Interrupt and Exception and NMI Handling

Functions for interrupt, exception and nmi handle available in system_<device>.c. More...

Macros
#define	MAX_SYSTEM_EXCEPTION_NUM   26
	Max exception handler number, don't include the NMI(0xFFF) one. More...

Typedefs
typedef void(*	EXC_HANDLER) (unsigned long cause, unsigned long sp)
	Exception Handler Function Typedef. More...

Functions
static void	system_default_exception_handler (unsigned long mcause, unsigned long sp)
	System Default Exception Handler. More...
static void	Exception_Init (void)
	Initialize all the default core exception handlers. More...
void	Exception_DumpFrame (unsigned long sp, uint8_t mode)
	Dump Exception Frame. More...
void	Exception_Register_EXC (uint32_t EXCn, unsigned long exc_handler)
	Register an exception handler for exception code EXCn. More...
unsigned long	Exception_Get_EXC (uint32_t EXCn)
	Get current exception handler for exception code EXCn. More...
uint32_t	core_exception_handler (unsigned long mcause, unsigned long sp)
	Common NMI and Exception handler entry. More...
static void	system_default_exception_handler_s (unsigned long scause, unsigned long sp)
	Supervisor mode system Default Exception Handler. More...
void	Exception_Register_EXC_S (uint32_t EXCn, unsigned long exc_handler)
	Register an exception handler for exception code EXCn of supervisor mode. More...
unsigned long	Exception_Get_EXC_S (uint32_t EXCn)
	Get current exception handler for exception code EXCn of supervisor mode. More...
uint32_t	core_exception_handler_s (unsigned long scause, unsigned long sp)
	common Exception handler entry of supervisor mode More...

Variables
static unsigned long	SystemExceptionHandlers [MAX_SYSTEM_EXCEPTION_NUM+1]
	Store the exception handlers for each exception ID. More...
static unsigned long	SystemExceptionHandlers_S [MAX_SYSTEM_EXCEPTION_NUM]
	Store the exception handlers for each exception ID in supervisor mode. More...

Detailed Description

Functions for interrupt, exception and nmi handle available in system_<device>.c.

Nuclei provide a template for interrupt, exception and NMI handling. Silicon Vendor could adapat according to their requirement. Silicon vendor could implement interface for different exception code and replace current implementation.

Macro Definition Documentation

MAX_SYSTEM_EXCEPTION_NUM

#define MAX_SYSTEM_EXCEPTION_NUM   26

Max exception handler number, don't include the NMI(0xFFF) one.

Definition at line 269 of file system_Device.c.

Typedef Documentation

EXC_HANDLER

typedef void(* EXC_HANDLER) (unsigned long cause, unsigned long sp)

Exception Handler Function Typedef.

Note

This typedef is only used internal in this system_<Device>.c file. It is used to do type conversion for registered exception handler before calling it.

Definition at line 297 of file system_Device.c.

Function Documentation

core_exception_handler()

uint32_t core_exception_handler	(	unsigned long	mcause,
		unsigned long	sp
	)

Common NMI and Exception handler entry.

This function provided a command entry for NMI and exception. Silicon Vendor could modify this template implementation according to requirement.

Parameters

[in]	mcause	code indicating the reason that caused the trap in machine mode
[in]	sp	stack pointer

Remarks

• RISCV provided common entry for all types of exception. This is proposed code template for exception entry function, Silicon Vendor could modify the implementation.
• For the core_exception_handler template, we provided exception register function Exception_Register_EXC which can help developer to register your exception handler for specific exception number.

Definition at line 425 of file system_Device.c.

{
    uint32_t EXCn = (uint32_t)(mcause & 0X00000fff);
    EXC_HANDLER exc_handler;
 
    if (EXCn < MAX_SYSTEM_EXCEPTION_NUM) {
        exc_handler = (EXC_HANDLER)SystemExceptionHandlers[EXCn];
    } else if (EXCn == NMI_EXCn) {
        exc_handler = (EXC_HANDLER)SystemExceptionHandlers[MAX_SYSTEM_EXCEPTION_NUM];
    } else {
        exc_handler = (EXC_HANDLER)system_default_exception_handler;
    }
    if (exc_handler != NULL) {
        exc_handler(mcause, sp);
    }
    return 0;
}

core_exception_handler_s()

uint32_t core_exception_handler_s	(	unsigned long	scause,
		unsigned long	sp
	)

common Exception handler entry of supervisor mode

This function provided a supervisor mode common entry for exception. Silicon Vendor could modify this template implementation according to requirement.

Parameters

[in]	scause	code indicating the reason that caused the trap in supervisor mode
[in]	sp	stack pointer

Remarks

• RISCV provided supervisor mode common entry for all types of exception. This is proposed code template for exception entry function, Silicon Vendor could modify the implementation.
• For the core_exception_handler_s template, we provided exception register function Exception_Register_EXC_S which can help developer to register your exception handler for specific exception number.

Definition at line 514 of file system_Device.c.

{
    uint32_t EXCn = (uint32_t)(scause & 0X00000fff);
    EXC_HANDLER exc_handler;
 
    if (EXCn < MAX_SYSTEM_EXCEPTION_NUM) {
        exc_handler = (EXC_HANDLER)SystemExceptionHandlers_S[EXCn];
    } else {
        exc_handler = (EXC_HANDLER)system_default_exception_handler_s;
    }
    if (exc_handler != NULL) {
        exc_handler(scause, sp);
    }
    return 0;
}

Exception_DumpFrame()

void Exception_DumpFrame	(	unsigned long	sp,
		uint8_t	mode
	)

Dump Exception Frame.

This function provided feature to dump exception frame stored in stack.

Parameters

[in]	sp	stackpoint
[in]	mode	privileged mode to decide whether to dump msubm CSR

Definition at line 351 of file system_Device.c.

{
    EXC_Frame_Type *exc_frame = (EXC_Frame_Type *)sp;
 
#ifndef __riscv_32e
    printf("ra: 0x%lx, tp: 0x%lx, t0: 0x%lx, t1: 0x%lx, t2: 0x%lx, t3: 0x%lx, t4: 0x%lx, t5: 0x%lx, t6: 0x%lx\n" \
           "a0: 0x%lx, a1: 0x%lx, a2: 0x%lx, a3: 0x%lx, a4: 0x%lx, a5: 0x%lx, a6: 0x%lx, a7: 0x%lx\n" \
           "cause: 0x%lx, epc: 0x%lx\n", exc_frame->ra, exc_frame->tp, exc_frame->t0, \
           exc_frame->t1, exc_frame->t2, exc_frame->t3, exc_frame->t4, exc_frame->t5, exc_frame->t6, \
           exc_frame->a0, exc_frame->a1, exc_frame->a2, exc_frame->a3, exc_frame->a4, exc_frame->a5, \
           exc_frame->a6, exc_frame->a7, exc_frame->cause, exc_frame->epc);
#else
    printf("ra: 0x%lx, tp: 0x%lx, t0: 0x%lx, t1: 0x%lx, t2: 0x%lx\n" \
           "a0: 0x%lx, a1: 0x%lx, a2: 0x%lx, a3: 0x%lx, a4: 0x%lx, a5: 0x%lx\n" \
           "cause: 0x%lx, epc: 0x%lx\n", exc_frame->ra, exc_frame->tp, exc_frame->t0, \
           exc_frame->t1, exc_frame->t2, exc_frame->a0, exc_frame->a1, exc_frame->a2, exc_frame->a3, \
           exc_frame->a4, exc_frame->a5, exc_frame->cause, exc_frame->epc);
#endif
 
    if (PRV_M == mode) {
        /* msubm is exclusive to machine mode */
        printf("msubm: 0x%lx\n", exc_frame->msubm);
    }
}

Exception_Get_EXC()

unsigned long Exception_Get_EXC

(

uint32_t

EXCn

)

Get current exception handler for exception code EXCn.

• For EXCn < MAX_SYSTEM_EXCEPTION_NUM, it will return SystemExceptionHandlers[EXCn-1].
• For EXCn == NMI_EXCn, it will return SystemExceptionHandlers[MAX_SYSTEM_EXCEPTION_NUM].

  Parameters

  [in]

  EXCn

  See EXCn_Type

  Returns

  Current exception handler for exception code EXCn, if not found, return 0.

Definition at line 401 of file system_Device.c.

{
    if (EXCn < MAX_SYSTEM_EXCEPTION_NUM) {
        return SystemExceptionHandlers[EXCn];
    } else if (EXCn == NMI_EXCn) {
        return SystemExceptionHandlers[MAX_SYSTEM_EXCEPTION_NUM];
    } else {
        return 0;
    }
}

Exception_Get_EXC_S()

unsigned long Exception_Get_EXC_S

(

uint32_t

EXCn

)

Get current exception handler for exception code EXCn of supervisor mode.

• For EXCn < MAX_SYSTEM_EXCEPTION_NUM, it will return SystemExceptionHandlers_S[EXCn-1].

  Parameters

  [in]

  EXCn

  See EXCn_Type

  Returns

  Current exception handler for exception code EXCn, if not found, return 0.

Definition at line 492 of file system_Device.c.

{
    if (EXCn < MAX_SYSTEM_EXCEPTION_NUM) {
        return SystemExceptionHandlers[EXCn];
    } else {
        return 0;
    }
}

Exception_Init()

static void Exception_Init ( void  )

static

Initialize all the default core exception handlers.

The core exception handler for each exception id will be initialized to system_default_exception_handler.

Note

Called in _init function, used to initialize default exception handlers for all exception IDs SystemExceptionHandlers contains NMI, but SystemExceptionHandlers_S not, because NMI can't be delegated to S-mode.

Definition at line 333 of file system_Device.c.

{
    for (int i = 0; i < MAX_SYSTEM_EXCEPTION_NUM; i++) {
        SystemExceptionHandlers[i] = (unsigned long)system_default_exception_handler;
#if defined(__TEE_PRESENT) && (__TEE_PRESENT == 1)
        SystemExceptionHandlers_S[i] = (unsigned long)system_default_exception_handler_s;
#endif
    }
    SystemExceptionHandlers[MAX_SYSTEM_EXCEPTION_NUM] = (unsigned long)system_default_exception_handler;
}

Exception_Register_EXC()

void Exception_Register_EXC	(	uint32_t	EXCn,
		unsigned long	exc_handler
	)

Register an exception handler for exception code EXCn.

• For EXCn < MAX_SYSTEM_EXCEPTION_NUM, it will be registered into SystemExceptionHandlers[EXCn-1].
• For EXCn == NMI_EXCn, it will be registered into SystemExceptionHandlers[MAX_SYSTEM_EXCEPTION_NUM].

  Parameters

  [in]	EXCn	See EXCn_Type
  [in]	exc_handler	The exception handler for this exception code EXCn

Definition at line 384 of file system_Device.c.

{
    if (EXCn < MAX_SYSTEM_EXCEPTION_NUM) {
        SystemExceptionHandlers[EXCn] = exc_handler;
    } else if (EXCn == NMI_EXCn) {
        SystemExceptionHandlers[MAX_SYSTEM_EXCEPTION_NUM] = exc_handler;
    }
}

Exception_Register_EXC_S()

void Exception_Register_EXC_S	(	uint32_t	EXCn,
		unsigned long	exc_handler
	)

Register an exception handler for exception code EXCn of supervisor mode.

-For EXCn < MAX_SYSTEM_EXCEPTION_NUM, it will be registered into SystemExceptionHandlers_S[EXCn-1]. -For EXCn == NMI_EXCn, The NMI (Non-maskable-interrupt) cannot be trapped to the supervisor-mode or user-mode for any configuration, so NMI won't be registered into SystemExceptionHandlers_S.

Parameters

[in]	EXCn	See EXCn_Type
[in]	exc_handler	The exception handler for this exception code EXCn

Definition at line 478 of file system_Device.c.

{
    if (EXCn < MAX_SYSTEM_EXCEPTION_NUM) {
        SystemExceptionHandlers_S[EXCn] = exc_handler;
    }
}

system_default_exception_handler()

static void system_default_exception_handler ( unsigned long  mcause, unsigned long  sp  )

static

System Default Exception Handler.

This function provides a default exception and NMI handler for all exception ids. By default, It will just print some information for debug, Vendor can customize it according to its requirements.

Parameters

[in]	mcause	code indicating the reason that caused the trap in machine mode
[in]	sp	stack pointer

Definition at line 307 of file system_Device.c.

{
    /* TODO: Uncomment this if you have implement printf function */
    printf("MCAUSE : 0x%lx\r\n", mcause);
    printf("MDCAUSE: 0x%lx\r\n", __RV_CSR_READ(CSR_MDCAUSE));
    printf("MEPC   : 0x%lx\r\n", __RV_CSR_READ(CSR_MEPC));
    printf("MTVAL  : 0x%lx\r\n", __RV_CSR_READ(CSR_MTVAL));
    printf("HARTID : %u\r\n", (unsigned int)__get_hart_id());
    Exception_DumpFrame(sp, PRV_M);
#if defined(SIMULATION_MODE)
    // directly exit if in SIMULATION
    extern void simulation_exit(int status);
    simulation_exit(1);
#else
    while (1);
#endif
}

system_default_exception_handler_s()

static void system_default_exception_handler_s ( unsigned long  scause, unsigned long  sp  )

static

Supervisor mode system Default Exception Handler.

This function provided a default supervisor mode exception and NMI handling code for all exception ids. By default, It will just print some information for debug, Vendor can customize it according to its requirements.

Parameters

[in]	scause	code indicating the reason that caused the trap in supervisor mode
[in]	sp	stack pointer

Definition at line 452 of file system_Device.c.

{
    /* TODO: Uncomment this if you have implement printf function */
    printf("SCAUSE : 0x%lx\r\n", scause);
    printf("SDCAUSE: 0x%lx\r\n", __RV_CSR_READ(CSR_SDCAUSE));
    printf("SEPC   : 0x%lx\r\n", __RV_CSR_READ(CSR_SEPC));
    printf("STVAL  : 0x%lx\r\n", __RV_CSR_READ(CSR_STVAL));
    Exception_DumpFrame(sp, PRV_S);
#if defined(SIMULATION_MODE)
    // directly exit if in SIMULATION
    extern void simulation_exit(int status);
    simulation_exit(1);
#else
    while (1);
#endif
}

Variable Documentation

SystemExceptionHandlers

unsigned long SystemExceptionHandlers[MAX_SYSTEM_EXCEPTION_NUM+1]

static

Store the exception handlers for each exception ID.

Note

• This SystemExceptionHandlers are used to store all the handlers for all the exception codes Nuclei N/NX core provided.
• Exception code 0 - 25, totally 26 exceptions are mapped to SystemExceptionHandlers[0:25]
• Exception for NMI is also re-routed to exception handling(exception code 0xFFF) in startup code configuration, the handler itself is mapped to SystemExceptionHandlers[MAX_SYSTEM_EXCEPTION_NUM]

Definition at line 278 of file system_Device.c.

SystemExceptionHandlers_S

unsigned long SystemExceptionHandlers_S[MAX_SYSTEM_EXCEPTION_NUM]

static

Store the exception handlers for each exception ID in supervisor mode.

Note

• This SystemExceptionHandlers_S are used to store all the handlers for all the exception codes Nuclei N/NX core provided.
• Exception code 0 - 11, totally 12 exceptions are mapped to SystemExceptionHandlers_S[0:11]
• The NMI (Non-maskable-interrupt) cannot be trapped to the supervisor-mode or user-mode for any configuration

Definition at line 289 of file system_Device.c.