kernel/irq/matrix.c

   1 /*
   2  * Copyright (C) 2017 Thomas Gleixner <tglx@linutronix.de>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0
   5  */
   6 #include <linux/spinlock.h>
   7 #include <linux/seq_file.h>
   8 #include <linux/bitmap.h>
   9 #include <linux/percpu.h>
  10 #include <linux/cpu.h>
  11 #include <linux/irq.h>
  12
  13 #define IRQ_MATRIX_SIZE (BITS_TO_LONGS(IRQ_MATRIX_BITS) * sizeof(unsigned long))
  14
  15 struct cpumap {
  16         unsigned int            available;
  17         unsigned int            allocated;
  18         unsigned int            managed;
  19         bool                    online;
  20         unsigned long           alloc_map[IRQ_MATRIX_SIZE];
  21         unsigned long           managed_map[IRQ_MATRIX_SIZE];
  22 };
  23
  24 struct irq_matrix {
  25         unsigned int            matrix_bits;
  26         unsigned int            alloc_start;
  27         unsigned int            alloc_end;
  28         unsigned int            alloc_size;
  29         unsigned int            global_available;
  30         unsigned int            global_reserved;
  31         unsigned int            systembits_inalloc;
  32         unsigned int            total_allocated;
  33         unsigned int            online_maps;
  34         struct cpumap __percpu  *maps;
  35         unsigned long           scratch_map[IRQ_MATRIX_SIZE];
  36         unsigned long           system_map[IRQ_MATRIX_SIZE];
  37 };
  38
  39 #define CREATE_TRACE_POINTS
  40 #include <trace/events/irq_matrix.h>
  41
  42 /**
  43  * irq_alloc_matrix - Allocate a irq_matrix structure and initialize it
  44  * @matrix_bits:        Number of matrix bits must be <= IRQ_MATRIX_BITS
  45  * @alloc_start:        From which bit the allocation search starts
  46  * @alloc_end:          At which bit the allocation search ends, i.e first
  47  *                      invalid bit
  48  */
  49 __init struct irq_matrix *irq_alloc_matrix(unsigned int matrix_bits,
  50                                            unsigned int alloc_start,
  51                                            unsigned int alloc_end)
  52 {
  53         struct irq_matrix *m;
  54
  55         if (matrix_bits > IRQ_MATRIX_BITS)
  56                 return NULL;
  57
  58         m = kzalloc(sizeof(*m), GFP_KERNEL);
  59         if (!m)
  60                 return NULL;
  61
  62         m->matrix_bits = matrix_bits;
  63         m->alloc_start = alloc_start;
  64         m->alloc_end = alloc_end;
  65         m->alloc_size = alloc_end - alloc_start;
  66         m->maps = alloc_percpu(*m->maps);
  67         if (!m->maps) {
  68                 kfree(m);
  69                 return NULL;
  70         }
  71         return m;
  72 }
  73
  74 /**
  75  * irq_matrix_online - Bring the local CPU matrix online
  76  * @m:          Matrix pointer
  77  */
  78 void irq_matrix_online(struct irq_matrix *m)
  79 {
  80         struct cpumap *cm = this_cpu_ptr(m->maps);
  81
  82         BUG_ON(cm->online);
  83
  84         bitmap_zero(cm->alloc_map, m->matrix_bits);
  85         cm->available = m->alloc_size - (cm->managed + m->systembits_inalloc);
  86         cm->allocated = 0;
  87         m->global_available += cm->available;
  88         cm->online = true;
  89         m->online_maps++;
  90         trace_irq_matrix_online(m);
  91 }
  92
  93 /**
  94  * irq_matrix_offline - Bring the local CPU matrix offline
  95  * @m:          Matrix pointer
  96  */
  97 void irq_matrix_offline(struct irq_matrix *m)
  98 {
  99         struct cpumap *cm = this_cpu_ptr(m->maps);
 100
 101         /* Update the global available size */
 102         m->global_available -= cm->available;
 103         cm->online = false;
 104         m->online_maps--;
 105         trace_irq_matrix_offline(m);
 106 }
 107
 108 static unsigned int matrix_alloc_area(struct irq_matrix *m, struct cpumap *cm,
 109                                       unsigned int num, bool managed)
 110 {
 111         unsigned int area, start = m->alloc_start;
 112         unsigned int end = m->alloc_end;
 113
 114         bitmap_or(m->scratch_map, cm->managed_map, m->system_map, end);
 115         bitmap_or(m->scratch_map, m->scratch_map, cm->alloc_map, end);
 116         area = bitmap_find_next_zero_area(m->scratch_map, end, start, num, 0);
 117         if (area >= end)
 118                 return area;
 119         if (managed)
 120                 bitmap_set(cm->managed_map, area, num);
 121         else
 122                 bitmap_set(cm->alloc_map, area, num);
 123         return area;
 124 }
 125
 126 /**
 127  * irq_matrix_assign_system - Assign system wide entry in the matrix
 128  * @m:          Matrix pointer
 129  * @bit:        Which bit to reserve
 130  * @replace:    Replace an already allocated vector with a system
 131  *              vector at the same bit position.
 132  *
 133  * The BUG_ON()s below are on purpose. If this goes wrong in the
 134  * early boot process, then the chance to survive is about zero.
 135  * If this happens when the system is life, it's not much better.
 136  */
 137 void irq_matrix_assign_system(struct irq_matrix *m, unsigned int bit,
 138                               bool replace)
 139 {
 140         struct cpumap *cm = this_cpu_ptr(m->maps);
 141
 142         BUG_ON(bit > m->matrix_bits);
 143         BUG_ON(m->online_maps > 1 || (m->online_maps && !replace));
 144
 145         set_bit(bit, m->system_map);
 146         if (replace) {
 147                 BUG_ON(!test_and_clear_bit(bit, cm->alloc_map));
 148                 cm->allocated--;
 149                 m->total_allocated--;
 150         }
 151         if (bit >= m->alloc_start && bit < m->alloc_end)
 152                 m->systembits_inalloc++;
 153
 154         trace_irq_matrix_assign_system(bit, m);
 155 }
 156
 157 /**
 158  * irq_matrix_reserve_managed - Reserve a managed interrupt in a CPU map
 159  * @m:          Matrix pointer
 160  * @msk:        On which CPUs the bits should be reserved.
 161  *
 162  * Can be called for offline CPUs. Note, this will only reserve one bit
 163  * on all CPUs in @msk, but it's not guaranteed that the bits are at the
 164  * same offset on all CPUs
 165  */
 166 int irq_matrix_reserve_managed(struct irq_matrix *m, const struct cpumask *msk)
 167 {
 168         unsigned int cpu, failed_cpu;
 169
 170         for_each_cpu(cpu, msk) {
 171                 struct cpumap *cm = per_cpu_ptr(m->maps, cpu);
 172                 unsigned int bit;
 173
 174                 bit = matrix_alloc_area(m, cm, 1, true);
 175                 if (bit >= m->alloc_end)
 176                         goto cleanup;
 177                 cm->managed++;
 178                 if (cm->online) {
 179                         cm->available--;
 180                         m->global_available--;
 181                 }
 182                 trace_irq_matrix_reserve_managed(bit, cpu, m, cm);
 183         }
 184         return 0;
 185 cleanup:
 186         failed_cpu = cpu;
 187         for_each_cpu(cpu, msk) {
 188                 if (cpu == failed_cpu)
 189                         break;
 190                 irq_matrix_remove_managed(m, cpumask_of(cpu));
 191         }
 192         return -ENOSPC;
 193 }
 194
 195 /**
 196  * irq_matrix_remove_managed - Remove managed interrupts in a CPU map
 197  * @m:          Matrix pointer
 198  * @msk:        On which CPUs the bits should be removed
 199  *
 200  * Can be called for offline CPUs
 201  *
 202  * This removes not allocated managed interrupts from the map. It does
 203  * not matter which one because the managed interrupts free their
 204  * allocation when they shut down. If not, the accounting is screwed,
 205  * but all what can be done at this point is warn about it.
 206  */
 207 void irq_matrix_remove_managed(struct irq_matrix *m, const struct cpumask *msk)
 208 {
 209         unsigned int cpu;
 210
 211         for_each_cpu(cpu, msk) {
 212                 struct cpumap *cm = per_cpu_ptr(m->maps, cpu);
 213                 unsigned int bit, end = m->alloc_end;
 214
 215                 if (WARN_ON_ONCE(!cm->managed))
 216                         continue;
 217
 218                 /* Get managed bit which are not allocated */
 219                 bitmap_andnot(m->scratch_map, cm->managed_map, cm->alloc_map, end);
 220
 221                 bit = find_first_bit(m->scratch_map, end);
 222                 if (WARN_ON_ONCE(bit >= end))
 223                         continue;
 224
 225                 clear_bit(bit, cm->managed_map);
 226
 227                 cm->managed--;
 228                 if (cm->online) {
 229                         cm->available++;
 230                         m->global_available++;
 231                 }
 232                 trace_irq_matrix_remove_managed(bit, cpu, m, cm);
 233         }
 234 }
 235
 236 /**
 237  * irq_matrix_alloc_managed - Allocate a managed interrupt in a CPU map
 238  * @m:          Matrix pointer
 239  * @cpu:        On which CPU the interrupt should be allocated
 240  */
 241 int irq_matrix_alloc_managed(struct irq_matrix *m, unsigned int cpu)
 242 {
 243         struct cpumap *cm = per_cpu_ptr(m->maps, cpu);
 244         unsigned int bit, end = m->alloc_end;
 245
 246         /* Get managed bit which are not allocated */
 247         bitmap_andnot(m->scratch_map, cm->managed_map, cm->alloc_map, end);
 248         bit = find_first_bit(m->scratch_map, end);
 249         if (bit >= end)
 250                 return -ENOSPC;
 251         set_bit(bit, cm->alloc_map);
 252         cm->allocated++;
 253         m->total_allocated++;
 254         trace_irq_matrix_alloc_managed(bit, cpu, m, cm);
 255         return bit;
 256 }
 257
 258 /**
 259  * irq_matrix_assign - Assign a preallocated interrupt in the local CPU map
 260  * @m:          Matrix pointer
 261  * @bit:        Which bit to mark
 262  *
 263  * This should only be used to mark preallocated vectors
 264  */
 265 void irq_matrix_assign(struct irq_matrix *m, unsigned int bit)
 266 {
 267         struct cpumap *cm = this_cpu_ptr(m->maps);
 268
 269         if (WARN_ON_ONCE(bit < m->alloc_start || bit >= m->alloc_end))
 270                 return;
 271         if (WARN_ON_ONCE(test_and_set_bit(bit, cm->alloc_map)))
 272                 return;
 273         cm->allocated++;
 274         m->total_allocated++;
 275         cm->available--;
 276         m->global_available--;
 277         trace_irq_matrix_assign(bit, smp_processor_id(), m, cm);
 278 }
 279
 280 /**
 281  * irq_matrix_reserve - Reserve interrupts
 282  * @m:          Matrix pointer
 283  *
 284  * This is merily a book keeping call. It increments the number of globally
 285  * reserved interrupt bits w/o actually allocating them. This allows to
 286  * setup interrupt descriptors w/o assigning low level resources to it.
 287  * The actual allocation happens when the interrupt gets activated.
 288  */
 289 void irq_matrix_reserve(struct irq_matrix *m)
 290 {
 291         if (m->global_reserved <= m->global_available &&
 292             m->global_reserved + 1 > m->global_available)
 293                 pr_warn("Interrupt reservation exceeds available resources\n");
 294
 295         m->global_reserved++;
 296         trace_irq_matrix_reserve(m);
 297 }
 298
 299 /**
 300  * irq_matrix_remove_reserved - Remove interrupt reservation
 301  * @m:          Matrix pointer
 302  *
 303  * This is merily a book keeping call. It decrements the number of globally
 304  * reserved interrupt bits. This is used to undo irq_matrix_reserve() when the
 305  * interrupt was never in use and a real vector allocated, which undid the
 306  * reservation.
 307  */
 308 void irq_matrix_remove_reserved(struct irq_matrix *m)
 309 {
 310         m->global_reserved--;
 311         trace_irq_matrix_remove_reserved(m);
 312 }
 313
 314 /**
 315  * irq_matrix_alloc - Allocate a regular interrupt in a CPU map
 316  * @m:          Matrix pointer
 317  * @msk:        Which CPUs to search in
 318  * @reserved:   Allocate previously reserved interrupts
 319  * @mapped_cpu: Pointer to store the CPU for which the irq was allocated
 320  */
 321 int irq_matrix_alloc(struct irq_matrix *m, const struct cpumask *msk,
 322                      bool reserved, unsigned int *mapped_cpu)
 323 {
 324         unsigned int cpu;
 325
 326         for_each_cpu(cpu, msk) {
 327                 struct cpumap *cm = per_cpu_ptr(m->maps, cpu);
 328                 unsigned int bit;
 329
 330                 if (!cm->online)
 331                         continue;
 332
 333                 bit = matrix_alloc_area(m, cm, 1, false);
 334                 if (bit < m->alloc_end) {
 335                         cm->allocated++;
 336                         cm->available--;
 337                         m->total_allocated++;
 338                         m->global_available--;
 339                         if (reserved)
 340                                 m->global_reserved--;
 341                         *mapped_cpu = cpu;
 342                         trace_irq_matrix_alloc(bit, cpu, m, cm);
 343                         return bit;
 344                 }
 345         }
 346         return -ENOSPC;
 347 }
 348
 349 /**
 350  * irq_matrix_free - Free allocated interrupt in the matrix
 351  * @m:          Matrix pointer
 352  * @cpu:        Which CPU map needs be updated
 353  * @bit:        The bit to remove
 354  * @managed:    If true, the interrupt is managed and not accounted
 355  *              as available.
 356  */
 357 void irq_matrix_free(struct irq_matrix *m, unsigned int cpu,
 358                      unsigned int bit, bool managed)
 359 {
 360         struct cpumap *cm = per_cpu_ptr(m->maps, cpu);
 361
 362         if (WARN_ON_ONCE(bit < m->alloc_start || bit >= m->alloc_end))
 363                 return;
 364
 365         if (cm->online) {
 366                 clear_bit(bit, cm->alloc_map);
 367                 cm->allocated--;
 368                 m->total_allocated--;
 369                 if (!managed) {
 370                         cm->available++;
 371                         m->global_available++;
 372                 }
 373         }
 374         trace_irq_matrix_free(bit, cpu, m, cm);
 375 }
 376
 377 /**
 378  * irq_matrix_available - Get the number of globally available irqs
 379  * @m:          Pointer to the matrix to query
 380  * @cpudown:    If true, the local CPU is about to go down, adjust
 381  *              the number of available irqs accordingly
 382  */
 383 unsigned int irq_matrix_available(struct irq_matrix *m, bool cpudown)
 384 {
 385         struct cpumap *cm = this_cpu_ptr(m->maps);
 386
 387         if (!cpudown)
 388                 return m->global_available;
 389         return m->global_available - cm->available;
 390 }
 391
 392 /**
 393  * irq_matrix_reserved - Get the number of globally reserved irqs
 394  * @m:          Pointer to the matrix to query
 395  */
 396 unsigned int irq_matrix_reserved(struct irq_matrix *m)
 397 {
 398         return m->global_reserved;
 399 }
 400
 401 /**
 402  * irq_matrix_allocated - Get the number of allocated irqs on the local cpu
 403  * @m:          Pointer to the matrix to search
 404  *
 405  * This returns number of allocated irqs
 406  */
 407 unsigned int irq_matrix_allocated(struct irq_matrix *m)
 408 {
 409         struct cpumap *cm = this_cpu_ptr(m->maps);
 410
 411         return cm->allocated;
 412 }
 413
 414 #ifdef CONFIG_GENERIC_IRQ_DEBUGFS
 415 /**
 416  * irq_matrix_debug_show - Show detailed allocation information
 417  * @sf:         Pointer to the seq_file to print to
 418  * @m:          Pointer to the matrix allocator
 419  * @ind:        Indentation for the print format
 420  *
 421  * Note, this is a lockless snapshot.
 422  */
 423 void irq_matrix_debug_show(struct seq_file *sf, struct irq_matrix *m, int ind)
 424 {
 425         unsigned int nsys = bitmap_weight(m->system_map, m->matrix_bits);
 426         int cpu;
 427
 428         seq_printf(sf, "Online bitmaps:   %6u\n", m->online_maps);
 429         seq_printf(sf, "Global available: %6u\n", m->global_available);
 430         seq_printf(sf, "Global reserved:  %6u\n", m->global_reserved);
 431         seq_printf(sf, "Total allocated:  %6u\n", m->total_allocated);
 432         seq_printf(sf, "System: %u: %*pbl\n", nsys, m->matrix_bits,
 433                    m->system_map);
 434         seq_printf(sf, "%*s| CPU | avl | man | act | vectors\n", ind, " ");
 435         cpus_read_lock();
 436         for_each_online_cpu(cpu) {
 437                 struct cpumap *cm = per_cpu_ptr(m->maps, cpu);
 438
 439                 seq_printf(sf, "%*s %4d  %4u  %4u  %4u  %*pbl\n", ind, " ",
 440                            cpu, cm->available, cm->managed, cm->allocated,
 441                            m->matrix_bits, cm->alloc_map);
 442         }
 443         cpus_read_unlock();
 444 }
 445 #endif