/*
* 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 <linux/numa.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 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;
}
/* 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) {
/*
* 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 == NUMA_NO_NODE)
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 = NUMA_NO_NODE;
}
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)
{
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;
}
/* Re-add/online previously removed/offlined memory */
if (memtrace_size) {
if (memtrace_online())
return -EAGAIN;
}
if (!val)
return 0;
/* Offline and remove memory */
if (memtrace_init_regions_runtime(val))
return -EINVAL;
if (memtrace_init_debugfs())
return -EINVAL;
memtrace_size = val;
return 0;
}
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);
