The TLB Lockdown Register characteristics are:
Controls where hardware translation table walks place the TLB entry. The TLB entry can be in either:
The set-associative region of the TLB.
The lockdown region of the TLB, and if in the lockdown region, the entry to write.
The lockdown region of the TLB contains four entries.
- Usage constraints
The TLB Lockdown Register is:
only accessible in privileged modes
common to Secure and Non-secure states
not accessible if NSACR.TL is 0.
Available in all configurations.
See the register summary in Table 4.11.
Figure 4.14 shows the TLB Lockdown Register bit assignments.
Table 4.41 shows the TLB Lockdown Register bit assignments
To access the TLB Lockdown Register, read or write the CP15 register with:
MRC p15, 0,<Rd>, c10, c0, 0; Read TLB Lockdown victim MCR p15, 0,<Rd>, c10, c0, 0; Write TLB Lockdown victim
Writing the TLB Lockdown Register with the preserve bit (P bit) set to:
Means subsequent hardware translation table walks place the TLB entry in the lockdown region at the entry specified by the victim, in the range 0 to 3.
Means subsequent hardware translation table walks place the TLB entry in the set-associative region of the TLB.