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 PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Sun, 19 Oct 2014 23:35:34 +0200 From: Peter Zijlstra <peterz@...radead.org> To: Andy Lutomirski <luto@...capital.net> Cc: Valdis Kletnieks <Valdis.Kletnieks@...edu>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Paul Mackerras <paulus@...ba.org>, Arnaldo Carvalho de Melo <acme@...nel.org>, Ingo Molnar <mingo@...hat.com>, Kees Cook <keescook@...omium.org>, Andrea Arcangeli <aarcange@...hat.com>, Erik Bosman <ebn310@....vu.nl> Subject: Re: [RFC 5/5] x86,perf: Only allow rdpmc if a perf_event is mapped On Thu, Oct 16, 2014 at 05:00:56PM -0700, Andy Lutomirski wrote: > The current cap_user_rdpmc code seems rather confused to me. On x86, > *all* events set cap_user_rdpmc if the global rdpmc control is set. > But only x86_pmu events define .event_idx, so amd uncore events won't > actually expose their rdpmc index to userspace. > > Would it make more sense to add a flag PERF_X86_EVENT_RDPMC_PERMITTED > that gets set on all events created while rdpmc == 1, to change > x86_pmu_event_idx to do something like: > > if (event->hw.flags & PERF_X86_EVENT_RDPMC_PERMITTED) > return event->hw.event_base_rdpmc + 1; > else > return 0; > > and to change arch_perf_update_userpage cap_user_rdpmc to match > PERF_X86_EVENT_RDPMC_PERMITTED? > > Then we could ditch the static key and greatly simplify writes to the > rdpmc flag by just counting PERF_X86_EVENT_RDPMC_PERMITTED events. > > This would be a user-visible change on AMD, and I can't test it. I have AMD hardware to test this. But yes something like that seems fine. -- 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