Call Stack Trace Generation Without Frame Pointers
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Solution Overview
Problem
Existing profilers generate inaccurate stack traces when dealing with call stacks that lack frame pointers, often resulting in false positives due to the inability to accurately identify return addresses.
Innovation Solution
A method and apparatus that analyze a call stack to identify potential return addresses, verify them using debugging information, and generate stack traces based on actual return addresses, employing a processing device with components running in both kernel and user contexts to ensure accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If profilers generate stack traces by walking through the call stack and recording return addresses, then stack traces can be generated for call stacks lacking frame pointers, but false positives occur where regions appearing to include return addresses do not actually include return addresses
Solution Approach 1:
The patent introduces an intermediary verification mechanism using debugging information and return address validation logic. This intermediary layer checks potential return addresses against actual return address expectations, filtering out false positives while maintaining the ability to handle call stacks without frame pointers.
Solution Approach 2:
The patent replaces the mechanical approach of simply recording any region that appears to be a return address with a more sophisticated verification system. This substitution uses debugging information and contextual analysis to distinguish actual return addresses from false positives, improving measurement precision while maintaining adaptability.
2Measurement precision
If profilers use frame pointers to generate stack traces, then stack trace accuracy is maintained, but the method fails when stack frames lack frame pointers
Solution Approach 1:
The patent performs preliminary analysis by capturing debugging information and establishing expected return address patterns before the actual stack trace generation. This preliminary action enables the system to handle call stacks without frame pointers by using alternative verification methods based on the pre-captured debugging context.
Solution Approach 2:
The patent changes the parameters used for return address identification when frame pointers are unavailable. Instead of relying solely on frame pointer relationships, the system uses debugging information, return address validation, and contextual analysis to determine actual return addresses, thereby maintaining accuracy across different call stack configurations.
Data Source
AI summary
A processing device executing an application analyzer analyzes a call stack having a plurality of stack frames to identify potential return addresses for the plurality of stack frames. The processing device records a value of each of the potential return addresses and records a location on the call stack for each of the potential return addresses. The processing device then determines which of the potential return addresses are actual return addresses based on debugging information and the recorded locations of the potential return addresses. The processing device generates a stack trace based on the actual return addresses.