On Tue, May 07, 2019 at 10:08:50AM -0700, Linus Torvalds wrote: > On Tue, May 7, 2019 at 9:34 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > > Would you consider my approach later on, under the guise of unification? > > WHY? > > The *only* advantage of your patch is that trivial "look up kernel stack" macro. > > Seriously. There's absolutely nothing else. The ftrace_regs_caller, the kprobe tramplines, the unwinder, they all have 'funny' bits because pt_regs isn't 'right'. > So the whole "let's clean up x86-32 to look like x86-64, which got > things right" is to me a completely bogus argument. x86-64 got the > "yes, push ss/sp unconditionally" part right, but got a lot of other > things horribly wrong. So this is all just one small detail that > differs, across two architectures that are similar but have very > different warts. It's a detail that leaks into the C code. Yes SWAPGS is horrible crap, but C code doesn't much care. The partial pt_regs thing otoh comes up a fair number of times. Anyway; I think we're at the point where we'll have to agree to disagree (or maybe slightly past it).
