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    SubjectRe: [PATCH 11/14] MIPS: memblock: Print out kernel virtual mem layout
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    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

    Thanks,
    Matt

    >
    >> --
    >> Florian

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