1 files changed, 85 insertions, 36 deletions

diff --git a/arch/powerpc/platforms/powernv/memtrace.c b/arch/powerpc/platforms/powernv/memtrace.c
index b99283df8584..51dc398ae3f7 100644
--- a/arch/powerpc/platforms/powernv/memtrace.c
+++ b/arch/powerpc/platforms/powernv/memtrace.c
@@ -47,38 +47,9 @@ static ssize_t memtrace_read(struct file *filp, char __user *ubuf,
 	return simple_read_from_buffer(ubuf, count, ppos, ent->mem, ent->size);
 }
 
-static bool valid_memtrace_range(struct memtrace_entry *dev,
-				 unsigned long start, unsigned long size)
-{
-	if ((start >= dev->start) &&
-	    ((start + size) <= (dev->start + dev->size)))
-		return true;
-
-	return false;
-}
-
-static int memtrace_mmap(struct file *filp, struct vm_area_struct *vma)
-{
-	unsigned long size = vma->vm_end - vma->vm_start;
-	struct memtrace_entry *dev = filp->private_data;
-
-	if (!valid_memtrace_range(dev, vma->vm_pgoff << PAGE_SHIFT, size))
-		return -EINVAL;
-
-	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
-
-	if (remap_pfn_range(vma, vma->vm_start,
-			    vma->vm_pgoff + (dev->start >> PAGE_SHIFT),
-			    size, vma->vm_page_prot))
-		return -EAGAIN;
-
-	return 0;
-}
-
 static const struct file_operations memtrace_fops = {
 	.llseek = default_llseek,
 	.read	= memtrace_read,
-	.mmap	= memtrace_mmap,
 	.open	= simple_open,
 };
 
@@ -206,8 +177,11 @@ static int memtrace_init_debugfs(void)
 
 		snprintf(ent->name, 16, "%08x", ent->nid);
 		dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);
-		if (!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);
@@ -218,18 +192,93 @@ static int memtrace_init_debugfs(void)
 	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) {
+			walk_memory_range(PFN_DOWN(ent->start),
+					  PFN_UP(ent->start + ent->size - 1),
+					  NULL, online_mem_block);
+		}
+
+		/*
+		 * 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)
 {
-	if (memtrace_size)
+	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;
+	}
 
-	if (!val)
-		return -EINVAL;
+	/* Re-add/online previously removed/offlined memory */
+	if (memtrace_size) {
+		if (memtrace_online())
+			return -EAGAIN;
+	}
 
-	/* Make sure size is aligned to a memory block */
-	if (val & (memory_block_size_bytes() - 1))
-		return -EINVAL;
+	if (!val)
+		return 0;
 
+	/* Offline and remove memory */
 	if (memtrace_init_regions_runtime(val))
 		return -EINVAL;