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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/x86/mm/pat_rbtree.c
Initial import
Diffstat (limited to 'arch/x86/mm/pat_rbtree.c')
-rw-r--r--arch/x86/mm/pat_rbtree.c249
1 files changed, 249 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..6582adcc8
--- /dev/null
+++ b/arch/x86/mm/pat_rbtree.c
@@ -0,0 +1,249 @@
+/*
+ * 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/module.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 = container_of(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 = container_of(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 */
+}
+
+static struct memtype *memtype_rb_exact_match(struct rb_root *root,
+ u64 start, u64 end)
+{
+ struct memtype *match;
+
+ match = memtype_rb_lowest_match(root, start, end);
+ while (match != NULL && match->start < end) {
+ struct rb_node *node;
+
+ if (match->start == start && match->end == end)
+ return match;
+
+ node = rb_next(&match->rb);
+ if (node)
+ match = container_of(node, struct memtype, rb);
+ else
+ match = NULL;
+ }
+
+ return NULL; /* Returns NULL if there is no exact 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 = container_of(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:
+ printk(KERN_INFO "%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 = container_of(*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;
+
+ data = memtype_rb_exact_match(&memtype_rbroot, start, end);
+ if (!data)
+ goto out;
+
+ rb_erase_augmented(&data->rb, &memtype_rbroot, &memtype_rb_augment_cb);
+out:
+ return data;
+}
+
+struct memtype *rbt_memtype_lookup(u64 addr)
+{
+ struct memtype *data;
+ data = memtype_rb_lowest_match(&memtype_rbroot, addr, addr + PAGE_SIZE);
+ return data;
+}
+
+#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 = container_of(node, struct memtype, rb);
+ *out = *this;
+ return 0;
+ } else {
+ return 1;
+ }
+}
+#endif