat) {
  		if (!boot_pat_state) {
  			pat_disable("PAT not supported by CPU.");
  			return;
  		} else {
  			/*
  			 * If this happens we are on a secondary CPU, but
  			 * switched to PAT on the boot CPU. We have no way to
  			 * undo PAT.
  			 */
  			printk(KERN_ERR "PAT enabled, "
  			       "but not supported by secondary CPU\n");
  			BUG();
  		}
  	}
  
  	/* Set PWT to Write-Combining. All other bits stay the same */
  	/*
  	 * PTE encoding used in Linux:
  	 *      PAT
  	 *      |PCD
  	 *      ||PWT
  	 *      |||
  	 *      000 WB		_PAGE_CACHE_WB
  	 *      001 WC		_PAGE_CACHE_WC
  	 *      010 UC-		_PAGE_CACHE_UC_MINUS
  	 *      011 UC		_PAGE_CACHE_UC
  	 * PAT bit unused
  	 */
  	pat = PAT(0, WB) | PAT(1, WC) | PAT(2, UC_MINUS) | PAT(3, UC) |
  	      PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, UC);
  
  	/* Boot CPU check */
  	if (!boot_pat_state) {
  		rdmsrl(MSR_IA32_CR_PAT, boot_pat_state);
  		if (!boot_pat_state) {
  			pat_disable("PAT read returns always zero, disabled.");
  			return;
  		}
  	}
  
  	wrmsrl(MSR_IA32_CR_PAT, pat);
  
  	if (boot_cpu)
  		pat_init_cache_modes();
  }
  
  #undef PAT
  
  static DEFINE_SPINLOCK(memtype_lock);	/* protects memtype accesses */
  
  /*
   * Does intersection of PAT memory type and MTRR memory type and returns
   * the resulting memory type as PAT understands it.
   * (Type in pat and mtrr will not have same value)
   * The intersection is based on "Effective Memory Type" tables in IA-32
   * SDM vol 3a
   */
  static unsigned long pat_x_mtrr_type(u64 start, u64 end,
  				     enum page_cache_mode req_type)
  {
  	/*
  	 * Look for MTRR hint to get the effective type in case where PAT
  	 * request is for WB.
  	 */
  	if (req_type == _PAGE_CACHE_MODE_WB) {
  		u8 mtrr_type;
  
  		mtrr_type = mtrr_type_lookup(start, end);
  		if (mtrr_type != MTRR_TYPE_WRBACK)
  			return _PAGE_CACHE_MODE_UC_MINUS;
  
  		return _PAGE_CACHE_MODE_WB;
  	}
  
  	return req_type;
  }
  
  struct pagerange_state {
  	unsigned long		cur_pfn;
  	int			ram;
  	int			not_ram;
  };
  
  static int
  pagerange_is_ram_callback(unsigned long initial_pfn, unsigned long total_nr_pages, void *arg)
  {
  	struct pagerange_state *state = arg;
  
  	state->not_ram	|= initial_pfn > state->cur_pfn;
  	state->ram	|= total_nr_pages > 0;
  	state->cur_pfn	 = initial_pfn + total_nr_pages;
  
  	return state->ram && state->not_ram;
  }
  
  static int pat_pagerange_is_ram(resource_size_t start, resource_size_t end)
  {
  	int ret = 0;
  	unsigned long start_pfn = start >> PAGE_SHIFT;
  	unsigned long end_pfn = (end + PAGE_SIZE - 1) >> PAGE_SHIFT;
  	struct pagerange_state state = {start_pfn, 0, 0};
  
  	/*
  	 * For legacy reasons, physical address range in the legacy ISA
  	 * region is tracked as non-RAM. This will allow users of
  	 * /dev/mem to map portions of legacy ISA region, even when
  	 * some of those portions are listed(or not even listed) with
  	 * different e820 types(RAM/reserved/..)
  	 */
  	if (start_pfn < ISA_END_ADDRESS >> PAGE_SHIFT)
  		start_pfn = ISA_END_ADDRESS >> PAGE_SHIFT;
  
  	if (start_pfn < end_pfn) {
  		ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn,
  				&state, pagerange_is_ram_callback);
  	}
  
  	return (ret > 0) ? -1 : (state.ram ? 1 : 0);
  }
  
  /*
   * For RAM pages, we use page flags to mark the pages with appropriate type.
   * Here we do two pass:
   * - Find the memtype of all the pages in the range, look for any conflicts
   * - In case of no conflicts, set the new memtype for pages in the range
   */
  static int reserve_ram_pages_type(u64 start, u64 end,
  				  enum page_cache_mode req_type,
  				  enum page_cache_mode *new_type)
  {
  	struct page *page;
  	u64 pfn;
  
  	if (req_type == _PAGE_CACHE_MODE_UC) {
  		/* We do not support strong UC */
  		WARN_ON_ONCE(1);
  		req_type = _PAGE_CACHE_MODE_UC_MINUS;
  	}
  
  	for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) {
  		enum page_cache_mode type;
  
  		page = pfn_to_page(pfn);
  		type = get_page_memtype(page);
  		if (type != -1) {
  			pr_info("reserve_ram_pages_type failed [mem %#010Lx-%#010Lx], track 0x%x, req 0x%x\n",
  				start, end - 1, type, req_type);
  			if (new_type)
  				*new_type = type;
  
  			return -EBUSY;
  		}
  	}
  
  	if (new_type)
  		*new_type = req_type;
  
  	for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) {
  		page = pfn_to_page(pfn);
  		set_page_memtype(page, req_type);
  	}
  	return 0;
  }
  
  static int free_ram_pages_type(u64 start, u64 end)
  {
  	struct page *page;
  	u64 pfn;
  
  	for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) {
  		page = pfn_to_page(pfn);
  		set_page_memtype(page, -1);
  	}
  	return 0;
  }
  
  /*
   * req_type typically has one of the:
   * - _PAGE_CACHE_MODE_WB
   * - _PAGE_CACHE_MODE_WC
   * - _PAGE_CACHE_MODE_UC_MINUS
   * - _PAGE_CACHE_MODE_UC
   *
   * If new_type is NULL, function will return an error if it cannot reserve the
   * region with req_type. If new_type is non-NULL, function will return
   * available type in new_type in case of no error. In case of any error
   * it will return a negative return value.
   */
  int reserve_memtype(u64 start, u64 end, enum page_cache_mode req_type,
  		    enum page_cache_mode *new_type)
  {
  	struct memtype *new;
  	enum page_cache_mode actual_type;
  	int is_range_ram;
  	int err = 0;
  
  	BUG_ON(start >= end); /* end is exclusive */
  
  	if (!pat_enabled) {
  		/* This is identical to page table setting without PAT */
  		if (new_type) {
  			if (req_type == _PAGE_CACHE_MODE_WC)
  				*new_type = _PAGE_CACHE_MODE_UC_MINUS;
  			else
  				*new_type = req_type;
  		}
  		return 0;
  	}
  
  	/* Low ISA region is always mapped WB in page table. No need to track */
  	if (x86_platform.is_untracked_pat_range(start, end)) {
  		if (new_type)
  			*new_type = _PAGE_CACHE_MODE_WB;
  		return 0;
  	}
  
  	/*
  	 * Call mtrr_lookup to get the type hint. This is an
  	 * optimization for /dev/mem mmap'ers into WB memory (BIOS
  	 * tools and ACPI tools). Use WB request for WB memory and use
  	 * UC_MINUS otherwise.
  	 */
  	actual_type = pat_x_mtrr_type(start, end, req_type);
  
  	if (new_type)
  		*new_type = actual_type;
  
  	is_range_ram = pat_pagerange_is_ram(start, end);
  	if (is_range_ram == 1) {
  
  		err = reserve_ram_pages_type(start, end, req_type, new_type);
  
  		return err;
  	} else if (is_range_ram < 0) {
  		return -EINVAL;
  	}
  
  	new  = kzalloc(sizeof(struct memtype), GFP_KERNEL);
  	if (!new)
  		return -ENOMEM;
  
  	new->start	= start;
  	new->end	= end;
  	new->type	= actual_type;
  
  	spin_lock(&memtype_lock);
  
  	err = rbt_memtype_check_insert(new, new_type);
  	if (err) {
  		printk(KERN_INFO "reserve_memtype failed [mem %#010Lx-%#010Lx], track %s, req %s\n",
  		       start, end - 1,
  		       cattr_name(new->type), cattr_name(req_type));
  		kfree(new);
  		spin_unlock(&memtype_lock);
  
  		return err;
  	}
  
  	spin_unlock(&memtype_lock);
  
  	dprintk("reserve_memtype added [mem %#010Lx-%#010Lx], track %s, req %s, ret %s\n",
  		start, end - 1, cattr_name(new->type), cattr_name(req_type),
  		new_type ? cattr_name(*new_type) : "-");
  
  	return err;
  }
  
  int free_memtype(u64 start, u64 end)
  {
  	int err = -EINVAL;
  	int is_range_ram;
  	struct memtype *entry;
  
  	if (!pat_enabled)
  		return 0;
  
  	/* Low ISA region is always mapped WB. No need to track */
  	if (x86_platform.is_untracked_pat_range(start, end))
  		return 0;
  
  	is_range_ram = pat_pagerange_is_ram(start, end);
  	if (is_range_ram == 1) {
  
  		err = free_ram_pages_type(start, end);
  
  		return err;
  	} else if (is_range_ram < 0) {
  		return -EINVAL;
  	}
  
  	spin_lock(&memtype_lock);
  	entry = rbt_memtype_erase(start, end);
  	spin_unlock(&memtype_lock);
  
  	if (!entry) {
  		printk(KERN_INFO "%s:%d freeing invalid memtype [mem %#010Lx-%#010Lx]\n",
  		       current->comm, current->pid, start, end - 1);
  		return -EINVAL;
  	}
  
  	kfree(entry);
  
  	dprintk("free_memtype request [mem %#010Lx-%#010Lx]\n", start, end - 1);
  
  	return 0;
  }
  
  
  /**
   * lookup_memtype - Looksup the memory type for a physical address
   * @paddr: physical address of which memory type needs to be looked up
   *
   * Only to be called when PAT is enabled
   *
   * Returns _PAGE_CACHE_MODE_WB, _PAGE_CACHE_MODE_WC, _PAGE_CACHE_MODE_UC_MINUS
   * or _PAGE_CACHE_MODE_UC
   */
  static enum page_cache_mode lookup_memtype(u64 paddr)
  {
  	enum page_cache_mode rettype = _PAGE_CACHE_MODE_WB;
  	struct memtype *entry;
  
  	if (x86_platform.is_untracked_pat_range(paddr, paddr + PAGE_SIZE))
  		return rettype;
  
  	if (pat_pagerange_is_ram(paddr, paddr + PAGE_SIZE)) {
  		struct page *page;
  		page = pfn_to_page(paddr >> PAGE_SHIFT);
  		rettype = get_page_memtype(page);
  		/*
  		 * -1 from get_page_memtype() implies RAM page is in its
  		 * default state and not reserved, and hence of type WB
  		 */
  		if (rettype == -1)
  			rettype = _PAGE_CACHE_MODE_WB;
  
  		return rettype;
  	}
  
  	spin_lock(&memtype_lock);
  
  	entry = rbt_memtype_lookup(paddr);
  	if (entry != NULL)
  		rettype = entry->type;
  	else
  		rettype = _PAGE_CACHE_MODE_UC_MINUS;
  
  	spin_unlock(&memtype_lock);
  	return rettype;
  }
  
  /**
   * io_reserve_memtype - Request a memory type mapping for a region of memory
   * @start: start (physical address) of the region
   * @end: end (physical address) of the region
   * @type: A pointer to memtype, with requested type. On success, requested
   * or any other compatible type that was available for the region is returned
   *
   * On success, returns 0
   * On failure, returns non-zero
   */
  int io_reserve_memtype(resource_size_t start, resource_size_t end,
  			enum page_cache_mode *type)
  {
  	resource_size_t size = end - start;
  	enum page_cache_mode req_type = *type;
  	enum page_cache_mode new_type;
  	int ret;
  
  	WARN_ON_ONCE(iomem_map_sanity_check(start, size));
  
  	ret = reserve_memtype(start, end, req_type, &new_type);
  	if (ret)
  		goto out_err;
  
  	if (!is_new_memtype_allowed(start, size, req_type, new_type))
  		goto out_free;
  
  	if (kernel_map_sync_memtype(start, size, new_type) < 0)
  		goto out_free;
  
  	*type = new_type;
  	return 0;
  
  out_free:
  	free_memtype(start, end);
  	ret = -EBUSY;
  out_err:
  	return ret;
  }
  
  /**
   * io_free_memtype - Release a memory type mapping for a region of memory
   * @start: start (physical address) of the region
   * @end: end (physical address) of the region
   */
  void io_free_memtype(resource_size_t start, resource_size_t end)
  {
  	free_memtype(start, end);
  }
  
  pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
  				unsigned long size, pgprot_t vma_prot)
  {
  	return vma_prot;
  }
  
  #ifdef CONFIG_STRICT_DEVMEM
  /* This check is done in drivers/char/mem.c in case of STRICT_DEVMEM */
  static inline int range_is_allowed(unsigned long pfn, unsigned long size)
  {
  	return 1;
  }
  #else
  /* This check is needed to avoid cache aliasing when PAT is enabled */
  static inline int range_is_allowed(unsigned long pfn, unsigned long size)
  {
  	u64 from = ((u64)pfn) << PAGE_SHIFT;
  	u64 to = from + size;
  	u64 cursor = from;
  
  	if (!pat_enabled)
  		return 1;
  
  	while (cursor < to) {
  		if (!devmem_is_allowed(pfn)) {
  			printk(KERN_INFO "Program %s tried to access /dev/mem between [mem %#010Lx-%#010Lx], PAT prevents it\n",
  			       current->comm, from, to - 1);
  			return 0;
  		}
  		cursor += PAGE_SIZE;
  		pfn++;
  	}
  	return 1;
  }
  #endif /* CONFIG_STRICT_DEVMEM */
  
  int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
  				unsigned long size, pgprot_t *vma_prot)
  {
  	enum page_cache_mode pcm = _PAGE_CACHE_MODE_WB;
  
  	if (!range_is_allowed(pfn, size))
  		return 0;
  
  	if (file->f_flags & O_DSYNC)
  		pcm = _PAGE_CACHE_MODE_UC_MINUS;
  
  #ifdef CONFIG_X86_32
  	/*
  	 * On the PPro and successors, the MTRRs are used to set
  	 * memory types for physical addresses outside main memory,
  	 * so blindly setting UC or PWT on those pages is wrong.
  	 * For Pentiums and earlier, the surround logic should disable
  	 * caching for the high addresses through the KEN pin, but
  	 * we maintain the tradition of paranoia in this code.
  	 */
  	if (!pat_enabled &&
  	    !(boot_cpu_has(X86_FEATURE_MTRR) ||
  	      boot_cpu_has(X86_FEATURE_K6_MTRR) ||
  	      boot_cpu_has(X86_FEATURE_CYRIX_ARR) ||
  	      boot_cpu_has(X86_FEATURE_CENTAUR_MCR)) &&
  	    (pfn << PAGE_SHIFT) >= __pa(high_memory)) {
  		pcm = _PAGE_CACHE_MODE_UC;
  	}
  #endif
  
  	*vma_prot = __pgprot((pgprot_val(*vma_prot) & ~_PAGE_CACHE_MASK) |
  			     cachemode2protval(pcm));
  	return 1;
  }
  
  /*
   * Change the memory type for the physial address range in kernel identity
   * mapping space if that range is a part of identity map.
   */
  int kernel_map_sync_memtype(u64 base, unsigned long size,
  			    enum page_cache_mode pcm)
  {
  	unsigned long id_sz;
  
  	if (base > __pa(high_memory-1))
  		return 0;
  
  	/*
  	 * some areas in the middle of the kernel identity range
  	 * are not mapped, like the PCI space.
  	 */
  	if (!page_is_ram(base >> PAGE_SHIFT))
  		return 0;
  
  	id_sz = (__pa(high_memory-1) <= base + size) ?
  				__pa(high_memory) - base :
  				size;
  
  	if (ioremap_change_attr((unsigned long)__va(base), id_sz, pcm) < 0) {
  		printk(KERN_INFO "%s:%d ioremap_change_attr failed %s "
  			"for [mem %#010Lx-%#010Lx]\n",
  			current->comm, current->pid,
  			cattr_name(pcm),
  			base, (unsigned long long)(base + size-1));
  		return -EINVAL;
  	}
  	return 0;
  }
  
  /*
   * Internal interface to reserve a range of physical memory with prot.
   * Reserved non RAM regions only and after successful reserve_memtype,
   * this func also keeps identity mapping (if any) in sync with this new prot.
   */
  static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
  				int strict_prot)
  {
  	int is_ram = 0;
  	int ret;
  	enum page_cache_mode want_pcm = pgprot2cachemode(*vma_prot);
  	enum page_cache_mode pcm = want_pcm;
  
  	is_ram = pat_pagerange_is_ram(paddr, paddr + size);
  
  	/*
  	 * reserve_pfn_range() for RAM pages. We do not refcount to keep
  	 * track of number of mappings of RAM pages. We can assert that
  	 * the type requested matches the type of first page in the range.
  	 */
  	if (is_ram) {
  		if (!pat_enabled)
  			return 0;
  
  		pcm = lookup_memtype(paddr);
  		if (want_pcm != pcm) {
  			printk(KERN_WARNING "%s:%d map pfn RAM range req %s for [mem %#010Lx-%#010Lx], got %s\n",
  				current->comm, current->pid,
  				cattr_name(want_pcm),
  				(unsigned long long)paddr,
  				(unsigned long long)(paddr + size - 1),
  				cattr_name(pcm));
  			*vma_prot = __pgprot((pgprot_val(*vma_prot) &
  					     (~_PAGE_CACHE_MASK)) |
  					     cachemode2protval(pcm));
  		}
  		return 0;
  	}
  
  	ret = reserve_memtype(paddr, paddr + size, want_pcm, &pcm);
  	if (ret)
  		return ret;
  
  	if (pcm != want_pcm) {
  		if (strict_prot ||
  		    !is_new_memtype_allowed(paddr, size, want_pcm, pcm)) {
  			free_memtype(paddr, paddr + size);
  			printk(KERN_ERR "%s:%d map pfn expected mapping type %s"
  				" for [mem %#010Lx-%#010Lx], got %s\n",
  				current->comm, current->pid,
  				cattr_name(want_pcm),
  				(unsigned long long)paddr,
  				(unsigned long long)(paddr + size - 1),
  				cattr_name(pcm));
  			return -EINVAL;
  		}
  		/*
  		 * We allow returning different type than the one requested in
  		 * non strict case.
  		 */
  		*vma_prot = __pgprot((pgprot_val(*vma_prot) &
  				      (~_PAGE_CACHE_MASK)) |
  				     cachemode2protval(pcm));
  	}
  
  	if (kernel_map_sync_memtype(paddr, size, pcm) < 0) {
  		free_memtype(paddr, paddr + size);
  		return -EINVAL;
  	}
  	return 0;
  }
  
  /*
   * Internal interface to free a range of physical memory.
   * Frees non RAM regions only.
   */
  static void free_pfn_range(u64 paddr, unsigned long size)
  {
  	int is_ram;
  
  	is_ram = pat_pagerange_is_ram(paddr, paddr + size);
  	if (is_ram == 0)
  		free_memtype(paddr, paddr + size);
  }
  
  /*
   * track_pfn_copy is called when vma that is covering the pfnmap gets
   * copied through copy_page_range().
   *
   * If the vma has a linear pfn mapping for the entire range, we get the prot
   * from pte and reserve the entire vma range with single reserve_pfn_range call.
   */
  int track_pfn_copy(struct vm_area_struct *vma)
  {
  	resource_size_t paddr;
  	unsigned long prot;
  	unsigned long vma_size = vma->vm_end - vma->vm_start;
  	pgprot_t pgprot;
  
  	if (vma->vm_flags & VM_PAT) {
  		/*
  		 * reserve the whole chunk covered by vma. We need the
  		 * starting address and protection from pte.
  		 */
  		if (follow_phys(vma, vma->vm_start, 0, &prot, &paddr)) {
  			WARN_ON_ONCE(1);
  			return -EINVAL;
  		}
  		pgprot = __pgprot(prot);
  		return reserve_pfn_range(paddr, vma_size, &pgprot, 1);
  	}
  
  	return 0;
  }
  
  /*
   * prot is passed in as a parameter for the new mapping. If the vma has a
   * linear pfn mapping for the entire range reserve the entire vma range with
   * single reserve_pfn_range call.
   */
  int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
  		    unsigned long pfn, unsigned long addr, unsigned long size)
  {
  	resource_size_t paddr = (resource_size_t)pfn << PAGE_SHIFT;
  	enum page_cache_mode pcm;
  
  	/* reserve the whole chunk starting from paddr */
  	if (addr == vma->vm_start && size == (vma->vm_end - vma->vm_start)) {
  		int ret;
  
  		ret = reserve_pfn_range(paddr, size, prot, 0);
  		if (!ret)
  			vma->vm_flags |= VM_PAT;
  		return ret;
  	}
  
  	if (!pat_enabled)
  		return 0;
  
  	/*
  	 * For anything smaller than the vma size we set prot based on the
  	 * lookup.
  	 */
  	pcm = lookup_memtype(paddr);
  
  	/* Check memtype for the remaining pages */
  	while (size > PAGE_SIZE) {
  		size -= PAGE_SIZE;
  		paddr += PAGE_SIZE;
  		if (pcm != lookup_memtype(paddr))
  			return -EINVAL;
  	}
  
  	*prot = __pgprot((pgprot_val(vma->vm_page_prot) & (~_PAGE_CACHE_MASK)) |
  			 cachemode2protval(pcm));
  
  	return 0;
  }
  
  int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
  		     unsigned long pfn)
  {
  	enum page_cache_mode pcm;
  
  	if (!pat_enabled)
  		return 0;
  
  	/* Set prot based on lookup */
  	pcm = lookup_memtype((resource_size_t)pfn << PAGE_SHIFT);
  	*prot = __pgprot((pgprot_val(vma->vm_page_prot) & (~_PAGE_CACHE_MASK)) |
  			 cachemode2protval(pcm));
  
  	return 0;
  }
  
  /*
   * untrack_pfn is called while unmapping a pfnmap for a region.
   * untrack can be called for a specific region indicated by pfn and size or
   * can be for the entire vma (in which case pfn, size are zero).
   */
  void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,
  		 unsigned long size)
  {
  	resource_size_t paddr;
  	unsigned long prot;
  
  	if (!(vma->vm_flags & VM_PAT))
  		return;
  
  	/* free the chunk starting from pfn or the whole chunk */
  	paddr = (resource_size_t)pfn << PAGE_SHIFT;
  	if (!paddr && !size) {
  		if (follow_phys(vma, vma->vm_start, 0, &prot, &paddr)) {
  			WARN_ON_ONCE(1);
  			return;
  		}
  
  		size = vma->vm_end - vma->vm_start;
  	}
  	free_pfn_range(paddr, size);
  	vma->vm_flags &= ~VM_PAT;
  }
  
  pgprot_t pgprot_writecombine(pgprot_t prot)
  {
  	if (pat_enabled)
  		return __pgprot(pgprot_val(prot) |
  				cachemode2protval(_PAGE_CACHE_MODE_WC));
  	else
  		return pgprot_noncached(prot);
  }
  EXPORT_SYMBOL_GPL(pgprot_writecombine);
  
  #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_X86_PAT)
  
  static struct memtype *memtype_get_idx(loff_t pos)
  {
  	struct memtype *print_entry;
  	int ret;
  
  	print_entry  = kzalloc(sizeof(struct memtype), GFP_KERNEL);
  	if (!print_entry)
  		return NULL;
  
  	spin_lock(&memtype_lock);
  	ret = rbt_memtype_copy_nth_element(print_entry, pos);
  	spin_unlock(&memtype_lock);
  
  	if (!ret) {
  		return print_entry;
  	} else {
  		kfree(print_entry);
  		return NULL;
  	}
  }
  
  static void *memtype_seq_start(struct seq_file *seq, loff_t *pos)
  {
  	if (*pos == 0) {
  		++*pos;
  		seq_puts(seq, "PAT memtype list:\n");
  	}
  
  	return memtype_get_idx(*pos);
  }
  
  static void *memtype_seq_next(struct seq_file *seq, void *v, loff_t *pos)
  {
  	++*pos;
  	return memtype_get_idx(*pos);
  }
  
  static void memtype_seq_stop(struct seq_file *seq, void *v)
  {
  }
  
  static int memtype_seq_show(struct seq_file *seq, void *v)
  {
  	struct memtype *print_entry = (struct memtype *)v;
  
  	seq_printf(seq, "%s @ 0x%Lx-0x%Lx\n", cattr_name(print_entry->type),
  			print_entry->start, print_entry->end);
  	kfree(print_entry);
  
  	return 0;
  }
  
  static const struct seq_operations memtype_seq_ops = {
  	.start = memtype_seq_start,
  	.next  = memtype_seq_next,
  	.stop  = memtype_seq_stop,
  	.show  = memtype_seq_show,
  };
  
  static int memtype_seq_open(struct inode *inode, struct file *file)
  {
  	return seq_open(file, &memtype_seq_ops);
  }
  
  static const struct file_operations memtype_fops = {
  	.open    = memtype_seq_open,
  	.read    = seq_read,
  	.llseek  = seq_lseek,
  	.release = seq_release,
  };
  
  static int __init pat_memtype_list_init(void)
  {
  	if (pat_enabled) {
  		debugfs_create_file("pat_memtype_list", S_IRUSR,
  				    arch_debugfs_dir, NULL, &memtype_fops);
  	}
  	return 0;
  }
  
  late_initcall(pat_memtype_list_init);
  
  #endif /* CONFIG_DEBUG_FS && CONFIG_X86_PAT */
  