272 lines
6.2 KiB
C
272 lines
6.2 KiB
C
/*
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* Handle caching attributes in page tables (PAT)
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*
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* Authors: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
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* Suresh B Siddha <suresh.b.siddha@intel.com>
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*
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* Interval tree (augmented rbtree) used to store the PAT memory type
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* reservations.
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*/
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#include <linux/seq_file.h>
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#include <linux/debugfs.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/rbtree.h>
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#include <linux/sched.h>
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#include <linux/gfp.h>
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#include <asm/pgtable.h>
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#include <asm/pat.h>
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#include "pat_internal.h"
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/*
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* The memtype tree keeps track of memory type for specific
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* physical memory areas. Without proper tracking, conflicting memory
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* types in different mappings can cause CPU cache corruption.
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*
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* The tree is an interval tree (augmented rbtree) with tree ordered
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* on starting address. Tree can contain multiple entries for
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* different regions which overlap. All the aliases have the same
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* cache attributes of course.
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*
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* memtype_lock protects the rbtree.
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*/
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static void memtype_rb_augment_cb(struct rb_node *node);
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static struct rb_root memtype_rbroot = RB_AUGMENT_ROOT(&memtype_rb_augment_cb);
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static int is_node_overlap(struct memtype *node, u64 start, u64 end)
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{
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if (node->start >= end || node->end <= start)
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return 0;
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return 1;
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}
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static u64 get_subtree_max_end(struct rb_node *node)
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{
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u64 ret = 0;
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if (node) {
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struct memtype *data = container_of(node, struct memtype, rb);
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ret = data->subtree_max_end;
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}
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return ret;
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}
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/* Update 'subtree_max_end' for a node, based on node and its children */
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static void update_node_max_end(struct rb_node *node)
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{
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struct memtype *data;
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u64 max_end, child_max_end;
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if (!node)
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return;
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data = container_of(node, struct memtype, rb);
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max_end = data->end;
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child_max_end = get_subtree_max_end(node->rb_right);
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if (child_max_end > max_end)
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max_end = child_max_end;
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child_max_end = get_subtree_max_end(node->rb_left);
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if (child_max_end > max_end)
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max_end = child_max_end;
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data->subtree_max_end = max_end;
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}
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/* Update 'subtree_max_end' for a node and all its ancestors */
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static void update_path_max_end(struct rb_node *node)
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{
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u64 old_max_end, new_max_end;
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while (node) {
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struct memtype *data = container_of(node, struct memtype, rb);
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old_max_end = data->subtree_max_end;
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update_node_max_end(node);
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new_max_end = data->subtree_max_end;
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if (new_max_end == old_max_end)
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break;
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node = rb_parent(node);
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}
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}
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/* Find the first (lowest start addr) overlapping range from rb tree */
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static struct memtype *memtype_rb_lowest_match(struct rb_root *root,
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u64 start, u64 end)
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{
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struct rb_node *node = root->rb_node;
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struct memtype *last_lower = NULL;
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while (node) {
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struct memtype *data = container_of(node, struct memtype, rb);
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if (get_subtree_max_end(node->rb_left) > start) {
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/* Lowest overlap if any must be on left side */
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node = node->rb_left;
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} else if (is_node_overlap(data, start, end)) {
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last_lower = data;
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break;
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} else if (start >= data->start) {
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/* Lowest overlap if any must be on right side */
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node = node->rb_right;
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} else {
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break;
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}
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}
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return last_lower; /* Returns NULL if there is no overlap */
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}
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static struct memtype *memtype_rb_exact_match(struct rb_root *root,
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u64 start, u64 end)
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{
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struct memtype *match;
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match = memtype_rb_lowest_match(root, start, end);
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while (match != NULL && match->start < end) {
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struct rb_node *node;
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if (match->start == start && match->end == end)
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return match;
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node = rb_next(&match->rb);
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if (node)
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match = container_of(node, struct memtype, rb);
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else
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match = NULL;
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}
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return NULL; /* Returns NULL if there is no exact match */
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}
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static int memtype_rb_check_conflict(struct rb_root *root,
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u64 start, u64 end,
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unsigned long reqtype, unsigned long *newtype)
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{
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struct rb_node *node;
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struct memtype *match;
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int found_type = reqtype;
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match = memtype_rb_lowest_match(&memtype_rbroot, start, end);
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if (match == NULL)
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goto success;
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if (match->type != found_type && newtype == NULL)
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goto failure;
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dprintk("Overlap at 0x%Lx-0x%Lx\n", match->start, match->end);
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found_type = match->type;
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node = rb_next(&match->rb);
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while (node) {
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match = container_of(node, struct memtype, rb);
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if (match->start >= end) /* Checked all possible matches */
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goto success;
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if (is_node_overlap(match, start, end) &&
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match->type != found_type) {
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goto failure;
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}
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node = rb_next(&match->rb);
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}
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success:
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if (newtype)
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*newtype = found_type;
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return 0;
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failure:
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printk(KERN_INFO "%s:%d conflicting memory types "
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"%Lx-%Lx %s<->%s\n", current->comm, current->pid, start,
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end, cattr_name(found_type), cattr_name(match->type));
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return -EBUSY;
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}
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static void memtype_rb_augment_cb(struct rb_node *node)
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{
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if (node)
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update_path_max_end(node);
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}
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static void memtype_rb_insert(struct rb_root *root, struct memtype *newdata)
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{
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struct rb_node **node = &(root->rb_node);
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struct rb_node *parent = NULL;
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while (*node) {
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struct memtype *data = container_of(*node, struct memtype, rb);
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parent = *node;
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if (newdata->start <= data->start)
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node = &((*node)->rb_left);
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else if (newdata->start > data->start)
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node = &((*node)->rb_right);
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}
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rb_link_node(&newdata->rb, parent, node);
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rb_insert_color(&newdata->rb, root);
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}
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int rbt_memtype_check_insert(struct memtype *new, unsigned long *ret_type)
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{
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int err = 0;
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err = memtype_rb_check_conflict(&memtype_rbroot, new->start, new->end,
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new->type, ret_type);
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if (!err) {
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new->type = *ret_type;
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memtype_rb_insert(&memtype_rbroot, new);
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}
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return err;
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}
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int rbt_memtype_erase(u64 start, u64 end)
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{
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struct memtype *data;
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data = memtype_rb_exact_match(&memtype_rbroot, start, end);
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if (!data)
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return -EINVAL;
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rb_erase(&data->rb, &memtype_rbroot);
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return 0;
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}
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struct memtype *rbt_memtype_lookup(u64 addr)
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{
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struct memtype *data;
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data = memtype_rb_lowest_match(&memtype_rbroot, addr, addr + PAGE_SIZE);
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return data;
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}
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#if defined(CONFIG_DEBUG_FS)
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int rbt_memtype_copy_nth_element(struct memtype *out, loff_t pos)
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{
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struct rb_node *node;
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int i = 1;
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node = rb_first(&memtype_rbroot);
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while (node && pos != i) {
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node = rb_next(node);
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i++;
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}
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if (node) { /* pos == i */
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struct memtype *this = container_of(node, struct memtype, rb);
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*out = *this;
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return 0;
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} else {
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return 1;
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}
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}
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#endif
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