kernel_structs.h

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/*
 * Copyright (c) 2016 Wind River Systems, Inc.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
/*
 * The purpose of this file is to provide essential/minimal kernel structure
 * definitions, so that they can be used without including kernel.h.
 *
 * The following rules must be observed:
 *  1. kernel_structs.h shall not depend on kernel.h both directly and
 *    indirectly (i.e. it shall not include any header files that include
 *    kernel.h in their dependency chain).
 *  2. kernel.h shall imply kernel_structs.h, such that it shall not be
 *    necessary to include kernel_structs.h explicitly when kernel.h is
 *    included.
 */
 
#ifndef ZEPHYR_KERNEL_INCLUDE_KERNEL_STRUCTS_H_
#define ZEPHYR_KERNEL_INCLUDE_KERNEL_STRUCTS_H_
 
#if !defined(_ASMLANGUAGE)
#include <zephyr/sys/atomic.h>
#include <zephyr/types.h>
#include <zephyr/sys/dlist.h>
#include <zephyr/sys/util.h>
#include <zephyr/sys/sys_heap.h>
#include <zephyr/arch/structs.h>
#include <zephyr/kernel/stats.h>
#include <zephyr/kernel/obj_core.h>
#include <zephyr/sys/rb.h>
#endif
 
#define K_NUM_THREAD_PRIO (CONFIG_NUM_PREEMPT_PRIORITIES + CONFIG_NUM_COOP_PRIORITIES + 1)
#define PRIQ_BITMAP_SIZE  (DIV_ROUND_UP(K_NUM_THREAD_PRIO, BITS_PER_LONG))
 
#ifdef __cplusplus
extern "C" {
#endif
 
/*
 * Bitmask definitions for the struct k_thread.thread_state field.
 *
 * Must be before kernel_arch_data.h because it might need them to be already
 * defined.
 */
 
/* states: common uses low bits, arch-specific use high bits */
 
/* Not a real thread */
#define _THREAD_DUMMY (BIT(0))
 
/* Thread is waiting on an object */
#define _THREAD_PENDING (BIT(1))
 
/* Thread is sleeping */
#define _THREAD_SLEEPING (BIT(2))
 
/* Thread has terminated */
#define _THREAD_DEAD (BIT(3))
 
/* Thread is suspended */
#define _THREAD_SUSPENDED (BIT(4))
 
/* Thread is in the process of aborting */
#define _THREAD_ABORTING (BIT(5))
 
/* Thread is in the process of suspending */
#define _THREAD_SUSPENDING (BIT(6))
 
/* Thread is present in the ready queue */
#define _THREAD_QUEUED (BIT(7))
 
/* end - states */
 
#ifdef CONFIG_STACK_SENTINEL
/* Magic value in lowest bytes of the stack */
#define STACK_SENTINEL 0xF0F0F0F0
#endif
 
/* lowest value of _thread_base.preempt at which a thread is non-preemptible */
#define _NON_PREEMPT_THRESHOLD 0x0080U
 
/* highest value of _thread_base.preempt at which a thread is preemptible */
#define _PREEMPT_THRESHOLD (_NON_PREEMPT_THRESHOLD - 1U)
 
#if !defined(_ASMLANGUAGE)
 
/* Two abstractions are defined here for "thread priority queues".
 *
 * One is a "dumb" list implementation appropriate for systems with
 * small numbers of threads and sensitive to code size.  It is stored
 * in sorted order, taking an O(N) cost every time a thread is added
 * to the list.  This corresponds to the way the original _wait_q_t
 * abstraction worked and is very fast as long as the number of
 * threads is small.
 *
 * The other is a balanced tree "fast" implementation with rather
 * larger code size (due to the data structure itself, the code here
 * is just stubs) and higher constant-factor performance overhead, but
 * much better O(logN) scaling in the presence of large number of
 * threads.
 *
 * Each can be used for either the wait_q or system ready queue,
 * configurable at build time.
 */
 
struct _priq_rb {
        struct rbtree tree;
        int next_order_key;
};
 
 
/* Traditional/textbook "multi-queue" structure.  Separate lists for a
 * small number (max 32 here) of fixed priorities.  This corresponds
 * to the original Zephyr scheduler.  RAM requirements are
 * comparatively high, but performance is very fast.  Won't work with
 * features like deadline scheduling which need large priority spaces
 * to represent their requirements.
 */
struct _priq_mq {
        sys_dlist_t queues[K_NUM_THREAD_PRIO];
        unsigned long bitmask[PRIQ_BITMAP_SIZE];
#ifndef CONFIG_SMP
        unsigned int cached_queue_index;
#endif
};
 
struct _ready_q {
#ifndef CONFIG_SMP
        /* always contains next thread to run: cannot be NULL */
        struct k_thread *cache;
#endif
 
#if defined(CONFIG_SCHED_DUMB)
        sys_dlist_t runq;
#elif defined(CONFIG_SCHED_SCALABLE)
        struct _priq_rb runq;
#elif defined(CONFIG_SCHED_MULTIQ)
        struct _priq_mq runq;
#endif
};
 
typedef struct _ready_q _ready_q_t;
 
struct _cpu {
        /* nested interrupt count */
        uint32_t nested;
 
        /* interrupt stack pointer base */
        char *irq_stack;
 
        /* currently scheduled thread */
        struct k_thread *current;
 
        /* one assigned idle thread per CPU */
        struct k_thread *idle_thread;
 
#ifdef CONFIG_SCHED_CPU_MASK_PIN_ONLY
        struct _ready_q ready_q;
#endif
 
#if (CONFIG_NUM_METAIRQ_PRIORITIES > 0) &&                                                         \
        (CONFIG_NUM_COOP_PRIORITIES > CONFIG_NUM_METAIRQ_PRIORITIES)
        /* Coop thread preempted by current metairq, or NULL */
        struct k_thread *metairq_preempted;
#endif
 
        uint8_t id;
 
#if defined(CONFIG_FPU_SHARING)
        void *fp_ctx;
#endif
 
#ifdef CONFIG_SMP
        /* True when _current is allowed to context switch */
        uint8_t swap_ok;
#endif
 
#ifdef CONFIG_SCHED_THREAD_USAGE
        /*
         * [usage0] is used as a timestamp to mark the beginning of an
         * execution window. [0] is a special value indicating that it
         * has been stopped (but not disabled).
         */
 
        uint32_t usage0;
 
#ifdef CONFIG_SCHED_THREAD_USAGE_ALL
        struct k_cycle_stats *usage;
#endif
#endif
 
#ifdef CONFIG_OBJ_CORE_SYSTEM
        struct k_obj_core  obj_core;
#endif
 
        /* Per CPU architecture specifics */
        struct _cpu_arch arch;
};
 
typedef struct _cpu _cpu_t;
 
struct z_kernel {
        struct _cpu cpus[CONFIG_MP_MAX_NUM_CPUS];
 
#ifdef CONFIG_PM
        int32_t idle; /* Number of ticks for kernel idling */
#endif
 
        /*
         * ready queue: can be big, keep after small fields, since some
         * assembly (e.g. ARC) are limited in the encoding of the offset
         */
#ifndef CONFIG_SCHED_CPU_MASK_PIN_ONLY
        struct _ready_q ready_q;
#endif
 
#ifdef CONFIG_FPU_SHARING
        /*
         * A 'current_sse' field does not exist in addition to the 'current_fp'
         * field since it's not possible to divide the IA-32 non-integer
         * registers into 2 distinct blocks owned by differing threads.  In
         * other words, given that the 'fxnsave/fxrstor' instructions
         * save/restore both the X87 FPU and XMM registers, it's not possible
         * for a thread to only "own" the XMM registers.
         */
 
        /* thread that owns the FP regs */
        struct k_thread *current_fp;
#endif
 
#if defined(CONFIG_THREAD_MONITOR)
        struct k_thread *threads; /* singly linked list of ALL threads */
#endif
#ifdef CONFIG_SCHED_THREAD_USAGE_ALL
        struct k_cycle_stats usage[CONFIG_MP_MAX_NUM_CPUS];
#endif
 
#ifdef CONFIG_OBJ_CORE_SYSTEM
        struct k_obj_core  obj_core;
#endif
 
#if defined(CONFIG_SMP) && defined(CONFIG_SCHED_IPI_SUPPORTED)
        /* Identify CPUs to send IPIs to at the next scheduling point */
        atomic_t pending_ipi;
#endif
};
 
typedef struct z_kernel _kernel_t;
 
extern struct z_kernel _kernel;
 
extern atomic_t _cpus_active;
 
#ifdef CONFIG_SMP
 
/* True if the current context can be preempted and migrated to
 * another SMP CPU.
 */
bool z_smp_cpu_mobile(void);
#define _current_cpu ({ __ASSERT_NO_MSG(!z_smp_cpu_mobile()); \
                        arch_curr_cpu(); })
 
__attribute_const__ struct k_thread *z_smp_current_get(void);
#define _current z_smp_current_get()
 
#else
#define _current_cpu (&_kernel.cpus[0])
#define _current _kernel.cpus[0].current
#endif
 
/* This is always invoked from a context where preemption is disabled */
#define z_current_thread_set(thread) ({ _current_cpu->current = (thread); })
 
#ifdef CONFIG_ARCH_HAS_CUSTOM_CURRENT_IMPL
#undef _current
#define _current arch_current_thread()
#undef z_current_thread_set
#define z_current_thread_set(thread) \
        arch_current_thread_set(({ _current_cpu->current = (thread); }))
#endif
 
/* kernel wait queue record */
#ifdef CONFIG_WAITQ_SCALABLE
 
typedef struct {
        struct _priq_rb waitq;
} _wait_q_t;
 
/* defined in kernel/priority_queues.c */
bool z_priq_rb_lessthan(struct rbnode *a, struct rbnode *b);
 
#define Z_WAIT_Q_INIT(wait_q) { { { .lessthan_fn = z_priq_rb_lessthan } } }
 
#else
 
typedef struct {
        sys_dlist_t waitq;
} _wait_q_t;
 
#define Z_WAIT_Q_INIT(wait_q) { SYS_DLIST_STATIC_INIT(&(wait_q)->waitq) }
 
#endif /* CONFIG_WAITQ_SCALABLE */
 
/* kernel timeout record */
struct _timeout;
typedef void (*_timeout_func_t)(struct _timeout *t);
 
struct _timeout {
        sys_dnode_t node;
        _timeout_func_t fn;
#ifdef CONFIG_TIMEOUT_64BIT
        /* Can't use k_ticks_t for header dependency reasons */
        int64_t dticks;
#else
        int32_t dticks;
#endif
};
 
typedef void (*k_thread_timeslice_fn_t)(struct k_thread *thread, void *data);
 
#ifdef __cplusplus
}
#endif
 
#endif /* _ASMLANGUAGE */
 
#endif /* ZEPHYR_KERNEL_INCLUDE_KERNEL_STRUCTS_H_ */