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Trap Diagnostic Facility
Today’s Software Diagnostic Tool
with innovative features for the z/OS software developer
Arney Computer Systems
Topics: Dynamic Program Intercepts (DPI)
• Diagnosis with no boundaries
• Intercepting startup
• SVC screening
• PC screening
• Branch Entry Intercept Breakpoints
• Inheritance and pass-through
Click for more information
Copyright Arney Computer Systems 2012-2014 2
Topics: ISPF User Interface
• Menu and panel driven
• Connecting sessions and targeting subtasks
• Symbols
• Single step tracing
• Breakpoints and triggers
• Displaying and zapping storage
• Session recording and scriptingClick for more information
Copyright Arney Computer Systems 2012-2014 3
Topics: Advanced Features
• Program identification
• Dynamic non-interactive tracing
• Grouping tasks into single diagnostic unit
• Remote Debugging Facility
• Amode and Rmode 64-able
Click for more information
Copyright Arney Computer Systems 2012-2014 4
Dynamic Program Intercepts: Diagnosis with No Boundaries
• Uses z/Architecture Trap Instruction
• Unaffected by applications RTM exits such as ESTAEX
• Executes in all z/OS environments; task, SRB, cross memory, locked, and so forth
• Does not require any program modifications to use any features
Click for more information
Copyright Arney Computer Systems 2012-2014 5
Dynamic Program Intercepts: Startup Intercept
TDFHOOK startup intercept
• Replace EXEC= for specified system startup
• Specify program as PARM= followed by the application’s parameters
• Breakpoint is dynamically inserted after program load and before program is executed
Click for more information
Copyright Arney Computer Systems 2012-2014 6
Dynamic Program Intercepts: SVC Screening
Allows interception of target programs in ATTACH,LOAD, LINK and XCTL SVC calls
Allows interception of RTM exits in SPIE, ESPIE, STAE, and ESTAE SVC calls
Inserts automatic system breakpoints in key points in these calls
Does not modify any programs
Click for more information
Copyright Arney Computer Systems 2012-2014 7
Dynamic Program Intercepts: PC Screening
Allows interception of target programs using ESTAEX
Allows interception of target programs using IEAMSCHD to schedule SRBs
Inserts automatic system breakpoints in key points in these calls
Does not modify any programs
Click for more information
Copyright Arney Computer Systems 2012-2014 8
Dynamic Program Intercepts:Branch Entry Intercept Breakpoints
Allows interception of branch entry calls such as SETFRR
Operates like other dynamic intercepts except it is specified by a breakpoint
Set using the BEI command in the User Interface
Click for more informationCopyright Arney Computer Systems 2012-2014 9
Dynamic Program Intercept: Inheritance and Pass-Through
Allows debugging the target program without hooking any of the programs that attach it
Target programs that are loaded, linked, or XCTLed by inherited task are not hooked
Allows debugging shared code without affecting non-debugged tasks
Click for more information
Copyright Arney Computer Systems 2012-2014 10
ISPF User Interface: Menu and Panel Driven
Ease of Use
• Menu items to setup session, gather diagnostics, and perform utility functions
• Both line mode and panel driven command entry
• Responses are saved in a memory object allowing scrolling of prior responses
Click for more information
Click for more information
Copyright Arney Computer Systems 2012-2014 11
ISPF User Interface: Connecting a Session
Programs in breakpoints are placed in a system queue
ISPF list panel shows current list of programs and their status
From list, a user can connect, end or release a dispatchable unit
Click for more information
Copyright Arney Computer Systems 2012-2014 12
ISPF User Interface: Targeting Subtasks and Shared Code
Program intercept command allows specifying target programs for SVC/PC screening
Program identification command allows specifying shared code (private and common) and unidentified code
Target programs that are loaded, linked, or xctled by inherited task are not hooked
Click for more informationCopyright Arney Computer Systems 2012-2014 13
ISPF User Interface: Symbols
• Programs are automatically assigned symbols
• Can be user defined
• Can be used in any command instead of an absolute value
• Can have properties: Name, Value, PC#, ASN, Length
• Makes a recorded session reusable Click for more information
Copyright Arney Computer Systems 2012-2014 14
ISPF User Interface: Single Step
• Allows the tracing of a program, instruction by instruction
• Supports Program Call (PC) and Program Returns (PR)
• Ranges can be specified to limit the trace to one or more address ranges
• Automatically skips calls into system code
Click for more information
Copyright Arney Computer Systems 2012-2014 15
ISPF User Interface: Breakpoints
• Setting breakpoints allow stopping a program at designated points Can be set by placing the TDFHOOK
macro in the program source Can be set via command
• A command breakpoint is single use and removed when encountered
Click for more information
Copyright Arney Computer Systems 2012-2014 16
ISPF User Interface: Triggers
• Triggers are breakpoints that trigger setting another breakpoint
• Used to set a breakpoint in common code when called from a specific point
• Can only be set by command
Click for more information
Copyright Arney Computer Systems 2012-2014 17
ISPF User Interface: Displaying storage
• Any storage accessible by the debugged task can be displayed
• Many MVS control blocks can be formatted using the AS keyword
• Display has commands to display formatted data such as task structures and PC structures
Click for more information
Copyright Arney Computer Systems 2012-2014 18
ISPF User Interface: Zapping storage
• Can be entered as a line mode command
• Can be entered in a panel which will retrieve the verify data allowing confirmation before the replace
• Can be displayed via a display command and using the ZAP option overtyped in full screen mode
Click for more information
Copyright Arney Computer Systems 2012-2014 19
ISPF User Interface: Session Recording
• All commands entered in a session can be recorded
• Session recording can be edited
• Session recording can be saved and executed in a later session or at a remote site
Click for more information
Copyright Arney Computer Systems 2012-2014 20
Advanced Features: Program Identification
Identification of programs reused between system startups
Identifying unidentified programs for use in symbols
Identifying shared CSA programs for targets in traps
Identifying shared code attached multiple times
Click for more information
Copyright Arney Computer Systems 2012-2014 21
Advanced Features: Dynamic Tracing Facility (Future feature)
Specifically designed for use in the Remote Debugging Facility
Non-interactive collection of specified data
• Specified PSW and state information
• Access, Control and General Purpose Registers
• Specified data areas up to 2K total size
Click for more information
Copyright Arney Computer Systems 2012-2014 22
Advanced Features: Grouping (Future feature)
• Allows treating any number of tasks across any number of address spaces as a single diagnostic unit
• Used in conjunction with dynamic tracing to resolve complex inter-task issues
• Used in conjunction with symbols and session recording to create scripts for Remote Debugging Facility
Click for more information
Copyright Arney Computer Systems 2012-2014 23
Advanced Features: Remote Debugging Facility (Future feature)
TDF is designed to not only provide the developer with the ability to debug code but to also:
• Create scripts that can be executed offsite with a distributable component
• The offsite user executes job using script
• Data is shipped back and analyzed
Click for more information
Copyright Arney Computer Systems 2012-2014 24
Advanced Features: AMODE and RMODE 64
• Uses server with 64 bit memory object to track debugging sessions Isolates diagnostic storage from application Minimizes diagnostic footprint in the
debugged address space
• In, z/OS 1.13 and later, about half of TDF can execute above the bar
Click for more information
Copyright Arney Computer Systems 2012-2014 25
Trap Diagnostic Facility
Today’s Software Diagnostic Tool
for today’s software developer
www.zosdebug.com
www.facebook.com/arneycomputer
Arney Computer Systems