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- /*
- * Copyright (C) IBM Corporation, 2014, 2017
- * Anton Blanchard, Rashmica Gupta.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- */
- #define pr_fmt(fmt) "memtrace: " fmt
- #include <linux/bitops.h>
- #include <linux/string.h>
- #include <linux/memblock.h>
- #include <linux/init.h>
- #include <linux/moduleparam.h>
- #include <linux/fs.h>
- #include <linux/debugfs.h>
- #include <linux/slab.h>
- #include <linux/memory.h>
- #include <linux/memory_hotplug.h>
- #include <asm/machdep.h>
- #include <asm/debugfs.h>
- /* This enables us to keep track of the memory removed from each node. */
- struct memtrace_entry {
- void *mem;
- u64 start;
- u64 size;
- u32 nid;
- struct dentry *dir;
- char name[16];
- };
- static DEFINE_MUTEX(memtrace_mutex);
- static u64 memtrace_size;
- static struct memtrace_entry *memtrace_array;
- static unsigned int memtrace_array_nr;
- static ssize_t memtrace_read(struct file *filp, char __user *ubuf,
- size_t count, loff_t *ppos)
- {
- struct memtrace_entry *ent = filp->private_data;
- return simple_read_from_buffer(ubuf, count, ppos, ent->mem, ent->size);
- }
- static const struct file_operations memtrace_fops = {
- .llseek = default_llseek,
- .read = memtrace_read,
- .open = simple_open,
- };
- static int check_memblock_online(struct memory_block *mem, void *arg)
- {
- if (mem->state != MEM_ONLINE)
- return -1;
- return 0;
- }
- static int change_memblock_state(struct memory_block *mem, void *arg)
- {
- unsigned long state = (unsigned long)arg;
- mem->state = state;
- return 0;
- }
- static void memtrace_clear_range(unsigned long start_pfn,
- unsigned long nr_pages)
- {
- unsigned long pfn;
- /*
- * As pages are offline, we cannot trust the memmap anymore. As HIGHMEM
- * does not apply, avoid passing around "struct page" and use
- * clear_page() instead directly.
- */
- for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++) {
- if (IS_ALIGNED(pfn, PAGES_PER_SECTION))
- cond_resched();
- clear_page(__va(PFN_PHYS(pfn)));
- }
- }
- /* called with device_hotplug_lock held */
- static bool memtrace_offline_pages(u32 nid, u64 start_pfn, u64 nr_pages)
- {
- u64 end_pfn = start_pfn + nr_pages - 1;
- if (walk_memory_range(start_pfn, end_pfn, NULL,
- check_memblock_online))
- return false;
- walk_memory_range(start_pfn, end_pfn, (void *)MEM_GOING_OFFLINE,
- change_memblock_state);
- if (offline_pages(start_pfn, nr_pages)) {
- walk_memory_range(start_pfn, end_pfn, (void *)MEM_ONLINE,
- change_memblock_state);
- return false;
- }
- walk_memory_range(start_pfn, end_pfn, (void *)MEM_OFFLINE,
- change_memblock_state);
- return true;
- }
- static u64 memtrace_alloc_node(u32 nid, u64 size)
- {
- u64 start_pfn, end_pfn, nr_pages, pfn;
- u64 base_pfn;
- u64 bytes = memory_block_size_bytes();
- if (!node_spanned_pages(nid))
- return 0;
- start_pfn = node_start_pfn(nid);
- end_pfn = node_end_pfn(nid);
- nr_pages = size >> PAGE_SHIFT;
- /* Trace memory needs to be aligned to the size */
- end_pfn = round_down(end_pfn - nr_pages, nr_pages);
- lock_device_hotplug();
- for (base_pfn = end_pfn; base_pfn > start_pfn; base_pfn -= nr_pages) {
- if (memtrace_offline_pages(nid, base_pfn, nr_pages) == true) {
- /*
- * Clear the range while we still have a linear
- * mapping.
- */
- memtrace_clear_range(base_pfn, nr_pages);
- /*
- * Remove memory in memory block size chunks so that
- * iomem resources are always split to the same size and
- * we never try to remove memory that spans two iomem
- * resources.
- */
- end_pfn = base_pfn + nr_pages;
- for (pfn = base_pfn; pfn < end_pfn; pfn += bytes>> PAGE_SHIFT) {
- __remove_memory(nid, pfn << PAGE_SHIFT, bytes);
- }
- unlock_device_hotplug();
- return base_pfn << PAGE_SHIFT;
- }
- }
- unlock_device_hotplug();
- return 0;
- }
- static int memtrace_init_regions_runtime(u64 size)
- {
- u32 nid;
- u64 m;
- memtrace_array = kcalloc(num_online_nodes(),
- sizeof(struct memtrace_entry), GFP_KERNEL);
- if (!memtrace_array) {
- pr_err("Failed to allocate memtrace_array\n");
- return -EINVAL;
- }
- for_each_online_node(nid) {
- m = memtrace_alloc_node(nid, size);
- /*
- * A node might not have any local memory, so warn but
- * continue on.
- */
- if (!m) {
- pr_err("Failed to allocate trace memory on node %d\n", nid);
- continue;
- }
- pr_info("Allocated trace memory on node %d at 0x%016llx\n", nid, m);
- memtrace_array[memtrace_array_nr].start = m;
- memtrace_array[memtrace_array_nr].size = size;
- memtrace_array[memtrace_array_nr].nid = nid;
- memtrace_array_nr++;
- }
- return 0;
- }
- static struct dentry *memtrace_debugfs_dir;
- static int memtrace_init_debugfs(void)
- {
- int ret = 0;
- int i;
- for (i = 0; i < memtrace_array_nr; i++) {
- struct dentry *dir;
- struct memtrace_entry *ent = &memtrace_array[i];
- ent->mem = ioremap(ent->start, ent->size);
- /* Warn but continue on */
- if (!ent->mem) {
- pr_err("Failed to map trace memory at 0x%llx\n",
- ent->start);
- ret = -1;
- continue;
- }
- snprintf(ent->name, 16, "%08x", ent->nid);
- dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
- if (!dir) {
- pr_err("Failed to create debugfs directory for node %d\n",
- ent->nid);
- return -1;
- }
- ent->dir = dir;
- debugfs_create_file("trace", 0400, dir, ent, &memtrace_fops);
- debugfs_create_x64("start", 0400, dir, &ent->start);
- debugfs_create_x64("size", 0400, dir, &ent->size);
- }
- return ret;
- }
- static int online_mem_block(struct memory_block *mem, void *arg)
- {
- return device_online(&mem->dev);
- }
- /*
- * Iterate through the chunks of memory we have removed from the kernel
- * and attempt to add them back to the kernel.
- */
- static int memtrace_online(void)
- {
- int i, ret = 0;
- struct memtrace_entry *ent;
- for (i = memtrace_array_nr - 1; i >= 0; i--) {
- ent = &memtrace_array[i];
- /* We have onlined this chunk previously */
- if (ent->nid == -1)
- continue;
- /* Remove from io mappings */
- if (ent->mem) {
- iounmap(ent->mem);
- ent->mem = 0;
- }
- if (add_memory(ent->nid, ent->start, ent->size)) {
- pr_err("Failed to add trace memory to node %d\n",
- ent->nid);
- ret += 1;
- continue;
- }
- /*
- * If kernel isn't compiled with the auto online option
- * we need to online the memory ourselves.
- */
- if (!memhp_auto_online) {
- lock_device_hotplug();
- walk_memory_range(PFN_DOWN(ent->start),
- PFN_UP(ent->start + ent->size - 1),
- NULL, online_mem_block);
- unlock_device_hotplug();
- }
- /*
- * Memory was added successfully so clean up references to it
- * so on reentry we can tell that this chunk was added.
- */
- debugfs_remove_recursive(ent->dir);
- pr_info("Added trace memory back to node %d\n", ent->nid);
- ent->size = ent->start = ent->nid = -1;
- }
- if (ret)
- return ret;
- /* If all chunks of memory were added successfully, reset globals */
- kfree(memtrace_array);
- memtrace_array = NULL;
- memtrace_size = 0;
- memtrace_array_nr = 0;
- return 0;
- }
- static int memtrace_enable_set(void *data, u64 val)
- {
- int rc = -EAGAIN;
- u64 bytes;
- /*
- * Don't attempt to do anything if size isn't aligned to a memory
- * block or equal to zero.
- */
- bytes = memory_block_size_bytes();
- if (val & (bytes - 1)) {
- pr_err("Value must be aligned with 0x%llx\n", bytes);
- return -EINVAL;
- }
- mutex_lock(&memtrace_mutex);
- /* Re-add/online previously removed/offlined memory */
- if (memtrace_size) {
- if (memtrace_online())
- goto out_unlock;
- }
- if (!val) {
- rc = 0;
- goto out_unlock;
- }
- /* Offline and remove memory */
- if (memtrace_init_regions_runtime(val))
- goto out_unlock;
- if (memtrace_init_debugfs())
- goto out_unlock;
- memtrace_size = val;
- rc = 0;
- out_unlock:
- mutex_unlock(&memtrace_mutex);
- return rc;
- }
- static int memtrace_enable_get(void *data, u64 *val)
- {
- *val = memtrace_size;
- return 0;
- }
- DEFINE_SIMPLE_ATTRIBUTE(memtrace_init_fops, memtrace_enable_get,
- memtrace_enable_set, "0x%016llx\n");
- static int memtrace_init(void)
- {
- memtrace_debugfs_dir = debugfs_create_dir("memtrace",
- powerpc_debugfs_root);
- if (!memtrace_debugfs_dir)
- return -1;
- debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
- NULL, &memtrace_init_fops);
- return 0;
- }
- machine_device_initcall(powernv, memtrace_init);
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