/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_UNWIND_USER_DEFERRED_TYPES_H
#define _LINUX_UNWIND_USER_DEFERRED_TYPES_H

#include <linux/types.h>
#include <linux/atomic.h>

struct unwind_cache {
        unsigned long           unwind_completed;
        unsigned int            nr_entries;
        unsigned long           entries[];
};

/*
 * The unwind_task_id is a unique identifier that maps to a user space
 * stacktrace. It is generated the first time a deferred user space
 * stacktrace is requested after a task has entered the kerenl and
 * is cleared to zero when it exits. The mapped id will be a non-zero
 * number.
 *
 * To simplify the generation of the 64 bit number, 32 bits will be
 * the CPU it was generated on, and the other 32 bits will be a per
 * cpu counter that gets incremented by two every time a new identifier
 * is generated. The LSB will always be set to keep the value
 * from being zero.
 */
union unwind_task_id {
        struct {
                u32             cpu;
                u32             cnt;
        };
        u64                     id;
};

struct unwind_task_info {
        atomic_long_t           unwind_mask;
        struct unwind_cache     *cache;
        struct callback_head    work;
        union unwind_task_id    id;
};

struct unwind_work;
struct unwind_stacktrace;

typedef void (*unwind_callback_t)(struct unwind_work *work,
                                  struct unwind_stacktrace *trace,
                                  u64 cookie);

struct unwind_work {
        struct list_head                list;
        unwind_callback_t               func;
        int                             bit;
};

#endif /* _LINUX_UNWIND_USER_DEFERRED_TYPES_H */