Initial import

1 files changed, 1008 insertions, 0 deletions

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
new file mode 100644
index 000000000..35af6771a
--- /dev/null
+++ b/arch/x86/mm/pat.c
@@ -0,0 +1,1008 @@
+/*
+ * 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 */