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
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