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 bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages)
 103 {
 104         u64 end_pfn = start_pfn + nr_pages - 1;
 105
 106         if (walk_memory_range(start_pfn, end_pfn, NULL,
 107             check_memblock_online))
 108                 return false;
 109
 110         walk_memory_range(start_pfn, end_pfn, (void *)MEM_GOING_OFFLINE,
 111                           change_memblock_state);
 112
 113         if (offline_pages(start_pfn, nr_pages)) {
 114                 walk_memory_range(start_pfn, end_pfn, (void *)MEM_ONLINE,
 115                                   change_memblock_state);
 116                 return false;
 117         }
 118
 119         walk_memory_range(start_pfn, end_pfn, (void *)MEM_OFFLINE,
 120                           change_memblock_state);
 121
 122         lock_device_hotplug();
 123         remove_memory(nid, start_pfn << PAGE_SHIFT, nr_pages << PAGE_SHIFT);
 124         unlock_device_hotplug();
 125
 126         return true;
 127 }
 128
 129 static u64 memtrace_alloc_node(u32 nid, u64 size)
 130 {
 131         u64 start_pfn, end_pfn, nr_pages;
 132         u64 base_pfn;
 133
 134         if (!NODE_DATA(nid) || !node_spanned_pages(nid))
 135                 return 0;
 136
 137         start_pfn = node_start_pfn(nid);
 138         end_pfn = node_end_pfn(nid);
 139         nr_pages = size >> PAGE_SHIFT;
 140
 141         /* Trace memory needs to be aligned to the size */
 142         end_pfn = round_down(end_pfn - nr_pages, nr_pages);
 143
 144         for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) {
 145                 if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true)
 146                         return base_pfn << PAGE_SHIFT;
 147         }
 148
 149         return 0;
 150 }
 151
 152 static int memtrace_init_regions_runtime(u64 size)
 153 {
 154         u32 nid;
 155         u64 m;
 156
 157         memtrace_array = kcalloc(num_online_nodes(),
 158                                 sizeof(struct memtrace_entry), GFP_KERNEL);
 159         if (!memtrace_array) {
 160                 pr_err("Failed to allocate memtrace_array\n");
 161                 return -EINVAL;
 162         }
 163
 164         for_each_online_node(nid) {
 165                 m = memtrace_alloc_node(nid, size);
 166
 167                 /*
 168                  * A node might not have any local memory, so warn but
 169                  * continue on.
 170                  */
 171                 if (!m) {
 172                         pr_err("Failed to allocate trace memory on node %d\n", nid);
 173                         continue;
 174                 }
 175
 176                 pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);
 177
 178                 memtrace_array[memtrace_array_nr].start = m;
 179                 memtrace_array[memtrace_array_nr].size = size;
 180                 memtrace_array[memtrace_array_nr].nid = nid;
 181                 memtrace_array_nr++;
 182         }
 183
 184         return 0;
 185 }
 186
 187 static struct dentry *memtrace_debugfs_dir;
 188
 189 static int memtrace_init_debugfs(void)
 190 {
 191         int ret = 0;
 192         int i;
 193
 194         for (i = 0; i < memtrace_array_nr; i++) {
 195                 struct dentry *dir;
 196                 struct memtrace_entry *ent = &memtrace_array[i];
 197
 198                 ent->mem = ioremap(ent->start, ent->size);
 199                 /* Warn but continue on */
 200                 if (!ent->mem) {
 201                         pr_err("Failed to map trace memory at 0x%llx\n",
 202                                  ent->start);
 203                         ret = -1;
 204                         continue;
 205                 }
 206
 207                 snprintf(ent->name, 16, "%08x", ent->nid);
 208                 dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
 209                 if (!dir)
 210                         return -1;
 211
 212                 ent->dir = dir;
 213                 debugfs_create_file("trace", 0400, dir, ent, &memtrace_fops);
 214                 debugfs_create_x64("start", 0400, dir, &ent->start);
 215                 debugfs_create_x64("size", 0400, dir, &ent->size);
 216         }
 217
 218         return ret;
 219 }
 220
 221 static int memtrace_enable_set(void *data, u64 val)
 222 {
 223         if (memtrace_size)
 224                 return -EINVAL;
 225
 226         if (!val)
 227                 return -EINVAL;
 228
 229         /* Make sure size is aligned to a memory block */
 230         if (val & (memory_block_size_bytes() - 1))
 231                 return -EINVAL;
 232
 233         if (memtrace_init_regions_runtime(val))
 234                 return -EINVAL;
 235
 236         if (memtrace_init_debugfs())
 237                 return -EINVAL;
 238
 239         memtrace_size = val;
 240
 241         return 0;
 242 }
 243
 244 static int memtrace_enable_get(void *data, u64 *val)
 245 {
 246         *val = memtrace_size;
 247         return 0;
 248 }
 249
 250 DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
 251                                         memtrace_enable_set, "0x%016llx\n");
 252
 253 static int memtrace_init(void)
 254 {
 255         memtrace_debugfs_dir = debugfs_create_dir("memtrace",
 256                                                   powerpc_debugfs_root);
 257         if (!memtrace_debugfs_dir)
 258                 return -1;
 259
 260         debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
 261                             NULL, &memtrace_init_fops);
 262
 263         return 0;
 264 }
 265 machine_device_initcall(powernv, memtrace_init);