Dynamic instrumentation event trace system and methods

• US 7,047,521 B2
• Filed: 06/07/2001
• Issued: 05/16/2006
• Est. Priority Date: 06/07/2001
• Status: Expired due to Fees

• Current Assignee: LynuxWorks Inc
• Original Assignee: Lynoxworks Incorporated
• Inventors: Bunnell, Mitchell
• Primary Examiner(s): Zhen, Wei Y.
• Assistant Examiner(s): Nahar, Qamrun
• Application Number:
  US09/876,675
• Publication Number:
  US 20020199172A1
• Time in Patent Office: 1,804 Days
• Field of Search: 717/128, 717/130
• US Class Current: 717/130
• CPC Class Codes: G06F 11/3466 Performance evaluation by tracing or monitoring
• CPC Class Codes: G06F 11/3636 by tracing the execution of the program
• CPC Class Codes: G06F 11/3644 by instrumenting at runtime

Abstract

Program code loaded for execution by a computer can be dynamically instrumented to collect event data by inserting an instruction at a trace point within the program code as loaded in a memory space of a computer, where the trace point corresponds to the beginning of a predefined function of the program selected for event tracing. The instruction provides for the direction of the execution of said computer to a function proxy routine, which includes a call to an instance of the predefined function. Event data is collected in connection with the calling of the instance of the predefined function.

Claims

1. A system providing for dynamic instrumentation and event data collection with respect to a target program as executed by a target computer, said system comprising:

a) a target data collection routine including a data collection buffer and wherein said target data collection routine is responsive to calls to store event data in said data collection buffer; and

b) a target driver including a trace control routine and an instrumentation routine, wherein execution of said instrumentation routine by said target computer subsequent to the loading and initial execution of said target program dynamically installs a deterministic program execution redirection instruction with respect to a named function of said target program to redirect execution of said target program by said target computer to said trace control routine, said instrumentation routine providing for the dynamic location and decoding of said named function to enable dynamic installation of said deterministic program execution redirection instruction, wherein execution of said instrumentation routine further provides, in response to a predetermined input signal provided to said target driver, for the dynamic removal of said deterministic program execution redirection instruction whereby said named function is restored to a non-instrumented state, wherein said instrumentation routine preserves an instance of said named function, wherein said trace control routine supports the collection and transfer of event data to said target data collection routine, and wherein execution of said trace control routine includes execution of said instance of said named function.

2. The system of claim 1 wherein said target driver is loaded for execution by said target computer separate from said target program, and wherein said system comprises a call interface layer associated by said system with said target program through which execution between said target program and said target driver is passed, whereby the execution space of said target program is minimally increased while allowing full instrumentation functionality to be implemented.

3. The system of claim 2 wherein said trace control routine selectively determines whether to collect event data with respect to said named function.

4. The system of claim 3 further comprising a remote host system coupled to said target driver to enable execution of said instrumentation routine and to said target data collection routine to retrieve event data from said data collection buffer.

5. The system of claim 4 wherein said target driver is responsive to said remote host system for enabling and disabling the collection of event data.

6. A method of dynamically instrumenting executable program code provided in the memory of a computer system, said method comprising the steps of:

a) dynamically provisioning a sequence of executable program code in response to a predetermined user input, wherein said sequence of executable program code is part of an executable program and wherein said step of dynamically provisioning is performed after initiation of execution of said executable program within the memory of said computer system, said dynamically provisioning including

i) enabling the interception of execution of said sequence through insertion of a deterministic branch instruction at a predetermined location within said sequence; and

ii) restoring said sequence by removal of said deterministic branch instruction from said predetermined location; and

b) executing an event capture routine in response to interception of said sequence, wherein execution of said event capture routine enables execution of said sequence and selectively enables execution of a data collection routine to record data associated with execution of said sequence.

7. The method of claim 6 wherein said step of dynamically provisioning provides for the copying of a first sequence instruction from said sequence to an executable buffer and placement of a first deterministic branch instruction in said sequence, said method further comprising the step of providing a second deterministic branch instruction following said sequence instruction in said executable buffer, wherein said second deterministic branch instruction identifies the address of a second sequence instruction in said sequence.

8. The method of claim 7 wherein said event capture routine provides for the execution of said sequence by execution of a third deterministic branch instruction that identifies the address of said first sequence instruction as provided in said executable buffer.

9. The method of claim 8 wherein said third deterministic branch instruction is a call-type branch instruction and wherein said first sequence instruction is copied from an entry point of said sequence.

10. The method of claim 9 wherein execution of said event capture routine further selectively enables execution of said data collection routine before and after execution of said sequence.

11. The method of claim 10 wherein execution of said event capture routine selectively enables execution of said data collection routine before execution of said sequence independently of selectively enabling execution of said data collection routine after execution of said sequence.

12. A diagnostic system supporting dynamic instrumentation of a target program executing within the memory of a computer system, said diagnostic system comprising:

a) a buffer providing for the storage of execution trace data reflective of the occurrence of traceable events within the execution of said target program; and

b) a trace program provided and concurrently executable within the memory of said computer system, said trace program including

i) a list of addresses within said target program designated as the source of traceable events;

ii) a trace data collection routine executable to selectively capture and provide trace data to said buffer;

iii) a dynamic patch routine executable to dynamically instrument said target program at each address of said list by establishing respective deterministic execution paths through said addresses that provide for execution of said trace data collection routine, wherein said dynamic patch routine includes a patch management routine that supports an instrumenting of said target program at a predetermined address subsequent to loading and initial execution of said target program by said computer system, and wherein said patch management routine is responsive to user provided trace commands issued with respect to said predetermined address to selectively apply and remove said instrumenting of said target program at said predetermined address; and

wherein trace data is collected through a deterministic flow of execution through said target program with minimal impact on the system behavior of said target program and said computer system.

13. The diagnostic system of claim 12 wherein said trace data collection routine includes a plurality of event-type specific data collection routines and wherein said dynamic patch routine provides for the selective execution of said event-type specific data collection routines for each said respective execution path established through said trace data collection routine.

14. The diagnostic system of claim 13 wherein execution of said event-type specific data collection routines provides for a programmable level of collection of event-type specific data and for creation of a corresponding data record storable by said buffer.

15. The diagnostic system of claim 14 further comprising a monitor program provided and concurrently executable within the memory of said computer system, said monitor program being coupled to said computer system to receive first messages providing said list of addresses and directing the retrieval of execution trace data from said buffer.

16. The diagnostic system of claim 15 wherein said trace program is coupled to said monitor program to receive second messages directing the execution of said dynamic patch routine, and the enabling of said trace data collection routine.

17. The diagnostic system of claim 16 wherein said monitor program is further coupled to receive said first and second messages from a remote host computer system and to return data stored by said buffer for examination and analysis by said remote host computer.

18. The diagnostic system of claim 12 wherein said addresses correspond to the entry points of executable subroutines of said target program and wherein each said deterministic execution path is dynamically established by placing a first instruction of an executable subroutine in an executable buffer, placing a deterministic branch instruction at the entry point of said executable subroutine with a target address of said trace data collection routine, and placing a deterministic branch instruction following said first instruction in said executable buffer with a target address of a second instruction of said executable subroutine.

19. The diagnostic system of claim 18 wherein said trace data collection routine includes a call-type branch instruction with a target address of said first instruction as stored in said executable buffer.