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
  94         return true;
  95 }
  96
  97 static u64 memtrace_alloc_node(u32 nid, u64 size)
  98 {
  99         u64 start_pfn, end_pfn, nr_pages, pfn;
 100         u64 base_pfn;
 101         u64 bytes = memory_block_size_bytes();
 102
 103         if (!node_spanned_pages(nid))
 104                 return 0;
 105
 106         start_pfn = node_start_pfn(nid);
 107         end_pfn = node_end_pfn(nid);
 108         nr_pages = size >> PAGE_SHIFT;
 109
 110         /* Trace memory needs to be aligned to the size */
 111         end_pfn = round_down(end_pfn - nr_pages, nr_pages);
 112
 113         for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) {
 114                 if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true) {
 115                         /*
 116                          * Remove memory in memory block size chunks so that
 117                          * iomem resources are always split to the same size and
 118                          * we never try to remove memory that spans two iomem
 119                          * resources.
 120                          */
 121                         lock_device_hotplug();
 122                         end_pfn = base_pfn + nr_pages;
 123                         for (pfn = base_pfn; pfn < end_pfn; pfn += bytes>> PAGE_SHIFT) {
 124                                 remove_memory(nid, pfn << PAGE_SHIFT, bytes);
 125                         }
 126                         unlock_device_hotplug();
 127                         return base_pfn << PAGE_SHIFT;
 128                 }
 129         }
 130
 131         return 0;
 132 }
 133
 134 static int memtrace_init_regions_runtime(u64 size)
 135 {
 136         u32 nid;
 137         u64 m;
 138
 139         memtrace_array = kcalloc(num_online_nodes(),
 140                                 sizeof(struct memtrace_entry), GFP_KERNEL);
 141         if (!memtrace_array) {
 142                 pr_err("Failed to allocate memtrace_array\n");
 143                 return -EINVAL;
 144         }
 145
 146         for_each_online_node(nid) {
 147                 m = memtrace_alloc_node(nid, size);
 148
 149                 /*
 150                  * A node might not have any local memory, so warn but
 151                  * continue on.
 152                  */
 153                 if (!m) {
 154                         pr_err("Failed to allocate trace memory on node %d\n", nid);
 155                         continue;
 156                 }
 157
 158                 pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);
 159
 160                 memtrace_array[memtrace_array_nr].start = m;
 161                 memtrace_array[memtrace_array_nr].size = size;
 162                 memtrace_array[memtrace_array_nr].nid = nid;
 163                 memtrace_array_nr++;
 164         }
 165
 166         return 0;
 167 }
 168
 169 static struct dentry *memtrace_debugfs_dir;
 170
 171 static int memtrace_init_debugfs(void)
 172 {
 173         int ret = 0;
 174         int i;
 175
 176         for (i = 0; i < memtrace_array_nr; i++) {
 177                 struct dentry *dir;
 178                 struct memtrace_entry *ent = &memtrace_array[i];
 179
 180                 ent->mem = ioremap(ent->start, ent->size);
 181                 /* Warn but continue on */
 182                 if (!ent->mem) {
 183                         pr_err("Failed to map trace memory at 0x%llx\n",
 184                                  ent->start);
 185                         ret = -1;
 186                         continue;
 187                 }
 188
 189                 snprintf(ent->name, 16, "%08x", ent->nid);
 190                 dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
 191                 if (!dir) {
 192                         pr_err("Failed to create debugfs directory for node %d\n",
 193                                 ent->nid);
 194                         return -1;
 195                 }
 196
 197                 ent->dir = dir;
 198                 debugfs_create_file("trace", 0400, dir, ent, &memtrace_fops);
 199                 debugfs_create_x64("start", 0400, dir, &ent->start);
 200                 debugfs_create_x64("size", 0400, dir, &ent->size);
 201         }
 202
 203         return ret;
 204 }
 205
 206 static int online_mem_block(struct memory_block *mem, void *arg)
 207 {
 208         return device_online(&mem->dev);
 209 }
 210
 211 /*
 212  * Iterate through the chunks of memory we have removed from the kernel
 213  * and attempt to add them back to the kernel.
 214  */
 215 static int memtrace_online(void)
 216 {
 217         int i, ret = 0;
 218         struct memtrace_entry *ent;
 219
 220         for (i = memtrace_array_nr - 1; i >= 0; i--) {
 221                 ent = &memtrace_array[i];
 222
 223                 /* We have onlined this chunk previously */
 224                 if (ent->nid == -1)
 225                         continue;
 226
 227                 /* Remove from io mappings */
 228                 if (ent->mem) {
 229                         iounmap(ent->mem);
 230                         ent->mem = 0;
 231                 }
 232
 233                 if (add_memory(ent->nid, ent->start, ent->size)) {
 234                         pr_err("Failed to add trace memory to node %d\n",
 235                                 ent->nid);
 236                         ret += 1;
 237                         continue;
 238                 }
 239
 240                 /*
 241                  * If kernel isn't compiled with the auto online option
 242                  * we need to online the memory ourselves.
 243                  */
 244                 if (!memhp_auto_online) {
 245                         walk_memory_range(PFN_DOWN(ent->start),
 246                                           PFN_UP(ent->start + ent->size - 1),
 247                                           NULL, online_mem_block);
 248                 }
 249
 250                 /*
 251                  * Memory was added successfully so clean up references to it
 252                  * so on reentry we can tell that this chunk was added.
 253                  */
 254                 debugfs_remove_recursive(ent->dir);
 255                 pr_info("Added trace memory back to node %d\n", ent->nid);
 256                 ent->size = ent->start = ent->nid = -1;
 257         }
 258         if (ret)
 259                 return ret;
 260
 261         /* If all chunks of memory were added successfully, reset globals */
 262         kfree(memtrace_array);
 263         memtrace_array = NULL;
 264         memtrace_size = 0;
 265         memtrace_array_nr = 0;
 266         return 0;
 267 }
 268
 269 static int memtrace_enable_set(void *data, u64 val)
 270 {
 271         u64 bytes;
 272
 273         /*
 274          * Don't attempt to do anything if size isn't aligned to a memory
 275          * block or equal to zero.
 276          */
 277         bytes = memory_block_size_bytes();
 278         if (val & (bytes - 1)) {
 279                 pr_err("Value must be aligned with 0x%llx\n", bytes);
 280                 return -EINVAL;
 281         }
 282
 283         /* Re-add/online previously removed/offlined memory */
 284         if (memtrace_size) {
 285                 if (memtrace_online())
 286                         return -EAGAIN;
 287         }
 288
 289         if (!val)
 290                 return 0;
 291
 292         /* Offline and remove memory */
 293         if (memtrace_init_regions_runtime(val))
 294                 return -EINVAL;
 295
 296         if (memtrace_init_debugfs())
 297                 return -EINVAL;
 298
 299         memtrace_size = val;
 300
 301         return 0;
 302 }
 303
 304 static int memtrace_enable_get(void *data, u64 *val)
 305 {
 306         *val = memtrace_size;
 307         return 0;
 308 }
 309
 310 DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
 311                                         memtrace_enable_set, "0x%016llx\n");
 312
 313 static int memtrace_init(void)
 314 {
 315         memtrace_debugfs_dir = debugfs_create_dir("memtrace",
 316                                                   powerpc_debugfs_root);
 317         if (!memtrace_debugfs_dir)
 318                 return -1;
 319
 320         debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
 321                             NULL, &memtrace_init_fops);
 322
 323         return 0;
 324 }
 325 machine_device_initcall(powernv, memtrace_init);