[PATCH 1/4] arm64: apply alternatives for !SMP kernels

[Ard Biesheuvel]

On 13 March 2015 at 17:14, Mark Rutland <mark.rutland at arm.com> wrote:
> Currently we only perform alternative patching for kernels built with
> CONFIG_SMP, as we call apply_alternatives_all() in smp.c, which is only
> built for CONFIG_SMP. Thus !SMP kernels may not have necessary
> alternatives patched in.
>
> This patch ensures that we call apply_alternatives_all() once all CPUs
> are booted, even for !SMP kernels, by having the smp_init_cpus() stub
> call this for !SMP kernels via up_late_init. A new wrapper,
> do_post_cpus_up_work, is added so we can hook other calls here later
> (e.g. boot mode logging).
>
> Fixes: e039ee4ee3fcf174 ("arm64: add alternative runtime patching")
> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
> Cc: Andre Przywara <andre.przywara at arm.com>
> Cc: Will Deacon <will.deacon at arm.com>
> Cc: Catalin Marinas <catalin.marinas at arm.com>


Tested-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>


> ---
>  arch/arm64/Kconfig                |  4 ++++
>  arch/arm64/include/asm/smp_plat.h |  2 ++
>  arch/arm64/kernel/setup.c         | 12 ++++++++++++
>  arch/arm64/kernel/smp.c           |  2 +-
>  4 files changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 1b8e973..0d46deb 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -470,6 +470,10 @@ config HOTPLUG_CPU
>
>  source kernel/Kconfig.preempt
>
> +config UP_LATE_INIT
> +       def_bool y
> +       depends on !SMP
> +
>  config HZ
>         int
>         default 100
> diff --git a/arch/arm64/include/asm/smp_plat.h b/arch/arm64/include/asm/smp_plat.h
> index 59e2823..8dcd61e 100644
> --- a/arch/arm64/include/asm/smp_plat.h
> +++ b/arch/arm64/include/asm/smp_plat.h
> @@ -40,4 +40,6 @@ static inline u32 mpidr_hash_size(void)
>  extern u64 __cpu_logical_map[NR_CPUS];
>  #define cpu_logical_map(cpu)    __cpu_logical_map[cpu]
>
> +void __init do_post_cpus_up_work(void);
> +
>  #endif /* __ASM_SMP_PLAT_H */
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index e8420f6..781f469 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -207,6 +207,18 @@ static void __init smp_build_mpidr_hash(void)
>  }
>  #endif
>
> +void __init do_post_cpus_up_work(void)
> +{
> +       apply_alternatives_all();
> +}
> +
> +#ifdef CONFIG_UP_LATE_INIT
> +void __init up_late_init(void)
> +{
> +       do_post_cpus_up_work();
> +}
> +#endif /* CONFIG_UP_LATE_INIT */
> +
>  static void __init setup_processor(void)
>  {
>         struct cpu_info *cpu_info;
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 328b8ce..4257369 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -309,7 +309,7 @@ void cpu_die(void)
>  void __init smp_cpus_done(unsigned int max_cpus)
>  {
>         pr_info("SMP: Total of %d processors activated.\n", num_online_cpus());
> -       apply_alternatives_all();
> +       do_post_cpus_up_work();
>  }
>
>  void __init smp_prepare_boot_cpu(void)
> --
> 1.9.1
>