Commit 83130ab2 authored by Andrey Konovalov's avatar Andrey Konovalov Committed by Andrew Morton
Browse files

lib/stackdepot: add depot_fetch_stack helper 

Add a helper depot_fetch_stack function that fetches the pointer to a
stack record.

With this change, all static depot_* functions now operate on stack pools
and the exported stack_depot_* functions operate on the hash table.

Link: https://lkml.kernel.org/r/170d8c202f29dc8e3d5491ee074d1e9e029a46db.1700502145.git.andreyknvl@google.com


Signed-off-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: default avatarAlexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5f9ce55e

lib/stackdepot.c

+28 −17
Original line number Diff line number Diff line
@@ -310,6 +310,7 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc) 
	stack->handle.extra = 0;

	memcpy(stack->entries, entries, flex_array_size(stack, entries, size));

	pool_offset += required_size;



	/*

	 * Let KMSAN know the stored stack record is initialized. This shall

	 * prevent false positive reports if instrumented code accesses it.
@@ -319,6 +320,32 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc) 
	return stack;

}



static struct stack_record *depot_fetch_stack(depot_stack_handle_t handle)

{

	union handle_parts parts = { .handle = handle };

	/*

	 * READ_ONCE pairs with potential concurrent write in

	 * depot_alloc_stack().

	 */

	int pool_index_cached = READ_ONCE(pool_index);

	void *pool;

	size_t offset = parts.offset << DEPOT_STACK_ALIGN;

	struct stack_record *stack;



	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;

}



/* Calculates the hash for a stack. */

static inline u32 hash_stack(unsigned long *entries, unsigned int size)

{
@@ -462,14 +489,6 @@ EXPORT_SYMBOL_GPL(stack_depot_save); 
unsigned int stack_depot_fetch(depot_stack_handle_t handle,

			       unsigned long **entries)

{

	union handle_parts parts = { .handle = handle };

	/*

	 * READ_ONCE pairs with potential concurrent write in

	 * depot_alloc_stack.

	 */

	int pool_index_cached = READ_ONCE(pool_index);

	void *pool;

	size_t offset = parts.offset << DEPOT_STACK_ALIGN;

	struct stack_record *stack;



	*entries = NULL;
@@ -482,15 +501,7 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle, 
	if (!handle || stack_depot_disabled)

		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)

		return 0;

	stack = pool + offset;

	stack = depot_fetch_stack(handle);



	*entries = stack->entries;

	return stack->size;