2022-03-11 22:40:02

by Randy Dunlap

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

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 <[email protected]>
Reported-by: kernel test robot <[email protected]>
Cc: Russell King <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: [email protected]
Cc: [email protected]
---
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);

2022-03-11 22:53:49

by Russell King (Oracle)

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

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 <[email protected]>
> Reported-by: kernel test robot <[email protected]>

Acked-by: Russell King (Oracle) <[email protected]>

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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