GD32W51x User Manual
254
1.
According to security mode TrustZone-aware AHB masters can drive HNONSEC signal,
secure transactions are signaled with HNONSEC = 0 on AHB bus, non-secure
transactions are signaled with HNONSEC = 1 on AHB bus. Peripherals connected
directly to AHB or APB bus and implementing a specific TrustZone® behavior (such as
TZSPC, whether non- privilege access is supported for secure configuration registers is
defined by privilege configuration registers).
9.3.2.
Illegal access definition
The types of illegal access of peripheral register and memory (internal block-based SRAM or
marked external memory) are different, as described below.
Peripheral register
Illegal non-secure access
Non-secure transfers to secure peripheral are blocked and thus the addressed resource
returns all zero data for read, ignores any write and generates an illegal access event for
illegal access, but no bus error is generated. However transactions to secure and privilege
configuration registers may have some differences, they are TrustZone-aware peripherals (for
more information please refer to the security protection description of TrustZone-aware
peripherals).
Illegal non-privilege access
If a privilege resource is accessed by a non-privilege resource, this will be considered as
illegal, but for this illegal access there is no event or bus error will generate, read access will
return zero, write access will be ignored.
Memory (internal block-based SRAM or marked external memory)
Illegal non-secure access
Non-secure transfers to secure block/regions are blocked and thus the addressed resource
generates an illegal access event for illegal access, and a bus error for illegal fetch access.
Illegal secure access
For SRAM or marked external memory, secure transfers to non-secure SRAM or external
memory is illegal and a bus error will
generate
. For SRAM, when configure SRWACFG bit in
the TZPCU_TZBMPCx_CTL register, it will make secure read/write aceess is legal, but secure
execution aceess is still illegal.
Illegal non-privilege access
Non-privilege transfers to privilege peripheral are blocked and thus the addressed resource
returning all zero data for read, ignoring any write and do not generate an illegal access event
and bus error.