Am Donnerstag, den 12.07.2018, 14:45 -0300 schrieb Fabio Estevam:
> Since 4.18-rc1 kernel the following warning is seen on i.MX51 and
> i.MX53:
>
> CPU0: Spectre v2: firmware did not set auxiliary control register IBE bit, system vulnerable
>
> Implement the suggested workaround by setting the IBE bit in the
> auxiliary control register, which allows the kernel to flush the
> BTB properly.
>
> Based on commit 7b37a9c732bf ("ARM: Introduce ability to enable ACR::IBE
> on Cortex-A8 for CVE-2017-5715") from U-Boot.
>
> With this patch applied the kernel now reports:
>
> CPU0: Spectre v2: using BPIALL workaround
>
> Tested on a imx51 babbage.
>
> Signed-off-by: Fabio Estevam <festevam@xxxxxxxxx>
Reviewed-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> ---
> Changes since v1:
> - Rename the function name (Lucas)
> - Improve the commit log (Lucas)
>
> arch/arm/include/asm/errata.h | 9 +++++++++
> arch/arm/mach-imx/cpu_init.c | 3 ++-
> 2 files changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/include/asm/errata.h b/arch/arm/include/asm/errata.h
> index 98137b5..c0e0f5a 100644
> --- a/arch/arm/include/asm/errata.h
> +++ b/arch/arm/include/asm/errata.h
> @@ -86,3 +86,12 @@ static inline void enable_arm_errata_845369_war(void)
> > > "mcr p15, 0, r0, c15, c0, 1\n"
> > );
> }
> +
> +static inline void enable_arm_errata_cortexa8_enable_ibe(void)
> +{
> > + __asm__ __volatile__ (
> > > + "mrc p15, 0, r0, c1, c0, 1\n"
> > > + "orr r0, r0, #1 << 6\n"
> > > + "mcr p15, 0, r0, c1, c0, 1\n"
> > + );
> +}
> diff --git a/arch/arm/mach-imx/cpu_init.c b/arch/arm/mach-imx/cpu_init.c
> index 5b93d12..e1d88c7 100644
> --- a/arch/arm/mach-imx/cpu_init.c
> +++ b/arch/arm/mach-imx/cpu_init.c
> @@ -22,6 +22,7 @@ void imx5_cpu_lowlevel_init(void)
> > arm_cpu_lowlevel_init();
>
> > enable_arm_errata_709718_war();
> > + enable_arm_errata_cortexa8_enable_ibe();
> }
>
> void imx6_cpu_lowlevel_init(void)
> @@ -51,4 +52,4 @@ void vf610_cpu_lowlevel_init(void)
> {
> > arm_cpu_lowlevel_init();
> }
> -#endif
> \ No newline at end of file
> +#endif
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