- •Contents
- •List of Tables
- •List of Figures
- •Preface
- •About this manual
- •Product revision status
- •Intended audience
- •Using this manual
- •Conventions
- •Additional reading
- •Feedback
- •Feedback on the product
- •Feedback on this book
- •Introduction
- •1.1 About the processor
- •1.2 Extensions to ARMv6
- •1.3 TrustZone security extensions
- •1.4.1 Instruction compression
- •1.4.2 The Thumb instruction set
- •1.4.3 Java bytecodes
- •1.5 Components of the processor
- •1.5.1 Integer core
- •1.5.2 Load Store Unit (LSU)
- •1.5.3 Prefetch unit
- •1.5.4 Memory system
- •1.5.5 AMBA AXI interface
- •1.5.6 Coprocessor interface
- •1.5.7 Debug
- •1.5.8 Instruction cycle summary and interlocks
- •1.5.9 System control
- •1.5.10 Interrupt handling
- •1.6 Power management
- •1.7 Configurable options
- •1.8 Pipeline stages
- •1.9 Typical pipeline operations
- •1.9.1 Instruction progression
- •1.10.1 Extended ARM instruction set summary
- •1.10.2 Thumb instruction set summary
- •1.11 Product revisions
- •Programmer’s Model
- •2.1 About the programmer’s model
- •2.2.1 TrustZone model
- •2.2.2 How the Secure model works
- •2.2.3 TrustZone write access disable
- •2.2.4 Secure Monitor bus
- •2.3 Processor operating states
- •2.3.1 Switching state
- •2.3.2 Interworking ARM and Thumb state
- •2.4 Instruction length
- •2.5 Data types
- •2.6 Memory formats
- •2.7 Addresses in a processor system
- •2.8 Operating modes
- •2.9 Registers
- •2.9.1 The ARM state core register set
- •2.9.2 The Thumb state core register set
- •2.9.3 Accessing high registers in Thumb state
- •2.9.4 ARM state and Thumb state registers relationship
- •2.10 The program status registers
- •2.10.1 The condition code flags
- •2.10.2 The Q flag
- •2.10.4 The GE[3:0] bits
- •2.10.7 The control bits
- •2.10.8 Modification of PSR bits by MSR instructions
- •2.10.9 Reserved bits
- •2.11 Additional instructions
- •2.11.1 Load or Store Byte Exclusive
- •2.11.2 Load or Store Halfword Exclusive
- •2.11.3 Load or Store Doubleword
- •2.11.4 CLREX
- •2.12 Exceptions
- •2.12.1 New instructions for exception handling
- •2.12.2 Exception entry and exit summary
- •2.12.3 Entering an ARM exception
- •2.12.4 Leaving an ARM exception
- •2.12.5 Reset
- •2.12.6 Fast interrupt request
- •2.12.7 Interrupt request
- •2.12.8 Low interrupt latency configuration
- •2.12.9 Interrupt latency example
- •2.12.10 Aborts
- •2.12.11 Imprecise Data Abort mask in the CPSR/SPSR
- •2.12.12 Supervisor call instruction
- •2.12.13 Secure Monitor Call (SMC)
- •2.12.14 Undefined instruction
- •2.12.15 Breakpoint instruction (BKPT)
- •2.12.16 Exception vectors
- •2.12.17 Exception priorities
- •2.13 Software considerations
- •2.13.1 Branch Target Address Cache flush
- •2.13.2 Waiting for DMA to complete
- •System Control Coprocessor
- •3.1 About the system control coprocessor
- •3.1.1 System control coprocessor functional groups
- •3.1.2 System control and configuration
- •3.1.3 MMU control and configuration
- •3.1.4 Cache control and configuration
- •3.1.5 TCM control and configuration
- •3.1.6 Cache Master Valid Registers
- •3.1.7 DMA control
- •3.1.8 System performance monitor
- •3.1.9 System validation
- •3.1.10 Use of the system control coprocessor
- •3.2 System control processor registers
- •3.2.1 Register allocation
- •3.2.2 c0, Main ID Register
- •3.2.3 c0, Cache Type Register
- •3.2.4 c0, TCM Status Register
- •3.2.5 c0, TLB Type Register
- •3.2.6 c0, CPUID registers
- •3.2.7 c1, Control Register
- •3.2.8 c1, Auxiliary Control Register
- •3.2.9 c1, Coprocessor Access Control Register
- •3.2.10 c1, Secure Configuration Register
- •3.2.11 c1, Secure Debug Enable Register
- •3.2.13 c2, Translation Table Base Register 0
- •3.2.14 c2, Translation Table Base Register 1
- •3.2.15 c2, Translation Table Base Control Register
- •3.2.16 c3, Domain Access Control Register
- •3.2.17 c5, Data Fault Status Register
- •3.2.18 c5, Instruction Fault Status Register
- •3.2.19 c6, Fault Address Register
- •3.2.20 c6, Watchpoint Fault Address Register
- •3.2.21 c6, Instruction Fault Address Register
- •3.2.22 c7, Cache operations
- •3.2.23 c8, TLB Operations Register
- •3.2.24 c9, Data and instruction cache lockdown registers
- •3.2.25 c9, Data TCM Region Register
- •3.2.26 c9, Instruction TCM Region Register
- •3.2.29 c9, TCM Selection Register
- •3.2.30 c9, Cache Behavior Override Register
- •3.2.31 c10, TLB Lockdown Register
- •3.2.32 c10, Memory region remap registers
- •3.2.33 c11, DMA identification and status registers
- •3.2.34 c11, DMA User Accessibility Register
- •3.2.35 c11, DMA Channel Number Register
- •3.2.36 c11, DMA enable registers
- •3.2.37 c11, DMA Control Register
- •3.2.38 c11, DMA Internal Start Address Register
- •3.2.39 c11, DMA External Start Address Register
- •3.2.40 c11, DMA Internal End Address Register
- •3.2.41 c11, DMA Channel Status Register
- •3.2.42 c11, DMA Context ID Register
- •3.2.44 c12, Monitor Vector Base Address Register
- •3.2.45 c12, Interrupt Status Register
- •3.2.46 c13, FCSE PID Register
- •3.2.47 c13, Context ID Register
- •3.2.48 c13, Thread and process ID registers
- •3.2.49 c15, Peripheral Port Memory Remap Register
- •3.2.51 c15, Performance Monitor Control Register
- •3.2.52 c15, Cycle Counter Register
- •3.2.53 c15, Count Register 0
- •3.2.54 c15, Count Register 1
- •3.2.55 c15, System Validation Counter Register
- •3.2.56 c15, System Validation Operations Register
- •3.2.57 c15, System Validation Cache Size Mask Register
- •3.2.58 c15, Instruction Cache Master Valid Register
- •3.2.59 c15, Data Cache Master Valid Register
- •3.2.60 c15, TLB lockdown access registers
- •Unaligned and Mixed-endian Data Access Support
- •4.2 Unaligned access support
- •4.2.1 Legacy support
- •4.2.2 ARMv6 extensions
- •4.2.3 Legacy and ARMv6 configurations
- •4.2.4 Legacy data access in ARMv6 (U=0)
- •4.2.5 Support for unaligned data access in ARMv6 (U=1)
- •4.2.6 ARMv6 unaligned data access restrictions
- •4.3 Endian support
- •4.3.1 Load unsigned byte, endian independent
- •4.3.2 Load signed byte, endian independent
- •4.3.3 Store byte, endian independent
- •4.4 Operation of unaligned accesses
- •4.5.1 Legacy fixed instruction and data endianness
- •4.5.3 Reset values of the U, B, and EE bits
- •4.6.1 All load and store operations
- •4.7 Instructions to change the CPSR E bit
- •Program Flow Prediction
- •5.1 About program flow prediction
- •5.2 Branch prediction
- •5.2.1 Enabling program flow prediction
- •5.2.2 Dynamic branch predictor
- •5.2.3 Static branch predictor
- •5.2.4 Branch folding
- •5.2.5 Incorrect predictions and correction
- •5.3 Return stack
- •5.4 Memory Barriers
- •5.4.1 Instruction Memory Barriers (IMBs)
- •5.5.1 Execution of IMB instructions
- •Memory Management Unit
- •6.1 About the MMU
- •6.2 TLB organization
- •6.2.1 MicroTLB
- •6.2.2 Main TLB
- •6.2.3 TLB control operations
- •6.2.5 Supersections
- •6.3 Memory access sequence
- •6.3.1 TLB match process
- •6.3.2 Virtual to physical translation mapping restrictions
- •6.4 Enabling and disabling the MMU
- •6.4.1 Enabling the MMU
- •6.4.2 Disabling the MMU
- •6.4.3 Behavior with MMU disabled
- •6.5 Memory access control
- •6.5.1 Domains
- •6.5.2 Access permissions
- •6.5.3 Execute never bits in the TLB entry
- •6.6 Memory region attributes
- •6.6.1 C and B bit, and type extension field encodings
- •6.6.2 Shared
- •6.6.3 NS attribute
- •6.7 Memory attributes and types
- •6.7.1 Normal memory attribute
- •6.7.2 Device memory attribute
- •6.7.3 Strongly Ordered memory attribute
- •6.7.4 Ordering requirements for memory accesses
- •6.7.5 Explicit Memory Barriers
- •6.7.6 Backwards compatibility
- •6.8 MMU aborts
- •6.8.1 External aborts
- •6.9 MMU fault checking
- •6.9.1 Fault checking sequence
- •6.9.2 Alignment fault
- •6.9.3 Translation fault
- •6.9.4 Access bit fault
- •6.9.5 Domain fault
- •6.9.6 Permission fault
- •6.9.7 Debug event
- •6.10 Fault status and address
- •6.11 Hardware page table translation
- •6.11.2 ARMv6 page table translation subpage AP bits disabled
- •6.11.3 Restrictions on page table mappings page coloring
- •6.12 MMU descriptors
- •Level One Memory System
- •7.1 About the level one memory system
- •7.2 Cache organization
- •7.2.1 Features of the cache system
- •7.2.2 Cache functional description
- •7.2.3 Cache control operations
- •7.2.4 Cache miss handling
- •7.2.5 Cache disabled behavior
- •7.2.6 Unexpected hit behavior
- •7.3.1 TCM behavior
- •7.3.2 Restriction on page table mappings
- •7.3.3 Restriction on page table attributes
- •7.5 TCM and cache interactions
- •7.5.1 Overlapping between TCM regions
- •7.5.2 DMA and core access arbitration
- •7.5.3 Instruction accesses to TCM
- •7.5.4 Data accesses to the Instruction TCM
- •7.6 Write buffer
- •Level Two Interface
- •8.1 About the level two interface
- •8.1.1 AXI parameters for the level 2 interconnect interfaces
- •8.2 Synchronization primitives
- •8.2.3 Example of LDREX and STREX usage
- •8.3 AXI control signals in the processor
- •8.3.1 Channel definition
- •8.3.2 Signal name suffixes
- •8.3.3 Address channel signals
- •8.4 Instruction Fetch Interface transfers
- •8.4.1 Cacheable fetches
- •8.4.2 Noncacheable fetches
- •8.5 Data Read/Write Interface transfers
- •8.5.1 Linefills
- •8.5.2 Noncacheable LDRB
- •8.5.3 Noncacheable LDRH
- •8.5.4 Noncacheable LDR or LDM1
- •8.5.5 Noncacheable LDRD or LDM2
- •8.5.6 Noncacheable LDM3
- •8.5.7 Noncacheable LDM4
- •8.5.8 Noncacheable LDM5
- •8.5.9 Noncacheable LDM6
- •8.5.10 Noncacheable LDM7
- •8.5.11 Noncacheable LDM8
- •8.5.12 Noncacheable LDM9
- •8.5.13 Noncacheable LDM10
- •8.5.14 Noncacheable LDM11
- •8.5.15 Noncacheable LDM12
- •8.5.16 Noncacheable LDM13
- •8.5.17 Noncacheable LDM14
- •8.5.18 Noncacheable LDM15
- •8.5.19 Noncacheable LDM16
- •8.6 Peripheral Interface transfers
- •8.7 Endianness
- •8.8 Locked access
- •Clocking and Resets
- •9.1 About clocking and resets
- •9.2 Clocking and resets with no IEM
- •9.2.1 Processor clocking with no IEM
- •9.2.2 Reset with no IEM
- •9.3 Clocking and resets with IEM
- •9.3.1 Processor clocking with IEM
- •9.3.2 Reset with IEM
- •9.4 Reset modes
- •9.4.1 Power-on reset
- •9.4.2 CP14 debug logic
- •9.4.3 Processor reset
- •9.4.4 DBGTAP reset
- •9.4.5 Normal operation
- •Power Control
- •10.1 About power control
- •10.2 Power management
- •10.2.1 Run mode
- •10.2.2 Standby mode
- •10.2.3 Shutdown mode
- •10.2.4 Dormant mode
- •10.2.5 Communication to the Power Management Controller
- •10.3 Intelligent Energy Management
- •10.3.1 Purpose of IEM
- •10.3.2 Structure of IEM
- •10.3.3 Operation of IEM
- •Coprocessor Interface
- •11.1 About the coprocessor interface
- •11.2 Coprocessor pipeline
- •11.2.1 Coprocessor instructions
- •11.2.2 Coprocessor control
- •11.2.3 Pipeline synchronization
- •11.2.4 Pipeline control
- •11.2.5 Instruction tagging
- •11.2.6 Flush broadcast
- •11.3 Token queue management
- •11.3.1 Queue implementation
- •11.3.2 Queue modification
- •11.3.3 Queue flushing
- •11.4 Token queues
- •11.4.1 Instruction queue
- •11.4.2 Length queue
- •11.4.3 Accept queue
- •11.4.4 Cancel queue
- •11.4.5 Finish queue
- •11.5 Data transfer
- •11.5.1 Loads
- •11.5.2 Stores
- •11.6 Operations
- •11.6.1 Normal operation
- •11.6.2 Cancel operations
- •11.6.3 Bounce operations
- •11.6.4 Flush operations
- •11.6.5 Retirement operations
- •11.7 Multiple coprocessors
- •11.7.1 Interconnect considerations
- •11.7.2 Coprocessor selection
- •11.7.3 Coprocessor switching
- •Vectored Interrupt Controller Port
- •12.1 About the PL192 Vectored Interrupt Controller
- •12.2 About the processor VIC port
- •12.2.1 Synchronization of the VIC port signals
- •12.2.2 Interrupt handler exit
- •12.3 Timing of the VIC port
- •12.3.1 PL192 VIC timing
- •12.3.2 Core timing
- •12.4 Interrupt entry flowchart
- •Debug
- •13.1 Debug systems
- •13.1.1 The debug host
- •13.1.2 The protocol converter
- •13.1.3 The processor
- •13.2 About the debug unit
- •13.2.3 Secure Monitor mode and debug
- •13.2.4 Virtual addresses and debug
- •13.2.5 Programming the debug unit
- •13.3 Debug registers
- •13.3.1 Accessing debug registers
- •13.3.2 CP14 c0, Debug ID Register (DIDR)
- •13.3.3 CP14 c1, Debug Status and Control Register (DSCR)
- •13.3.4 CP14 c5, Data Transfer Registers (DTR)
- •13.3.5 CP14 c6, Watchpoint Fault Address Register (WFAR)
- •13.3.6 CP14 c7, Vector Catch Register (VCR)
- •13.3.10 CP14 c112-c113, Watchpoint Control Registers (WCR)
- •13.3.11 CP14 c10, Debug State Cache Control Register
- •13.3.12 CP14 c11, Debug State MMU Control Register
- •13.4 CP14 registers reset
- •13.5 CP14 debug instructions
- •13.5.1 Executing CP14 debug instructions
- •13.6 External debug interface
- •13.7 Changing the debug enable signals
- •13.8 Debug events
- •13.8.1 Software debug event
- •13.8.2 External debug request signal
- •13.8.3 Halt DBGTAP instruction
- •13.8.4 Behavior of the processor on debug events
- •13.8.5 Effect of a debug event on CP15 registers
- •13.9 Debug exception
- •13.10 Debug state
- •13.10.1 Behavior of the PC in Debug state
- •13.10.2 Interrupts
- •13.10.3 Exceptions
- •13.11 Debug communications channel
- •13.12 Debugging in a cached system
- •13.12.1 Data cache writes
- •13.13 Debugging in a system with TLBs
- •13.14 Monitor debug-mode debugging
- •13.14.1 Entering the debug monitor target
- •13.14.2 Setting breakpoints, watchpoints, and vector catch debug events
- •13.14.3 Setting software breakpoint debug events (BKPT)
- •13.14.4 Using the debug communications channel
- •13.15 Halting debug-mode debugging
- •13.15.1 Entering Debug state
- •13.15.2 Exiting Debug state
- •13.15.3 Programming debug events
- •13.16 External signals
- •Debug Test Access Port
- •14.1 Debug Test Access Port and Debug state
- •14.2 Synchronizing RealView ICE
- •14.3 Entering Debug state
- •14.4 Exiting Debug state
- •14.5 The DBGTAP port and debug registers
- •14.6 Debug registers
- •14.6.1 Bypass register
- •14.6.2 Device ID code register
- •14.6.3 Instruction register
- •14.6.4 Scan chain select register (SCREG)
- •14.6.5 Scan chains
- •14.6.6 Reset
- •14.7 Using the Debug Test Access Port
- •14.7.1 Entering and leaving Debug state
- •14.7.2 Executing instructions in Debug state
- •14.7.3 Using the ITRsel IR instruction
- •14.7.4 Transferring data between the host and the core
- •14.7.5 Using the debug communications channel
- •14.7.6 Target to host debug communications channel sequence
- •14.7.7 Host to target debug communications channel
- •14.7.8 Transferring data in Debug state
- •14.7.9 Example sequences
- •14.8 Debug sequences
- •14.8.1 Debug macros
- •14.8.2 General setup
- •14.8.3 Forcing the processor to halt
- •14.8.4 Entering Debug state
- •14.8.5 Leaving Debug state
- •14.8.8 Reading the CPSR/SPSR
- •14.8.9 Writing the CPSR/SPSR
- •14.8.10 Reading the PC
- •14.8.11 Writing the PC
- •14.8.12 General notes about reading and writing memory
- •14.8.13 Reading memory as words
- •14.8.14 Writing memory as words
- •14.8.15 Reading memory as halfwords or bytes
- •14.8.16 Writing memory as halfwords/bytes
- •14.8.17 Coprocessor register reads and writes
- •14.8.18 Reading coprocessor registers
- •14.8.19 Writing coprocessor registers
- •14.9 Programming debug events
- •14.9.1 Reading registers using scan chain 7
- •14.9.2 Writing registers using scan chain 7
- •14.9.3 Setting breakpoints, watchpoints and vector traps
- •14.9.4 Setting software breakpoints
- •14.10 Monitor debug-mode debugging
- •14.10.1 Receiving data from the core
- •14.10.2 Sending data to the core
- •Trace Interface Port
- •15.1 About the ETM interface
- •15.1.1 Instruction interface
- •15.1.2 Secure control bus
- •15.1.3 Data address interface
- •15.1.4 Data value interface
- •15.1.5 Pipeline advance interface
- •15.1.6 Coprocessor interface
- •15.1.7 Other connections to the core
- •Cycle Timings and Interlock Behavior
- •16.1 About cycle timings and interlock behavior
- •16.1.1 Changes in instruction flow overview
- •16.1.2 Instruction execution overview
- •16.1.3 Conditional instructions
- •16.1.4 Opposite condition code checks
- •16.1.5 Definition of terms
- •16.2 Register interlock examples
- •16.3 Data processing instructions
- •16.3.1 Cycle counts if destination is not PC
- •16.3.2 Cycle counts if destination is the PC
- •16.3.3 Example interlocks
- •16.4 QADD, QDADD, QSUB, and QDSUB instructions
- •16.6 ARMv6 Sum of Absolute Differences (SAD)
- •16.6.1 Example interlocks
- •16.7 Multiplies
- •16.8 Branches
- •16.9 Processor state updating instructions
- •16.10 Single load and store instructions
- •16.10.1 Base register update
- •16.11 Load and Store Double instructions
- •16.12 Load and Store Multiple Instructions
- •16.12.1 Load and Store Multiples, other than load multiples including the PC
- •16.12.2 Load Multiples, where the PC is in the register list
- •16.12.3 Example Interlocks
- •16.13 RFE and SRS instructions
- •16.14 Synchronization instructions
- •16.15 Coprocessor instructions
- •16.16 SVC, SMC, BKPT, Undefined, and Prefetch Aborted instructions
- •16.17 No operation
- •16.18 Thumb instructions
- •AC Characteristics
- •17.1 Processor timing diagrams
- •17.2 Processor timing parameters
- •Signal Descriptions
- •A.1 Global signals
- •A.2 Static configuration signals
- •A.3 TrustZone internal signals
- •A.4 Interrupt signals, including VIC interface
- •A.5 AXI interface signals
- •A.5.1 Instruction read port signals
- •A.5.2 Data port signals
- •A.5.3 Peripheral port signals
- •A.5.4 DMA port signals
- •A.6 Coprocessor interface signals
- •A.7 Debug interface signals, including JTAG
- •A.8 ETM interface signals
- •A.9 Test signals
- •B.1 About the differences between the ARM1136J-S and ARM1176JZ-S processors
- •B.2 Summary of differences
- •B.2.1 TrustZone
- •B.2.2 ARMv6k extensions support
- •B.2.3 Power management
- •B.2.4 SmartCache
- •B.2.7 Tightly-Coupled Memories
- •B.2.8 Fault Address Register
- •B.2.9 Fault Status Register
- •B.2.10 Prefetch Unit
- •B.2.11 System control coprocessor operations
- •B.2.13 Debug
- •B.2.14 Level two interface
- •B.2.15 Memory BIST
- •Revisions
- •Glossary
Debug
13.6External debug interface
The debug architecture provides two control signals called SPIDEN and SPNIDEN. that are part of the external debug interface.
SPIDEN The Secure Privileged Invasive Debug Enable input pin, SPIDEN, that enables and disables invasive debug in the Secure world:
•If this input signal is HIGH, invasive debug is permitted in all Secure modes. In this case invasive debug is permitted in Secure User mode, regardless value of SUIDEN bit.
•If this input signal is LOW, invasive debug is not permitted in any Secure privileged mode. Invasive debug is permitted in Secure User mode according to the SUIDEN bit.
SPNIDEN The Secure Privileged Non-Invasive Debug Enable input pin, SPNIDEN, that enables and disables non-invasive debug in the Secure world:
•If this input signal is HIGH, non-invasive debug is permitted in all Secure modes. In this case non-invasive debug is permitted in Secure User mode, regardless of the value of the SUNIDEN bit.
•If this input signal is LOW, non-invasive debug is not permitted in all Secure privileged modes. Non-invasive debug is permitted in Secure User mode according to the SUNIDEN bit.
Note
•You must control access to the SPIDEN and SPNIDEN pins, as they represent a significant security risk. For example, it must not be possible to set these pins through the boundary scan in a final device.
•For software systems that do not use any TrustZone security features, the SPIDEN and SPNIDEN pins must be driven HIGH to enable debug by default.
Table 13-21 lists the relationship between the DBGEN input pin, the SPIDEN input pin, the SUIDEN control bit, the NS bit, the processor mode and the debug capabilities.
Table 13-21 Secure debug behavior
DBGEN |
DSCR |
SPIDEN |
SUIDEN |
NS |
Mode |
Debug-mode |
Notes |
|
[15:14] |
bit |
|||||||
|
|
|
|
|
|
|||
|
|
|
|
|
|
|
|
|
0 |
XX |
X |
X |
X |
X |
Debug disabled. |
DSCR[15:14] reads as zero |
|
|
|
|
|
|
|
|
|
|
1 |
00 |
1 |
X |
X |
X |
No debug mode |
Permitted in Non-secure |
|
|
|
|
|
|
|
selecteda |
state and in all modes in |
|
|
|
|
|
|
|
|
Secure state. |
|
|
|
|
|
|
|
|
|
|
1 |
00 |
0 |
0 |
1 |
not Secure |
No debug mode |
Permitted only in |
|
|
|
|
|
|
Monitor |
selecteda |
Non-secure state. |
|
1 |
00 |
0 |
0 |
X |
Secure |
Debug not |
Not permitted in Secure |
|
|
|
|
|
|
Monitor |
permittedb |
state. |
|
1 |
00 |
0 |
0 |
0 |
X |
Debug not |
Not permitted in Secure |
|
|
|
|
|
|
|
permittedb |
state. |
|
1 |
00 |
0 |
1 |
1 |
not Secure |
No debug mode |
Permitted in Non-secure |
|
|
|
|
|
|
Monitor |
selecteda |
state. |
ARM DDI 0333H |
Copyright © 2004-2009 ARM Limited. All rights reserved. |
13-28 |
ID012410 |
Non-Confidential, Unrestricted Access |
|
Debug
Table 13-21 Secure debug behavior (continued)
DBGEN |
DSCR |
SPIDEN |
SUIDEN |
NS |
Mode |
Debug-mode |
Notes |
|
[15:14] |
bit |
|||||||
|
|
|
|
|
|
|||
|
|
|
|
|
|
|
|
|
1 |
00 |
0 |
1 |
X |
Secure |
Debug not |
Not permitted in privileged |
|
|
|
|
|
|
Monitor |
permittedb |
modes in Secure state. |
|
1 |
00 |
0 |
1 |
0 |
not User |
Debug not |
Not permitted in privileged |
|
|
|
|
|
|
|
permittedb |
modes in Secure state. |
|
1 |
00 |
0 |
1 |
0 |
User |
No debug mode |
Permitted in User mode in |
|
|
|
|
|
|
|
selecteda |
Secure state.c |
|
1 |
10 |
1 |
X |
X |
X |
Monitor |
Permitted in Non-secure |
|
|
|
|
|
|
|
debug-mode |
state and in all modes in |
|
|
|
|
|
|
|
|
Secure state. |
|
|
|
|
|
|
|
|
|
|
1 |
10 |
0 |
0 |
1 |
not Secure |
Monitor |
Permitted only in |
|
|
|
|
|
|
Monitor |
debug-mode |
Non-secure state. |
|
|
|
|
|
|
|
|
|
|
1 |
10 |
0 |
0 |
X |
Secure |
Debug not |
Not permitted in Secure |
|
|
|
|
|
|
Monitor |
permittedb |
state. |
|
1 |
10 |
0 |
0 |
0 |
X |
Debug not |
Not permitted in Secure |
|
|
|
|
|
|
|
permittedb |
state. |
|
1 |
10 |
0 |
1 |
1 |
not Secure |
Monitor |
Permitted in Non-secure |
|
|
|
|
|
|
Monitor |
debug-mode |
state. |
|
|
|
|
|
|
|
|
|
|
1 |
10 |
0 |
1 |
X |
Secure |
Debug not |
Not permitted in privileged |
|
|
|
|
|
|
Monitor |
permittedb |
modes in Secure state. |
|
1 |
10 |
0 |
1 |
0 |
not User |
Debug not |
Not permitted in privileged |
|
|
|
|
|
|
|
permittedb |
modes in Secure state. |
|
1 |
10 |
0 |
1 |
0 |
User |
Monitor |
Permitted in User mode in |
|
|
|
|
|
|
|
debug-mode |
Secure state.c |
|
1 |
X1 |
1 |
X |
X |
X |
Halting |
Permitted in Non-secure |
|
|
|
|
|
|
|
debug-mode |
state and in all modes in |
|
|
|
|
|
|
|
|
Secure state. |
|
|
|
|
|
|
|
|
|
|
1 |
X1 |
0 |
0 |
1 |
not Secure |
Halting |
Permitted in Non-secure |
|
|
|
|
|
|
Monitor |
debug-mode |
state. |
|
|
|
|
|
|
|
|
|
|
1 |
X1 |
0 |
0 |
X |
Secure |
Debug not |
Not permitted in Secure |
|
|
|
|
|
|
Monitor |
permittedb |
state. |
|
1 |
X1 |
0 |
0 |
0 |
X |
Debug not |
Not permitted in Secure |
|
|
|
|
|
|
|
permittedb |
state. |
|
1 |
X1 |
0 |
1 |
1 |
not Secure |
Halting |
Permitted in Non-secure |
|
|
|
|
|
|
Monitor |
debug-mode |
state. |
|
|
|
|
|
|
|
|
|
|
1 |
X1 |
0 |
1 |
X |
Secure |
Debug not |
Not permitted in privileged |
|
|
|
|
|
|
Monitor |
permittedb |
modes in Secure state. |
|
1 |
X1 |
0 |
1 |
0 |
not User |
Debug not |
Not permitted in privileged |
|
|
|
|
|
|
|
permittedb |
modes in Secure state. |
|
1 |
X1 |
0 |
1 |
0 |
User |
Halting |
Permitted in User mode in |
|
|
|
|
|
|
|
debug-mode |
Secure state. Capabilities |
|
|
|
|
|
|
|
|
restricted. |
|
|
|
|
|
|
|
|
|
ARM DDI 0333H |
Copyright © 2004-2009 ARM Limited. All rights reserved. |
13-29 |
ID012410 |
Non-Confidential, Unrestricted Access |
|
Debug
a.Behavior of the processor on debug events on page 13-33 describes the behavior when no debug mode is selected. Only the BKPT instruction external debug request signal, and Halt DBGTAP instructions have an effect when no debug mode is selected. All other debug events are ignored.
b.Behavior of the processor on debug events on page 13-33 describes the behavior marked as not permitted. Logically, the processor is still configured for either Halting debug-mode or Monitor debug-mode, as appropriate.
c.Debug exceptions are handled in a privileged mode.
ARM DDI 0333H |
Copyright © 2004-2009 ARM Limited. All rights reserved. |
13-30 |
ID012410 |
Non-Confidential, Unrestricted Access |
|
Debug
13.7Changing the debug enable signals
The behavior of these control signals, DBGEN, SPIDEN, and SPNIDEN, is primarily a concern of the external debug interface. It is recommended that these signals do not change. However, the architecture permits these signals to change when the processor is running or when the processor is in Debug state.
If software running on the processor changes the state of one of these signals, before performing debug or analysis operations that rely on the new value it must:
1.Execute the device specific sequence of instructions to change the signal value. For instance, the software might have to write a value to a control register in a system peripheral.
2.Perform a Data Memory Barrier operation. This stage can be omitted if the previous stage does not involve any memory operations.
3.Poll debug registers for the view that the processor has of the signal values. This stage is required because system specific issues might result in the processor not receiving a signal change until some cycles after the Data Memory Barrier completes.
4.Issue an Instruction Memory Barrier sequence.
The same rules apply for instructions executed through the ITR when in Debug state.
The view that the processor has of the SPIDEN and SPNIDEN signals can be polled through the DSCR. The processor has no register that shows its view of DBGEN. However, if DBGEN is LOW, DSCR[15:14] read as zero, and therefore the view that the processor has of DBGEN
can be polled by writing to DSCR[15:14] and using the value read back to determine its setting.
ARM DDI 0333H |
Copyright © 2004-2009 ARM Limited. All rights reserved. |
13-31 |
ID012410 |
Non-Confidential, Unrestricted Access |
|