include/linux/stackdepot.h

3  * Stack depot - a stack trace storage that avoids duplication.
5  * Stack depot is intended to be used by subsystems that need to store and
6  * later retrieve many potentially duplicated stack traces without wasting
9  * For example, KASAN needs to save allocation and free stack traces for each
10  * object. Storing two stack traces per object requires a lot of memory (e.g.
12  * stack traces often repeat, using stack depot allows to save about 100x space.
28  * Number of bits in the handle that stack depot doesn't use. Users may store
43 /* Compact structure that stores a reference to a stack. */
64 			 * only place a stack record onto the freelist iff its
65 			 * refcount is zero. Because stack records with a zero
92  * Using stack depot requires its initialization, which can be done in 3 ways:
95  *    scenarios where it's known at compile time that stack depot will be used.
96  *    Enabling this config makes the kernel initialize stack depot in mm_init().
108  * config is disabled. The save/fetch/print stack depot functions can only be
110  * initializes stack depot via one of the ways listed above.
128  * stack_depot_save_flags - Save a stack trace to stack depot
130  * @entries:		Pointer to the stack trace
131  * @nr_entries:		Number of frames in the stack
133  * @depot_flags:	Stack depot flags
135  * Saves a stack trace from @entries array of size @nr_entries.
137  * If STACK_DEPOT_FLAG_CAN_ALLOC is set in @depot_flags, stack depot can
138  * replenish the stack pools in case no space is left (allocates using GFP
139  * flags of @alloc_flags). Otherwise, stack depot avoids any allocations and
140  * fails if no space is left to store the stack trace.
142  * If STACK_DEPOT_FLAG_GET is set in @depot_flags, stack depot will increment
143  * the refcount on the saved stack trace if it already exists in stack depot.
144  * Users of this flag must also call stack_depot_put() when keeping the stack
147  * If the provided stack trace comes from the interrupt context, only the part
155  * Return: Handle of the stack struct stored in depot, 0 on failure
163  * stack_depot_save - Save a stack trace to stack depot
165  * @entries:		Pointer to the stack trace
166  * @nr_entries:		Number of frames in the stack
169  * Does not increment the refcount on the saved stack trace; see
175  * Return: Handle of the stack trace stored in depot, 0 on failure
183  * @handle: Stack depot handle
192  * stack_depot_fetch - Fetch a stack trace from stack depot
194  * @handle:	Stack depot handle returned from stack_depot_save()
195  * @entries:	Pointer to store the address of the stack trace
197  * Return: Number of frames for the fetched stack
203  * stack_depot_print - Print a stack trace from stack depot
205  * @stack:	Stack depot handle returned from stack_depot_save()
207 void stack_depot_print(depot_stack_handle_t stack);
210  * stack_depot_snprint - Print a stack trace from stack depot into a buffer
212  * @handle:	Stack depot handle returned from stack_depot_save()
223  * stack_depot_put - Drop a reference to a stack trace from stack depot
225  * @handle:	Stack depot handle returned from stack_depot_save()
227  * The stack trace is evicted from stack depot once all references to it have
230  * this stack trace).
235  * stack_depot_set_extra_bits - Set extra bits in a stack depot handle
237  * @handle:	Stack depot handle returned from stack_depot_save()
240  * Return: Stack depot handle with extra bits set
242  * Stack depot handles have a few unused bits, which can be used for storing
243  * user-specific information. These bits are transparent to the stack depot.
249  * stack_depot_get_extra_bits - Retrieve extra bits from a stack depot handle
251  * @handle:	Stack depot handle with extra bits saved
253  * Return: Extra bits retrieved from the stack depot handle