linux-kernel - [PATCH 2/2] ARM: add KEEP() keyword to ARM

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Message-Id: <20250311-arm-fix-vectors-with-linker-dce-v1-2-ec4c382e3bfd@kernel.org>
Date: Tue, 11 Mar 2025 20:43:43 +0100
From: Nathan Chancellor <nathan@...nel.org>
To: Russell King <linux@...linux.org.uk>
Cc: Christian Eggers <ceggers@...i.de>, Arnd Bergmann <arnd@...db.de>, 
 Linus Walleij <linus.walleij@...aro.org>, 
 Yuntao Liu <liuyuntao12@...wei.com>, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, llvm@...ts.linux.dev, stable@...r.kernel.org, 
 Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH 2/2] ARM: add KEEP() keyword to ARM_VECTORS

From: Christian Eggers <ceggers@...i.de>

Without this, the vectors are removed if LD_DEAD_CODE_DATA_ELIMINATION
is enabled.  At startup, the CPU (silently) hangs in the undefined
instruction exception as soon as the first timer interrupt arrives.

On my setup, the system also boots fine without the 2nd and 3rd KEEP()
statements, so I cannot tell whether these are actually required.

Cc: stable@...r.kernel.org
Fixes: ed0f94102251 ("ARM: 9404/1: arm32: enable HAVE_LD_DEAD_CODE_DATA_ELIMINATION")
Signed-off-by: Christian Eggers <ceggers@...i.de>
[nathan: Use OVERLAY_KEEP() to avoid breaking old ld.lld versions]
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---
 arch/arm/include/asm/vmlinux.lds.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm/include/asm/vmlinux.lds.h b/arch/arm/include/asm/vmlinux.lds.h
index 0f8ef1ed725e..14811b4f48ec 100644
--- a/arch/arm/include/asm/vmlinux.lds.h
+++ b/arch/arm/include/asm/vmlinux.lds.h
@@ -131,13 +131,13 @@
 	__vectors_lma = .;						\
 	OVERLAY 0xffff0000 : NOCROSSREFS AT(__vectors_lma) {		\
 		.vectors {						\
-			*(.vectors)					\
+			OVERLAY_KEEP(*(.vectors))			\
 		}							\
 		.vectors.bhb.loop8 {					\
-			*(.vectors.bhb.loop8)				\
+			OVERLAY_KEEP(*(.vectors.bhb.loop8))		\
 		}							\
 		.vectors.bhb.bpiall {					\
-			*(.vectors.bhb.bpiall)				\
+			OVERLAY_KEEP(*(.vectors.bhb.bpiall))		\
 		}							\
 	}								\
 	ARM_LMA(__vectors, .vectors);					\

-- 
2.48.1