blob: 5fc9408bb0b3f22edff5d0cf1d3041e0bd4cb71e [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) IBM Corporation, 2014, 2017
* Anton Blanchard, Rashmica Gupta.
*/
#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 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 void memtrace_clear_range(unsigned long start_pfn,
unsigned long nr_pages)
{
unsigned long pfn;
/* As HIGHMEM does not apply, use clear_page() 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)));
}
}
static u64 memtrace_alloc_node(u32 nid, u64 size)
{
const unsigned long nr_pages = PHYS_PFN(size);
unsigned long pfn, start_pfn;
struct page *page;
/*
* Trace memory needs to be aligned to the size, which is guaranteed
* by alloc_contig_pages().
*/
page = alloc_contig_pages(nr_pages, GFP_KERNEL | __GFP_THISNODE |
__GFP_NOWARN, nid, NULL);
if (!page)
return 0;
start_pfn = page_to_pfn(page);
/*
* Clear the range while we still have a linear mapping.
*
* TODO: use __GFP_ZERO with alloc_contig_pages() once supported.
*/
memtrace_clear_range(start_pfn, nr_pages);
/*
* Set pages PageOffline(), to indicate that nobody (e.g., hibernation,
* dumping, ...) should be touching these pages.
*/
for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++)
__SetPageOffline(pfn_to_page(pfn));
arch_remove_linear_mapping(PFN_PHYS(start_pfn), size);
return PFN_PHYS(start_pfn);
}
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);
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 memtrace_free(int nid, u64 start, u64 size)
{
struct mhp_params params = { .pgprot = PAGE_KERNEL };
const unsigned long nr_pages = PHYS_PFN(size);
const unsigned long start_pfn = PHYS_PFN(start);
unsigned long pfn;
int ret;
ret = arch_create_linear_mapping(nid, start, size, &params);
if (ret)
return ret;
for (pfn = start_pfn; pfn < start_pfn + nr_pages; pfn++)
__ClearPageOffline(pfn_to_page(pfn));
free_contig_range(start_pfn, nr_pages);
return 0;
}
/*
* Iterate through the chunks of memory we allocated and attempt to expose
* them back to the kernel.
*/
static int memtrace_free_regions(void)
{
int i, ret = 0;
struct memtrace_entry *ent;
for (i = memtrace_array_nr - 1; i >= 0; i--) {
ent = &memtrace_array[i];
/* We have freed this chunk previously */
if (ent->nid == NUMA_NO_NODE)
continue;
/* Remove from io mappings */
if (ent->mem) {
iounmap(ent->mem);
ent->mem = 0;
}
if (memtrace_free(ent->nid, ent->start, ent->size)) {
pr_err("Failed to free trace memory on node %d\n",
ent->nid);
ret += 1;
continue;
}
/*
* Memory was freed successfully so clean up references to it
* so on reentry we can tell that this chunk was freed.
*/
debugfs_remove_recursive(ent->dir);
pr_info("Freed trace memory back on node %d\n", ent->nid);
ent->size = ent->start = ent->nid = NUMA_NO_NODE;
}
if (ret)
return ret;
/* If all chunks of memory were freed 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);
/* Free all previously allocated memory. */
if (memtrace_size && memtrace_free_regions())
goto out_unlock;
if (!val) {
rc = 0;
goto out_unlock;
}
/* Allocate 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);
debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
NULL, &memtrace_init_fops);
return 0;
}
machine_device_initcall(powernv, memtrace_init);