From: Balbir Singh <bsingharora@gmail.com>
To: David Laight <David.Laight@aculab.com>
Cc: "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"mpe@ellerman.id.au" <mpe@ellerman.id.au>,
"naveen.n.rao@linux.vnet.ibm.com"
<naveen.n.rao@linux.vnet.ibm.com>,
"paulus@samba.org" <paulus@samba.org>
Subject: Re: [PATCH v5 2/7] powerpc/vmlinux.lds: Align __init_begin to 16M
Date: Thu, 29 Jun 2017 21:36:27 +1000 [thread overview]
Message-ID: <CAKTCnzkptf=p9SzpyFRtDXEHRMDznukFsaeFxVERZvDLq5Bf_w@mail.gmail.com> (raw)
In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6DD002D97F@AcuExch.aculab.com>
On Thu, Jun 29, 2017 at 9:29 PM, David Laight <David.Laight@aculab.com> wrote:
> From: Balbir Singh
>> Sent: 28 June 2017 18:04
>> For CONFIG_STRICT_KERNEL_RWX align __init_begin to 16M.
>> We use 16M since its the larger of 2M on radix and 16M
>> on hash for our linear mapping. The plan is to have
>> .text, .rodata and everything upto __init_begin marked
>> as RX. Note we still have executable read only data.
>> We could further align rodata to another 16M boundary.
>> I've used keeping text plus rodata as read-only-executable
>> as a trade-off to doing read-only-executable for text and
>> read-only for rodata.
> ...
>
> Doesn't this go against 'address space randomisation'?
> (Yes I realise a PIC kernel is probably non-trivial to compile
> and load.)
I presume you mean Kernel ASLR. I am not sure why you think
it goes against KASLR, it's just aligning the _stext and __init_begin,
they can be anywhere in memory. I've tested with a relocatable kernel
Balbir Singh.
next prev parent reply other threads:[~2017-06-29 11:36 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-28 17:04 [PATCH v5 0/7] Provide STRICT_KERNEL_RWX for powerpc Balbir Singh
2017-06-28 17:04 ` [PATCH v5 1/7] powerpc/lib/code-patching: Use alternate map for patch_instruction() Balbir Singh
2017-06-28 17:04 ` [PATCH v5 2/7] powerpc/vmlinux.lds: Align __init_begin to 16M Balbir Singh
2017-06-29 11:29 ` David Laight
2017-06-29 11:36 ` Balbir Singh [this message]
2017-06-28 17:04 ` [PATCH v5 3/7] powerpc/platform/pseries/lpar: Fix updatepp and updateboltedpp Balbir Singh
2017-06-28 17:04 ` [PATCH v5 4/7] powerpc/mm/hash: Implement mark_rodata_ro() for hash Balbir Singh
2017-06-28 17:04 ` [PATCH v5 5/7] powerpc/mm/radix: Implement mark_rodata_ro() for radix Balbir Singh
2017-06-28 17:04 ` [PATCH v5 6/7] mm/radix: Fix permissions correctly for interrupt_vectors Balbir Singh
2017-06-28 17:04 ` [PATCH v5 7/7] powerpc/Kconfig: Enable STRICT_KERNEL_RWX Balbir Singh
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