1 files changed, 339 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..877720c64
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/memtrace.c
@@ -0,0 +1,339 @@
+// 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/cacheflush.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 int memtrace_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	struct memtrace_entry *ent = filp->private_data;
+
+	if (ent->size < vma->vm_end - vma->vm_start)
+		return -EINVAL;
+
+	if (vma->vm_pgoff << PAGE_SHIFT >= ent->size)
+		return -EINVAL;
+
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+	return remap_pfn_range(vma, vma->vm_start, PHYS_PFN(ent->start) + vma->vm_pgoff,
+			       vma->vm_end - vma->vm_start, vma->vm_page_prot);
+}
+
+static const struct file_operations memtrace_fops = {
+	.llseek = default_llseek,
+	.read	= memtrace_read,
+	.open	= simple_open,
+	.mmap   = memtrace_mmap,
+};
+
+#define FLUSH_CHUNK_SIZE SZ_1G
+/**
+ * flush_dcache_range_chunked(): Write any modified data cache blocks out to
+ * memory and invalidate them, in chunks of up to FLUSH_CHUNK_SIZE
+ * Does not invalidate the corresponding instruction cache blocks.
+ *
+ * @start: the start address
+ * @stop: the stop address (exclusive)
+ * @chunk: the max size of the chunks
+ */
+static void flush_dcache_range_chunked(unsigned long start, unsigned long stop,
+				       unsigned long chunk)
+{
+	unsigned long i;
+
+	for (i = start; i < stop; i += chunk) {
+		flush_dcache_range(i, min(stop, i + chunk));
+		cond_resched();
+	}
+}
+
+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)));
+	}
+	/*
+	 * Before we go ahead and use this range as cache inhibited range
+	 * flush the cache.
+	 */
+	flush_dcache_range_chunked((unsigned long)pfn_to_kaddr(start_pfn),
+				   (unsigned long)pfn_to_kaddr(start_pfn + nr_pages),
+				   FLUSH_CHUNK_SIZE);
+}
+
+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_unsafe("trace", 0600, 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",
+						  arch_debugfs_dir);
+
+	debugfs_create_file("enable", 0600, memtrace_debugfs_dir,
+			    NULL, &memtrace_init_fops);
+
+	return 0;
+}
+machine_device_initcall(powernv, memtrace_init);