1 files changed, 118 insertions, 10 deletions

diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 2f5aa851834e..7053221ce1d8 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -29,6 +29,7 @@
 #include <linux/types.h>
 #include <linux/memblock.h>
 #include <linux/kasan-enabled.h>
+#include <linux/seq_file.h>
 
 #define DEPOT_HANDLE_BITS (sizeof(depot_stack_handle_t) * 8)
 
@@ -60,6 +61,7 @@ struct stack_record {
 	u32 hash;			/* Hash in the hash table */
 	u32 size;			/* Number of stored frames */
 	union handle_parts handle;
+	refcount_t count;		/* Number of the same repeated stacks */
 	unsigned long entries[];	/* Variable-sized array of frames */
 };
 
@@ -305,6 +307,7 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc)
 	stack->handle.offset = pool_offset >> DEPOT_STACK_ALIGN;
 	stack->handle.valid = 1;
 	stack->handle.extra = 0;
+	refcount_set(&stack->count, 1);
 	memcpy(stack->entries, entries, flex_array_size(stack, entries, size));
 	pool_offset += required_size;
 	/*
@@ -457,8 +460,7 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries,
 }
 EXPORT_SYMBOL_GPL(stack_depot_save);
 
-unsigned int stack_depot_fetch(depot_stack_handle_t handle,
-			       unsigned long **entries)
+static struct stack_record *stack_depot_getstack(depot_stack_handle_t handle)
 {
 	union handle_parts parts = { .handle = handle };
 	/*
@@ -470,6 +472,100 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
 	size_t offset = parts.offset << DEPOT_STACK_ALIGN;
 	struct stack_record *stack;
 
+	if (!handle)
+		return NULL;
+
+	if (parts.pool_index > pool_index_cached) {
+		WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n",
+			parts.pool_index, pool_index_cached, handle);
+		return NULL;
+	}
+	pool = stack_pools[parts.pool_index];
+	if (!pool)
+		return NULL;
+	stack = pool + offset;
+	return stack;
+}
+
+#ifdef CONFIG_PAGE_OWNER
+
+extern unsigned long page_owner_stack_threshold;
+
+void *stack_start(struct seq_file *m, loff_t *ppos)
+{
+	unsigned long *table = m->private;
+	struct stack_record **stacks, *stack;
+
+	/* First time */
+	if (*ppos == 0)
+		*table = 0;
+
+	if (*ppos == -1UL)
+		return NULL;
+
+	stacks = &stack_table[*table];
+	stack = (struct stack_record *)stacks;
+
+	return stack;
+}
+
+void *stack_next(struct seq_file *m, void *v, loff_t *ppos)
+{
+	unsigned long *table = m->private;
+	unsigned long nr_table = *table;
+	struct stack_record *next = NULL, *stack = v, **stacks;
+	unsigned long stack_table_entries = stack_hash_mask + 1;
+
+	if (!stack) {
+new_table:
+		/* New table */
+		nr_table++;
+		if (nr_table >= stack_table_entries)
+			goto out;
+		stacks = &stack_table[nr_table];
+		stack = (struct stack_record *)stacks;
+		next = stack;
+	} else {
+		next = stack->next;
+	}
+
+	if (!next)
+		goto new_table;
+
+out:
+	*table = nr_table;
+	*ppos = (nr_table >= stack_table_entries) ? -1UL : *ppos + 1;
+	return next;
+}
+
+int stack_print(struct seq_file *m, void *v)
+{
+	char *buf;
+	int ret = 0;
+	struct stack_record *stack = v;
+
+	if (!stack->size || stack->size < 0 ||
+	    stack->size > PAGE_SIZE || stack->handle.valid != 1 ||
+	    refcount_read(&stack->count) < page_owner_stack_threshold)
+		return 0;
+
+	buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	ret += stack_trace_snprint(buf, PAGE_SIZE, stack->entries, stack->size, 0);
+	scnprintf(buf + ret, PAGE_SIZE - ret, "stack count: %d\n\n",
+		  refcount_read(&stack->count));
+	seq_printf(m, buf);
+	seq_puts(m, "\n\n");
+	kfree(buf);
+
+	return 0;
+}
+#endif
+
+unsigned int stack_depot_fetch(depot_stack_handle_t handle,
+			       unsigned long **entries)
+{
+	struct stack_record *stack;
+
 	*entries = NULL;
 	/*
 	 * Let KMSAN know *entries is initialized. This shall prevent false
@@ -480,21 +576,33 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
 	if (!handle)
 		return 0;
 
-	if (parts.pool_index > pool_index_cached) {
-		WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n",
-			parts.pool_index, pool_index_cached, handle);
-		return 0;
-	}
-	pool = stack_pools[parts.pool_index];
-	if (!pool)
+	stack = stack_depot_getstack(handle);
+	if (!stack)
 		return 0;
-	stack = pool + offset;
 
 	*entries = stack->entries;
 	return stack->size;
 }
 EXPORT_SYMBOL_GPL(stack_depot_fetch);
 
+void stack_depot_inc_count(depot_stack_handle_t handle)
+{
+	struct stack_record *stack = NULL;
+
+	stack = stack_depot_getstack(handle);
+	if (stack)
+		refcount_inc(&stack->count);
+}
+
+void stack_depot_dec_count(depot_stack_handle_t handle)
+{
+	struct stack_record *stack = NULL;
+
+	stack = stack_depot_getstack(handle);
+	if (stack)
+		refcount_dec(&stack->count);
+}
+
 void stack_depot_print(depot_stack_handle_t stack)
 {
 	unsigned long *entries;