linux-kernel - Re: [PATCH 0/3] perf_events: update extra shared registers management (v2)

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <BANLkTinN92UpxU85r17zB+Khba8k59nJTA@mail.gmail.com>
Date:	Mon, 23 May 2011 12:58:20 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	"mingo@...e.hu" <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>,
	Lin Ming <ming.m.lin@...el.com>
Subject: Re: [PATCH 0/3] perf_events: update extra shared registers management (v2)

On Mon, May 23, 2011 at 11:36 AM, Stephane Eranian <eranian@...gle.com> wrote:
> On Mon, May 23, 2011 at 11:32 AM, Peter Zijlstra <peterz@...radead.org> wrote:
>> On Mon, 2011-05-23 at 11:11 +0200, Peter Zijlstra wrote:
>>> +       if (event->hw.extra_reg.idx == EXTRA_REG_RSP_0) {
>>> +               event->attr.config = 0x01bb;
>>> +               event->hw.extra_reg.idx = EXTRA_REG_RSP_1;
>>> +               event->hw.extra_reg.msr = MSR_OFFCORE_RSP_1;
>>> +       } else if (event->hw.extra_reg.idx == EXTRA_REG_RSP_1) {
>>> +               event->attr.config = 0x01b7;
>>> +               event->hw.extra_reg.idx = EXTRA_REG_RSP_0;
>>> +               event->hw.extra_reg.msr = MSR_OFFCORE_RSP_0;
>>> +       }
>>
>> clearly I meant to write:
>>
>> event->hw.config &= ~X86_RAW_EVENT_MASK;

Not quite, you want INTEL_ARCH_EVENT_MASK instead
because you only want to modify umask+event code.

There is a major issue as it stands, though. You can
get into an infinite loop bouncing between RSP_0 and RSP_1
in case there is no solution in the group, i.e., you have 3 values
for the extra MSR. I think you need to count the number of times
you've called intel_try_alt_er() with success or maintain some sort
of bitmask of possible alternate choices and when you exhaust that,
you simply fail.
--
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/