linux-kernel - [PATCH 1/2] modules: Ensure natural alignment for .altinstructions and __bug

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Message-Id: <20220627190551.517561-1-deller@gmx.de>
Date:   Mon, 27 Jun 2022 21:05:50 +0200
From:   Helge Deller <deller@....de>
To:     mcgrof@...nel.org, jeyu@...nel.org, linux-modules@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-parisc@...r.kernel.org
Subject: [PATCH 1/2] modules: Ensure natural alignment for .altinstructions and __bug_table sections

In the kernel image vmlinux.lds.S linker scripts the .altinstructions
and __bug_table sections are 32- or 64-bit aligned because they hold 32-
and/or 64-bit values.

But for modules the module.lds.S linker script doesn't define a default
alignment yet, so the linker chooses the default byte-alignment, which
then leads to unnecessary unaligned memory accesses at runtime.

This patch adds the missing alignments.

Signed-off-by: Helge Deller <deller@....de>
---
 scripts/module.lds.S | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/scripts/module.lds.S b/scripts/module.lds.S
index 1d0e1e4dc3d2..3a3aa2354ed8 100644
--- a/scripts/module.lds.S
+++ b/scripts/module.lds.S
@@ -27,6 +27,8 @@ SECTIONS {
 	.ctors			0 : ALIGN(8) { *(SORT(.ctors.*)) *(.ctors) }
 	.init_array		0 : ALIGN(8) { *(SORT(.init_array.*)) *(.init_array) }

+	.altinstructions	0 : ALIGN(8) { KEEP(*(.altinstructions)) }
+	__bug_table		0 : ALIGN(8) { KEEP(*(__bug_table)) }
 	__jump_table		0 : ALIGN(8) { KEEP(*(__jump_table)) }

 	__patchable_function_entries : { *(__patchable_function_entries) }
--
2.35.3