1 files changed, 281 insertions, 0 deletions
diff --git a/arch/x86/mm/pat_rbtree.c b/arch/x86/mm/pat_rbtree.c
new file mode 100644
index 000000000..fa16036fa
--- /dev/null
+++ b/arch/x86/mm/pat_rbtree.c
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Handle caching attributes in page tables (PAT)
+ *
+ * Authors: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
+ *          Suresh B Siddha <suresh.b.siddha@intel.com>
+ *
+ * Interval tree (augmented rbtree) used to store the PAT memory type
+ * reservations.
+ */
+
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
+#include <linux/kernel.h>
+#include <linux/rbtree_augmented.h>
+#include <linux/sched.h>
+#include <linux/gfp.h>
+
+#include <asm/pgtable.h>
+#include <asm/pat.h>
+
+#include "pat_internal.h"
+
+/*
+ * The memtype tree keeps track of memory type for specific
+ * physical memory areas. Without proper tracking, conflicting memory
+ * types in different mappings can cause CPU cache corruption.
+ *
+ * The tree is an interval tree (augmented rbtree) with tree ordered
+ * on starting address. Tree can contain multiple entries for
+ * different regions which overlap. All the aliases have the same
+ * cache attributes of course.
+ *
+ * memtype_lock protects the rbtree.
+ */
+
+static struct rb_root memtype_rbroot = RB_ROOT;
+
+static int is_node_overlap(struct memtype *node, u64 start, u64 end)
+{
+	if (node->start >= end || node->end <= start)
+		return 0;
+
+	return 1;
+}
+
+static u64 get_subtree_max_end(struct rb_node *node)
+{
+	u64 ret = 0;
+	if (node) {
+		struct memtype *data = rb_entry(node, struct memtype, rb);
+		ret = data->subtree_max_end;
+	}
+	return ret;
+}
+
+static u64 compute_subtree_max_end(struct memtype *data)
+{
+	u64 max_end = data->end, child_max_end;
+
+	child_max_end = get_subtree_max_end(data->rb.rb_right);
+	if (child_max_end > max_end)
+		max_end = child_max_end;
+
+	child_max_end = get_subtree_max_end(data->rb.rb_left);
+	if (child_max_end > max_end)
+		max_end = child_max_end;
+
+	return max_end;
+}
+
+RB_DECLARE_CALLBACKS(static, memtype_rb_augment_cb, struct memtype, rb,
+		     u64, subtree_max_end, compute_subtree_max_end)
+
+/* Find the first (lowest start addr) overlapping range from rb tree */
+static struct memtype *memtype_rb_lowest_match(struct rb_root *root,
+				u64 start, u64 end)
+{
+	struct rb_node *node = root->rb_node;
+	struct memtype *last_lower = NULL;
+
+	while (node) {
+		struct memtype *data = rb_entry(node, struct memtype, rb);
+
+		if (get_subtree_max_end(node->rb_left) > start) {
+			/* Lowest overlap if any must be on left side */
+			node = node->rb_left;
+		} else if (is_node_overlap(data, start, end)) {
+			last_lower = data;
+			break;
+		} else if (start >= data->start) {
+			/* Lowest overlap if any must be on right side */
+			node = node->rb_right;
+		} else {
+			break;
+		}
+	}
+	return last_lower; /* Returns NULL if there is no overlap */
+}
+
+enum {
+	MEMTYPE_EXACT_MATCH	= 0,
+	MEMTYPE_END_MATCH	= 1
+};
+
+static struct memtype *memtype_rb_match(struct rb_root *root,
+				u64 start, u64 end, int match_type)
+{
+	struct memtype *match;
+
+	match = memtype_rb_lowest_match(root, start, end);
+	while (match != NULL && match->start < end) {
+		struct rb_node *node;
+
+		if ((match_type == MEMTYPE_EXACT_MATCH) &&
+		    (match->start == start) && (match->end == end))
+			return match;
+
+		if ((match_type == MEMTYPE_END_MATCH) &&
+		    (match->start < start) && (match->end == end))
+			return match;
+
+		node = rb_next(&match->rb);
+		if (node)
+			match = rb_entry(node, struct memtype, rb);
+		else
+			match = NULL;
+	}
+
+	return NULL; /* Returns NULL if there is no match */
+}
+
+static int memtype_rb_check_conflict(struct rb_root *root,
+				u64 start, u64 end,
+				enum page_cache_mode reqtype,
+				enum page_cache_mode *newtype)
+{
+	struct rb_node *node;
+	struct memtype *match;
+	enum page_cache_mode found_type = reqtype;
+
+	match = memtype_rb_lowest_match(&memtype_rbroot, start, end);
+	if (match == NULL)
+		goto success;
+
+	if (match->type != found_type && newtype == NULL)
+		goto failure;
+
+	dprintk("Overlap at 0x%Lx-0x%Lx\n", match->start, match->end);
+	found_type = match->type;
+
+	node = rb_next(&match->rb);
+	while (node) {
+		match = rb_entry(node, struct memtype, rb);
+
+		if (match->start >= end) /* Checked all possible matches */
+			goto success;
+
+		if (is_node_overlap(match, start, end) &&
+		    match->type != found_type) {
+			goto failure;
+		}
+
+		node = rb_next(&match->rb);
+	}
+success:
+	if (newtype)
+		*newtype = found_type;
+
+	return 0;
+
+failure:
+	pr_info("x86/PAT: %s:%d conflicting memory types %Lx-%Lx %s<->%s\n",
+		current->comm, current->pid, start, end,
+		cattr_name(found_type), cattr_name(match->type));
+	return -EBUSY;
+}
+
+static void memtype_rb_insert(struct rb_root *root, struct memtype *newdata)
+{
+	struct rb_node **node = &(root->rb_node);
+	struct rb_node *parent = NULL;
+
+	while (*node) {
+		struct memtype *data = rb_entry(*node, struct memtype, rb);
+
+		parent = *node;
+		if (data->subtree_max_end < newdata->end)
+			data->subtree_max_end = newdata->end;
+		if (newdata->start <= data->start)
+			node = &((*node)->rb_left);
+		else if (newdata->start > data->start)
+			node = &((*node)->rb_right);
+	}
+
+	newdata->subtree_max_end = newdata->end;
+	rb_link_node(&newdata->rb, parent, node);
+	rb_insert_augmented(&newdata->rb, root, &memtype_rb_augment_cb);
+}
+
+int rbt_memtype_check_insert(struct memtype *new,
+			     enum page_cache_mode *ret_type)
+{
+	int err = 0;
+
+	err = memtype_rb_check_conflict(&memtype_rbroot, new->start, new->end,
+						new->type, ret_type);
+
+	if (!err) {
+		if (ret_type)
+			new->type = *ret_type;
+
+		new->subtree_max_end = new->end;
+		memtype_rb_insert(&memtype_rbroot, new);
+	}
+	return err;
+}
+
+struct memtype *rbt_memtype_erase(u64 start, u64 end)
+{
+	struct memtype *data;
+
+	/*
+	 * Since the memtype_rbroot tree allows overlapping ranges,
+	 * rbt_memtype_erase() checks with EXACT_MATCH first, i.e. free
+	 * a whole node for the munmap case.  If no such entry is found,
+	 * it then checks with END_MATCH, i.e. shrink the size of a node
+	 * from the end for the mremap case.
+	 */
+	data = memtype_rb_match(&memtype_rbroot, start, end,
+				MEMTYPE_EXACT_MATCH);
+	if (!data) {
+		data = memtype_rb_match(&memtype_rbroot, start, end,
+					MEMTYPE_END_MATCH);
+		if (!data)
+			return ERR_PTR(-EINVAL);
+	}
+
+	if (data->start == start) {
+		/* munmap: erase this node */
+		rb_erase_augmented(&data->rb, &memtype_rbroot,
+					&memtype_rb_augment_cb);
+	} else {
+		/* mremap: update the end value of this node */
+		rb_erase_augmented(&data->rb, &memtype_rbroot,
+					&memtype_rb_augment_cb);
+		data->end = start;
+		data->subtree_max_end = data->end;
+		memtype_rb_insert(&memtype_rbroot, data);
+		return NULL;
+	}
+
+	return data;
+}
+
+struct memtype *rbt_memtype_lookup(u64 addr)
+{
+	return memtype_rb_lowest_match(&memtype_rbroot, addr, addr + PAGE_SIZE);
+}
+
+#if defined(CONFIG_DEBUG_FS)
+int rbt_memtype_copy_nth_element(struct memtype *out, loff_t pos)
+{
+	struct rb_node *node;
+	int i = 1;
+
+	node = rb_first(&memtype_rbroot);
+	while (node && pos != i) {
+		node = rb_next(node);
+		i++;
+	}
+
+	if (node) { /* pos == i */
+		struct memtype *this = rb_entry(node, struct memtype, rb);
+		*out = *this;
+		return 0;
+	} else {
+		return 1;
+	}
+}
+#endif