1 files changed, 359 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..ce6597a29
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/memtrace.c
@@ -0,0 +1,359 @@
+/*
+ * 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);