linux-kernel - [PATCH AUTOSEL for 4.4 05/32] module: set __jump

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Date:   Wed, 29 Nov 2017 17:21:49 +0000
From:   alexander.levin@...izon.com
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     David Daney <david.daney@...ium.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        alexander.levin@...izon.com
Subject: [PATCH AUTOSEL for 4.4 05/32] module: set __jump_table alignment to 8

From: David Daney <david.daney@...ium.com>

[ Upstream commit ab42632156becd35d3884ee5c14da2bedbf3149a ]

For powerpc the __jump_table section in modules is not aligned, this
causes a WARN_ON() splat when loading a module containing a __jump_table.

Strict alignment became necessary with commit 3821fd35b58d
("jump_label: Reduce the size of struct static_key"), currently in
linux-next, which uses the two least significant bits of pointers to
__jump_table elements.

Fix by forcing __jump_table to 8, which is the same alignment used for
this section in the kernel proper.

Link: http://lkml.kernel.org/r/20170301220453.4756-1-david.daney@cavium.com

Reviewed-by: Jason Baron <jbaron@...mai.com>
Acked-by: Jessica Yu <jeyu@...hat.com>
Acked-by: Michael Ellerman <mpe@...erman.id.au> (powerpc)
Tested-by: Sachin Sant <sachinp@...ux.vnet.ibm.com>
Signed-off-by: David Daney <david.daney@...ium.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 scripts/module-common.lds | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/scripts/module-common.lds b/scripts/module-common.lds
index 73a2c7da0e55..53234e85192a 100644
--- a/scripts/module-common.lds
+++ b/scripts/module-common.lds
@@ -19,4 +19,6 @@ SECTIONS {
 
 	. = ALIGN(8);
 	.init_array		0 : { *(SORT(.init_array.*)) *(.init_array) }
+
+	__jump_table		0 : ALIGN(8) { KEEP(*(__jump_table)) }
 }
-- 
2.11.0