Pallipadi, Venkatesh | 9e41a49 | 2010-02-10 15:26:07 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Handle caching attributes in page tables (PAT) |
| 3 | * |
| 4 | * Authors: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> |
| 5 | * Suresh B Siddha <suresh.b.siddha@intel.com> |
| 6 | * |
| 7 | * Interval tree (augmented rbtree) used to store the PAT memory type |
| 8 | * reservations. |
| 9 | */ |
| 10 | |
| 11 | #include <linux/seq_file.h> |
| 12 | #include <linux/debugfs.h> |
| 13 | #include <linux/kernel.h> |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/rbtree.h> |
| 16 | #include <linux/sched.h> |
| 17 | #include <linux/gfp.h> |
| 18 | |
| 19 | #include <asm/pgtable.h> |
| 20 | #include <asm/pat.h> |
| 21 | |
| 22 | #include "pat_internal.h" |
| 23 | |
| 24 | /* |
| 25 | * The memtype tree keeps track of memory type for specific |
| 26 | * physical memory areas. Without proper tracking, conflicting memory |
| 27 | * types in different mappings can cause CPU cache corruption. |
| 28 | * |
| 29 | * The tree is an interval tree (augmented rbtree) with tree ordered |
| 30 | * on starting address. Tree can contain multiple entries for |
| 31 | * different regions which overlap. All the aliases have the same |
| 32 | * cache attributes of course. |
| 33 | * |
| 34 | * memtype_lock protects the rbtree. |
| 35 | */ |
| 36 | |
| 37 | static void memtype_rb_augment_cb(struct rb_node *node); |
| 38 | static struct rb_root memtype_rbroot = RB_AUGMENT_ROOT(&memtype_rb_augment_cb); |
| 39 | |
| 40 | static int is_node_overlap(struct memtype *node, u64 start, u64 end) |
| 41 | { |
| 42 | if (node->start >= end || node->end <= start) |
| 43 | return 0; |
| 44 | |
| 45 | return 1; |
| 46 | } |
| 47 | |
| 48 | static u64 get_subtree_max_end(struct rb_node *node) |
| 49 | { |
| 50 | u64 ret = 0; |
| 51 | if (node) { |
| 52 | struct memtype *data = container_of(node, struct memtype, rb); |
| 53 | ret = data->subtree_max_end; |
| 54 | } |
| 55 | return ret; |
| 56 | } |
| 57 | |
| 58 | /* Update 'subtree_max_end' for a node, based on node and its children */ |
| 59 | static void update_node_max_end(struct rb_node *node) |
| 60 | { |
| 61 | struct memtype *data; |
| 62 | u64 max_end, child_max_end; |
| 63 | |
| 64 | if (!node) |
| 65 | return; |
| 66 | |
| 67 | data = container_of(node, struct memtype, rb); |
| 68 | max_end = data->end; |
| 69 | |
| 70 | child_max_end = get_subtree_max_end(node->rb_right); |
| 71 | if (child_max_end > max_end) |
| 72 | max_end = child_max_end; |
| 73 | |
| 74 | child_max_end = get_subtree_max_end(node->rb_left); |
| 75 | if (child_max_end > max_end) |
| 76 | max_end = child_max_end; |
| 77 | |
| 78 | data->subtree_max_end = max_end; |
| 79 | } |
| 80 | |
| 81 | /* Update 'subtree_max_end' for a node and all its ancestors */ |
| 82 | static void update_path_max_end(struct rb_node *node) |
| 83 | { |
| 84 | u64 old_max_end, new_max_end; |
| 85 | |
| 86 | while (node) { |
| 87 | struct memtype *data = container_of(node, struct memtype, rb); |
| 88 | |
| 89 | old_max_end = data->subtree_max_end; |
| 90 | update_node_max_end(node); |
| 91 | new_max_end = data->subtree_max_end; |
| 92 | |
| 93 | if (new_max_end == old_max_end) |
| 94 | break; |
| 95 | |
| 96 | node = rb_parent(node); |
| 97 | } |
| 98 | } |
| 99 | |
| 100 | /* Find the first (lowest start addr) overlapping range from rb tree */ |
| 101 | static struct memtype *memtype_rb_lowest_match(struct rb_root *root, |
| 102 | u64 start, u64 end) |
| 103 | { |
| 104 | struct rb_node *node = root->rb_node; |
| 105 | struct memtype *last_lower = NULL; |
| 106 | |
| 107 | while (node) { |
| 108 | struct memtype *data = container_of(node, struct memtype, rb); |
| 109 | |
| 110 | if (get_subtree_max_end(node->rb_left) > start) { |
| 111 | /* Lowest overlap if any must be on left side */ |
| 112 | node = node->rb_left; |
| 113 | } else if (is_node_overlap(data, start, end)) { |
| 114 | last_lower = data; |
| 115 | break; |
| 116 | } else if (start >= data->start) { |
| 117 | /* Lowest overlap if any must be on right side */ |
| 118 | node = node->rb_right; |
| 119 | } else { |
| 120 | break; |
| 121 | } |
| 122 | } |
| 123 | return last_lower; /* Returns NULL if there is no overlap */ |
| 124 | } |
| 125 | |
| 126 | static struct memtype *memtype_rb_exact_match(struct rb_root *root, |
| 127 | u64 start, u64 end) |
| 128 | { |
| 129 | struct memtype *match; |
| 130 | |
| 131 | match = memtype_rb_lowest_match(root, start, end); |
| 132 | while (match != NULL && match->start < end) { |
| 133 | struct rb_node *node; |
| 134 | |
| 135 | if (match->start == start && match->end == end) |
| 136 | return match; |
| 137 | |
| 138 | node = rb_next(&match->rb); |
| 139 | if (node) |
| 140 | match = container_of(node, struct memtype, rb); |
| 141 | else |
| 142 | match = NULL; |
| 143 | } |
| 144 | |
| 145 | return NULL; /* Returns NULL if there is no exact match */ |
| 146 | } |
| 147 | |
| 148 | static int memtype_rb_check_conflict(struct rb_root *root, |
| 149 | u64 start, u64 end, |
| 150 | unsigned long reqtype, unsigned long *newtype) |
| 151 | { |
| 152 | struct rb_node *node; |
| 153 | struct memtype *match; |
| 154 | int found_type = reqtype; |
| 155 | |
| 156 | match = memtype_rb_lowest_match(&memtype_rbroot, start, end); |
| 157 | if (match == NULL) |
| 158 | goto success; |
| 159 | |
| 160 | if (match->type != found_type && newtype == NULL) |
| 161 | goto failure; |
| 162 | |
| 163 | dprintk("Overlap at 0x%Lx-0x%Lx\n", match->start, match->end); |
| 164 | found_type = match->type; |
| 165 | |
| 166 | node = rb_next(&match->rb); |
| 167 | while (node) { |
| 168 | match = container_of(node, struct memtype, rb); |
| 169 | |
| 170 | if (match->start >= end) /* Checked all possible matches */ |
| 171 | goto success; |
| 172 | |
| 173 | if (is_node_overlap(match, start, end) && |
| 174 | match->type != found_type) { |
| 175 | goto failure; |
| 176 | } |
| 177 | |
| 178 | node = rb_next(&match->rb); |
| 179 | } |
| 180 | success: |
| 181 | if (newtype) |
| 182 | *newtype = found_type; |
| 183 | |
| 184 | return 0; |
| 185 | |
| 186 | failure: |
| 187 | printk(KERN_INFO "%s:%d conflicting memory types " |
| 188 | "%Lx-%Lx %s<->%s\n", current->comm, current->pid, start, |
| 189 | end, cattr_name(found_type), cattr_name(match->type)); |
| 190 | return -EBUSY; |
| 191 | } |
| 192 | |
| 193 | static void memtype_rb_augment_cb(struct rb_node *node) |
| 194 | { |
| 195 | if (node) |
| 196 | update_path_max_end(node); |
| 197 | } |
| 198 | |
| 199 | static void memtype_rb_insert(struct rb_root *root, struct memtype *newdata) |
| 200 | { |
| 201 | struct rb_node **node = &(root->rb_node); |
| 202 | struct rb_node *parent = NULL; |
| 203 | |
| 204 | while (*node) { |
| 205 | struct memtype *data = container_of(*node, struct memtype, rb); |
| 206 | |
| 207 | parent = *node; |
| 208 | if (newdata->start <= data->start) |
| 209 | node = &((*node)->rb_left); |
| 210 | else if (newdata->start > data->start) |
| 211 | node = &((*node)->rb_right); |
| 212 | } |
| 213 | |
| 214 | rb_link_node(&newdata->rb, parent, node); |
| 215 | rb_insert_color(&newdata->rb, root); |
| 216 | } |
| 217 | |
| 218 | int rbt_memtype_check_insert(struct memtype *new, unsigned long *ret_type) |
| 219 | { |
| 220 | int err = 0; |
| 221 | |
| 222 | err = memtype_rb_check_conflict(&memtype_rbroot, new->start, new->end, |
| 223 | new->type, ret_type); |
| 224 | |
| 225 | if (!err) { |
Pallipadi, Venkatesh | 4daa2a8 | 2010-02-24 13:43:55 -0800 | [diff] [blame] | 226 | if (ret_type) |
| 227 | new->type = *ret_type; |
| 228 | |
Venkatesh Pallipadi | 6a4f3b5 | 2010-06-10 17:45:01 -0700 | [diff] [blame^] | 229 | new->subtree_max_end = new->end; |
Pallipadi, Venkatesh | 9e41a49 | 2010-02-10 15:26:07 -0800 | [diff] [blame] | 230 | memtype_rb_insert(&memtype_rbroot, new); |
| 231 | } |
| 232 | return err; |
| 233 | } |
| 234 | |
Xiaotian Feng | 20413f2 | 2010-05-26 09:51:10 +0800 | [diff] [blame] | 235 | struct memtype *rbt_memtype_erase(u64 start, u64 end) |
Pallipadi, Venkatesh | 9e41a49 | 2010-02-10 15:26:07 -0800 | [diff] [blame] | 236 | { |
| 237 | struct memtype *data; |
| 238 | |
| 239 | data = memtype_rb_exact_match(&memtype_rbroot, start, end); |
| 240 | if (!data) |
Xiaotian Feng | 20413f2 | 2010-05-26 09:51:10 +0800 | [diff] [blame] | 241 | goto out; |
Pallipadi, Venkatesh | 9e41a49 | 2010-02-10 15:26:07 -0800 | [diff] [blame] | 242 | |
| 243 | rb_erase(&data->rb, &memtype_rbroot); |
Xiaotian Feng | 20413f2 | 2010-05-26 09:51:10 +0800 | [diff] [blame] | 244 | out: |
| 245 | return data; |
Pallipadi, Venkatesh | 9e41a49 | 2010-02-10 15:26:07 -0800 | [diff] [blame] | 246 | } |
| 247 | |
| 248 | struct memtype *rbt_memtype_lookup(u64 addr) |
| 249 | { |
| 250 | struct memtype *data; |
| 251 | data = memtype_rb_lowest_match(&memtype_rbroot, addr, addr + PAGE_SIZE); |
| 252 | return data; |
| 253 | } |
| 254 | |
| 255 | #if defined(CONFIG_DEBUG_FS) |
| 256 | int rbt_memtype_copy_nth_element(struct memtype *out, loff_t pos) |
| 257 | { |
| 258 | struct rb_node *node; |
| 259 | int i = 1; |
| 260 | |
| 261 | node = rb_first(&memtype_rbroot); |
| 262 | while (node && pos != i) { |
| 263 | node = rb_next(node); |
| 264 | i++; |
| 265 | } |
| 266 | |
| 267 | if (node) { /* pos == i */ |
| 268 | struct memtype *this = container_of(node, struct memtype, rb); |
| 269 | *out = *this; |
| 270 | return 0; |
| 271 | } else { |
| 272 | return 1; |
| 273 | } |
| 274 | } |
| 275 | #endif |