S32K144 System MPU fails to write protect Flash memory region

[karnik_somani]

Dear Community members,

I have been working on NXP S32K144 System MPU.

I have successfully,

1] Read protect flash memory region.[0x10000800 - 0x1000081F]

2] Read/Write protect SRAM memory region.[0x0100 0001 - 0x0100 0020]

For every memory access violations exception is thrown.

But for,

3] Write protect flash memory region.[0x10000800 - 0x1000081F] there is no exception generated and the memory 

gets written successfully. 

Following is the profile i have initialized MPU with.

/*! Master access rights configuration 0 */
const mpu_master_access_right_t memProtect1_AccessRightConfig0[] =
{
/*! CORE */
{
.masterNum = FEATURE_MPU_MASTER_CORE, /*!< Master number */
.accessRight = MPU_SUPERVISOR_USER_NONE, /*!< Access right */
.processIdentifierEnable = false /*!< Process identifier enable */
},
/*! DEBUGGER */
{
.masterNum = FEATURE_MPU_MASTER_DEBUGGER, /*!< Master number */
.accessRight = MPU_SUPERVISOR_USER_RWX, /*!< Access right */
.processIdentifierEnable = false /*!< Process identifier enable */
},
/*! DMA */
{
.masterNum = FEATURE_MPU_MASTER_DMA, /*!< Master number */
.accessRight = MPU_SUPERVISOR_USER_RWX, /*!< Access right */
.processIdentifierEnable = false /*!< Process identifier enable */
}
};

/*! Master access rights configuration 1 */
const mpu_master_access_right_t memProtect1_AccessRightConfig1[] =
{
/*! CORE */
{
.masterNum = FEATURE_MPU_MASTER_CORE, /*!< Master number */
.accessRight = MPU_SUPERVISOR_USER_RWX, /*!< Access right */
.processIdentifierEnable = false /*!< Process identifier enable */
},
/*! DEBUGGER */
{
.masterNum = FEATURE_MPU_MASTER_DEBUGGER, /*!< Master number */
.accessRight = MPU_SUPERVISOR_USER_RWX, /*!< Access right */
.processIdentifierEnable = false /*!< Process identifier enable */
},
/*! DMA */
{
.masterNum = FEATURE_MPU_MASTER_DMA, /*!< Master number */
.accessRight = MPU_SUPERVISOR_USER_RWX, /*!< Access right */
.processIdentifierEnable = false /*!< Process identifier enable */
}
};

/*! Master access rights configuration 2 */
const mpu_master_access_right_t memProtect1_AccessRightConfig2[] =
{
/*! CORE */
{
.masterNum = FEATURE_MPU_MASTER_CORE, /*!< Master number */
.accessRight = MPU_SUPERVISOR_USER_R, /*!< Access right */
.processIdentifierEnable = false /*!< Process identifier enable */
},
/*! DEBUGGER */
{
.masterNum = FEATURE_MPU_MASTER_DEBUGGER, /*!< Master number */
.accessRight = MPU_SUPERVISOR_USER_RWX, /*!< Access right */
.processIdentifierEnable = false /*!< Process identifier enable */
},
/*! DMA */
{
.masterNum = FEATURE_MPU_MASTER_DMA, /*!< Master number */
.accessRight = MPU_SUPERVISOR_USER_RWX, /*!< Access right */
.processIdentifierEnable = false /*!< Process identifier enable */
}
};

/*! User configuration */
const mpu_user_config_t mpu_memConfig[] =
{
/*! Region number 0 */
{
.startAddr = 0x00000000U, /*!< Memory region start address */
.endAddr = 0xFFFFFFFFU, /*!< Memory region end address */
.masterAccRight = memProtect1_AccessRightConfig0, /*!< Master access right */
.processIdentifier = 0x00U, /*!< Process identifier */
.processIdMask = 0x00U /*!< Process identifier mask */
},
/*! Region number 1 */
{
.startAddr = MPU_REG1_START_ADDR,//0x00000000U, /*!< Memory region start address */
.endAddr = MPU_REG1_END_ADDR,//0x0007FEFFU, /*!< Memory region end address */
.masterAccRight = memProtect1_AccessRightConfig2, /*!< Master access right */
.processIdentifier = 0x00U, /*!< Process identifier */
.processIdMask = 0x00U /*!< Process identifier mask */
},
/*! Region number 2 */
{
.startAddr = 0x00000000U, /*!< Memory region start address */
.endAddr = 0x100007FFU, /*!< Memory region end address */
.masterAccRight = memProtect1_AccessRightConfig1, /*!< Master access right */
.processIdentifier = 0x00U, /*!< Process identifier */
.processIdMask = 0x00U /*!< Process identifier mask */
},
/*! Region number 3 */
{
.startAddr = 0x10000820U, /*!< Memory region start address */
.endAddr = 0xFFFFFFFFU, /*!< Memory region end address */
.masterAccRight = memProtect1_AccessRightConfig1, /*!< Master access right */
.processIdentifier = 0x00U, /*!< Process identifier */
.processIdMask = 0x00U /*!< Process identifier mask */
},
/*! Region number 4 */
{
.startAddr = 0x0007FF20U, /*!< Memory region start address */
.endAddr = 0xFFFFFFFFU, /*!< Memory region end address */
.masterAccRight = memProtect1_AccessRightConfig1, /*!< Master access right */
.processIdentifier = 0x00U, /*!< Process identifier */
.processIdMask = 0x00U /*!< Process identifier mask */
}
};

[danielmartynek]

Hello karnik.somani@acclivistechnologies.com,

The flash memory is not writable by the core itself but by the FTFC module.

The core can only write the FTFC registers and launch a command such as the Program Phrase command.

Flash protection can be used instead, please refer to the reference manual:

36.5.1 Flash protection.

36.4.4.1.9 Data Flash Protection Register (FDPROT).

The FDPROT register is loaded from the flash configuration field during the reset sequence.

startup_S32K144.S

Regards,

Daniel

[karnik_somani]

Dear Daniel,

Thanks for the insight.

The application we are seeking is to lock and unlock flash region in during execution.

As from the RM it can be understood that write protection provided by flash protection module 

is irreversible.i.e once write protect will stay until reset.

Is there any way we can protect flash memory via System MPU.

Is it possible to use Arm provided MPU?

Regards,

Karnik

[danielmartynek]

Hello Karnik,

I’m sorry for the delayed response.
The Arm M4 core version in this family does not integrate the Arm Core MPU.

One possibility is to write-protect the FTFC registers when needed.
The peripherals (including FTFC) cannot be protected by the MPU but the Bridge provides some protection.

S32K1xx_Memory_Map.xlsx

You can therefore write-protect the FTFC module in the AIPS_OPACRA[WP0] register.

Regards,
Daniel

[karnik_somani]

Thanks for the support Daniel.