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 bool valid_memtrace_range(struct memtrace_entry *dev,
  51                                  unsigned long start, unsigned long size)
  52 {
  53         if ((start >= dev->start) &&
  54             ((start + size) <= (dev->start + dev->size)))
  55                 return true;
  56
  57         return false;
  58 }
  59
  60 static int memtrace_mmap(struct file *filp, struct vm_area_struct *vma)
  61 {
  62         unsigned long size = vma->vm_end - vma->vm_start;
  63         struct memtrace_entry *dev = filp->private_data;
  64
  65         if (!valid_memtrace_range(dev, vma->vm_pgoff << PAGE_SHIFT, size))
  66                 return -EINVAL;
  67
  68         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
  69
  70         if (remap_pfn_range(vma, vma->vm_start,
  71                             vma->vm_pgoff + (dev->start >> PAGE_SHIFT),
  72                             size, vma->vm_page_prot))
  73                 return -EAGAIN;
  74
  75         return 0;
  76 }
  77
  78 static const struct file_operations memtrace_fops = {
  79         .llseek = default_llseek,
  80         .read   = memtrace_read,
  81         .mmap   = memtrace_mmap,
  82         .open   = simple_open,
  83 };
  84
  85 static int check_memblock_online(struct memory_block *mem, void *arg)
  86 {
  87         if (mem->state != MEM_ONLINE)
  88                 return -1;
  89
  90         return 0;
  91 }
  92
  93 static int change_memblock_state(struct memory_block *mem, void *arg)
  94 {
  95         unsigned long state = (unsigned long)arg;
  96
  97         mem->state = state;
  98
  99         return 0;
 100 }
 101
 102 static void memtrace_clear_range(unsigned long start_pfn,
 103                                  unsigned long nr_pages)
 104 {
 105         unsigned long pfn;
 106
 107         /*
 108          * As pages are offline, we cannot trust the memmap anymore. As HIGHMEM
 109          * does not apply, avoid passing around "struct page" and use
 110          * clear_page() instead directly.
 111          */
 112         for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++) {
 113                 if (IS_ALIGNED(pfn, PAGES_PER_SECTION))
 114                         cond_resched();
 115                 clear_page(__va(PFN_PHYS(pfn)));
 116         }
 117 }
 118
 119 /* called with device_hotplug_lock held */
 120 static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages)
 121 {
 122         u64 end_pfn = start_pfn + nr_pages - 1;
 123
 124         if (walk_memory_range(start_pfn, end_pfn, NULL,
 125             check_memblock_online))
 126                 return false;
 127
 128         walk_memory_range(start_pfn, end_pfn, (void *)MEM_GOING_OFFLINE,
 129                           change_memblock_state);
 130
 131         if (offline_pages(start_pfn, nr_pages)) {
 132                 walk_memory_range(start_pfn, end_pfn, (void *)MEM_ONLINE,
 133                                   change_memblock_state);
 134                 return false;
 135         }
 136
 137         walk_memory_range(start_pfn, end_pfn, (void *)MEM_OFFLINE,
 138                           change_memblock_state);
 139
 140
 141         return true;
 142 }
 143
 144 static u64 memtrace_alloc_node(u32 nid, u64 size)
 145 {
 146         u64 start_pfn, end_pfn, nr_pages, pfn;
 147         u64 base_pfn;
 148         u64 bytes = memory_block_size_bytes();
 149
 150         if (!NODE_DATA(nid) || !node_spanned_pages(nid))
 151                 return 0;
 152
 153         start_pfn = node_start_pfn(nid);
 154         end_pfn = node_end_pfn(nid);
 155         nr_pages = size >> PAGE_SHIFT;
 156
 157         /* Trace memory needs to be aligned to the size */
 158         end_pfn = round_down(end_pfn - nr_pages, nr_pages);
 159
 160         lock_device_hotplug();
 161         for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) {
 162                 if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true) {
 163                         /*
 164                          * Clear the range while we still have a linear
 165                          * mapping.
 166                          */
 167                         memtrace_clear_range(base_pfn, nr_pages);
 168                         /*
 169                          * Remove memory in memory block size chunks so that
 170                          * iomem resources are always split to the same size and
 171                          * we never try to remove memory that spans two iomem
 172                          * resources.
 173                          */
 174                         end_pfn = base_pfn + nr_pages;
 175                         for (pfn = base_pfn; pfn < end_pfn; pfn += bytes>> PAGE_SHIFT) {
 176                                 remove_memory(nid, pfn << PAGE_SHIFT, bytes);
 177                         }
 178                         unlock_device_hotplug();
 179                         return base_pfn << PAGE_SHIFT;
 180                 }
 181         }
 182         unlock_device_hotplug();
 183
 184         return 0;
 185 }
 186
 187 static int memtrace_init_regions_runtime(u64 size)
 188 {
 189         u32 nid;
 190         u64 m;
 191
 192         memtrace_array = kcalloc(num_online_nodes(),
 193                                 sizeof(struct memtrace_entry), GFP_KERNEL);
 194         if (!memtrace_array) {
 195                 pr_err("Failed to allocate memtrace_array\n");
 196                 return -EINVAL;
 197         }
 198
 199         for_each_online_node(nid) {
 200                 m = memtrace_alloc_node(nid, size);
 201
 202                 /*
 203                  * A node might not have any local memory, so warn but
 204                  * continue on.
 205                  */
 206                 if (!m) {
 207                         pr_err("Failed to allocate trace memory on node %d\n", nid);
 208                         continue;
 209                 }
 210
 211                 pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);
 212
 213                 memtrace_array[memtrace_array_nr].start = m;
 214                 memtrace_array[memtrace_array_nr].size = size;
 215                 memtrace_array[memtrace_array_nr].nid = nid;
 216                 memtrace_array_nr++;
 217         }
 218
 219         return 0;
 220 }
 221
 222 static struct dentry *memtrace_debugfs_dir;
 223
 224 static int memtrace_init_debugfs(void)
 225 {
 226         int ret = 0;
 227         int i;
 228
 229         for (i = 0; i < memtrace_array_nr; i++) {
 230                 struct dentry *dir;
 231                 struct memtrace_entry *ent = &memtrace_array[i];
 232
 233                 ent->mem = ioremap(ent->start, ent->size);
 234                 /* Warn but continue on */
 235                 if (!ent->mem) {
 236                         pr_err("Failed to map trace memory at 0x%llx\n",
 237                                  ent->start);
 238                         ret = -1;
 239                         continue;
 240                 }
 241
 242                 snprintf(ent->name, 16, "%08x", ent->nid);
 243                 dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
 244                 if (!dir)
 245                         return -1;
 246
 247                 ent->dir = dir;
 248                 debugfs_create_file("trace", 0400, dir, ent, &memtrace_fops);
 249                 debugfs_create_x64("start", 0400, dir, &ent->start);
 250                 debugfs_create_x64("size", 0400, dir, &ent->size);
 251         }
 252
 253         return ret;
 254 }
 255
 256 static int memtrace_enable_set(void *data, u64 val)
 257 {
 258         if (memtrace_size)
 259                 return -EINVAL;
 260
 261         if (!val)
 262                 return -EINVAL;
 263
 264         /* Make sure size is aligned to a memory block */
 265         if (val & (memory_block_size_bytes() - 1))
 266                 return -EINVAL;
 267
 268         if (memtrace_init_regions_runtime(val))
 269                 return -EINVAL;
 270
 271         if (memtrace_init_debugfs())
 272                 return -EINVAL;
 273
 274         memtrace_size = val;
 275
 276         return 0;
 277 }
 278
 279 static int memtrace_enable_get(void *data, u64 *val)
 280 {
 281         *val = memtrace_size;
 282         return 0;
 283 }
 284
 285 DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
 286                                         memtrace_enable_set, "0x%016llx\n");
 287
 288 static int memtrace_init(void)
 289 {
 290         memtrace_debugfs_dir = debugfs_create_dir("memtrace",
 291                                                   powerpc_debugfs_root);
 292         if (!memtrace_debugfs_dir)
 293                 return -1;
 294
 295         debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
 296                             NULL, &memtrace_init_fops);
 297
 298         return 0;
 299 }
 300 machine_device_initcall(powernv, memtrace_init);