linux-kernel - [PATCH] tile: handle RO_AFTER_INIT

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Date:   Mon,  7 Nov 2016 14:50:27 -0500
From:   Chris Metcalf <cmetcalf@...lanox.com>
To:     linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>
Cc:     Chris Metcalf <cmetcalf@...lanox.com>
Subject: [PATCH] tile: handle RO_AFTER_INIT_DATA

This is the minimal change to handle RO_AFTER_INIT_DATA.
The tile architecture already marks RO_DATA as read-only in
the kernel, so grouping RO_AFTER_INIT_DATA with RO_DATA, as is
done by default, means the kernel faults in init when it tries
to write to RO_AFTER_INIT_DATA.  For now, just move it past the
end of the RODATA section so it is not specially treated.
---
This is just to fix 4.9; I will post a more complete fix shortly
targeting 4.10.

 arch/tile/kernel/vmlinux.lds.S | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/tile/kernel/vmlinux.lds.S b/arch/tile/kernel/vmlinux.lds.S
index e1baf094fba4..dcd7445c31a2 100644
--- a/arch/tile/kernel/vmlinux.lds.S
+++ b/arch/tile/kernel/vmlinux.lds.S
@@ -1,3 +1,6 @@
+/* Handle ro_after_init data on our own. */
+#define RO_AFTER_INIT_DATA
+
 #include <asm-generic/vmlinux.lds.h>
 #include <asm/page.h>
 #include <asm/cache.h>
@@ -87,6 +90,7 @@ SECTIONS
 
   _sdata = .;                   /* Start of data section */
   RO_DATA_SECTION(PAGE_SIZE)
+  RO_AFTER_INIT_DATA
   RW_DATA_SECTION(L2_CACHE_BYTES, PAGE_SIZE, THREAD_SIZE)
   _edata = .;
 
-- 
2.7.2