Re: [RFC PATCH for 4.15 v12 00/22] Restartable sequences and CPU op vector

From: Andi Kleen
Date: Wed Nov 22 2017 - 13:10:38 EST

> > If anyone ever reports that as a problem, I'll gladly fix it in the
> > kernel. That's doable without an ABI change. If rseq-like things
> > started breaking single-stepping, we can't just fix it in the kernel.

AFAIK nobody ever complained about it since we have vsyscalls and vDSOs.

> Very true. And rseq does break both line-level and instruction-level
> single-stepping.

They can just set a break point after it and continue.

In fact it could be even expressed to the debugger to do
that automatically based on some dwarf extension.

I also disagree that opv somehow "solves" debugging: it's a completely
different code path that has nothing to do with the original code path.
That's not debugging, that's at best a workaround. I don't think it's
any better than the break point method.