System and method for implementing software breakpoints
View Patent ↗The disclosure is directed to a method of loading a breakpoint enabled page of a computer program into a computer readable memory. The method includes identifying a page of a computer program to be loaded into the computer readable memory and reading a breakpoint table to identify a set of breakpoints having memory addresses located within the page of the computer program prior to loading the page of the computer program. Each breakpoint has an instruction address and an instruction storage location. For each of the set of breakpoints, the method includes reading an operating instruction of the page of the computer program located at the instruction address, storing a copy of the operating instruction at the instruction storage location within the breakpoint table, and loading a trap instruction at the instruction address to replace the operating instruction in the page of the computer program to create a breakpoint enabled page of the computer program.
1. A method of loading a breakpoint enabled page of a computer program into a computer readable memory, the method comprising:
identifying a page of a computer program to be loaded into the computer readable memory;
prior to loading the page of the computer program, reading a breakpoint table to identify a set of breakpoints having memory addresses located within the page of the computer program, each breakpoint in the set of breakpoints having an instruction address, and an instruction storage location, and a task identifier;
for each of the set of breakpoints, reading an operating instruction of the page of the computer program located at the instruction address, storing a copy of the operating instruction at the instruction storage location within the breakpoint table, and loading a trap instruction at the instruction address to replace the operating instruction in the page of the computer program when the task identifier of the respective breakpoint matches a task to be executed as checked before the trap instruction is loaded to replace the operating instruction, to create a breakpoint enabled page of the computer program; and
loading the breakpoint enabled page of the computer program into the computer readable memory, wherein access to the breakpoint table by a debugger routine is prevented during creation and loading of the breakpoint enable page.
2. The method of claim 1 , wherein the computer program has a total size that is greater than the size of the computer readable memory and wherein the page of the computer program has a size that is less than the size of the computer readable memory.
3. The method of claim 1 , further comprising executing at least one of the trap instructions corresponding to at least one of the set of breakpoints and initiating a debug routine in response to executing the trap instruction.
4. The method of claim 3 , further comprising, after executing the at least one trap instruction and after initiating the debug routine, reading the previously stored copy of the operating instruction from the instruction storage location of the breakpoint table and executing the operating instruction to continue execution of the computer program after invocation of the breakpoint.
5. The method of claim 1 , wherein the computer readable memory and a processor configured to execute the instructions in the page of the computer program are disposed within an embedded processor system.
6. The method of claim 5 , wherein the embedded processor system comprises a handheld computer device.
7. The method of claim 6 , wherein the embedded processor system is an MP3 device.
8. The method of claim 5 , wherein the embedded processor system is a personal digital assistant.
9. The method of claim 1 , further comprising loading the breakpoint table from a host computer into the computer readable memory.
10. The method of claim 9 , wherein the host computer includes a debugger routine that is invoked upon execution of at least one of the trap instructions.
11. The method of claim 1 , wherein each task identifier represents a particular program task associated with activation of the breakpoint.
12. The method of claim 11 , wherein when a task other than the particular program task is being executed, the breakpoint is disabled by a real-time operating system kernel program before program execution is halted and when the particular program task is being executed, the breakpoint is enabled by the real-time operating system kernel program.
13. The method of claim 1 , further comprising adjusting a busy flag to prevent a debugger program from accessing the breakpoint table.
14. The method of claim 1 , further comprising evaluating a checksum value associated with the breakpoint table.
15. The method of claim 14 , wherein evaluating the checksum value is performed prior to reading the breakpoint table.
16. A method of loading a breakpoint enabled page of a computer program into a computer readable memory, the method comprising:
identifying a page of a computer program to be loaded into the computer readable memory;
prior to loading the page of the computer program, reading a breakpoint table to identify a set of breakpoints having memory addresses located within the page of the computer program, each breakpoint in the set of breakpoints having an instruction address and an instruction storage location;
for each of the set of breakpoints, reading an operating instruction of the page of the computer program located at the instruction address, storing a copy of the operating instruction at the instruction storage location within the breakpoint table, and loading a trap instruction at the instruction address to replace the operating instruction in the page of the computer program, to create a breakpoint enabled page of the computer program;
loading the breakpoint enabled page of the computer program into the computer readable memory; and
loading the breakpoint table from a host computer into the computer readable memory;
wherein the host computer includes a debugger routine that is invoked upon execution of at least one of the trap instructions, wherein the debugger routine is prevented from accessing the breakpoint table while a memory paging routine within an embedded processor system is in the process of generating and then loading the breakpoint enabled page into the computer readable memory.
17. A method of loading a breakpoint enabled page of a computer program into a computer readable memory, the method comprising:
identifying a page of a computer program to be loaded into the computer readable memory;
prior to loading the page of the computer program, reading a breakpoint table to identify a set of breakpoints having memory addresses located within the page of the computer program, each breakpoint in the set of breakpoints having an instruction address and an instruction storage location;
for each of set of breakpoints, reading an operation instruction of page of the computer program located at the instrucrion address, storing a copy of the operating instruction at the instruction storage location within the breakpoint table, and loading a trap instruction at the instruction at the instruction address to replace the operating instruction in the page of the computer program, to create a breakpoint enabled page of the computer program; and
loading the breakpoint enabled page of the computer program into the computer readable memory, wherein the breakpoint enabled page of the computer memory is to be reading the breakpoint table to identify at least one breakpoint having an address located within the second page of the computer program prior to loading the second page of the computer program into the computer readable memory.
18. The method of claim 17 , further comprising, for the at least one breakpoint, reading an operating instruction of the second page of the computer program located at the instruction address, storing a copy of the operating instruction at the instruction storage location within the breakpoint table for the at least one breakpoint, and loading a trap instruction at the instruction address to replace the operating instruction in the second page of the computer program, to create a breakpoint enabled second page of the computer program.
19. The method of claim 18 , further comprising loading the breakpoint enabled second page of the computer program into the computer readable memory.
20. The method of claim 17 , wherein the second page of the computer program is received from an external media source.
21. The method of claim 20 , wherein the external media source is selected form a hard disk drive, optical storage, and a flash memory.
22. The method of claim 20 , wherein the external media source is within a host computer and wherein the host computer communicates with the computer readable memory using a JTAG interface.
23. An embedded system comprising:
a processor; and
memory accessible to the processor, the memory including:
a breakpoint table including a set of entries, each entry of the set of entries identifying an instruction address and including a storage cell for a replaced instruction and including a task identifier; and
computer implemented instructions operable by the processor to access the breakpoint table and when the task identifier matches a task to be executed to insert a trap instruction associated with each of the set of entries included in the breakpoint table at the identified instruction addresses within a program page prior to loading the program page with the trap instruction for execution, wherein access to the breakpoint table by a debugger routine is prevented during creation and loading of the breakpoint enabled page.
24. The embedded system of claim 23 , wherein the memory has an available capacity that is smaller than a program associated with the program page.
25. A system comprising:
a host computer including debugger software; and
an embedded system accessible to the host computer, the embedded system including:
a processor; and
memory accessible to the processor, the memory including:
a breakpoint table including a set of entries, each entry of the set of entries identifying an instruction address associated with an instruction included in a page of a program that is to be replaced by a trap instruction, each entry including a storage cell for storing the replaced instruction, each entry including a task identifier for identifying a task to be executed, wherein the memory includes computer instructions operable by the processor to access the breakpoint table and when the task identifier matches a task to be executed to insert the trap instruction at the instruction address within the page prior to loading the page with the trap instruction for execution, wherein access to the breakpoint table by a debugger routine is prevented during creation and loading of the breakpoint enabled page.
26. The system of claim 25 , wherein the breakpoint table is created by the debugger software and transferred to the embedded system.
27. The system of claim 25 , wherein a capacity of the memory is less than a size of the program.
28. The system of claim 25 , wherein the program is stored on a media source accessible to the memory.