linux-kernel - Re: [PATCH 4.9 20/76] powerpc/64: Disable the speculation barrier from the command line

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Date:   Tue, 16 Apr 2019 15:43:40 +0000
From:   Diana Madalina Craciun <diana.craciun@....com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.9 20/76] powerpc/64: Disable the speculation barrier
 from the command line

Hi,

I have tested the patches on NXP platforms and they worked as expected.

Diana

On 4/15/2019 9:45 PM, Greg Kroah-Hartman wrote:
> commit cf175dc315f90185128fb061dc05b6fbb211aa2f upstream.
>
> The speculation barrier can be disabled from the command line
> with the parameter: "nospectre_v1".
>
> Signed-off-by: Diana Craciun <diana.craciun@....com>
> Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  arch/powerpc/kernel/security.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
> index bf298d0c475f..813e38ff81ce 100644
> --- a/arch/powerpc/kernel/security.c
> +++ b/arch/powerpc/kernel/security.c
> @@ -17,6 +17,7 @@
>  unsigned long powerpc_security_features __read_mostly = SEC_FTR_DEFAULT;
>
>  bool barrier_nospec_enabled;
> +static bool no_nospec;
>
>  static void enable_barrier_nospec(bool enable)
>  {
> @@ -43,9 +44,18 @@ void setup_barrier_nospec(void)
>         enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&
>                  security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR);
>
> -       enable_barrier_nospec(enable);
> +       if (!no_nospec)
> +               enable_barrier_nospec(enable);
>  }
>
> +static int __init handle_nospectre_v1(char *p)
> +{
> +       no_nospec = true;
> +
> +       return 0;
> +}
> +early_param("nospectre_v1", handle_nospectre_v1);
> +
>  #ifdef CONFIG_DEBUG_FS
>  static int barrier_nospec_set(void *data, u64 val)
>  {
> --
> 2.19.1
>
>
>
>