4.9-stable review patch. If anyone has any objections, please let me know.
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Commit 3a4d0c2172bcf15b7a3d9d498b2b355f9864286b upstream.
Marek Szyprowski reported problems with CPU hotplug in current kernels. This was tracked down to the processor vtables being located in an init section, and therefore discarded after kernel boot, despite being required after boot to properly initialise the non-boot CPUs.
Arrange for these tables to end up in .rodata when required.
Reported-by: Marek Szyprowski m.szyprowski@samsung.com Tested-by: Krzysztof Kozlowski krzk@kernel.org Fixes: 383fb3ee8024 ("ARM: spectre-v2: per-CPU vtables to work around big.Little systems") Signed-off-by: Russell King rmk+kernel@armlinux.org.uk Signed-off-by: David A. Long dave.long@linaro.org Reviewed-by: Julien Thierry julien.thierry@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm/mm/proc-macros.S | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/arch/arm/mm/proc-macros.S b/arch/arm/mm/proc-macros.S index 7d9176c4a21d..7be1d7921342 100644 --- a/arch/arm/mm/proc-macros.S +++ b/arch/arm/mm/proc-macros.S @@ -275,6 +275,13 @@ .endm
.macro define_processor_functions name:req, dabort:req, pabort:req, nommu=0, suspend=0, bugs=0 +/* + * If we are building for big.Little with branch predictor hardening, + * we need the processor function tables to remain available after boot. + */ +#if 1 // defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR) + .section ".rodata" +#endif .type \name()_processor_functions, #object .align 2 ENTRY(\name()_processor_functions) @@ -310,6 +317,9 @@ ENTRY(\name()_processor_functions) .endif
.size \name()_processor_functions, . - \name()_processor_functions +#if 1 // defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR) + .previous +#endif .endm
.macro define_cache_functions name:req