Unwind past Go runtime.morestack
#184
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gnurizen
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Dec 16, 2025
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gnurizen
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Looks good, seems like the perfect candidate for a coredump unit test(s). It also seems like these changes will probably cause a fair bit of merge headache so once they are polished up we should look at upstreaming them.
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In Go,
runtime.morestackis called by goroutines that have exhausted their stack space and need to create more. This can be a significant bottleneck in some programs. As can be seen from the above link, the function in question clears the frame pointer before calling intonewstack, making it impossible for us to unwind further. Luckily, before doing so, it stashes the necessary registers on the current goroutine.This PR introduces a new unwinding command specifically for unwinding past
runtime.morestack. It uses the infrastructure already developed for Go Custom Labels to find the current goroutine, then grabs the appropriate values. Currently, this only works in Go 1.25 and does not work for kernel stacks; making it more general will be done in a later follow-up.