Messages in this thread | | | Date | Mon, 29 Feb 2016 23:37:22 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 02/10] x86/entry/compat: In SYSENTER, sink AC clearing below the existing FLAGS test |
| |
On Mon, Feb 29, 2016 at 05:33:16PM -0500, Brian Gerst wrote: > SYSENTER doesn't save EFLAGS so we have to fudge it by pushing the > kernel's flags. Most user programs never set AC, so by adding it to > the test for flags to clear we can avoid the CLAC or POPF in the > common case that it is already clear.
Yeah, Andy just explained it to me on IRC. Thanks guys.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply.
| |