MOTOROLA
Chapter 7. Exceptions
7-9
Part II. PowerPC Microprocessor Module
an alignment exception or they may cause the processor to break the memory access into
multiple, smaller accesses with respect to the cache and the memory subsystem.
7.1.2.7 Program Exception (0x00700)
A program exception occurs when no higher priority exception exists and one or more of
the following exception conditions, which correspond to bit settings in SRR1, occur during
execution of an instruction:
¥
An lswx instruction for which rA or rB is in the range of registers to be loaded (may
cause results that are boundedly undeÞned)
¥
Privileged instructionÑA privileged instruction type program exception is
generated when the execution of a privileged instruction is attempted and the
processor is operating in user mode (MSR[PR] is set). It is also generated for mtspr
or mfspr instructions that have an invalid SPR Þeld that contain one of the deÞned
values having spr[0] = 1 and if MSR[PR] = 1. Some implementations may also
generate a privileged instruction program exception if a speciÞed SPR Þeld (for a
move to/from SPR instruction) is not deÞned for a particular implementation, but
spr[0] = 1; in this case, the implementation may cause either a privileged instruction
program exception, or an illegal instruction program exception may occur instead.
¥
TrapÑA trap program exception is generated when any of the conditions speciÞed
in a trap instruction is met. Trap instructions are described in Section 6.2.4.4, ÒTrap
Instructions.Ó
The register settings when a program exception is taken are shown in Table 7-8.
When a program exception is taken, instruction execution resumes at offset 0x00700 from
the physical base address indicated by MSR[IP].
Table 7-8. Register Settings after a Program Exception
Register
Setting Description
SRR0
Set to the EA of the instruction that causes the exception.
SRR1
0
Loaded with equivalent bits from the MSR
1Ð4
Cleared
5Ð9
Loaded with equivalent bits from the MSR
10 Cleared
Note that only one of bits 11Ð14 of SRR1 can be set at a time.
11
Cleared.
12
Set for an illegal instruction program exception; otherwise cleared.
13
Set for a privileged instruction program exception; otherwise cleared.
14
Set for a trap program exception; otherwise cleared.
15
Cleared if SRR0 contains the address of the instruction causing the exception, and set if
SRR0 contains the address of a subsequent instruction.
16Ð31
Loaded with equivalent bits from the MSR
Note that depending on the implementation, reserved bits in the MSR may not be copied to SRR1.
MSR
POW 0
ILE
Ñ
EE
0
PR
0
FP
0
ME Ñ
SE
0
BE
0
IP
Ñ
IR
0
DR
0
RI
0
LE
Set to value of ILE
Summary of Contents for MPC860 PowerQUICC
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Page 78: ...I iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
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Page 226: ...8 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
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Page 274: ...III iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
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Page 325: ...MOTOROLA Part IV Hardware Interface IV v Part IV Hardware Interface ...
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Page 632: ...21 44 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
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Page 998: ...37 48 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part VI Debug and Test ...
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