linux-kernel - [PATCH] ARM; fix cpu_v7_bugs

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Message-Id: <20180529102301.1145470-1-arnd@arndb.de>
Date:   Tue, 29 May 2018 12:22:06 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Russell King <linux@...linux.org.uk>,
        Florian Fainelli <f.fainelli@...il.com>
Cc:     Arnd Bergmann <arnd@...db.de>, Marc Zyngier <marc.zyngier@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] ARM; fix cpu_v7_bugs_init reference

The cpu_v7_bugs_init() function is referenced by the ARMv7 processor
implementation, but is defined conditionally, leading to a link error when
CONFIG_HARDEN_BRANCH_PREDICTOR is disabled:

arch/arm/mm/proc-v7.o:(.init.data+0xc): undefined reference to `cpu_v7_bugs_init'
arch/arm/mm/proc-v7.o:(.init.data+0x74): undefined reference to `cpu_v7_bugs_init'
arch/arm/mm/proc-v7-bugs.o: In function `cpu_v7_ca8_ibe':
proc-v7-bugs.c:(.text+0x14): undefined reference to `cpu_v7_bugs_init'
arch/arm/mm/proc-v7-bugs.o: In function `cpu_v7_ca15_ibe':
proc-v7-bugs.c:(.text+0x30): undefined reference to `cpu_v7_bugs_init'

There is a '.weak' directive for this symbol, which was apparently
intended to avoid the problem, but the file is lacking an actual global
definition for the function, so it has no effect.

This adds an empty function definition for it, which can now get used
as the fallback.

Fixes: 8d9267cedb9e ("ARM: spectre-v2: harden user aborts in kernel space")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 arch/arm/mm/proc-v7.S | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 6fe52819e014..8f980e8b0867 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -547,6 +547,11 @@ __v7_setup_stack_ptr:
 	.word	PHYS_RELATIVE(__v7_setup_stack, .)
 ENDPROC(__v7_setup)
 
+	.weak cpu_v7_bugs_init
+ENTRY(cpu_v7_bugs_init)
+	ret	lr
+ENDPROC(cpu_v7_bugs_init)
+
 	.bss
 	.align	2
 __v7_setup_stack:
@@ -554,8 +559,6 @@ __v7_setup_stack:
 
 	__INITDATA
 
-	.weak cpu_v7_bugs_init
-
 	@ define struct processor (see <asm/proc-fns.h> and proc-macros.S)
 	define_processor_functions v7, dabort=v7_early_abort, pabort=v7_pabort, suspend=1, bugs=cpu_v7_bugs_init
 
-- 
2.9.0