linux-kernel - [PATCH 0/2] Proper ro_after

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Date:	Tue,  7 Jun 2016 14:06:59 +0200
From:	Heiko Carstens <heiko.carstens@...ibm.com>
To:	Kees Cook <keescook@...omium.org>, Ingo Molnar <mingo@...nel.org>
Cc:	Martin Schwidefsky <schwidefsky@...ibm.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 0/2] Proper ro_after_init implementation on s390

These two patches allow a proper ro_after_init implementation on s390.

The current implementation maps __ro_after_init to __read_mostly,
which means that ro_after_init data won't be write protected at all.

Reason for this is that s390 write protects rodata very early (before
init calls) and therefore adding ro_after_init data to rodata would
lead to crashes.

Since I don't want to mark the page table entries much later read-only
on s390 just to make this work, allow an architecture specific
handling which can be used to move the ro_after_init data to a
different place which can be marked read-only later when
mark_rodata_ro gets executed.

Note: these patches require the s390 kernel page table splitting
support which currently is only available at

git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux.git features

(included in linux-next)

Therefore, if we can agree on this solution I'd like to add these
patches to the s390 tree, so it can be merged during the next merge
window.

Heiko Carstens (2):
  vmlinux.lds.h: allow arch specific handling of ro_after_init data section
  s390/mm: add proper __ro_after_init support

 arch/s390/include/asm/cache.h     |  3 ---
 arch/s390/include/asm/sections.h  |  1 +
 arch/s390/kernel/vmlinux.lds.S    | 12 +++++++++++-
 arch/s390/mm/init.c               |  7 ++++---
 arch/s390/mm/vmem.c               |  7 +++----
 include/asm-generic/vmlinux.lds.h | 10 +++++++++-
 6 files changed, 28 insertions(+), 12 deletions(-)

-- 
2.6.6