Figure 6-5. Zone Protection Register (Zpr) - IBM PowerPC 405GP User Manual

The ZSEL values 0-15 select ZPR fields ZO-Z15, respectively.
The fields are defined within the ZPR as follows:
While it is common for TLB_entry[EX, WR] to be "identical for all member pages in a group, this is not
required. The ZPR field alters the protection defined by TLB_entry[EX] and TLB_entry[WR], on a
page-by-page basis, as shown in the ZPR illustration. An application program (presumed to be
running in the problem state) can have execute and write permissions as defined by TLB_entry[EX]
and TLB_entry[WR] for the individual pages, or no access (denies loads, as well as stores and
execution), or complete access.
ZO Z2 Z4
Z6 Z8
Z10 Z12 Z14
Figure 6-5. Zone Protection Register (ZPR)
0:1 ZO TLB page access control for all pages in this zone.
In the problem state (MSR[PR]
=
1): In the supervisor state (MSR[PR]
=
0):
00 No access 00 Access controlled by
applicabl~
01 Access controlled by applicable TLB_entry[EX, WR]
TLB_entry[EX, WR] 01 Access controlled by applicable
10 Access controlled by applicable TLB_entry[EX, WR]
TLB_entry[EX, WR] 10 Access controlled by applicable
11 Accessed as if execute and write TLB_entry[EX, WR]
permissions (TLB_entry[EX, WR)) are
11 Accessed as if execute and write
granted. permissions (TLB_entry[EX, WR)) are
granted.
2:3 Z1 See the description of ZOo
4:5
Z2 See the description of ZOo
6:7
Z3
See the description of ZOo
8:9 Z4 See the description of ZOo
10:11 Z5 See the description of ZOo
12:13 Z6 See the description of ZOo
14:15 Z7 See the description of ZOo
16:17 Z8 See the description of ZOo
18:19 Z9 See the description of ZOo
20:21 Z10 See the description of ZOo
22:23 Z11 See the description of ZOo
24:25 Z12 See the description of ZOo
26:27 Z13 See the description of ZOo
28:29
Z14 See the description of ZOo
6-14
PPC405GP User's Manual Preliminary