A8.2 AXI privilege information

AXI provides information about the privilege level of an access on the ARPROTM[0] and AWPROTM[0] signals. However, when accesses might be cached or merged together, the resulting transaction can have both privileged and unprivileged data combined. If this happens, the processor marks the transaction as privileged, even it if was initiated by an unprivileged process.

The following table shows exception levels and corresponding ARPROTM[0] and AWPROTM[0] values.

Table A8-1 ARPROT and AWPROT values

Processor exception level Type of access

Value of ARPROT[0] and AWPROT[0]

EL0, EL1, EL2, EL3 Cacheable read access Privileged access
EL0 Device, or normal Non-cacheable read access Unprivileged access
EL1, EL2, EL3 Privileged access
EL0, EL1, EL2, EL3 Cacheable write access Privileged access
EL0 Device, nGnRnE, nGnRE, and nGRE write Unprivileged access
EL1, EL2, EL3 Privileged access
EL0 Normal Non-cacheable or Device GRE write, except for STREX, STREXB, STREXH, STREXD, STXR, STXRB, STXRH, STXP, STLXR, STLXRB, STLXRH and STLXP to shareable memory Privileged access
EL0 Normal Non-cacheable write for STREX, STREXB, STREXH, STREXD, STXR STXRB, STXRH, STXP, STLXR, STLXRB, STLXRH and STLXP to shareable memory Unprivileged access
EL1, EL2, EL3 Normal Non-cacheable write Privileged access
EL0, EL1, EL2, EL3 TLB pagewalk Privileged access
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