linux-kernel - Re: [PATCH] x86/mm: Disable branch profiling in mem

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Date:   Fri, 29 Sep 2017 18:51:54 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] x86/mm: Disable branch profiling in mem_encrypt.c

On Fri, Sep 29, 2017 at 11:24:19AM -0500, Tom Lendacky wrote:
> Some routines in mem_encrypt.c are called very early in the boot process,
> e.g. sme_encrypt_kernel(). When CONFIG_TRACE_BRANCH_PROFILING is defined
> the resulting branch profiling associated with the check to see if SME is
> active results in a kernel crash. Disable branch profiling for
> mem_encrypt.c by defining DISABLE_BRANCH_PROFILING before including any
> header files.
> 
> Reported-by: kernel test robot <lkp@...org>
> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
> ---
>  arch/x86/mm/mem_encrypt.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index 3fcc8e0..16c5f37 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -10,6 +10,8 @@
>   * published by the Free Software Foundation.
>   */
>  
> +#define DISABLE_BRANCH_PROFILING
> +
>  #include <linux/linkage.h>
>  #include <linux/init.h>
>  #include <linux/mm.h>

Acked-by: Borislav Petkov <bp@...e.de>

-- 
Regards/Gruss,
    Boris.

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