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    SubjectRe: [PATCH 11/14] MIPS: memblock: Print out kernel virtual mem layout
    On Fri, Jan 19, 2018 at 07:59:43AM +0000, Matt Redfearn <matt.redfearn@mips.com> wrote:

    Hello Matt,

    > Hi Serge,
    >
    >
    >
    > On 18/01/18 20:18, Serge Semin wrote:
    > >On Thu, Jan 18, 2018 at 12:03:03PM -0800, Florian Fainelli <f.fainelli@gmail.com> wrote:
    > >>On 01/17/2018 02:23 PM, Serge Semin wrote:
    > >>>It is useful to have the kernel virtual memory layout printed
    > >>>at boot time so to have the full information about the booted
    > >>>kernel. In some cases it might be unsafe to have virtual
    > >>>addresses freely visible in logs, so the %pK format is used if
    > >>>one want to hide them.
    > >>>
    > >>>Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
    > >>
    > >>I personally like having that information because that helps debug and
    > >>have a quick reference, but there appears to be a trend to remove this
    > >>in the name of security:
    > >>
    > >>https://patchwork.kernel.org/patch/10124007/
    > >>
    > >>maybe hide this behind a configuration option?
    > >
    > >Yeah, arm code was the place I picked the function up.) But in my case
    > >I've used %pK so the pointers would disappear from logging when
    > >kptr_restrict sysctl is 1 or 2.
    > >I agree, that we might need to make the printouts optional. If there is
    > >any kernel config, which for instance increases the kernel security we
    > >could also use it or anything else to discard the printouts at compile
    > >time.
    >
    >
    > Certainly, when KASLR is active it would be preferable to hide this
    > information, so you could use CONFIG_RELOCATABLE. The existing KASLR stuff
    > additionally hides this kind of information behind CONFIG_DEBUG_KERNEL, so
    > that only people actively debugging the kernel see it:
    >
    > http://elixir.free-electrons.com/linux/v4.15-rc8/source/arch/mips/kernel/setup.c#L604

    Ok. I'll hide the printouts behind both of that config macros in the next patchset
    version.

    Regards,
    -Sergey

    >
    > Thanks,
    > Matt
    >
    > >
    > >>--
    > >>Florian

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