> On Nov 29, 2018, at 9:07 AM, Peter Zijlstra <pet...@infradead.org> wrote: > > On Thu, Nov 29, 2018 at 09:02:23AM -0800, Andy Lutomirski wrote: >>> On Nov 29, 2018, at 8:50 AM, Linus Torvalds <torva...@linux-foundation.org> >>> wrote: > >>> So no. Do *not* try to change %rsp on the stack in the bp handler. >>> Instead, I'd suggest: >>> >>> - just restart the instruction (with the suggested "ptregs->rip --") >>> >>> - to avoid any "oh, we're not making progress" issues, just fix the >>> instruction yourself to be the right call, by looking it up in the >>> "what needs to be fixed" tables. >>> >>> No? > >> Or do you think we can avoid the IPI while the int3 is there? > > I'm thinking Linus is suggesting the #BP handler does the text write too > (as a competing store) and then sync_core() and restarts. > > But I think that is broken, because then there is no telling what the > other CPUs will observe. Does anyone know what the actual hardware semantics are? The SDM is not particularly informative unless I looked at the wrong section.
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Steven Rostedt
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Andy Lutomirski
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Josh Poimboeuf
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Andy Lutomirski
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Steven Rostedt
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Josh Poimboeuf
- Re: [PATCH v2 4/4] x86/static_call: Add inline static call... Linus Torvalds
- Re: [PATCH v2 4/4] x86/static_call: Add inline static... Steven Rostedt
- Re: [PATCH v2 4/4] x86/static_call: Add inline static... Andy Lutomirski
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Peter Zijlstra
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Andy Lutomirski
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Jiri Kosina
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Steven Rostedt
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Linus Torvalds
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Steven Rostedt
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Linus Torvalds
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Linus Torvalds
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Steven Rostedt
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Linus Torvalds
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Steven Rostedt
- Re: [PATCH v2 4/4] x86/static_call: Add inline st... Linus Torvalds