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 void flush_memory_region(u64 base, u64 size)
  86 {
  87         unsigned long line_size = ppc64_caches.l1d.size;
  88         u64 end = base + size;
  89         u64 addr;
  90
  91         base = round_down(base, line_size);
  92         end = round_up(end, line_size);
  93
  94         for (addr = base; addr < end; addr += line_size)
  95                 asm volatile("dcbf 0,%0" : "=r" (addr) :: "memory");
  96 }
  97
  98 static int check_memblock_online(struct memory_block *mem, void *arg)
  99 {
 100         if (mem->state != MEM_ONLINE)
 101                 return -1;
 102
 103         return 0;
 104 }
 105
 106 static int change_memblock_state(struct memory_block *mem, void *arg)
 107 {
 108         unsigned long state = (unsigned long)arg;
 109
 110         mem->state = state;
 111
 112         return 0;
 113 }
 114
 115 static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages)
 116 {
 117         u64 end_pfn = start_pfn + nr_pages - 1;
 118
 119         if (walk_memory_range(start_pfn, end_pfn, NULL,
 120             check_memblock_online))
 121                 return false;
 122
 123         walk_memory_range(start_pfn, end_pfn, (void *)MEM_GOING_OFFLINE,
 124                           change_memblock_state);
 125
 126         if (offline_pages(start_pfn, nr_pages)) {
 127                 walk_memory_range(start_pfn, end_pfn, (void *)MEM_ONLINE,
 128                                   change_memblock_state);
 129                 return false;
 130         }
 131
 132         walk_memory_range(start_pfn, end_pfn, (void *)MEM_OFFLINE,
 133                           change_memblock_state);
 134
 135         /* RCU grace period? */
 136         flush_memory_region((u64)__va(start_pfn << PAGE_SHIFT),
 137                             nr_pages << PAGE_SHIFT);
 138
 139         lock_device_hotplug();
 140         remove_memory(nid, start_pfn << PAGE_SHIFT, nr_pages << PAGE_SHIFT);
 141         unlock_device_hotplug();
 142
 143         return true;
 144 }
 145
 146 static u64 memtrace_alloc_node(u32 nid, u64 size)
 147 {
 148         u64 start_pfn, end_pfn, nr_pages;
 149         u64 base_pfn;
 150
 151         if (!NODE_DATA(nid) || !node_spanned_pages(nid))
 152                 return 0;
 153
 154         start_pfn = node_start_pfn(nid);
 155         end_pfn = node_end_pfn(nid);
 156         nr_pages = size >> PAGE_SHIFT;
 157
 158         /* Trace memory needs to be aligned to the size */
 159         end_pfn = round_down(end_pfn - nr_pages, nr_pages);
 160
 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                         return base_pfn << PAGE_SHIFT;
 164         }
 165
 166         return 0;
 167 }
 168
 169 static int memtrace_init_regions_runtime(u64 size)
 170 {
 171         u32 nid;
 172         u64 m;
 173
 174         memtrace_array = kcalloc(num_online_nodes(),
 175                                 sizeof(struct memtrace_entry), GFP_KERNEL);
 176         if (!memtrace_array) {
 177                 pr_err("Failed to allocate memtrace_array\n");
 178                 return -EINVAL;
 179         }
 180
 181         for_each_online_node(nid) {
 182                 m = memtrace_alloc_node(nid, size);
 183
 184                 /*
 185                  * A node might not have any local memory, so warn but
 186                  * continue on.
 187                  */
 188                 if (!m) {
 189                         pr_err("Failed to allocate trace memory on node %d\n", nid);
 190                         continue;
 191                 }
 192
 193                 pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);
 194
 195                 memtrace_array[memtrace_array_nr].start = m;
 196                 memtrace_array[memtrace_array_nr].size = size;
 197                 memtrace_array[memtrace_array_nr].nid = nid;
 198                 memtrace_array_nr++;
 199         }
 200
 201         return 0;
 202 }
 203
 204 static struct dentry *memtrace_debugfs_dir;
 205
 206 static int memtrace_init_debugfs(void)
 207 {
 208         int ret = 0;
 209         int i;
 210
 211         for (i = 0; i < memtrace_array_nr; i++) {
 212                 struct dentry *dir;
 213                 struct memtrace_entry *ent = &memtrace_array[i];
 214
 215                 ent->mem = ioremap(ent->start, ent->size);
 216                 /* Warn but continue on */
 217                 if (!ent->mem) {
 218                         pr_err("Failed to map trace memory at 0x%llx\n",
 219                                  ent->start);
 220                         ret = -1;
 221                         continue;
 222                 }
 223
 224                 snprintf(ent->name, 16, "%08x", ent->nid);
 225                 dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
 226                 if (!dir)
 227                         return -1;
 228
 229                 ent->dir = dir;
 230                 debugfs_create_file("trace", 0400, dir, ent, &memtrace_fops);
 231                 debugfs_create_x64("start", 0400, dir, &ent->start);
 232                 debugfs_create_x64("size", 0400, dir, &ent->size);
 233         }
 234
 235         return ret;
 236 }
 237
 238 static int memtrace_enable_set(void *data, u64 val)
 239 {
 240         if (memtrace_size)
 241                 return -EINVAL;
 242
 243         if (!val)
 244                 return -EINVAL;
 245
 246         /* Make sure size is aligned to a memory block */
 247         if (val & (memory_block_size_bytes() - 1))
 248                 return -EINVAL;
 249
 250         if (memtrace_init_regions_runtime(val))
 251                 return -EINVAL;
 252
 253         if (memtrace_init_debugfs())
 254                 return -EINVAL;
 255
 256         memtrace_size = val;
 257
 258         return 0;
 259 }
 260
 261 static int memtrace_enable_get(void *data, u64 *val)
 262 {
 263         *val = memtrace_size;
 264         return 0;
 265 }
 266
 267 DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
 268                                         memtrace_enable_set, "0x%016llx\n");
 269
 270 static int memtrace_init(void)
 271 {
 272         memtrace_debugfs_dir = debugfs_create_dir("memtrace",
 273                                                   powerpc_debugfs_root);
 274         if (!memtrace_debugfs_dir)
 275                 return -1;
 276
 277         debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
 278                             NULL, &memtrace_init_fops);
 279
 280         return 0;
 281 }
 282 machine_device_initcall(powernv, memtrace_init);