linuxppc-dev.lists.ozlabs.org archive mirror
 help / color / mirror / Atom feed
From: Balbir Singh <bsingharora@gmail.com>
To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au
Cc: naveen.n.rao@linux.vnet.ibm.com, christophe.leroy@c-s.fr,
	paulus@samba.org, Balbir Singh <bsingharora@gmail.com>
Subject: [PATCH v5 2/7] powerpc/vmlinux.lds: Align __init_begin to 16M
Date: Thu, 29 Jun 2017 03:04:06 +1000	[thread overview]
Message-ID: <20170628170411.28864-3-bsingharora@gmail.com> (raw)
In-Reply-To: <20170628170411.28864-1-bsingharora@gmail.com>

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.

We don't use multi PT_LOAD in PHDRS because we are
not sure if all bootloaders support them. This patch keeps
PHDRS in vmlinux.lds.S as the same they are with just one
PT_LOAD for all of the kernel marked as RWX (7).

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
 arch/powerpc/kernel/vmlinux.lds.S | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index ace6b65..b1a2505 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -8,6 +8,12 @@
 #include <asm/cache.h>
 #include <asm/thread_info.h>
 
+#ifdef CONFIG_STRICT_KERNEL_RWX
+#define STRICT_ALIGN_SIZE	(1 << 24)
+#else
+#define STRICT_ALIGN_SIZE	PAGE_SIZE
+#endif
+
 ENTRY(_stext)
 
 PHDRS {
@@ -123,7 +129,7 @@ SECTIONS
 	PROVIDE32 (etext = .);
 
 	/* Read-only data */
-	RODATA
+	RO_DATA(PAGE_SIZE)
 
 	EXCEPTION_TABLE(0)
 
@@ -140,7 +146,7 @@ SECTIONS
 /*
  * Init sections discarded at runtime
  */
-	. = ALIGN(PAGE_SIZE);
+	. = ALIGN(STRICT_ALIGN_SIZE);
 	__init_begin = .;
 	INIT_TEXT_SECTION(PAGE_SIZE) :kernel
 
-- 
2.9.4

  parent reply	other threads:[~2017-06-28 17:04 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 ` Balbir Singh [this message]
2017-06-29 11:29   ` [PATCH v5 2/7] powerpc/vmlinux.lds: Align __init_begin to 16M David Laight
2017-06-29 11:36     ` Balbir Singh
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170628170411.28864-3-bsingharora@gmail.com \
    --to=bsingharora@gmail.com \
    --cc=christophe.leroy@c-s.fr \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mpe@ellerman.id.au \
    --cc=naveen.n.rao@linux.vnet.ibm.com \
    --cc=paulus@samba.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).