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); 283