Patch "ARM: Spectre-BHB: provide empty stub for non-config" has been added to the 4.9-stable tree

[gregkh at linuxfoundation.org]

This is a note to let you know that I've just added the patch titled

    ARM: Spectre-BHB: provide empty stub for non-config

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     arm-spectre-bhb-provide-empty-stub-for-non-config.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From 68453767131a5deec1e8f9ac92a9042f929e585d Mon Sep 17 00:00:00 2001
From: Randy Dunlap <rdunlap at infradead.org>
Date: Fri, 11 Mar 2022 11:49:12 -0800
Subject: ARM: Spectre-BHB: provide empty stub for non-config

From: Randy Dunlap <rdunlap at infradead.org>

commit 68453767131a5deec1e8f9ac92a9042f929e585d upstream.

When CONFIG_GENERIC_CPU_VULNERABILITIES is not set, references
to spectre_v2_update_state() cause a build error, so provide an
empty stub for that function when the Kconfig option is not set.

Fixes this build error:

  arm-linux-gnueabi-ld: arch/arm/mm/proc-v7-bugs.o: in function `cpu_v7_bugs_init':
  proc-v7-bugs.c:(.text+0x52): undefined reference to `spectre_v2_update_state'
  arm-linux-gnueabi-ld: proc-v7-bugs.c:(.text+0x82): undefined reference to `spectre_v2_update_state'

Fixes: b9baf5c8c5c3 ("ARM: Spectre-BHB workaround")
Signed-off-by: Randy Dunlap <rdunlap at infradead.org>
Reported-by: kernel test robot <lkp at intel.com>
Cc: Russell King <rmk+kernel at armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: linux-arm-kernel at lists.infradead.org
Cc: patches at armlinux.org.uk
Acked-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 arch/arm/include/asm/spectre.h |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/arch/arm/include/asm/spectre.h
+++ b/arch/arm/include/asm/spectre.h
@@ -25,7 +25,13 @@ enum {
 	SPECTRE_V2_METHOD_LOOP8 = BIT(__SPECTRE_V2_METHOD_LOOP8),
 };
 
+#ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
 void spectre_v2_update_state(unsigned int state, unsigned int methods);
+#else
+static inline void spectre_v2_update_state(unsigned int state,
+					   unsigned int methods)
+{}
+#endif
 
 int spectre_bhb_update_vectors(unsigned int method);
 


Patches currently in stable-queue which might be from rdunlap at infradead.org are

queue-4.9/arm-spectre-bhb-provide-empty-stub-for-non-config.patch