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 static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages)
  74 {
  75         u64 end_pfn = start_pfn + nr_pages - 1;
  76
  77         if (walk_memory_range(start_pfn, end_pfn, NULL,
  78             check_memblock_online))
  79                 return false;
  80
  81         walk_memory_range(start_pfn, end_pfn, (void *)MEM_GOING_OFFLINE,
  82                           change_memblock_state);
  83
  84         if (offline_pages(start_pfn, nr_pages)) {
  85                 walk_memory_range(start_pfn, end_pfn, (void *)MEM_ONLINE,
  86                                   change_memblock_state);
  87                 return false;
  88         }
  89
  90         walk_memory_range(start_pfn, end_pfn, (void *)MEM_OFFLINE,
  91                           change_memblock_state);
  92
  93         lock_device_hotplug();
  94         remove_memory(nid, start_pfn << PAGE_SHIFT, nr_pages << PAGE_SHIFT);
  95         unlock_device_hotplug();
  96
  97         return true;
  98 }
  99
 100 static u64 memtrace_alloc_node(u32 nid, u64 size)
 101 {
 102         u64 start_pfn, end_pfn, nr_pages;
 103         u64 base_pfn;
 104
 105         if (!node_spanned_pages(nid))
 106                 return 0;
 107
 108         start_pfn = node_start_pfn(nid);
 109         end_pfn = node_end_pfn(nid);
 110         nr_pages = size >> PAGE_SHIFT;
 111
 112         /* Trace memory needs to be aligned to the size */
 113         end_pfn = round_down(end_pfn - nr_pages, nr_pages);
 114
 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                         return base_pfn << PAGE_SHIFT;
 118         }
 119
 120         return 0;
 121 }
 122
 123 static int memtrace_init_regions_runtime(u64 size)
 124 {
 125         u32 nid;
 126         u64 m;
 127
 128         memtrace_array = kcalloc(num_online_nodes(),
 129                                 sizeof(struct memtrace_entry), GFP_KERNEL);
 130         if (!memtrace_array) {
 131                 pr_err("Failed to allocate memtrace_array\n");
 132                 return -EINVAL;
 133         }
 134
 135         for_each_online_node(nid) {
 136                 m = memtrace_alloc_node(nid, size);
 137
 138                 /*
 139                  * A node might not have any local memory, so warn but
 140                  * continue on.
 141                  */
 142                 if (!m) {
 143                         pr_err("Failed to allocate trace memory on node %d\n", nid);
 144                         continue;
 145                 }
 146
 147                 pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);
 148
 149                 memtrace_array[memtrace_array_nr].start = m;
 150                 memtrace_array[memtrace_array_nr].size = size;
 151                 memtrace_array[memtrace_array_nr].nid = nid;
 152                 memtrace_array_nr++;
 153         }
 154
 155         return 0;
 156 }
 157
 158 static struct dentry *memtrace_debugfs_dir;
 159
 160 static int memtrace_init_debugfs(void)
 161 {
 162         int ret = 0;
 163         int i;
 164
 165         for (i = 0; i < memtrace_array_nr; i++) {
 166                 struct dentry *dir;
 167                 struct memtrace_entry *ent = &memtrace_array[i];
 168
 169                 ent->mem = ioremap(ent->start, ent->size);
 170                 /* Warn but continue on */
 171                 if (!ent->mem) {
 172                         pr_err("Failed to map trace memory at 0x%llx\n",
 173                                  ent->start);
 174                         ret = -1;
 175                         continue;
 176                 }
 177
 178                 snprintf(ent->name, 16, "%08x", ent->nid);
 179                 dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
 180                 if (!dir) {
 181                         pr_err("Failed to create debugfs directory for node %d\n",
 182                                 ent->nid);
 183                         return -1;
 184                 }
 185
 186                 ent->dir = dir;
 187                 debugfs_create_file("trace", 0400, dir, ent, &memtrace_fops);
 188                 debugfs_create_x64("start", 0400, dir, &ent->start);
 189                 debugfs_create_x64("size", 0400, dir, &ent->size);
 190         }
 191
 192         return ret;
 193 }
 194
 195 static int online_mem_block(struct memory_block *mem, void *arg)
 196 {
 197         return device_online(&mem->dev);
 198 }
 199
 200 /*
 201  * Iterate through the chunks of memory we have removed from the kernel
 202  * and attempt to add them back to the kernel.
 203  */
 204 static int memtrace_online(void)
 205 {
 206         int i, ret = 0;
 207         struct memtrace_entry *ent;
 208
 209         for (i = memtrace_array_nr - 1; i >= 0; i--) {
 210                 ent = &memtrace_array[i];
 211
 212                 /* We have onlined this chunk previously */
 213                 if (ent->nid == -1)
 214                         continue;
 215
 216                 /* Remove from io mappings */
 217                 if (ent->mem) {
 218                         iounmap(ent->mem);
 219                         ent->mem = 0;
 220                 }
 221
 222                 if (add_memory(ent->nid, ent->start, ent->size)) {
 223                         pr_err("Failed to add trace memory to node %d\n",
 224                                 ent->nid);
 225                         ret += 1;
 226                         continue;
 227                 }
 228
 229                 /*
 230                  * If kernel isn't compiled with the auto online option
 231                  * we need to online the memory ourselves.
 232                  */
 233                 if (!memhp_auto_online) {
 234                         walk_memory_range(PFN_DOWN(ent->start),
 235                                           PFN_UP(ent->start + ent->size - 1),
 236                                           NULL, online_mem_block);
 237                 }
 238
 239                 /*
 240                  * Memory was added successfully so clean up references to it
 241                  * so on reentry we can tell that this chunk was added.
 242                  */
 243                 debugfs_remove_recursive(ent->dir);
 244                 pr_info("Added trace memory back to node %d\n", ent->nid);
 245                 ent->size = ent->start = ent->nid = -1;
 246         }
 247         if (ret)
 248                 return ret;
 249
 250         /* If all chunks of memory were added successfully, reset globals */
 251         kfree(memtrace_array);
 252         memtrace_array = NULL;
 253         memtrace_size = 0;
 254         memtrace_array_nr = 0;
 255         return 0;
 256 }
 257
 258 static int memtrace_enable_set(void *data, u64 val)
 259 {
 260         u64 bytes;
 261
 262         /*
 263          * Don't attempt to do anything if size isn't aligned to a memory
 264          * block or equal to zero.
 265          */
 266         bytes = memory_block_size_bytes();
 267         if (val & (bytes - 1)) {
 268                 pr_err("Value must be aligned with 0x%llx\n", bytes);
 269                 return -EINVAL;
 270         }
 271
 272         /* Re-add/online previously removed/offlined memory */
 273         if (memtrace_size) {
 274                 if (memtrace_online())
 275                         return -EAGAIN;
 276         }
 277
 278         if (!val)
 279                 return 0;
 280
 281         /* Offline and remove memory */
 282         if (memtrace_init_regions_runtime(val))
 283                 return -EINVAL;
 284
 285         if (memtrace_init_debugfs())
 286                 return -EINVAL;
 287
 288         memtrace_size = val;
 289
 290         return 0;
 291 }
 292
 293 static int memtrace_enable_get(void *data, u64 *val)
 294 {
 295         *val = memtrace_size;
 296         return 0;
 297 }
 298
 299 DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
 300                                         memtrace_enable_set, "0x%016llx\n");
 301
 302 static int memtrace_init(void)
 303 {
 304         memtrace_debugfs_dir = debugfs_create_dir("memtrace",
 305                                                   powerpc_debugfs_root);
 306         if (!memtrace_debugfs_dir)
 307                 return -1;
 308
 309         debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
 310                             NULL, &memtrace_init_fops);
 311
 312         return 0;
 313 }
 314 machine_device_initcall(powernv, memtrace_init);