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-rw-r--r--arch/powerpc/platforms/powernv/memtrace.c342
1 files changed, 342 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powernv/memtrace.c b/arch/powerpc/platforms/powernv/memtrace.c
new file mode 100644
index 000000000..0e42fe2d7
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/memtrace.c
@@ -0,0 +1,342 @@
+// 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 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)
+{
+ const unsigned long start = PFN_PHYS(start_pfn);
+ const unsigned long size = PFN_PHYS(nr_pages);
+
+ if (walk_memory_blocks(start, size, NULL, check_memblock_online))
+ return false;
+
+ walk_memory_blocks(start, size, (void *)MEM_GOING_OFFLINE,
+ change_memblock_state);
+
+ if (offline_pages(start_pfn, nr_pages)) {
+ walk_memory_blocks(start, size, (void *)MEM_ONLINE,
+ change_memblock_state);
+ return false;
+ }
+
+ walk_memory_blocks(start, size, (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);
+
+ 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, MHP_NONE)) {
+ pr_err("Failed to add trace memory to node %d\n",
+ ent->nid);
+ ret += 1;
+ continue;
+ }
+
+ lock_device_hotplug();
+ walk_memory_blocks(ent->start, ent->size, 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)
+{
+ 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);
+
+ debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
+ NULL, &memtrace_init_fops);
+
+ return 0;
+}
+machine_device_initcall(powernv, memtrace_init);