System Control Coprocessor
ARM DDI 0301H Copyright © 2004-2009 ARM Limited. All rights reserved. 3-100
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3.2.31 c10, TLB Lockdown Register
The purpose of the TLB Lockdown Register is to control where hardware page table walks place
the TLB entry 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.
Table 3-97 lists the purposes of the individual bits in the TLB Lockdown Register.
The TLB Lockdown Register is:
• in CP15 c10
• 32-bit read/write register common to Secure and Non-secure worlds
• accessible in privileged modes only.
Figure 3-56 shows the bit arrangement of the TLB Lockdown Register.
Figure 3-56 TLB Lockdown Register format
Table 3-97 lists how the bit values correspond with the TLB Lockdown Register functions.
The TLB lockdown behavior depends on the TL bit, see c1, Non-Secure Access Control Register
on page 3-55. If the TL bit is not set, the Lockdown entries are reserved for the Secure world.
Table 3-98 lists the results of attempted access for each mode.
The lockdown region of the TLB contains eight entries. TLB organization on page 6-4 describes
the structure of the TLB.
PSBZ
31 29 28 26 25 10
Victim SBZ/UNP
Table 3-97 TLB Lockdown Register bit functions
Bits Field name Function
[31:29] - UNP/SBZ.
[28:26] Victim Specifies the entry in the lockdown region where a subsequent hardware page table walk can
place a TLB entry. The reset value is 0.
0-7, defines the Lockdown region for the TLB entry.
[25:1] - UNP/SBZ.
[0] P Determines if subsequent hardware page table walks place a TLB entry in the lockdown region
or in the set associative region of the TLB:
0 = Place the TLB entry in the set associative region of the TLB, reset value.
1 = Place the TLB entry in the lockdown region of the TLB as defined by the Victim bits
[28:26].
Table 3-98 Results of access to the TLB Lockdown Register
TL bit value
Secure Privileged Non-secure Privileged
User
Read Write Read Write
0 Data Data Undefined exception Undefined exception Undefined exception
1 Data Data Data Data Undefined exception
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