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: Sat, 01 Feb 2014 13:36:54 -0800 From: "H. Peter Anvin" <hpa@...or.com> To: George Spelvin <linux@...izon.com>, torvalds@...ux-foundation.org CC: jack@...e.cz, linux-kernel@...r.kernel.org, maarten-baert@...mail.com, mingo@...nel.org, nate@...tsmathematics.com, priikone@....fi, sbsiddha@...il.com, stable@...r.kernel.org, tglx@...utronix.de, x86@...nel.org Subject: Re: [PATCH] Make math_state_restore() save and restore the interrupt flag It would be good to know how often #3 happens on a real workload. On February 1, 2014 1:17:10 PM PST, George Spelvin <linux@...izon.com> wrote: >> .. which *does* actually bring up something that might work, and >might >> be a good idea: remove the "restore math state or set TS" from the >> normal kernel paths *entirely*, and move it to the "return to user >> space" phase. > >This definitely seems much more sensible. For processors without >optimized context save/restore, the decision whether to restore eagerly >is best made once the kernel has decided what it's returning *to*. > >>From an interrupt handler, there are now three cases: >1) FPU not in use, available for immediate use. >2) FPU in use by user-space; save to <location> before using. >3) FPU in use by kernel code; may not be used (unless we want > to add nested FPU state save hair). -- Sent from my mobile phone. Please pardon brevity and lack of formatting. -- 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