gd32vf103 PMP内存保护疑问

// See LICENSE for license details.

#include <stdio.h>

#include <string.h>

#include "nuclei_sdk_soc.h"



/* different trigger condition */

#define INSTRUCTION_FETCH_EXCEPTION    0

#define LOAD_EXCEPTION                 1

#define STORE_EXCEPTION                2

#define RUN_WITH_NO_PMP_CHECK          3



/* Just choose one from above defines to test PMP */

#define TRIGGER_PMP_VIOLATION_MODE     INSTRUCTION_FETCH_EXCEPTION



volatile uint8_t protected_data[0x2000] __attribute__((aligned(0x2000))) =    \

{0xaa, 0x1, 0x02, 0x03, 0x04, 0x05, 0x06, 0xaa};



#ifndef __ICCRISCV__

#define __PMP_PROTECT   __attribute__((section (".text"), aligned(0x2000)))

#else

/* IAR CC currently don't support align function in section,

 * so we provide a workaround using a customized iar_evalsoc_ilm.icf in this demo

 * we define a block called PMPFUNC alignment set to 0x2000 */

#define __PMP_PROTECT   __attribute__((section (".text.pmpfunc")))

#endif



static void __PMP_PROTECT protected_execute(void)

{

    printf("----protected_execute succeed!----\r\n");



    printf("Attempting to read protected_data[0]\r\n");

    printf("protected_data[0]: 0x%0X succeed\r\n", protected_data[0]);



    printf("Attempting to write protected_data[0]\r\n");

    protected_data[0] = 0xFF;



    printf("Won't run here if violates L R\\W\\X permission check!\r\n");

}



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

{

    EXC_Frame_Type *exc_frame = (EXC_Frame_Type *)sp;



    switch (mcause & MCAUSE_CAUSE) {

        case InsAccFault_EXCn:

            printf("Instruction access fault occurs, cause: 0x%lx, epc: 0x%lx\r\n", exc_frame->cause, exc_frame->epc);

            break;

        case LdFault_EXCn:

            printf("Load access fault occurs, cause: 0x%lx, epc: 0x%lx\r\n", exc_frame->cause, exc_frame->epc);

            break;

        case StAccessFault_EXCn:

            printf("Store/AMO access fault occurs, cause: 0x%lx, epc: 0x%lx\r\n", exc_frame->cause, exc_frame->epc);

            break;

        default: break;

    }

    while(1);

}



typedef void(*__funcpt)(void);



int main(void)

{

    /* Configuration of execution region*/

    pmp_config pmp_config_x = {

        /*

         * Locked PMP entries remain locked until the hart is reset,

         * the L bit also indicates whether the R/W/X permissions are enforced on M-mode accesses

         */

        .protection = PMP_L | PMP_R | PMP_W | PMP_X,

        /* Initial protected excutable address range is 2^12 = 4K bytes*/

        .order = 12,

        /* initial base address is 0, change it to your memory assignment */

        .base_addr = 0,

    };



    /* configuration of read/write region*/

    pmp_config pmp_config_rw = {

        /*

         * Locked PMP entries remain locked until the hart is reset,

         * the L bit also indicates whether the R/W/X permissions are enforced on M-mode accesses

         */

        .protection = PMP_L | PMP_R | PMP_W | PMP_X,

        /* initial protected readable/writable address range is 2^12 = 4K bytes */

        .order = 12,

        /* initial base address is 0, change it to your memory assignment */

        .base_addr = 0,

    };



    pmp_config_x.base_addr = (unsigned long)protected_execute;

    pmp_config_rw.base_addr = (unsigned long)protected_data;



#if (INSTRUCTION_FETCH_EXCEPTION == TRIGGER_PMP_VIOLATION_MODE)

    /* Remove X permission of protected_execute region */

    pmp_config_x.protection = PMP_L | PMP_R | PMP_W;



    pmp_config_rw.protection = PMP_L | PMP_R | PMP_W;

#elif (LOAD_EXCEPTION == TRIGGER_PMP_VIOLATION_MODE)

    /* Retrive X permission of protected_execute region */

    pmp_config_x.protection = PMP_L | PMP_R | PMP_W | PMP_X;



    /* Remove R permission of protected_data region */

    pmp_config_rw.protection = PMP_L | PMP_W;

#elif (STORE_EXCEPTION == TRIGGER_PMP_VIOLATION_MODE)

    /* Retrive X permission of protected_execute region */

    pmp_config_x.protection = PMP_L | PMP_R | PMP_W | PMP_X;



    /* Remove W permission of protected_data region */

    pmp_config_rw.protection = PMP_L | PMP_R ;

#elif (RUN_WITH_NO_PMP_CHECK == TRIGGER_PMP_VIOLATION_MODE)

    /* Unset Locking bit, any M-mode access matching the PMP entry will succeed */

    pmp_config_x.protection = PMP_R | PMP_W | PMP_X;



    pmp_config_rw.protection = PMP_R | PMP_W ;

#endif



    printf("------PMP demo with trigger condition %d------\r\n", TRIGGER_PMP_VIOLATION_MODE);



    __set_PMPENTRYx(0, &pmp_config_x);

    /* Verify the configuration takes effect */

    memset(&pmp_config_x, 0, sizeof(pmp_config));

    __get_PMPENTRYx(0, &pmp_config_x);

    printf("Get pmp entry: index %d, prot_out: 0x%x, addr_out: 0x%lx, order_out: %lu\r\n", \

        0, pmp_config_x.protection, pmp_config_x.base_addr, pmp_config_x.order);



    __set_PMPENTRYx(1, &pmp_config_rw);

    /* Verify the configuration takes effect */

    memset(&pmp_config_rw, 0, sizeof(pmp_config));

    __get_PMPENTRYx(1, &pmp_config_rw);

    printf("Get pmp entry: index %d, prot_out: 0x%x, addr_out: 0x%lx, order_out: %lu\r\n", \

        1, pmp_config_rw.protection, pmp_config_rw.base_addr, pmp_config_rw.order);



    /* register corresponding exception */

    Exception_Register_EXC(InsAccFault_EXCn, (unsigned long)pmp_violation_fault_handler);

    Exception_Register_EXC(LdFault_EXCn, (unsigned long)pmp_violation_fault_handler);

    Exception_Register_EXC(StAccessFault_EXCn, (unsigned long)pmp_violation_fault_handler);



    /* In case compiler use inline optimization of protected_execute */

    __funcpt fncptr = ((__funcpt)protected_execute);

    printf("Attempting to fetch instruction from protected address\n");

    fncptr();



    while(1);

    return 0;

}