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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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b945d6b255
Reimplement augmented RB-trees without sprinkling extra branches all over the RB-tree code (which lives in the scheduler hot path). This approach is 'borrowed' from Fabio's BFQ implementation and relies on traversing the rebalance path after the RB-tree-op to correct the heap property for insertion/removal and make up for the damage done by the tree rotations. For insertion the rebalance path is trivially that from the new node upwards to the root, for removal it is that from the deepest node in the path from the to be removed node that will still be around after the removal. [ This patch also fixes a video driver regression reported by Ali Gholami Rudi - the memtype->subtree_max_end was updated incorrectly. ] Acked-by: Suresh Siddha <suresh.b.siddha@intel.com> Acked-by: Venkatesh Pallipadi <venki@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: Ali Gholami Rudi <ali@rudi.ir> Cc: Fabio Checconi <fabio@gandalf.sssup.it> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <1275414172.27810.27961.camel@twins> Signed-off-by: Ingo Molnar <mingo@elte.hu>
254 lines
5.9 KiB
C
254 lines
5.9 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 struct rb_root memtype_rbroot = RB_ROOT;
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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 memtype_rb_augment_cb(struct rb_node *node, void *__unused)
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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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/* 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_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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rb_augment_insert(&newdata->rb, memtype_rb_augment_cb, NULL);
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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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if (ret_type)
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new->type = *ret_type;
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new->subtree_max_end = new->end;
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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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struct memtype *rbt_memtype_erase(u64 start, u64 end)
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{
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struct rb_node *deepest;
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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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goto out;
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deepest = rb_augment_erase_begin(&data->rb);
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rb_erase(&data->rb, &memtype_rbroot);
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rb_augment_erase_end(deepest, memtype_rb_augment_cb, NULL);
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out:
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return data;
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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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