arch/powerpc/platforms/powernv/memtrace.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) IBM Corporation, 2014, 2017
   4  * Anton Blanchard, Rashmica Gupta.
   5  */
   6
   7 #define pr_fmt(fmt) "memtrace: " fmt
   8
   9 #include <linux/bitops.h>
  10 #include <linux/string.h>
  11 #include <linux/memblock.h>
  12 #include <linux/init.h>
  13 #include <linux/moduleparam.h>
  14 #include <linux/fs.h>
  15 #include <linux/debugfs.h>
  16 #include <linux/slab.h>
  17 #include <linux/memory.h>
  18 #include <linux/memory_hotplug.h>
  19 #include <linux/numa.h>
  20 #include <asm/machdep.h>
  21 #include <asm/debugfs.h>
  22
  23 /* This enables us to keep track of the memory removed from each node. */
  24 struct memtrace_entry {
  25         void *mem;
  26         u64 start;
  27         u64 size;
  28         u32 nid;
  29         struct dentry *dir;
  30         char name[16];
  31 };
  32
  33 static u64 memtrace_size;
  34
  35 static struct memtrace_entry *memtrace_array;
  36 static unsigned int memtrace_array_nr;
  37
  38
  39 static ssize_t memtrace_read(struct file *filp, char __user *ubuf,
  40                              size_t count, loff_t *ppos)
  41 {
  42         struct memtrace_entry *ent = filp->private_data;
  43
  44         return simple_read_from_buffer(ubuf, count, ppos, ent->mem, ent->size);
  45 }
  46
  47 static const struct file_operations memtrace_fops = {
  48         .llseek = default_llseek,
  49         .read   = memtrace_read,
  50         .open   = simple_open,
  51 };
  52
  53 static int check_memblock_online(struct memory_block *mem, void *arg)
  54 {
  55         if (mem->state != MEM_ONLINE)
  56                 return -1;
  57
  58         return 0;
  59 }
  60
  61 static int change_memblock_state(struct memory_block *mem, void *arg)
  62 {
  63         unsigned long state = (unsigned long)arg;
  64
  65         mem->state = state;
  66
  67         return 0;
  68 }
  69
  70 /* called with device_hotplug_lock held */
  71 static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages)
  72 {
  73         const unsigned long start = PFN_PHYS(start_pfn);
  74         const unsigned long size = PFN_PHYS(nr_pages);
  75
  76         if (walk_memory_blocks(start, size, NULL, check_memblock_online))
  77                 return false;
  78
  79         walk_memory_blocks(start, size, (void *)MEM_GOING_OFFLINE,
  80                            change_memblock_state);
  81
  82         if (offline_pages(start_pfn, nr_pages)) {
  83                 walk_memory_blocks(start, size, (void *)MEM_ONLINE,
  84                                    change_memblock_state);
  85                 return false;
  86         }
  87
  88         walk_memory_blocks(start, size, (void *)MEM_OFFLINE,
  89                            change_memblock_state);
  90
  91
  92         return true;
  93 }
  94
  95 static u64 memtrace_alloc_node(u32 nid, u64 size)
  96 {
  97         u64 start_pfn, end_pfn, nr_pages, pfn;
  98         u64 base_pfn;
  99         u64 bytes = memory_block_size_bytes();
 100
 101         if (!node_spanned_pages(nid))
 102                 return 0;
 103
 104         start_pfn = node_start_pfn(nid);
 105         end_pfn = node_end_pfn(nid);
 106         nr_pages = size >> PAGE_SHIFT;
 107
 108         /* Trace memory needs to be aligned to the size */
 109         end_pfn = round_down(end_pfn - nr_pages, nr_pages);
 110
 111         lock_device_hotplug();
 112         for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) {
 113                 if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true) {
 114                         /*
 115                          * Remove memory in memory block size chunks so that
 116                          * iomem resources are always split to the same size and
 117                          * we never try to remove memory that spans two iomem
 118                          * resources.
 119                          */
 120                         end_pfn = base_pfn + nr_pages;
 121                         for (pfn = base_pfn; pfn < end_pfn; pfn += bytes>> PAGE_SHIFT) {
 122                                 __remove_memory(nid, pfn << PAGE_SHIFT, bytes);
 123                         }
 124                         unlock_device_hotplug();
 125                         return base_pfn << PAGE_SHIFT;
 126                 }
 127         }
 128         unlock_device_hotplug();
 129
 130         return 0;
 131 }
 132
 133 static int memtrace_init_regions_runtime(u64 size)
 134 {
 135         u32 nid;
 136         u64 m;
 137
 138         memtrace_array = kcalloc(num_online_nodes(),
 139                                 sizeof(struct memtrace_entry), GFP_KERNEL);
 140         if (!memtrace_array) {
 141                 pr_err("Failed to allocate memtrace_array\n");
 142                 return -EINVAL;
 143         }
 144
 145         for_each_online_node(nid) {
 146                 m = memtrace_alloc_node(nid, size);
 147
 148                 /*
 149                  * A node might not have any local memory, so warn but
 150                  * continue on.
 151                  */
 152                 if (!m) {
 153                         pr_err("Failed to allocate trace memory on node %d\n", nid);
 154                         continue;
 155                 }
 156
 157                 pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);
 158
 159                 memtrace_array[memtrace_array_nr].start = m;
 160                 memtrace_array[memtrace_array_nr].size = size;
 161                 memtrace_array[memtrace_array_nr].nid = nid;
 162                 memtrace_array_nr++;
 163         }
 164
 165         return 0;
 166 }
 167
 168 static struct dentry *memtrace_debugfs_dir;
 169
 170 static int memtrace_init_debugfs(void)
 171 {
 172         int ret = 0;
 173         int i;
 174
 175         for (i = 0; i < memtrace_array_nr; i++) {
 176                 struct dentry *dir;
 177                 struct memtrace_entry *ent = &memtrace_array[i];
 178
 179                 ent->mem = ioremap(ent->start, ent->size);
 180                 /* Warn but continue on */
 181                 if (!ent->mem) {
 182                         pr_err("Failed to map trace memory at 0x%llx\n",
 183                                  ent->start);
 184                         ret = -1;
 185                         continue;
 186                 }
 187
 188                 snprintf(ent->name, 16, "%08x", ent->nid);
 189                 dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
 190                 if (!dir) {
 191                         pr_err("Failed to create debugfs directory for node %d\n",
 192                                 ent->nid);
 193                         return -1;
 194                 }
 195
 196                 ent->dir = dir;
 197                 debugfs_create_file("trace", 0400, dir, ent, &memtrace_fops);
 198                 debugfs_create_x64("start", 0400, dir, &ent->start);
 199                 debugfs_create_x64("size", 0400, dir, &ent->size);
 200         }
 201
 202         return ret;
 203 }
 204
 205 static int online_mem_block(struct memory_block *mem, void *arg)
 206 {
 207         return device_online(&mem->dev);
 208 }
 209
 210 /*
 211  * Iterate through the chunks of memory we have removed from the kernel
 212  * and attempt to add them back to the kernel.
 213  */
 214 static int memtrace_online(void)
 215 {
 216         int i, ret = 0;
 217         struct memtrace_entry *ent;
 218
 219         for (i = memtrace_array_nr - 1; i >= 0; i--) {
 220                 ent = &memtrace_array[i];
 221
 222                 /* We have onlined this chunk previously */
 223                 if (ent->nid == NUMA_NO_NODE)
 224                         continue;
 225
 226                 /* Remove from io mappings */
 227                 if (ent->mem) {
 228                         iounmap(ent->mem);
 229                         ent->mem = 0;
 230                 }
 231
 232                 if (add_memory(ent->nid, ent->start, ent->size)) {
 233                         pr_err("Failed to add trace memory to node %d\n",
 234                                 ent->nid);
 235                         ret += 1;
 236                         continue;
 237                 }
 238
 239                 /*
 240                  * If kernel isn't compiled with the auto online option
 241                  * we need to online the memory ourselves.
 242                  */
 243                 if (!memhp_auto_online) {
 244                         lock_device_hotplug();
 245                         walk_memory_blocks(ent->start, ent->size, NULL,
 246                                            online_mem_block);
 247                         unlock_device_hotplug();
 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 = NUMA_NO_NODE;
 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);