thread.h

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/*
 * Copyright (c) 2017 Intel Corporation
 * Copyright 2025-2026 Arm Limited and/or its affiliates <open-source-office@arm.com>
 *
 * SPDX-License-Identifier: Apache-2.0
 */

 
#ifndef ZEPHYR_INCLUDE_ARCH_ARM_THREAD_H_
#define ZEPHYR_INCLUDE_ARCH_ARM_THREAD_H_
 
#ifndef _ASMLANGUAGE
#include <zephyr/types.h>
 
/* Cortex M's USE_SWITCH implementation is somewhat unique and doesn't
 * use much of the thread struct
 */
#if defined(CONFIG_CPU_CORTEX_M) && defined(CONFIG_USE_SWITCH)
#define _ARM_M_SWITCH
#endif
 
struct _callee_saved {
        uint32_t v1;  /* r4 */
        uint32_t v2;  /* r5 */
        uint32_t v3;  /* r6 */
        uint32_t v4;  /* r7 */
        uint32_t v5;  /* r8 */
        uint32_t v6;  /* r9 */
        uint32_t v7;  /* r10 */
        uint32_t v8;  /* r11 */
        uint32_t psp; /* r13 */
#ifdef CONFIG_USE_SWITCH
        uint32_t lr;  /* lr */
#endif
};
 
typedef struct _callee_saved _callee_saved_t;
 
#if defined(CONFIG_FPU) && defined(CONFIG_FPU_SHARING)
struct _preempt_float {
#ifndef _ARM_M_SWITCH
        float  s16;
        float  s17;
        float  s18;
        float  s19;
        float  s20;
        float  s21;
        float  s22;
        float  s23;
        float  s24;
        float  s25;
        float  s26;
        float  s27;
        float  s28;
        float  s29;
        float  s30;
        float  s31;
#endif /* !_ARM_M_SWITCH */
};
#endif
 
#if defined(CONFIG_ARM_PAC_PER_THREAD)
struct pac_keys {
        uint32_t key_0;
        uint32_t key_1;
        uint32_t key_2;
        uint32_t key_3;
};
#endif
 
struct _thread_arch {
 
#ifndef _ARM_M_SWITCH
        /* interrupt locking key */
        uint32_t basepri;
 
        /* r0 in stack frame cannot be written to reliably */
        uint32_t swap_return_value;
#endif
 
#ifdef _ARM_M_SWITCH
        uint32_t iciit_pc;
        uint32_t iciit_apsr;
#endif
 
#if defined(CONFIG_FPU) && defined(CONFIG_FPU_SHARING)
        /*
         * No cooperative floating point register set structure exists for
         * the Cortex-M as it automatically saves the necessary registers
         * in its exception stack frame.
         */
        struct _preempt_float  preempt_float;
#endif
 
#if defined(CONFIG_CPU_AARCH32_CORTEX_A) || defined(CONFIG_CPU_AARCH32_CORTEX_R)
        int8_t exception_depth;
#endif
 
#if defined(CONFIG_ARM_STORE_EXC_RETURN) || defined(CONFIG_USERSPACE)
        /*
         * Status variable holding several thread status flags
         * as follows:
         *
         * byte 0
         * +-bits 4-7-----bit-3----------bit-2--------bit-1---+----bit-0------+
         * :          |             |              |          |               |
         * : reserved |<Guard FLOAT>|   reserved   | reserved |  <priv mode>  |
         * :   bits   |             |              |          | CONTROL.nPRIV |
         * +------------------------------------------------------------------+
         *
         * byte 1
         * +----------------------------bits 8-15-----------------------------+
         * :              Least significant byte of EXC_RETURN                |
         * : bit 15| bit 14| bit 13 | bit 12| bit 11 | bit 10 | bit 9 | bit 8 |
         * :  Res  |   S   |  DCRS  | FType |  Mode  | SPSel  |  Res  |  ES   |
         * +------------------------------------------------------------------+
         *
         * Bit 0: thread's current privileged mode (Supervisor or User mode)
         *        Mirrors CONTROL.nPRIV flag.
         * Bit 2: Deprecated in favor of FType. Note: FType = !CONTROL.FPCA.
         *        indicating whether the thread has an active FP context.
         *        Mirrors CONTROL.FPCA flag.
         * Bit 3: indicating whether the thread is applying the long (FLOAT)
         *        or the default MPU stack guard size.
         *
         * Bits 8-15: Least significant octet of the EXC_RETURN value when a
         *            thread is switched-out. The value is copied from LR when
         *            entering the PendSV handler. When the thread is
         *            switched in again, the value is restored to LR before
         *            exiting the PendSV handler.
         */
        union {
                uint32_t mode;
 
#if defined(CONFIG_ARM_STORE_EXC_RETURN)
                struct {
                        uint8_t mode_bits;
                        uint8_t mode_exc_return;
                        uint16_t mode_reserved2;
                };
#endif
        };
 
#if defined(CONFIG_USERSPACE)
        uint32_t priv_stack_start;
        uint32_t priv_stack_end;
#if defined(CONFIG_CPU_AARCH32_CORTEX_R)
        uint32_t sp_usr;
#endif
#endif
#endif
 
#if defined(CONFIG_ARM_PAC_PER_THREAD)
        struct pac_keys pac_keys;
#endif
};
 
#if defined(CONFIG_FPU_SHARING) && defined(CONFIG_MPU_STACK_GUARD)
#define Z_ARM_MODE_MPU_GUARD_FLOAT_Msk (1 << 3)
#endif
typedef struct _thread_arch _thread_arch_t;
 
#endif /* _ASMLANGUAGE */
 
#endif /* ZEPHYR_INCLUDE_ARCH_ARM_THREAD_H_ */