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Memory Management Unit

6.10Fault status and address

Table 6-11 lists the encodings for the Fault Status Register.

Table 6-11 Fault Status Register encoding

Priority

Sources

 

FSR[10,3:0]

Domain

FSR[12]

 

 

 

 

 

 

Highest

Alignment

 

b00001

Invalid

SBZ

 

 

 

 

 

 

 

TLB miss

 

b00000

Invalid

SBZ

 

 

 

 

 

 

 

Instruction cache maintenancea

 

b00100

Invalid

SBZ

 

operation fault

 

 

 

 

 

 

 

 

 

 

 

External abort on translation

first-level

b01100

Invalid

SLVERR !DECERR

 

 

 

 

 

 

 

 

second-level

b01110

Valid

SLVERR !DECERR

 

 

 

 

 

 

 

Translation

Section

b00101

Invalid

SBZ

 

 

 

 

 

 

 

 

Page

b00111

Valid

SBZ

 

 

 

 

 

 

 

Access Bit Fault, Force AP only

Section

b00011

Valid

SBZ

 

 

 

 

 

 

 

 

Page

b00110

Valid

SBZ

 

 

 

 

 

 

 

Domain

Section

b01001

Valid

SBZ

 

 

 

 

 

 

 

 

Page

b01011

Valid

SBZ

 

 

 

 

 

 

 

Permission

Section

b01101

Valid

SBZ

 

 

 

 

 

 

 

 

Page

b01111

Valid

SBZ

 

 

 

 

 

 

 

Precise external abort

 

b01000

Valid

SLVERR !DECERR

 

 

 

 

 

 

 

Imprecise external abort

 

b10110

Invalid

SLVERR !DECERR

 

 

 

 

 

 

 

Parity error exception, not supported

 

b11000

Invalid

SBZ

 

 

 

 

 

 

Lowest

Instruction debug event

 

b00010

Valid

SBZ

a. These aborts cannot be signaled with the IFSR because they do not occur on the instruction side.

Note

All other Fault Status encodings are reserved.

If a translation abort occurs during a Data Cache maintenance operation by virtual address, then a Data Abort is taken and the DFSR indicates the reason. The FAR indicates the faulting address, and the IFAR indicates the address of the instruction causing the abort.

If a translation abort occurs during an Instruction Cache maintenance operation by virtual address, then a Data Abort is taken, and an Instruction Cache Maintenance Operation Fault is indicated in the DFSR. The IFSR indicates the reason. The FAR indicates the faulting address, and the IFAR indicates the address of the instruction causing the abort.

Domain and fault address information is only available for data accesses. For instruction aborts R14 must be used to determine the faulting address. You can determine the domain information by performing a TLB lookup for the faulting address and extracting the domain field.

Table 6-12 on page 6-35 lists a summary of the abort vector that is taken, and the Fault Status and Fault Address Registers that are updated for each abort type.

ARM DDI 0333H

Copyright © 2004-2009 ARM Limited. All rights reserved.

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Memory Management Unit

Table 6-12 Summary of aborts

Abort type

Abort taken

Precise?

Register updated?

 

 

IFSR

IFAR

DFSR

FAR

WFAR

 

 

 

 

 

 

 

 

 

 

 

Instruction MMU fault

Prefetch Abort

Yes

Yes

Yes

No

No

No

 

 

 

 

 

 

 

 

Instruction debug abort

Prefetch Abort

Yes

Yes

No

No

No

No

 

 

 

 

 

 

 

 

Instruction external abort on translation

Prefetch Abort

Yesa

Yesa

Yes

No

No

No

Instruction external abort

Prefetch Abort

Yesa

Yesa

Yes

No

No

No

Instruction cache maintenance operation

Data Abort

Yes

Yes

No

Yes

Yes

No

 

 

 

 

 

 

 

 

Data MMU fault

Data Abort

Yes

No

No

Yes

Yes

No

 

 

 

 

 

 

 

 

Data debug abort

Data Abort

No

No

No

Yes

Yes

Yes

 

 

 

 

 

 

 

 

Data external abort on translation

Data Abort

Yesa

No

No

Yesa

Yesa

Noa

Data external abort

Data Abort

Nob

No

No

Yesa

Yes

No

Data cache maintenance operation

Data Abort

Yes

No

No

Yes

Yes

No

a.When the EA bit is set, the updated FSR or FAR is always Secure.

b.Data Aborts can be precise, see External aborts on page 6-27 for more details.

ARM DDI 0333H

Copyright © 2004-2009 ARM Limited. All rights reserved.

6-35

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Non-Confidential, Unrestricted Access

 

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