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Groups > linux.kernel > #1241581
| From | Borislav Petkov <bp@alien8.de> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v2 05/36] x86/entry/64/compat: Fix SYSENTER's NT flag before user memory access |
| Date | 2015-10-07 17:10 +0200 |
| Message-ID | <qgYvU-8pw-5@gated-at.bofh.it> (permalink) |
| References | <qgoC6-715-5@gated-at.bofh.it> <qgoLN-7cw-31@gated-at.bofh.it> <qgUVj-39p-9@gated-at.bofh.it> <qgY2S-7BV-39@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Wed, Oct 07, 2015 at 10:33:10AM -0400, Brian Gerst wrote:
> This is an optimization, since NT is unlikely to be set. The forward
> branch is usually predicted as not taken, and it keeps these rarely
> used instructions out of the hot cache.
Ah, slick. Because branch predictors mark new branches as not taken and
this particular one will remain non-taken in the majority of the cases.
I think this warrants a mention in the comment above it though...
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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[PATCH v2 05/36] x86/entry/64/compat: Fix SYSENTER's NT flag before user memory access Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
Re: [PATCH v2 05/36] x86/entry/64/compat: Fix SYSENTER's NT flag before user memory access Borislav Petkov <bp@alien8.de> - 2015-10-07 13:20 +0200
Re: [PATCH v2 05/36] x86/entry/64/compat: Fix SYSENTER's NT flag before user memory access Brian Gerst <brgerst@gmail.com> - 2015-10-07 16:40 +0200
Re: [PATCH v2 05/36] x86/entry/64/compat: Fix SYSENTER's NT flag before user memory access Borislav Petkov <bp@alien8.de> - 2015-10-07 17:10 +0200
[PATCH] x86/entry/64/compat: Document sysenter_fix_flags's reason for existence Borislav Petkov <bp@alien8.de> - 2015-10-09 19:10 +0200
Re: [PATCH] x86/entry/64/compat: Document sysenter_fix_flags's reason for existence Andy Lutomirski <luto@amacapital.net> - 2015-10-09 21:10 +0200
[tip:x86/asm] x86/entry/64/compat: Document sysenter_fix_flags' s reason for existence tip-bot for Borislav Petkov <tipbot@zytor.com> - 2015-10-11 11:20 +0200
[tip:x86/asm] x86/entry/64/compat: Fix SYSENTER' s NT flag before user memory access tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-07 18:20 +0200
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