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1/* cpumap.c: used for optimizing CPU assignment
2 *
3 * Copyright (C) 2009 Hong H. Pham <hong.pham@windriver.com>
4 */
5
6#include <linux/export.h>
7#include <linux/slab.h>
8#include <linux/kernel.h>
9#include <linux/init.h>
10#include <linux/cpumask.h>
11#include <linux/spinlock.h>
12#include <asm/cpudata.h>
13#include "cpumap.h"
14
15
16enum {
17 CPUINFO_LVL_ROOT = 0,
18 CPUINFO_LVL_NODE,
19 CPUINFO_LVL_CORE,
20 CPUINFO_LVL_PROC,
21 CPUINFO_LVL_MAX,
22};
23
24enum {
25 ROVER_NO_OP = 0,
26 /* Increment rover every time level is visited */
27 ROVER_INC_ON_VISIT = 1 << 0,
28 /* Increment parent's rover every time rover wraps around */
29 ROVER_INC_PARENT_ON_LOOP = 1 << 1,
30};
31
32struct cpuinfo_node {
33 int id;
34 int level;
35 int num_cpus; /* Number of CPUs in this hierarchy */
36 int parent_index;
37 int child_start; /* Array index of the first child node */
38 int child_end; /* Array index of the last child node */
39 int rover; /* Child node iterator */
40};
41
42struct cpuinfo_level {
43 int start_index; /* Index of first node of a level in a cpuinfo tree */
44 int end_index; /* Index of last node of a level in a cpuinfo tree */
45 int num_nodes; /* Number of nodes in a level in a cpuinfo tree */
46};
47
48struct cpuinfo_tree {
49 int total_nodes;
50
51 /* Offsets into nodes[] for each level of the tree */
52 struct cpuinfo_level level[CPUINFO_LVL_MAX];
53 struct cpuinfo_node nodes[0];
54};
55
56
57static struct cpuinfo_tree *cpuinfo_tree;
58
59static u16 cpu_distribution_map[NR_CPUS];
60static DEFINE_SPINLOCK(cpu_map_lock);
61
62
63/* Niagara optimized cpuinfo tree traversal. */
64static const int niagara_iterate_method[] = {
65 [CPUINFO_LVL_ROOT] = ROVER_NO_OP,
66
67 /* Strands (or virtual CPUs) within a core may not run concurrently
68 * on the Niagara, as instruction pipeline(s) are shared. Distribute
69 * work to strands in different cores first for better concurrency.
70 * Go to next NUMA node when all cores are used.
71 */
72 [CPUINFO_LVL_NODE] = ROVER_INC_ON_VISIT|ROVER_INC_PARENT_ON_LOOP,
73
74 /* Strands are grouped together by proc_id in cpuinfo_sparc, i.e.
75 * a proc_id represents an instruction pipeline. Distribute work to
76 * strands in different proc_id groups if the core has multiple
77 * instruction pipelines (e.g. the Niagara 2/2+ has two).
78 */
79 [CPUINFO_LVL_CORE] = ROVER_INC_ON_VISIT,
80
81 /* Pick the next strand in the proc_id group. */
82 [CPUINFO_LVL_PROC] = ROVER_INC_ON_VISIT,
83};
84
85/* Generic cpuinfo tree traversal. Distribute work round robin across NUMA
86 * nodes.
87 */
88static const int generic_iterate_method[] = {
89 [CPUINFO_LVL_ROOT] = ROVER_INC_ON_VISIT,
90 [CPUINFO_LVL_NODE] = ROVER_NO_OP,
91 [CPUINFO_LVL_CORE] = ROVER_INC_PARENT_ON_LOOP,
92 [CPUINFO_LVL_PROC] = ROVER_INC_ON_VISIT|ROVER_INC_PARENT_ON_LOOP,
93};
94
95
96static int cpuinfo_id(int cpu, int level)
97{
98 int id;
99
100 switch (level) {
101 case CPUINFO_LVL_ROOT:
102 id = 0;
103 break;
104 case CPUINFO_LVL_NODE:
105 id = cpu_to_node(cpu);
106 break;
107 case CPUINFO_LVL_CORE:
108 id = cpu_data(cpu).core_id;
109 break;
110 case CPUINFO_LVL_PROC:
111 id = cpu_data(cpu).proc_id;
112 break;
113 default:
114 id = -EINVAL;
115 }
116 return id;
117}
118
119/*
120 * Enumerate the CPU information in __cpu_data to determine the start index,
121 * end index, and number of nodes for each level in the cpuinfo tree. The
122 * total number of cpuinfo nodes required to build the tree is returned.
123 */
124static int enumerate_cpuinfo_nodes(struct cpuinfo_level *tree_level)
125{
126 int prev_id[CPUINFO_LVL_MAX];
127 int i, n, num_nodes;
128
129 for (i = CPUINFO_LVL_ROOT; i < CPUINFO_LVL_MAX; i++) {
130 struct cpuinfo_level *lv = &tree_level[i];
131
132 prev_id[i] = -1;
133 lv->start_index = lv->end_index = lv->num_nodes = 0;
134 }
135
136 num_nodes = 1; /* Include the root node */
137
138 for (i = 0; i < num_possible_cpus(); i++) {
139 if (!cpu_online(i))
140 continue;
141
142 n = cpuinfo_id(i, CPUINFO_LVL_NODE);
143 if (n > prev_id[CPUINFO_LVL_NODE]) {
144 tree_level[CPUINFO_LVL_NODE].num_nodes++;
145 prev_id[CPUINFO_LVL_NODE] = n;
146 num_nodes++;
147 }
148 n = cpuinfo_id(i, CPUINFO_LVL_CORE);
149 if (n > prev_id[CPUINFO_LVL_CORE]) {
150 tree_level[CPUINFO_LVL_CORE].num_nodes++;
151 prev_id[CPUINFO_LVL_CORE] = n;
152 num_nodes++;
153 }
154 n = cpuinfo_id(i, CPUINFO_LVL_PROC);
155 if (n > prev_id[CPUINFO_LVL_PROC]) {
156 tree_level[CPUINFO_LVL_PROC].num_nodes++;
157 prev_id[CPUINFO_LVL_PROC] = n;
158 num_nodes++;
159 }
160 }
161
162 tree_level[CPUINFO_LVL_ROOT].num_nodes = 1;
163
164 n = tree_level[CPUINFO_LVL_NODE].num_nodes;
165 tree_level[CPUINFO_LVL_NODE].start_index = 1;
166 tree_level[CPUINFO_LVL_NODE].end_index = n;
167
168 n++;
169 tree_level[CPUINFO_LVL_CORE].start_index = n;
170 n += tree_level[CPUINFO_LVL_CORE].num_nodes;
171 tree_level[CPUINFO_LVL_CORE].end_index = n - 1;
172
173 tree_level[CPUINFO_LVL_PROC].start_index = n;
174 n += tree_level[CPUINFO_LVL_PROC].num_nodes;
175 tree_level[CPUINFO_LVL_PROC].end_index = n - 1;
176
177 return num_nodes;
178}
179
180/* Build a tree representation of the CPU hierarchy using the per CPU
181 * information in __cpu_data. Entries in __cpu_data[0..NR_CPUS] are
182 * assumed to be sorted in ascending order based on node, core_id, and
183 * proc_id (in order of significance).
184 */
185static struct cpuinfo_tree *build_cpuinfo_tree(void)
186{
187 struct cpuinfo_tree *new_tree;
188 struct cpuinfo_node *node;
189 struct cpuinfo_level tmp_level[CPUINFO_LVL_MAX];
190 int num_cpus[CPUINFO_LVL_MAX];
191 int level_rover[CPUINFO_LVL_MAX];
192 int prev_id[CPUINFO_LVL_MAX];
193 int n, id, cpu, prev_cpu, last_cpu, level;
194
195 n = enumerate_cpuinfo_nodes(tmp_level);
196
197 new_tree = kzalloc(sizeof(struct cpuinfo_tree) +
198 (sizeof(struct cpuinfo_node) * n), GFP_ATOMIC);
199 if (!new_tree)
200 return NULL;
201
202 new_tree->total_nodes = n;
203 memcpy(&new_tree->level, tmp_level, sizeof(tmp_level));
204
205 prev_cpu = cpu = cpumask_first(cpu_online_mask);
206
207 /* Initialize all levels in the tree with the first CPU */
208 for (level = CPUINFO_LVL_PROC; level >= CPUINFO_LVL_ROOT; level--) {
209 n = new_tree->level[level].start_index;
210
211 level_rover[level] = n;
212 node = &new_tree->nodes[n];
213
214 id = cpuinfo_id(cpu, level);
215 if (unlikely(id < 0)) {
216 kfree(new_tree);
217 return NULL;
218 }
219 node->id = id;
220 node->level = level;
221 node->num_cpus = 1;
222
223 node->parent_index = (level > CPUINFO_LVL_ROOT)
224 ? new_tree->level[level - 1].start_index : -1;
225
226 node->child_start = node->child_end = node->rover =
227 (level == CPUINFO_LVL_PROC)
228 ? cpu : new_tree->level[level + 1].start_index;
229
230 prev_id[level] = node->id;
231 num_cpus[level] = 1;
232 }
233
234 for (last_cpu = (num_possible_cpus() - 1); last_cpu >= 0; last_cpu--) {
235 if (cpu_online(last_cpu))
236 break;
237 }
238
239 while (++cpu <= last_cpu) {
240 if (!cpu_online(cpu))
241 continue;
242
243 for (level = CPUINFO_LVL_PROC; level >= CPUINFO_LVL_ROOT;
244 level--) {
245 id = cpuinfo_id(cpu, level);
246 if (unlikely(id < 0)) {
247 kfree(new_tree);
248 return NULL;
249 }
250
251 if ((id != prev_id[level]) || (cpu == last_cpu)) {
252 prev_id[level] = id;
253 node = &new_tree->nodes[level_rover[level]];
254 node->num_cpus = num_cpus[level];
255 num_cpus[level] = 1;
256
257 if (cpu == last_cpu)
258 node->num_cpus++;
259
260 /* Connect tree node to parent */
261 if (level == CPUINFO_LVL_ROOT)
262 node->parent_index = -1;
263 else
264 node->parent_index =
265 level_rover[level - 1];
266
267 if (level == CPUINFO_LVL_PROC) {
268 node->child_end =
269 (cpu == last_cpu) ? cpu : prev_cpu;
270 } else {
271 node->child_end =
272 level_rover[level + 1] - 1;
273 }
274
275 /* Initialize the next node in the same level */
276 n = ++level_rover[level];
277 if (n <= new_tree->level[level].end_index) {
278 node = &new_tree->nodes[n];
279 node->id = id;
280 node->level = level;
281
282 /* Connect node to child */
283 node->child_start = node->child_end =
284 node->rover =
285 (level == CPUINFO_LVL_PROC)
286 ? cpu : level_rover[level + 1];
287 }
288 } else
289 num_cpus[level]++;
290 }
291 prev_cpu = cpu;
292 }
293
294 return new_tree;
295}
296
297static void increment_rover(struct cpuinfo_tree *t, int node_index,
298 int root_index, const int *rover_inc_table)
299{
300 struct cpuinfo_node *node = &t->nodes[node_index];
301 int top_level, level;
302
303 top_level = t->nodes[root_index].level;
304 for (level = node->level; level >= top_level; level--) {
305 node->rover++;
306 if (node->rover <= node->child_end)
307 return;
308
309 node->rover = node->child_start;
310 /* If parent's rover does not need to be adjusted, stop here. */
311 if ((level == top_level) ||
312 !(rover_inc_table[level] & ROVER_INC_PARENT_ON_LOOP))
313 return;
314
315 node = &t->nodes[node->parent_index];
316 }
317}
318
319static int iterate_cpu(struct cpuinfo_tree *t, unsigned int root_index)
320{
321 const int *rover_inc_table;
322 int level, new_index, index = root_index;
323
324 switch (sun4v_chip_type) {
325 case SUN4V_CHIP_NIAGARA1:
326 case SUN4V_CHIP_NIAGARA2:
327 case SUN4V_CHIP_NIAGARA3:
328 case SUN4V_CHIP_NIAGARA4:
329 case SUN4V_CHIP_NIAGARA5:
330 rover_inc_table = niagara_iterate_method;
331 break;
332 default:
333 rover_inc_table = generic_iterate_method;
334 }
335
336 for (level = t->nodes[root_index].level; level < CPUINFO_LVL_MAX;
337 level++) {
338 new_index = t->nodes[index].rover;
339 if (rover_inc_table[level] & ROVER_INC_ON_VISIT)
340 increment_rover(t, index, root_index, rover_inc_table);
341
342 index = new_index;
343 }
344 return index;
345}
346
347static void _cpu_map_rebuild(void)
348{
349 int i;
350
351 if (cpuinfo_tree) {
352 kfree(cpuinfo_tree);
353 cpuinfo_tree = NULL;
354 }
355
356 cpuinfo_tree = build_cpuinfo_tree();
357 if (!cpuinfo_tree)
358 return;
359
360 /* Build CPU distribution map that spans all online CPUs. No need
361 * to check if the CPU is online, as that is done when the cpuinfo
362 * tree is being built.
363 */
364 for (i = 0; i < cpuinfo_tree->nodes[0].num_cpus; i++)
365 cpu_distribution_map[i] = iterate_cpu(cpuinfo_tree, 0);
366}
367
368/* Fallback if the cpuinfo tree could not be built. CPU mapping is linear
369 * round robin.
370 */
371static int simple_map_to_cpu(unsigned int index)
372{
373 int i, end, cpu_rover;
374
375 cpu_rover = 0;
376 end = index % num_online_cpus();
377 for (i = 0; i < num_possible_cpus(); i++) {
378 if (cpu_online(cpu_rover)) {
379 if (cpu_rover >= end)
380 return cpu_rover;
381
382 cpu_rover++;
383 }
384 }
385
386 /* Impossible, since num_online_cpus() <= num_possible_cpus() */
387 return cpumask_first(cpu_online_mask);
388}
389
390static int _map_to_cpu(unsigned int index)
391{
392 struct cpuinfo_node *root_node;
393
394 if (unlikely(!cpuinfo_tree)) {
395 _cpu_map_rebuild();
396 if (!cpuinfo_tree)
397 return simple_map_to_cpu(index);
398 }
399
400 root_node = &cpuinfo_tree->nodes[0];
401#ifdef CONFIG_HOTPLUG_CPU
402 if (unlikely(root_node->num_cpus != num_online_cpus())) {
403 _cpu_map_rebuild();
404 if (!cpuinfo_tree)
405 return simple_map_to_cpu(index);
406 }
407#endif
408 return cpu_distribution_map[index % root_node->num_cpus];
409}
410
411int map_to_cpu(unsigned int index)
412{
413 int mapped_cpu;
414 unsigned long flag;
415
416 spin_lock_irqsave(&cpu_map_lock, flag);
417 mapped_cpu = _map_to_cpu(index);
418
419#ifdef CONFIG_HOTPLUG_CPU
420 while (unlikely(!cpu_online(mapped_cpu)))
421 mapped_cpu = _map_to_cpu(index);
422#endif
423 spin_unlock_irqrestore(&cpu_map_lock, flag);
424 return mapped_cpu;
425}
426EXPORT_SYMBOL(map_to_cpu);
427
428void cpu_map_rebuild(void)
429{
430 unsigned long flag;
431
432 spin_lock_irqsave(&cpu_map_lock, flag);
433 _cpu_map_rebuild();
434 spin_unlock_irqrestore(&cpu_map_lock, flag);
435}
1// SPDX-License-Identifier: GPL-2.0
2/* cpumap.c: used for optimizing CPU assignment
3 *
4 * Copyright (C) 2009 Hong H. Pham <hong.pham@windriver.com>
5 */
6
7#include <linux/export.h>
8#include <linux/slab.h>
9#include <linux/kernel.h>
10#include <linux/cpumask.h>
11#include <linux/spinlock.h>
12#include <asm/cpudata.h>
13#include "cpumap.h"
14
15
16enum {
17 CPUINFO_LVL_ROOT = 0,
18 CPUINFO_LVL_NODE,
19 CPUINFO_LVL_CORE,
20 CPUINFO_LVL_PROC,
21 CPUINFO_LVL_MAX,
22};
23
24enum {
25 ROVER_NO_OP = 0,
26 /* Increment rover every time level is visited */
27 ROVER_INC_ON_VISIT = 1 << 0,
28 /* Increment parent's rover every time rover wraps around */
29 ROVER_INC_PARENT_ON_LOOP = 1 << 1,
30};
31
32struct cpuinfo_node {
33 int id;
34 int level;
35 int num_cpus; /* Number of CPUs in this hierarchy */
36 int parent_index;
37 int child_start; /* Array index of the first child node */
38 int child_end; /* Array index of the last child node */
39 int rover; /* Child node iterator */
40};
41
42struct cpuinfo_level {
43 int start_index; /* Index of first node of a level in a cpuinfo tree */
44 int end_index; /* Index of last node of a level in a cpuinfo tree */
45 int num_nodes; /* Number of nodes in a level in a cpuinfo tree */
46};
47
48struct cpuinfo_tree {
49 int total_nodes;
50
51 /* Offsets into nodes[] for each level of the tree */
52 struct cpuinfo_level level[CPUINFO_LVL_MAX];
53 struct cpuinfo_node nodes[] __counted_by(total_nodes);
54};
55
56
57static struct cpuinfo_tree *cpuinfo_tree;
58
59static u16 cpu_distribution_map[NR_CPUS];
60static DEFINE_SPINLOCK(cpu_map_lock);
61
62
63/* Niagara optimized cpuinfo tree traversal. */
64static const int niagara_iterate_method[] = {
65 [CPUINFO_LVL_ROOT] = ROVER_NO_OP,
66
67 /* Strands (or virtual CPUs) within a core may not run concurrently
68 * on the Niagara, as instruction pipeline(s) are shared. Distribute
69 * work to strands in different cores first for better concurrency.
70 * Go to next NUMA node when all cores are used.
71 */
72 [CPUINFO_LVL_NODE] = ROVER_INC_ON_VISIT|ROVER_INC_PARENT_ON_LOOP,
73
74 /* Strands are grouped together by proc_id in cpuinfo_sparc, i.e.
75 * a proc_id represents an instruction pipeline. Distribute work to
76 * strands in different proc_id groups if the core has multiple
77 * instruction pipelines (e.g. the Niagara 2/2+ has two).
78 */
79 [CPUINFO_LVL_CORE] = ROVER_INC_ON_VISIT,
80
81 /* Pick the next strand in the proc_id group. */
82 [CPUINFO_LVL_PROC] = ROVER_INC_ON_VISIT,
83};
84
85/* Generic cpuinfo tree traversal. Distribute work round robin across NUMA
86 * nodes.
87 */
88static const int generic_iterate_method[] = {
89 [CPUINFO_LVL_ROOT] = ROVER_INC_ON_VISIT,
90 [CPUINFO_LVL_NODE] = ROVER_NO_OP,
91 [CPUINFO_LVL_CORE] = ROVER_INC_PARENT_ON_LOOP,
92 [CPUINFO_LVL_PROC] = ROVER_INC_ON_VISIT|ROVER_INC_PARENT_ON_LOOP,
93};
94
95
96static int cpuinfo_id(int cpu, int level)
97{
98 int id;
99
100 switch (level) {
101 case CPUINFO_LVL_ROOT:
102 id = 0;
103 break;
104 case CPUINFO_LVL_NODE:
105 id = cpu_to_node(cpu);
106 break;
107 case CPUINFO_LVL_CORE:
108 id = cpu_data(cpu).core_id;
109 break;
110 case CPUINFO_LVL_PROC:
111 id = cpu_data(cpu).proc_id;
112 break;
113 default:
114 id = -EINVAL;
115 }
116 return id;
117}
118
119/*
120 * Enumerate the CPU information in __cpu_data to determine the start index,
121 * end index, and number of nodes for each level in the cpuinfo tree. The
122 * total number of cpuinfo nodes required to build the tree is returned.
123 */
124static int enumerate_cpuinfo_nodes(struct cpuinfo_level *tree_level)
125{
126 int prev_id[CPUINFO_LVL_MAX];
127 int i, n, num_nodes;
128
129 for (i = CPUINFO_LVL_ROOT; i < CPUINFO_LVL_MAX; i++) {
130 struct cpuinfo_level *lv = &tree_level[i];
131
132 prev_id[i] = -1;
133 lv->start_index = lv->end_index = lv->num_nodes = 0;
134 }
135
136 num_nodes = 1; /* Include the root node */
137
138 for (i = 0; i < num_possible_cpus(); i++) {
139 if (!cpu_online(i))
140 continue;
141
142 n = cpuinfo_id(i, CPUINFO_LVL_NODE);
143 if (n > prev_id[CPUINFO_LVL_NODE]) {
144 tree_level[CPUINFO_LVL_NODE].num_nodes++;
145 prev_id[CPUINFO_LVL_NODE] = n;
146 num_nodes++;
147 }
148 n = cpuinfo_id(i, CPUINFO_LVL_CORE);
149 if (n > prev_id[CPUINFO_LVL_CORE]) {
150 tree_level[CPUINFO_LVL_CORE].num_nodes++;
151 prev_id[CPUINFO_LVL_CORE] = n;
152 num_nodes++;
153 }
154 n = cpuinfo_id(i, CPUINFO_LVL_PROC);
155 if (n > prev_id[CPUINFO_LVL_PROC]) {
156 tree_level[CPUINFO_LVL_PROC].num_nodes++;
157 prev_id[CPUINFO_LVL_PROC] = n;
158 num_nodes++;
159 }
160 }
161
162 tree_level[CPUINFO_LVL_ROOT].num_nodes = 1;
163
164 n = tree_level[CPUINFO_LVL_NODE].num_nodes;
165 tree_level[CPUINFO_LVL_NODE].start_index = 1;
166 tree_level[CPUINFO_LVL_NODE].end_index = n;
167
168 n++;
169 tree_level[CPUINFO_LVL_CORE].start_index = n;
170 n += tree_level[CPUINFO_LVL_CORE].num_nodes;
171 tree_level[CPUINFO_LVL_CORE].end_index = n - 1;
172
173 tree_level[CPUINFO_LVL_PROC].start_index = n;
174 n += tree_level[CPUINFO_LVL_PROC].num_nodes;
175 tree_level[CPUINFO_LVL_PROC].end_index = n - 1;
176
177 return num_nodes;
178}
179
180/* Build a tree representation of the CPU hierarchy using the per CPU
181 * information in __cpu_data. Entries in __cpu_data[0..NR_CPUS] are
182 * assumed to be sorted in ascending order based on node, core_id, and
183 * proc_id (in order of significance).
184 */
185static struct cpuinfo_tree *build_cpuinfo_tree(void)
186{
187 struct cpuinfo_tree *new_tree;
188 struct cpuinfo_node *node;
189 struct cpuinfo_level tmp_level[CPUINFO_LVL_MAX];
190 int num_cpus[CPUINFO_LVL_MAX];
191 int level_rover[CPUINFO_LVL_MAX];
192 int prev_id[CPUINFO_LVL_MAX];
193 int n, id, cpu, prev_cpu, last_cpu, level;
194
195 n = enumerate_cpuinfo_nodes(tmp_level);
196
197 new_tree = kzalloc(struct_size(new_tree, nodes, n), GFP_ATOMIC);
198 if (!new_tree)
199 return NULL;
200
201 new_tree->total_nodes = n;
202 memcpy(&new_tree->level, tmp_level, sizeof(tmp_level));
203
204 prev_cpu = cpu = cpumask_first(cpu_online_mask);
205
206 /* Initialize all levels in the tree with the first CPU */
207 for (level = CPUINFO_LVL_PROC; level >= CPUINFO_LVL_ROOT; level--) {
208 n = new_tree->level[level].start_index;
209
210 level_rover[level] = n;
211 node = &new_tree->nodes[n];
212
213 id = cpuinfo_id(cpu, level);
214 if (unlikely(id < 0)) {
215 kfree(new_tree);
216 return NULL;
217 }
218 node->id = id;
219 node->level = level;
220 node->num_cpus = 1;
221
222 node->parent_index = (level > CPUINFO_LVL_ROOT)
223 ? new_tree->level[level - 1].start_index : -1;
224
225 node->child_start = node->child_end = node->rover =
226 (level == CPUINFO_LVL_PROC)
227 ? cpu : new_tree->level[level + 1].start_index;
228
229 prev_id[level] = node->id;
230 num_cpus[level] = 1;
231 }
232
233 for (last_cpu = (num_possible_cpus() - 1); last_cpu >= 0; last_cpu--) {
234 if (cpu_online(last_cpu))
235 break;
236 }
237
238 while (++cpu <= last_cpu) {
239 if (!cpu_online(cpu))
240 continue;
241
242 for (level = CPUINFO_LVL_PROC; level >= CPUINFO_LVL_ROOT;
243 level--) {
244 id = cpuinfo_id(cpu, level);
245 if (unlikely(id < 0)) {
246 kfree(new_tree);
247 return NULL;
248 }
249
250 if ((id != prev_id[level]) || (cpu == last_cpu)) {
251 prev_id[level] = id;
252 node = &new_tree->nodes[level_rover[level]];
253 node->num_cpus = num_cpus[level];
254 num_cpus[level] = 1;
255
256 if (cpu == last_cpu)
257 node->num_cpus++;
258
259 /* Connect tree node to parent */
260 if (level == CPUINFO_LVL_ROOT)
261 node->parent_index = -1;
262 else
263 node->parent_index =
264 level_rover[level - 1];
265
266 if (level == CPUINFO_LVL_PROC) {
267 node->child_end =
268 (cpu == last_cpu) ? cpu : prev_cpu;
269 } else {
270 node->child_end =
271 level_rover[level + 1] - 1;
272 }
273
274 /* Initialize the next node in the same level */
275 n = ++level_rover[level];
276 if (n <= new_tree->level[level].end_index) {
277 node = &new_tree->nodes[n];
278 node->id = id;
279 node->level = level;
280
281 /* Connect node to child */
282 node->child_start = node->child_end =
283 node->rover =
284 (level == CPUINFO_LVL_PROC)
285 ? cpu : level_rover[level + 1];
286 }
287 } else
288 num_cpus[level]++;
289 }
290 prev_cpu = cpu;
291 }
292
293 return new_tree;
294}
295
296static void increment_rover(struct cpuinfo_tree *t, int node_index,
297 int root_index, const int *rover_inc_table)
298{
299 struct cpuinfo_node *node = &t->nodes[node_index];
300 int top_level, level;
301
302 top_level = t->nodes[root_index].level;
303 for (level = node->level; level >= top_level; level--) {
304 node->rover++;
305 if (node->rover <= node->child_end)
306 return;
307
308 node->rover = node->child_start;
309 /* If parent's rover does not need to be adjusted, stop here. */
310 if ((level == top_level) ||
311 !(rover_inc_table[level] & ROVER_INC_PARENT_ON_LOOP))
312 return;
313
314 node = &t->nodes[node->parent_index];
315 }
316}
317
318static int iterate_cpu(struct cpuinfo_tree *t, unsigned int root_index)
319{
320 const int *rover_inc_table;
321 int level, new_index, index = root_index;
322
323 switch (sun4v_chip_type) {
324 case SUN4V_CHIP_NIAGARA1:
325 case SUN4V_CHIP_NIAGARA2:
326 case SUN4V_CHIP_NIAGARA3:
327 case SUN4V_CHIP_NIAGARA4:
328 case SUN4V_CHIP_NIAGARA5:
329 case SUN4V_CHIP_SPARC_M6:
330 case SUN4V_CHIP_SPARC_M7:
331 case SUN4V_CHIP_SPARC_M8:
332 case SUN4V_CHIP_SPARC_SN:
333 case SUN4V_CHIP_SPARC64X:
334 rover_inc_table = niagara_iterate_method;
335 break;
336 default:
337 rover_inc_table = generic_iterate_method;
338 }
339
340 for (level = t->nodes[root_index].level; level < CPUINFO_LVL_MAX;
341 level++) {
342 new_index = t->nodes[index].rover;
343 if (rover_inc_table[level] & ROVER_INC_ON_VISIT)
344 increment_rover(t, index, root_index, rover_inc_table);
345
346 index = new_index;
347 }
348 return index;
349}
350
351static void _cpu_map_rebuild(void)
352{
353 int i;
354
355 if (cpuinfo_tree) {
356 kfree(cpuinfo_tree);
357 cpuinfo_tree = NULL;
358 }
359
360 cpuinfo_tree = build_cpuinfo_tree();
361 if (!cpuinfo_tree)
362 return;
363
364 /* Build CPU distribution map that spans all online CPUs. No need
365 * to check if the CPU is online, as that is done when the cpuinfo
366 * tree is being built.
367 */
368 for (i = 0; i < cpuinfo_tree->nodes[0].num_cpus; i++)
369 cpu_distribution_map[i] = iterate_cpu(cpuinfo_tree, 0);
370}
371
372/* Fallback if the cpuinfo tree could not be built. CPU mapping is linear
373 * round robin.
374 */
375static int simple_map_to_cpu(unsigned int index)
376{
377 int i, end, cpu_rover;
378
379 cpu_rover = 0;
380 end = index % num_online_cpus();
381 for (i = 0; i < num_possible_cpus(); i++) {
382 if (cpu_online(cpu_rover)) {
383 if (cpu_rover >= end)
384 return cpu_rover;
385
386 cpu_rover++;
387 }
388 }
389
390 /* Impossible, since num_online_cpus() <= num_possible_cpus() */
391 return cpumask_first(cpu_online_mask);
392}
393
394static int _map_to_cpu(unsigned int index)
395{
396 struct cpuinfo_node *root_node;
397
398 if (unlikely(!cpuinfo_tree)) {
399 _cpu_map_rebuild();
400 if (!cpuinfo_tree)
401 return simple_map_to_cpu(index);
402 }
403
404 root_node = &cpuinfo_tree->nodes[0];
405#ifdef CONFIG_HOTPLUG_CPU
406 if (unlikely(root_node->num_cpus != num_online_cpus())) {
407 _cpu_map_rebuild();
408 if (!cpuinfo_tree)
409 return simple_map_to_cpu(index);
410 }
411#endif
412 return cpu_distribution_map[index % root_node->num_cpus];
413}
414
415int map_to_cpu(unsigned int index)
416{
417 int mapped_cpu;
418 unsigned long flag;
419
420 spin_lock_irqsave(&cpu_map_lock, flag);
421 mapped_cpu = _map_to_cpu(index);
422
423#ifdef CONFIG_HOTPLUG_CPU
424 while (unlikely(!cpu_online(mapped_cpu)))
425 mapped_cpu = _map_to_cpu(index);
426#endif
427 spin_unlock_irqrestore(&cpu_map_lock, flag);
428 return mapped_cpu;
429}
430EXPORT_SYMBOL(map_to_cpu);
431
432void cpu_map_rebuild(void)
433{
434 unsigned long flag;
435
436 spin_lock_irqsave(&cpu_map_lock, flag);
437 _cpu_map_rebuild();
438 spin_unlock_irqrestore(&cpu_map_lock, flag);
439}