linux-kernel - Re: [RFC PATCH v2] perf/x86: make perf callchain work without CONFIG_FRAME

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: <CACPcB9eXWcvFvx6RpRLXc-jKTuejYx4ZiYMPj-Da3fESB=tYng@mail.gmail.com>
Date:   Wed, 17 Apr 2019 22:41:52 +0800
From:   Kairui Song <kasong@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>, Dave Young <dyoung@...hat.com>
Subject: Re: [RFC PATCH v2] perf/x86: make perf callchain work without CONFIG_FRAME_POINTER

On Wed, Apr 17, 2019 at 1:45 AM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Wed, Apr 17, 2019 at 01:39:19AM +0800, Kairui Song wrote:
> > And I also think the "fake"/"real" reg is fragile, could we abuse
> > another eflag (just like PERF_EFLAGS_EXACT) to indicate the regs are
> > partially dumped fake registers?
>
> Sure, the SDM seems to suggest bits 1,3,5,15 are 'available'. We've
> already used 3 and 5, and I think we can use !X86_EFLAGS_FIXED to
> indicate a fake regs set. Any real regs set will always have that set.

Thanks! This is a good idea. Will update accordingly in V3 later.





--
Best Regards,
Kairui Song