From: Serge Semin <fancer.lancer@gmail.com>
To: Matt Redfearn <matt.redfearn@mips.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>,
ralf@linux-mips.org, miodrag.dinic@mips.com, jhogan@kernel.org,
goran.ferenc@mips.com, david.daney@cavium.com,
paul.gortmaker@windriver.com, paul.burton@mips.com,
alex.belits@cavium.com, Steven.Hill@cavium.com,
alexander.sverdlin@nokia.com, kumba@gentoo.org,
marcin.nowakowski@mips.com, James.hogan@mips.com,
Peter.Wotton@mips.com, Sergey.Semin@t-platforms.ru,
linux-mips@linux-mips.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 11/14] MIPS: memblock: Print out kernel virtual mem layout
Date: Fri, 19 Jan 2018 17:27:12 +0300 [thread overview]
Message-ID: <20180119142712.GA3101@mobilestation> (raw)
In-Reply-To: <b2797958-d217-9c8d-10ca-b9bc43ae585b@mips.com>
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
next prev parent reply other threads:[~2018-01-19 14:27 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-17 22:22 [PATCH 00/14] MIPS: memblock: Switch arch code to NO_BOOTMEM Serge Semin
2018-01-17 22:22 ` [PATCH 01/14] MIPS: memblock: Add RESERVED_NOMAP memory flag Serge Semin
2018-01-17 22:23 ` [PATCH 02/14] MIPS: memblock: Surely map BSS kernel memory section Serge Semin
2018-01-22 16:35 ` Matt Redfearn
2018-01-22 21:47 ` Serge Semin
2018-01-23 11:03 ` Matt Redfearn
2018-01-23 19:27 ` Serge Semin
2018-01-24 9:49 ` Matt Redfearn
2018-01-24 10:03 ` Serge Semin
2018-01-17 22:23 ` [PATCH 03/14] MIPS: memblock: Reserve initrd memory in memblock Serge Semin
2018-01-17 22:23 ` [PATCH 04/14] MIPS: memblock: Discard bootmem initialization Serge Semin
2018-01-17 22:23 ` [PATCH 05/14] MIPS: memblock: Add reserved memory regions to memblock Serge Semin
2018-01-17 22:23 ` [PATCH 06/14] MIPS: memblock: Reserve kdump/crash regions in memblock Serge Semin
2018-01-17 22:23 ` [PATCH 07/14] MIPS: memblock: Mark present sparsemem sections Serge Semin
2018-01-24 6:13 ` Marcin Nowakowski
2018-01-24 7:27 ` Serge Semin
2018-01-17 22:23 ` [PATCH 08/14] MIPS: memblock: Simplify DMA contiguous reservation Serge Semin
2018-01-17 22:23 ` [PATCH 09/14] MIPS: memblock: Allow memblock regions resize Serge Semin
2018-01-17 22:23 ` [PATCH 10/14] MIPS: memblock: Perform early low memory test Serge Semin
2018-01-17 22:23 ` [PATCH 11/14] MIPS: memblock: Print out kernel virtual mem layout Serge Semin
2018-01-18 20:03 ` Florian Fainelli
2018-01-18 20:18 ` Serge Semin
2018-01-19 7:59 ` Matt Redfearn
2018-01-19 14:27 ` Serge Semin [this message]
2018-01-23 15:35 ` Matt Redfearn
2018-01-23 19:10 ` Serge Semin
2018-01-24 9:46 ` Matt Redfearn
2018-01-24 10:08 ` Serge Semin
2018-01-17 22:23 ` [PATCH 12/14] MIPS: memblock: Discard bootmem from Loongson3 code Serge Semin
2018-01-23 22:28 ` Jiaxun Yang
2018-01-23 19:36 ` Serge Semin
2018-01-17 22:23 ` [PATCH 13/14] MIPS: memblock: Discard bootmem from SGI IP27 code Serge Semin
2018-01-17 22:23 ` [PATCH 14/14] MIPS: memblock: Deactivate bootmem allocator Serge Semin
2018-01-23 23:59 ` James Hogan
2018-01-24 8:28 ` Serge Semin
2018-01-22 16:36 ` [PATCH 00/14] MIPS: memblock: Switch arch code to NO_BOOTMEM Matt Redfearn
2018-01-22 21:33 ` Serge Semin
2018-01-23 11:29 ` Mathieu Malaterre
2018-01-23 14:01 ` Matt Redfearn
2018-01-25 17:58 ` Alexander Sverdlin
2018-01-25 20:17 ` Serge Semin
2018-01-31 0:21 ` Serge Semin
2018-02-02 3:54 ` [PATCH v2 00/15] " Serge Semin
2018-02-02 3:54 ` [PATCH v2 01/15] MIPS: memblock: Add RESERVED_NOMAP memory flag Serge Semin
2018-02-13 11:21 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 02/15] MIPS: memblock: Surely map BSS kernel memory section Serge Semin
2018-02-13 11:22 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 03/15] MIPS: memblock: Reserve initrd memory in memblock Serge Semin
2018-02-13 11:22 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 04/15] MIPS: memblock: Discard bootmem initialization Serge Semin
2018-02-13 11:28 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 05/15] MIPS: KASLR: Drop relocatable fixup from reservation_init Serge Semin
2018-02-13 11:30 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 06/15] MIPS: memblock: Add reserved memory regions to memblock Serge Semin
2018-02-13 13:44 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 07/15] MIPS: memblock: Reserve kdump/crash regions in memblock Serge Semin
2018-02-13 13:45 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 08/15] MIPS: memblock: Mark present sparsemem sections Serge Semin
2018-02-13 13:50 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 09/15] MIPS: memblock: Simplify DMA contiguous reservation Serge Semin
2018-02-13 13:51 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 10/15] MIPS: memblock: Allow memblock regions resize Serge Semin
2018-02-13 13:55 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 11/15] MIPS: memblock: Perform early low memory test Serge Semin
2018-02-13 14:01 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 12/15] MIPS: memblock: Print out kernel virtual mem layout Serge Semin
2018-02-13 14:05 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 13/15] MIPS: memblock: Discard bootmem from Loongson3 code Serge Semin
2018-02-13 14:09 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 14/15] MIPS: memblock: Discard bootmem from SGI IP27 code Serge Semin
2018-02-13 14:17 ` Matt Redfearn
2018-02-02 3:54 ` [PATCH v2 15/15] MIPS: memblock: Deactivate bootmem allocator Serge Semin
2018-02-13 14:18 ` Matt Redfearn
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