arch.h

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/*
 * Copyright (c) 2016 Jean-Paul Etienne <fractalclone@gmail.com>
 * Contributors: 2018 Antmicro <www.antmicro.com>
 *
 * SPDX-License-Identifier: Apache-2.0
 */

 
#ifndef ZEPHYR_INCLUDE_ARCH_RISCV_ARCH_H_
#define ZEPHYR_INCLUDE_ARCH_RISCV_ARCH_H_
 
#include <zephyr/arch/riscv/thread.h>
#include <zephyr/arch/exception.h>
#include <zephyr/arch/riscv/irq.h>
#include <zephyr/arch/riscv/sys_io.h>
#include <zephyr/arch/common/sys_bitops.h>
#include <zephyr/arch/common/ffs.h>
#if defined(CONFIG_USERSPACE)
#include <zephyr/arch/riscv/syscall.h>
#endif /* CONFIG_USERSPACE */
#include <zephyr/irq.h>
#include <zephyr/sw_isr_table.h>
#include <zephyr/devicetree.h>
#include <zephyr/arch/riscv/csr.h>
 
/* stacks, for RISCV architecture stack should be 16byte-aligned */
#define ARCH_STACK_PTR_ALIGN  16
 
#define Z_RISCV_STACK_PMP_ALIGN \
        MAX(CONFIG_PMP_GRANULARITY, ARCH_STACK_PTR_ALIGN)
 
#ifdef CONFIG_PMP_STACK_GUARD
/*
 * The StackGuard is an area at the bottom of the kernel-mode stack made to
 * fault when accessed. It is _not_ faulting when in exception mode as we rely
 * on that area to save the exception stack frame and to process said fault.
 * Therefore the guard area must be large enough to hold the esf, plus some
 * configurable stack wiggle room to execute the fault handling code off of,
 * as well as some guard size to cover possible sudden stack pointer
 * displacement before the fault.
 */
#ifdef CONFIG_PMP_POWER_OF_TWO_ALIGNMENT
#define Z_RISCV_STACK_GUARD_SIZE \
        Z_POW2_CEIL(MAX(sizeof(struct arch_esf) + CONFIG_PMP_STACK_GUARD_MIN_SIZE, \
                        Z_RISCV_STACK_PMP_ALIGN))
#define ARCH_KERNEL_STACK_OBJ_ALIGN     Z_RISCV_STACK_GUARD_SIZE
#else
#define Z_RISCV_STACK_GUARD_SIZE \
        ROUND_UP(sizeof(struct arch_esf) + CONFIG_PMP_STACK_GUARD_MIN_SIZE, \
                 Z_RISCV_STACK_PMP_ALIGN)
#define ARCH_KERNEL_STACK_OBJ_ALIGN     Z_RISCV_STACK_PMP_ALIGN
#endif
 
/* Kernel-only stacks have the following layout if a stack guard is enabled:
 *
 * +------------+ <- thread.stack_obj
 * | Guard      | } Z_RISCV_STACK_GUARD_SIZE
 * +------------+ <- thread.stack_info.start
 * | Kernel     |
 * | stack      |
 * |            |
 * +............|
 * | TLS        | } thread.stack_info.delta
 * +------------+ <- thread.stack_info.start + thread.stack_info.size
 */
#define ARCH_KERNEL_STACK_RESERVED      Z_RISCV_STACK_GUARD_SIZE
 
#else /* !CONFIG_PMP_STACK_GUARD */
#define Z_RISCV_STACK_GUARD_SIZE 0
#endif
 
#ifdef CONFIG_PMP_POWER_OF_TWO_ALIGNMENT
/* The privilege elevation stack is located in another area of memory
 * generated at build time by gen_kobject_list.py
 *
 * +------------+ <- thread.arch.priv_stack_start
 * | Guard      | } Z_RISCV_STACK_GUARD_SIZE
 * +------------+
 * | Priv Stack | } CONFIG_PRIVILEGED_STACK_SIZE
 * +------------+ <- thread.arch.priv_stack_start +
 *                   CONFIG_PRIVILEGED_STACK_SIZE +
 *                   Z_RISCV_STACK_GUARD_SIZE
 *
 * The main stack will be initially (or potentially only) used by kernel
 * mode so we need to make room for a possible stack guard area when enabled:
 *
 * +------------+ <- thread.stack_obj
 * | Guard      | } Z_RISCV_STACK_GUARD_SIZE
 * +............| <- thread.stack_info.start
 * | Thread     |
 * | stack      |
 * |            |
 * +............|
 * | TLS        | } thread.stack_info.delta
 * +------------+ <- thread.stack_info.start + thread.stack_info.size
 *
 * When transitioning to user space, the guard area will be removed from
 * the main stack. Any thread running in user mode will have full access
 * to the region denoted by thread.stack_info. Make it PMP-NAPOT compatible.
 *
 * +------------+ <- thread.stack_obj = thread.stack_info.start
 * | Thread     |
 * | stack      |
 * |            |
 * +............|
 * | TLS        | } thread.stack_info.delta
 * +------------+ <- thread.stack_info.start + thread.stack_info.size
 */
#define ARCH_THREAD_STACK_RESERVED Z_RISCV_STACK_GUARD_SIZE
#define ARCH_THREAD_STACK_SIZE_ADJUST(size) \
        Z_POW2_CEIL(MAX(MAX(size, CONFIG_PRIVILEGED_STACK_SIZE), \
                        Z_RISCV_STACK_PMP_ALIGN))
#define ARCH_THREAD_STACK_OBJ_ALIGN(size) \
                ARCH_THREAD_STACK_SIZE_ADJUST(size)
 
#else /* !CONFIG_PMP_POWER_OF_TWO_ALIGNMENT */
 
/* The stack object will contain the PMP guard, the privilege stack, and then
 * the usermode stack buffer in that order:
 *
 * +------------+ <- thread.stack_obj
 * | Guard      | } Z_RISCV_STACK_GUARD_SIZE
 * +------------+
 * | Priv Stack | } CONFIG_PRIVILEGED_STACK_SIZE
 * +------------+ <- thread.stack_info.start
 * | Thread     |
 * | stack      |
 * |            |
 * +............|
 * | TLS        | } thread.stack_info.delta
 * +------------+ <- thread.stack_info.start + thread.stack_info.size
 */
#define ARCH_THREAD_STACK_RESERVED \
        ROUND_UP(Z_RISCV_STACK_GUARD_SIZE + CONFIG_PRIVILEGED_STACK_SIZE, \
                 Z_RISCV_STACK_PMP_ALIGN)
#define ARCH_THREAD_STACK_SIZE_ADJUST(size) \
        ROUND_UP(size, Z_RISCV_STACK_PMP_ALIGN)
#define ARCH_THREAD_STACK_OBJ_ALIGN(size)       Z_RISCV_STACK_PMP_ALIGN
#endif /* CONFIG_PMP_POWER_OF_TWO_ALIGNMENT */
 
#ifdef CONFIG_64BIT
#define RV_REGSIZE 8
#define RV_REGSHIFT 3
#else
#define RV_REGSIZE 4
#define RV_REGSHIFT 2
#endif
 
/* Common mstatus bits. All supported cores today have the same
 * layouts.
 */
 
#define MSTATUS_IEN     (1UL << 3)
#define MSTATUS_MPP_U   (PRV_U << 11)
#define MSTATUS_MPP_S   (PRV_S << 11)
#define MSTATUS_MPP_M   (PRV_M << 11)
#define MSTATUS_MPIE_EN (1UL << 7)
 
#define MSTATUS_FS_OFF   (0UL << 13)
#define MSTATUS_FS_INIT  (1UL << 13)
#define MSTATUS_FS_CLEAN (2UL << 13)
#define MSTATUS_FS_DIRTY (3UL << 13)

#ifdef CONFIG_RISCV_S_MODE
#define RV_STATUS_DEF_RESTORE (SSTATUS_SPP | SSTATUS_SPIE)
#else
#define RV_STATUS_DEF_RESTORE (MSTATUS_MPP_M | MSTATUS_MPIE_EN)
#endif
 
/* Previous-privilege field and its user-mode value, abstracted across M/S mode.
 * Use as: (esf->mstatus & RV_STATUS_PP) == RV_STATUS_PP_U
 */
#ifdef CONFIG_RISCV_S_MODE
#define RV_STATUS_PP    SSTATUS_SPP
#define RV_STATUS_PP_U  0
#else
#define RV_STATUS_PP    MSTATUS_MPP
#define RV_STATUS_PP_U  PRV_U
#endif
 
#ifndef _ASMLANGUAGE
#include <zephyr/sys/util.h>
#include <zephyr/sys/slist.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
#ifdef CONFIG_IRQ_VECTOR_TABLE_JUMP_BY_CODE
#define ARCH_IRQ_VECTOR_JUMP_CODE(v) "j " STRINGIFY(v)
#endif
 
/* Kernel macros for memory attribution
 * (access permissions and cache-ability).
 *
 * The macros are to be stored in k_mem_partition_attr_t
 * objects. The format of a k_mem_partition_attr_t object
 * is an uint8_t composed by configuration register flags
 * located in arch/riscv/include/core_pmp.h
 */
 
/* Read-Write access permission attributes */
#define K_MEM_PARTITION_P_RW_U_RW ((k_mem_partition_attr_t) \
        {PMP_R | PMP_W})
#define K_MEM_PARTITION_P_RW_U_RO ((k_mem_partition_attr_t) \
        {PMP_R})
#define K_MEM_PARTITION_P_RW_U_NA ((k_mem_partition_attr_t) \
        {0})
#define K_MEM_PARTITION_P_RO_U_RO ((k_mem_partition_attr_t) \
        {PMP_R})
#define K_MEM_PARTITION_P_RO_U_NA ((k_mem_partition_attr_t) \
        {0})
#define K_MEM_PARTITION_P_NA_U_NA ((k_mem_partition_attr_t) \
        {0})
 
/* Execution-allowed attributes */
#define K_MEM_PARTITION_P_RWX_U_RWX ((k_mem_partition_attr_t) \
        {PMP_R | PMP_W | PMP_X})
#define K_MEM_PARTITION_P_RX_U_RX ((k_mem_partition_attr_t) \
        {PMP_R | PMP_X})
 
/* Typedef for the k_mem_partition attribute */
typedef struct {
        uint8_t pmp_attr;
} k_mem_partition_attr_t;
 
struct arch_mem_domain {
        unsigned int pmp_update_nr;
};
 
extern void z_irq_spurious(const void *unused);
 
/* Privilege-level abstraction for IRQ enable/disable CSR and bit */
#ifdef CONFIG_RISCV_S_MODE
#define RV_STATUS_CSR "sstatus"
#define RV_STATUS_IE  SSTATUS_SIE
#define RV_STATUS_PIE SSTATUS_SPIE
#else
#define RV_STATUS_CSR "mstatus"
#define RV_STATUS_IE  MSTATUS_IEN
#define RV_STATUS_PIE MSTATUS_MPIE_EN
#endif

static ALWAYS_INLINE unsigned long z_riscv_status_read(void)
{
        unsigned long __rv;
 
        __asm__ volatile ("csrr %0, " RV_STATUS_CSR : "=r" (__rv));
        return __rv;
}

static ALWAYS_INLINE void z_riscv_status_set(unsigned long val)
{
        __asm__ volatile ("csrs " RV_STATUS_CSR ", %0" : : "rK" (val) : "memory");
}

static ALWAYS_INLINE void z_riscv_status_clear(unsigned long val)
{
        __asm__ volatile ("csrc " RV_STATUS_CSR ", %0" : : "rK" (val) : "memory");
}
 
/*
 * use atomic instruction csrrc to lock global irq
 * csrrc: atomic read and clear bits in CSR register
 */
static ALWAYS_INLINE unsigned int arch_irq_lock(void)
{
#ifdef CONFIG_RISCV_SOC_HAS_CUSTOM_IRQ_LOCK_OPS
        return z_soc_irq_lock();
#else
        unsigned int key;
 
        __asm__ volatile ("csrrc %0, " RV_STATUS_CSR ", %1"
                          : "=r" (key)
                          : "rK" (RV_STATUS_IE)
                          : "memory");
 
        return key;
#endif
}
 
/*
 * use atomic instruction csrs to unlock global irq
 * csrs: atomic set bits in CSR register
 */
static ALWAYS_INLINE void arch_irq_unlock(unsigned int key)
{
#ifdef CONFIG_RISCV_SOC_HAS_CUSTOM_IRQ_LOCK_OPS
        z_soc_irq_unlock(key);
#else
        __asm__ volatile ("csrs " RV_STATUS_CSR ", %0"
                          :
                          : "r" (key & RV_STATUS_IE)
                          : "memory");
#endif
}
 
static ALWAYS_INLINE bool arch_irq_unlocked(unsigned int key)
{
#ifdef CONFIG_RISCV_SOC_HAS_CUSTOM_IRQ_LOCK_OPS
        return z_soc_irq_unlocked(key);
#else
        return (key & RV_STATUS_IE) != 0;
#endif
}

static ALWAYS_INLINE bool arch_cpu_irqs_are_enabled(void)
{
#ifdef CONFIG_RISCV_SOC_HAS_CUSTOM_IRQ_LOCK_OPS
        /* No direct probe primitive in the SoC ops; fall back to
         * briefly locking and restoring.
         */
        unsigned int key = z_soc_irq_lock();
        bool enabled = z_soc_irq_unlocked(key);
 
        z_soc_irq_unlock(key);
        return enabled;
#else
        unsigned int status = z_riscv_status_read();
 
        return (status & RV_STATUS_IE) != 0;
#endif
}
 
static ALWAYS_INLINE void arch_nop(void)
{
        __asm__ volatile("nop");
}
 
extern uint32_t sys_clock_cycle_get_32(void);
 
static inline uint32_t arch_k_cycle_get_32(void)
{
        return sys_clock_cycle_get_32();
}
 
extern uint64_t sys_clock_cycle_get_64(void);
 
static inline uint64_t arch_k_cycle_get_64(void)
{
        return sys_clock_cycle_get_64();
}
 
#include <zephyr/arch/riscv/error.h>
 
#ifdef __cplusplus
}
#endif
 
#endif /*_ASMLANGUAGE */
 
#if defined(CONFIG_RISCV_PRIVILEGED)
#include <zephyr/arch/riscv/riscv-privileged/asm_inline.h>
#endif
 
 
#endif