linux-kernel - Re: [PATCH] x86/mm: Disable various instrumentations of mem

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Message-ID: <20171011095726.fzilylt32rpmkson@pd.tnic>
Date:   Wed, 11 Oct 2017 11:57:26 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     x86@...nel.org, Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] x86/mm: Disable various instrumentations of mem_encrypt.c

On Tue, Oct 10, 2017 at 02:45:04PM -0500, Tom Lendacky wrote:
> Some routines in mem_encrypt.c are called very early in the boot process,
> e.g. sme_enable().  When CONFIG_KCOV is defined the resulting code added
> to sme_enable() (and others) for KCOV instrumentation results in a kernel
> crash.  Disable the KCOV instrumentation for mem_encrypt.c by adding
> KCOV_INSTRUMENT_mem_encrypt.o := n to arch/x86/mm/Makefile.
> 
> In order to avoid other possible early boot issues, model mem_encrypt.c
> after head64.c in regards to tools. In addition to disabling KCOV as
> stated above and a previous patch that disables branch profiling, also
> remove the "-pg" CFLAG if CONFIG_FUNCTION_TRACER is enabled and set
> KASAN_SANITIZE to "n", each of which are done on a file basis.
> 
> Reported-by: kernel test robot <lkp@...org>
> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
> ---
>  arch/x86/mm/Makefile |   11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)

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

-- 
Regards/Gruss,
    Boris.

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