[PATCH] ARM: Spectre-BHB: provide empty stub for non-config

[PATCH] ARM: Spectre-BHB: provide empty stub for non-config

[Randy Dunlap]

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@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: patches@armlinux.org.uk
---
KernelVersion: v5.17-rc7-205-g79b00034e9dc

 arch/arm/include/asm/spectre.h |    6 ++++++
 1 file changed, 6 insertions(+)

--- linux-next-20220310.orig/arch/arm/include/asm/spectre.h
+++ linux-next-20220310/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);
 

Re: [PATCH] ARM: Spectre-BHB: provide empty stub for non-config

[Russell King (Oracle)]

On Fri, Mar 11, 2022 at 11:18:20AM -0800, Randy Dunlap wrote:
> 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@infradead.org>
> Reported-by: kernel test robot <lkp@intel.com>

Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

I'd suggest sending this direct to Linus as I've been doing with the
other fixes for Spectre BHB. Trying to fit it now into a pull request
is just going to be very messy.

Thanks.

-- 
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