linux/arch/powerpc/platforms/powernv/memtrace.c
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   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#include <asm/cacheflush.h>
  23
  24/* This enables us to keep track of the memory removed from each node. */
  25struct memtrace_entry {
  26        void *mem;
  27        u64 start;
  28        u64 size;
  29        u32 nid;
  30        struct dentry *dir;
  31        char name[16];
  32};
  33
  34static DEFINE_MUTEX(memtrace_mutex);
  35static u64 memtrace_size;
  36
  37static struct memtrace_entry *memtrace_array;
  38static unsigned int memtrace_array_nr;
  39
  40
  41static ssize_t memtrace_read(struct file *filp, char __user *ubuf,
  42                             size_t count, loff_t *ppos)
  43{
  44        struct memtrace_entry *ent = filp->private_data;
  45
  46        return simple_read_from_buffer(ubuf, count, ppos, ent->mem, ent->size);
  47}
  48
  49static int memtrace_mmap(struct file *filp, struct vm_area_struct *vma)
  50{
  51        struct memtrace_entry *ent = filp->private_data;
  52
  53        if (ent->size < vma->vm_end - vma->vm_start)
  54                return -EINVAL;
  55
  56        if (vma->vm_pgoff << PAGE_SHIFT >= ent->size)
  57                return -EINVAL;
  58
  59        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
  60        return remap_pfn_range(vma, vma->vm_start, PHYS_PFN(ent->start) + vma->vm_pgoff,
  61                               vma->vm_end - vma->vm_start, vma->vm_page_prot);
  62}
  63
  64static const struct file_operations memtrace_fops = {
  65        .llseek = default_llseek,
  66        .read   = memtrace_read,
  67        .open   = simple_open,
  68        .mmap   = memtrace_mmap,
  69};
  70
  71#define FLUSH_CHUNK_SIZE SZ_1G
  72/**
  73 * flush_dcache_range_chunked(): Write any modified data cache blocks out to
  74 * memory and invalidate them, in chunks of up to FLUSH_CHUNK_SIZE
  75 * Does not invalidate the corresponding instruction cache blocks.
  76 *
  77 * @start: the start address
  78 * @stop: the stop address (exclusive)
  79 * @chunk: the max size of the chunks
  80 */
  81static void flush_dcache_range_chunked(unsigned long start, unsigned long stop,
  82                                       unsigned long chunk)
  83{
  84        unsigned long i;
  85
  86        for (i = start; i < stop; i += chunk) {
  87                flush_dcache_range(i, min(stop, i + chunk));
  88                cond_resched();
  89        }
  90}
  91
  92static void memtrace_clear_range(unsigned long start_pfn,
  93                                 unsigned long nr_pages)
  94{
  95        unsigned long pfn;
  96
  97        /* As HIGHMEM does not apply, use clear_page() directly. */
  98        for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++) {
  99                if (IS_ALIGNED(pfn, PAGES_PER_SECTION))
 100                        cond_resched();
 101                clear_page(__va(PFN_PHYS(pfn)));
 102        }
 103        /*
 104         * Before we go ahead and use this range as cache inhibited range
 105         * flush the cache.
 106         */
 107        flush_dcache_range_chunked((unsigned long)pfn_to_kaddr(start_pfn),
 108                                   (unsigned long)pfn_to_kaddr(start_pfn + nr_pages),
 109                                   FLUSH_CHUNK_SIZE);
 110}
 111
 112static u64 memtrace_alloc_node(u32 nid, u64 size)
 113{
 114        const unsigned long nr_pages = PHYS_PFN(size);
 115        unsigned long pfn, start_pfn;
 116        struct page *page;
 117
 118        /*
 119         * Trace memory needs to be aligned to the size, which is guaranteed
 120         * by alloc_contig_pages().
 121         */
 122        page = alloc_contig_pages(nr_pages, GFP_KERNEL | __GFP_THISNODE |
 123                                  __GFP_NOWARN, nid, NULL);
 124        if (!page)
 125                return 0;
 126        start_pfn = page_to_pfn(page);
 127
 128        /*
 129         * Clear the range while we still have a linear mapping.
 130         *
 131         * TODO: use __GFP_ZERO with alloc_contig_pages() once supported.
 132         */
 133        memtrace_clear_range(start_pfn, nr_pages);
 134
 135        /*
 136         * Set pages PageOffline(), to indicate that nobody (e.g., hibernation,
 137         * dumping, ...) should be touching these pages.
 138         */
 139        for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++)
 140                __SetPageOffline(pfn_to_page(pfn));
 141
 142        arch_remove_linear_mapping(PFN_PHYS(start_pfn), size);
 143
 144        return PFN_PHYS(start_pfn);
 145}
 146
 147static int memtrace_init_regions_runtime(u64 size)
 148{
 149        u32 nid;
 150        u64 m;
 151
 152        memtrace_array = kcalloc(num_online_nodes(),
 153                                sizeof(struct memtrace_entry), GFP_KERNEL);
 154        if (!memtrace_array) {
 155                pr_err("Failed to allocate memtrace_array\n");
 156                return -EINVAL;
 157        }
 158
 159        for_each_online_node(nid) {
 160                m = memtrace_alloc_node(nid, size);
 161
 162                /*
 163                 * A node might not have any local memory, so warn but
 164                 * continue on.
 165                 */
 166                if (!m) {
 167                        pr_err("Failed to allocate trace memory on node %d\n", nid);
 168                        continue;
 169                }
 170
 171                pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);
 172
 173                memtrace_array[memtrace_array_nr].start = m;
 174                memtrace_array[memtrace_array_nr].size = size;
 175                memtrace_array[memtrace_array_nr].nid = nid;
 176                memtrace_array_nr++;
 177        }
 178
 179        return 0;
 180}
 181
 182static struct dentry *memtrace_debugfs_dir;
 183
 184static int memtrace_init_debugfs(void)
 185{
 186        int ret = 0;
 187        int i;
 188
 189        for (i = 0; i < memtrace_array_nr; i++) {
 190                struct dentry *dir;
 191                struct memtrace_entry *ent = &memtrace_array[i];
 192
 193                ent->mem = ioremap(ent->start, ent->size);
 194                /* Warn but continue on */
 195                if (!ent->mem) {
 196                        pr_err("Failed to map trace memory at 0x%llx\n",
 197                                 ent->start);
 198                        ret = -1;
 199                        continue;
 200                }
 201
 202                snprintf(ent->name, 16, "%08x", ent->nid);
 203                dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
 204
 205                ent->dir = dir;
 206                debugfs_create_file_unsafe("trace", 0600, dir, ent, &memtrace_fops);
 207                debugfs_create_x64("start", 0400, dir, &ent->start);
 208                debugfs_create_x64("size", 0400, dir, &ent->size);
 209        }
 210
 211        return ret;
 212}
 213
 214static int memtrace_free(int nid, u64 start, u64 size)
 215{
 216        struct mhp_params params = { .pgprot = PAGE_KERNEL };
 217        const unsigned long nr_pages = PHYS_PFN(size);
 218        const unsigned long start_pfn = PHYS_PFN(start);
 219        unsigned long pfn;
 220        int ret;
 221
 222        ret = arch_create_linear_mapping(nid, start, size, &params);
 223        if (ret)
 224                return ret;
 225
 226        for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++)
 227                __ClearPageOffline(pfn_to_page(pfn));
 228
 229        free_contig_range(start_pfn, nr_pages);
 230        return 0;
 231}
 232
 233/*
 234 * Iterate through the chunks of memory we allocated and attempt to expose
 235 * them back to the kernel.
 236 */
 237static int memtrace_free_regions(void)
 238{
 239        int i, ret = 0;
 240        struct memtrace_entry *ent;
 241
 242        for (i = memtrace_array_nr - 1; i >= 0; i--) {
 243                ent = &memtrace_array[i];
 244
 245                /* We have freed this chunk previously */
 246                if (ent->nid == NUMA_NO_NODE)
 247                        continue;
 248
 249                /* Remove from io mappings */
 250                if (ent->mem) {
 251                        iounmap(ent->mem);
 252                        ent->mem = 0;
 253                }
 254
 255                if (memtrace_free(ent->nid, ent->start, ent->size)) {
 256                        pr_err("Failed to free trace memory on node %d\n",
 257                                ent->nid);
 258                        ret += 1;
 259                        continue;
 260                }
 261
 262                /*
 263                 * Memory was freed successfully so clean up references to it
 264                 * so on reentry we can tell that this chunk was freed.
 265                 */
 266                debugfs_remove_recursive(ent->dir);
 267                pr_info("Freed trace memory back on node %d\n", ent->nid);
 268                ent->size = ent->start = ent->nid = NUMA_NO_NODE;
 269        }
 270        if (ret)
 271                return ret;
 272
 273        /* If all chunks of memory were freed successfully, reset globals */
 274        kfree(memtrace_array);
 275        memtrace_array = NULL;
 276        memtrace_size = 0;
 277        memtrace_array_nr = 0;
 278        return 0;
 279}
 280
 281static int memtrace_enable_set(void *data, u64 val)
 282{
 283        int rc = -EAGAIN;
 284        u64 bytes;
 285
 286        /*
 287         * Don't attempt to do anything if size isn't aligned to a memory
 288         * block or equal to zero.
 289         */
 290        bytes = memory_block_size_bytes();
 291        if (val & (bytes - 1)) {
 292                pr_err("Value must be aligned with 0x%llx\n", bytes);
 293                return -EINVAL;
 294        }
 295
 296        mutex_lock(&memtrace_mutex);
 297
 298        /* Free all previously allocated memory. */
 299        if (memtrace_size && memtrace_free_regions())
 300                goto out_unlock;
 301
 302        if (!val) {
 303                rc = 0;
 304                goto out_unlock;
 305        }
 306
 307        /* Allocate memory. */
 308        if (memtrace_init_regions_runtime(val))
 309                goto out_unlock;
 310
 311        if (memtrace_init_debugfs())
 312                goto out_unlock;
 313
 314        memtrace_size = val;
 315        rc = 0;
 316out_unlock:
 317        mutex_unlock(&memtrace_mutex);
 318        return rc;
 319}
 320
 321static int memtrace_enable_get(void *data, u64 *val)
 322{
 323        *val = memtrace_size;
 324        return 0;
 325}
 326
 327DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
 328                                        memtrace_enable_set, "0x%016llx\n");
 329
 330static int memtrace_init(void)
 331{
 332        memtrace_debugfs_dir = debugfs_create_dir("memtrace",
 333                                                  powerpc_debugfs_root);
 334
 335        debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
 336                            NULL, &memtrace_init_fops);
 337
 338        return 0;
 339}
 340machine_device_initcall(powernv, memtrace_init);
 341
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