lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Fri, 3 Oct 2014 15:53:08 -0700 From: Andy Lutomirski <luto@...capital.net> To: Chuck Ebbert <cebbert.lkml@...il.com> Cc: Oleg Nesterov <oleg@...hat.com>, Sasha Levin <sasha.levin@...cle.com>, Ingo Molnar <mingo@...nel.org>, "H. Peter Anvin" <hpa@...or.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Peter Zijlstra <peterz@...radead.org>, Denys Vlasenko <dvlasenk@...hat.com>, Thomas Gleixner <tglx@...utronix.de> Subject: Re: [tip:x86/asm] x86: Speed up ___preempt_schedule*() by using THUNK helpers On Fri, Oct 3, 2014 at 3:48 PM, Chuck Ebbert <cebbert.lkml@...il.com> wrote: > On Fri, 3 Oct 2014 23:41:24 +0200 > Oleg Nesterov <oleg@...hat.com> wrote: > >> On 10/03, Chuck Ebbert wrote: >> > >> > > [ 921.917752] ? ___preempt_schedule_context (arch/x86/lib/thunk_64.S:44) >> > > [ 921.917752] ? preempt_schedule_context (kernel/context_tracking.c:145) >> > > [ 921.917752] ? ___preempt_schedule_context (arch/x86/lib/thunk_64.S:44) >> > > [ 921.917752] ? preempt_schedule_context (kernel/context_tracking.c:145) >> > > [ 921.917752] ? ___preempt_schedule_context (arch/x86/lib/thunk_64.S:44) >> > > [ 921.917752] ? preempt_schedule_context (kernel/context_tracking.c:145) >> > > [ 921.917752] ? ___preempt_schedule_context (arch/x86/lib/thunk_64.S:44) >> > > [ 921.917752] ? preempt_schedule_context (kernel/context_tracking.c:145) >> > > [ 921.917752] ? ___preempt_schedule_context (arch/x86/lib/thunk_64.S:44) >> > > [ 921.917752] ? preempt_schedule_context (kernel/context_tracking.c:145) >> > >> > <snip lots of repeats of this> >> > >> > I *think* this is because RBP isn't being saved across task switch >> > anymore? >> > >> > Without CONFIG_FRAME_POINTERS that night not be a problem... >> >> Could you please spell? >> >> I don't even understand "RBP isn't being saved", SAVE_CONTEXT/RESTORE_CONTEXT >> do push/pop %rbp? >> > > SAVE_ARGS/RESTORE_ARGS, which is what THUNK uses, doesn't push/pop %rbp > > Before, SAVE_ALL/RESTORE_ALL were being used around the call to > preempt_schedule(). So from the symptoms I thought this was the problem. rbp is callee-saved no matter what, unless my memory of the ABI is *waaaaay* off. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists