arch/powerpc/platforms/powernv/memtrace.c

   1 /*
   2  * Copyright (C) IBM Corporation, 2014, 2017
   3  * Anton Blanchard, Rashmica Gupta.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  */
  10
  11 #define pr_fmt(fmt) "memtrace: " fmt
  12
  13 #include <linux/bitops.h>
  14 #include <linux/string.h>
  15 #include <linux/memblock.h>
  16 #include <linux/init.h>
  17 #include <linux/moduleparam.h>
  18 #include <linux/fs.h>
  19 #include <linux/debugfs.h>
  20 #include <linux/slab.h>
  21 #include <linux/memory.h>
  22 #include <linux/memory_hotplug.h>
  23 #include <asm/machdep.h>
  24 #include <asm/debugfs.h>
  25
  26 /* This enables us to keep track of the memory removed from each node. */
  27 struct memtrace_entry {
  28         void *mem;
  29         u64 start;
  30         u64 size;
  31         u32 nid;
  32         struct dentry *dir;
  33         char name[16];
  34 };
  35
  36 static u64 memtrace_size;
  37
  38 static struct memtrace_entry *memtrace_array;
  39 static unsigned int memtrace_array_nr;
  40
  41
  42 static ssize_t memtrace_read(struct file *filp, char __user *ubuf,
  43                              size_t count, loff_t *ppos)
  44 {
  45         struct memtrace_entry *ent = filp->private_data;
  46
  47         return simple_read_from_buffer(ubuf, count, ppos, ent->mem, ent->size);
  48 }
  49
  50 static const struct file_operations memtrace_fops = {
  51         .llseek = default_llseek,
  52         .read   = memtrace_read,
  53         .open   = simple_open,
  54 };
  55
  56 static int check_memblock_online(struct memory_block *mem, void *arg)
  57 {
  58         if (mem->state != MEM_ONLINE)
  59                 return -1;
  60
  61         return 0;
  62 }
  63
  64 static int change_memblock_state(struct memory_block *mem, void *arg)
  65 {
  66         unsigned long state = (unsigned long)arg;
  67
  68         mem->state = state;
  69
  70         return 0;
  71 }
  72
  73 /* called with device_hotplug_lock held */
  74 static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages)
  75 {
  76         u64 end_pfn = start_pfn + nr_pages - 1;
  77
  78         if (walk_memory_range(start_pfn, end_pfn, NULL,
  79             check_memblock_online))
  80                 return false;
  81
  82         walk_memory_range(start_pfn, end_pfn, (void *)MEM_GOING_OFFLINE,
  83                           change_memblock_state);
  84
  85         if (offline_pages(start_pfn, nr_pages)) {
  86                 walk_memory_range(start_pfn, end_pfn, (void *)MEM_ONLINE,
  87                                   change_memblock_state);
  88                 return false;
  89         }
  90
  91         walk_memory_range(start_pfn, end_pfn, (void *)MEM_OFFLINE,
  92                           change_memblock_state);
  93
  94
  95         return true;
  96 }
  97
  98 static u64 memtrace_alloc_node(u32 nid, u64 size)
  99 {
 100         u64 start_pfn, end_pfn, nr_pages, pfn;
 101         u64 base_pfn;
 102         u64 bytes = memory_block_size_bytes();
 103
 104         if (!node_spanned_pages(nid))
 105                 return 0;
 106
 107         start_pfn = node_start_pfn(nid);
 108         end_pfn = node_end_pfn(nid);
 109         nr_pages = size >> PAGE_SHIFT;
 110
 111         /* Trace memory needs to be aligned to the size */
 112         end_pfn = round_down(end_pfn - nr_pages, nr_pages);
 113
 114         lock_device_hotplug();
 115         for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) {
 116                 if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true) {
 117                         /*
 118                          * Remove memory in memory block size chunks so that
 119                          * iomem resources are always split to the same size and
 120                          * we never try to remove memory that spans two iomem
 121                          * resources.
 122                          */
 123                         end_pfn = base_pfn + nr_pages;
 124                         for (pfn = base_pfn; pfn < end_pfn; pfn += bytes>> PAGE_SHIFT) {
 125                                 __remove_memory(nid, pfn << PAGE_SHIFT, bytes);
 126                         }
 127                         unlock_device_hotplug();
 128                         return base_pfn << PAGE_SHIFT;
 129                 }
 130         }
 131         unlock_device_hotplug();
 132
 133         return 0;
 134 }
 135
 136 static int memtrace_init_regions_runtime(u64 size)
 137 {
 138         u32 nid;
 139         u64 m;
 140
 141         memtrace_array = kcalloc(num_online_nodes(),
 142                                 sizeof(struct memtrace_entry), GFP_KERNEL);
 143         if (!memtrace_array) {
 144                 pr_err("Failed to allocate memtrace_array\n");
 145                 return -EINVAL;
 146         }
 147
 148         for_each_online_node(nid) {
 149                 m = memtrace_alloc_node(nid, size);
 150
 151                 /*
 152                  * A node might not have any local memory, so warn but
 153                  * continue on.
 154                  */
 155                 if (!m) {
 156                         pr_err("Failed to allocate trace memory on node %d\n", nid);
 157                         continue;
 158                 }
 159
 160                 pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);
 161
 162                 memtrace_array[memtrace_array_nr].start = m;
 163                 memtrace_array[memtrace_array_nr].size = size;
 164                 memtrace_array[memtrace_array_nr].nid = nid;
 165                 memtrace_array_nr++;
 166         }
 167
 168         return 0;
 169 }
 170
 171 static struct dentry *memtrace_debugfs_dir;
 172
 173 static int memtrace_init_debugfs(void)
 174 {
 175         int ret = 0;
 176         int i;
 177
 178         for (i = 0; i < memtrace_array_nr; i++) {
 179                 struct dentry *dir;
 180                 struct memtrace_entry *ent = &memtrace_array[i];
 181
 182                 ent->mem = ioremap(ent->start, ent->size);
 183                 /* Warn but continue on */
 184                 if (!ent->mem) {
 185                         pr_err("Failed to map trace memory at 0x%llx\n",
 186                                  ent->start);
 187                         ret = -1;
 188                         continue;
 189                 }
 190
 191                 snprintf(ent->name, 16, "%08x", ent->nid);
 192                 dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
 193                 if (!dir) {
 194                         pr_err("Failed to create debugfs directory for node %d\n",
 195                                 ent->nid);
 196                         return -1;
 197                 }
 198
 199                 ent->dir = dir;
 200                 debugfs_create_file("trace", 0400, dir, ent, &memtrace_fops);
 201                 debugfs_create_x64("start", 0400, dir, &ent->start);
 202                 debugfs_create_x64("size", 0400, dir, &ent->size);
 203         }
 204
 205         return ret;
 206 }
 207
 208 static int online_mem_block(struct memory_block *mem, void *arg)
 209 {
 210         return device_online(&mem->dev);
 211 }
 212
 213 /*
 214  * Iterate through the chunks of memory we have removed from the kernel
 215  * and attempt to add them back to the kernel.
 216  */
 217 static int memtrace_online(void)
 218 {
 219         int i, ret = 0;
 220         struct memtrace_entry *ent;
 221
 222         for (i = memtrace_array_nr - 1; i >= 0; i--) {
 223                 ent = &memtrace_array[i];
 224
 225                 /* We have onlined this chunk previously */
 226                 if (ent->nid == -1)
 227                         continue;
 228
 229                 /* Remove from io mappings */
 230                 if (ent->mem) {
 231                         iounmap(ent->mem);
 232                         ent->mem = 0;
 233                 }
 234
 235                 if (add_memory(ent->nid, ent->start, ent->size)) {
 236                         pr_err("Failed to add trace memory to node %d\n",
 237                                 ent->nid);
 238                         ret += 1;
 239                         continue;
 240                 }
 241
 242                 /*
 243                  * If kernel isn't compiled with the auto online option
 244                  * we need to online the memory ourselves.
 245                  */
 246                 if (!memhp_auto_online) {
 247                         lock_device_hotplug();
 248                         walk_memory_range(PFN_DOWN(ent->start),
 249                                           PFN_UP(ent->start + ent->size - 1),
 250                                           NULL, online_mem_block);
 251                         unlock_device_hotplug();
 252                 }
 253
 254                 /*
 255                  * Memory was added successfully so clean up references to it
 256                  * so on reentry we can tell that this chunk was added.
 257                  */
 258                 debugfs_remove_recursive(ent->dir);
 259                 pr_info("Added trace memory back to node %d\n", ent->nid);
 260                 ent->size = ent->start = ent->nid = -1;
 261         }
 262         if (ret)
 263                 return ret;
 264
 265         /* If all chunks of memory were added successfully, reset globals */
 266         kfree(memtrace_array);
 267         memtrace_array = NULL;
 268         memtrace_size = 0;
 269         memtrace_array_nr = 0;
 270         return 0;
 271 }
 272
 273 static int memtrace_enable_set(void *data, u64 val)
 274 {
 275         u64 bytes;
 276
 277         /*
 278          * Don't attempt to do anything if size isn't aligned to a memory
 279          * block or equal to zero.
 280          */
 281         bytes = memory_block_size_bytes();
 282         if (val & (bytes - 1)) {
 283                 pr_err("Value must be aligned with 0x%llx\n", bytes);
 284                 return -EINVAL;
 285         }
 286
 287         /* Re-add/online previously removed/offlined memory */
 288         if (memtrace_size) {
 289                 if (memtrace_online())
 290                         return -EAGAIN;
 291         }
 292
 293         if (!val)
 294                 return 0;
 295
 296         /* Offline and remove memory */
 297         if (memtrace_init_regions_runtime(val))
 298                 return -EINVAL;
 299
 300         if (memtrace_init_debugfs())
 301                 return -EINVAL;
 302
 303         memtrace_size = val;
 304
 305         return 0;
 306 }
 307
 308 static int memtrace_enable_get(void *data, u64 *val)
 309 {
 310         *val = memtrace_size;
 311         return 0;
 312 }
 313
 314 DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
 315                                         memtrace_enable_set, "0x%016llx\n");
 316
 317 static int memtrace_init(void)
 318 {
 319         memtrace_debugfs_dir = debugfs_create_dir("memtrace",
 320                                                   powerpc_debugfs_root);
 321         if (!memtrace_debugfs_dir)
 322                 return -1;
 323
 324         debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
 325                             NULL, &memtrace_init_fops);
 326
 327         return 0;
 328 }
 329 machine_device_initcall(powernv, memtrace_init);