Re: [REGRESSION] x86/entry: TIF_SINGLESTEP handling is still broken

From: Andy Lutomirski
Date: Sun Jan 31 2021 - 17:15:02 EST

> On Jan 31, 2021, at 1:30 PM, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> Btw Kyle, do you have a good simple test-case for this? Clearly this
> is some weird special case use, and regular single-stepping works
> fine.

Indeed, and I have tests for this.

TBH, the TIF_SINGLESTEP code makes no sense, and I think it has at least three overloaded meanings. I can try to look in a bit. I’ve mostly avoided breaking it in the past, but that doesn’t mean I understand the original intent.