TMS320F28P559SJ-Q1: Some question about DCSM

Shuqing Zhou

Hi team,

I ask this for my customer.

1.Because of the limitation of flash size, they would set all the flash sector is unsecure, but set one RAMLS as security.

Then they would copy the code from unsecure flash to secure ram, and use this code to write and read secure variable(some secure variable also in the secure ram, some secure variable in the unsecure flash/ram)

what should be attention in this process(for example, the memcpy function should be placed where? or is it need to unlock the ram during the process)

2.If they use the DCSM_forceFlashErrorStatus to set the SECERRFRC.ERR, what would happen?(generate the interrupt or something else)

BRs

Shuqing

11 months ago

+1 Luke Jones 11 months ago

TI__Mastermind 28580 points

Hi Shuqing,

If you want to use the memcpy function in this scenario you will need to unlock the DCSM module first. Normally code copy functions are not performed between unsecure and secure memory. What is the reason to secure the LSRAM but not the flash by the way? Since you'll be required to unsecure the zone to copy code from flash to RAM, this won't provide very robust security unless the unlocking function is only possible in a secure environment.

Thank you,

Luke

0 Shuqing Zhou 11 months ago in reply to Luke Jones

TI__Expert 4245 points

Hi Luke,

How about the second question:

2.If they use the DCSM_forceFlashErrorStatus to set the SECERRFRC.ERR, what would happen?(generate the interrupt or something else)

BRs

Shuqing

0 Luke Jones 11 months ago in reply to Shuqing Zhou

TI__Mastermind 28580 points

Hi Shuqing,

I checked the security spec for F28P55x and none of the sources of an SECERR.ERR flag being set will cause an interrupt. I believe the only effect is the SECERR.ERR bit being set.

Thank you,

Luke

0 Shuqing Zhou 10 months ago in reply to Luke Jones

TI__Expert 4245 points

Hi Luke,

In our safety function manual, it has a SM for DCSM:

They needs use this SM in their safety function design, so they needs to know the action when they set the SECERRFRC.ERR, could you help to check it further? Is it just set the flag in register?

BRs

Shuqing

0 Shuqing Zhou 10 months ago in reply to Shuqing Zhou

TI__Expert 4245 points

Hi Luke,

Any feedback about this?

BRs

0 AJ Favela 10 months ago in reply to Shuqing Zhou

TI__Expert 4290 points

Hi Shuqing,

I apologize for the late response, do you still require support?

Kind Regards,

AJ Favela

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TMS320F28P559SJ-Q1: Some question about DCSM