linux-kernel - Re: [PATCH v5 1/2] x86/purgatory: Disable various profiling and sanitizing options

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Message-ID: <20200313182815.GF8142@zn.tnic>
Date:   Fri, 13 Mar 2020 19:28:15 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/2] x86/purgatory: Disable various profiling and
 sanitizing options

On Thu, Mar 12, 2020 at 12:49:50PM +0100, Hans de Goede wrote:
> Since the purgatory is a special stand-alone binary, we need to disable

Pls use passive voice in your commit message: no "we" or "I", etc, and
describe your changes in imperative mood.

Also, pls read section "2) Describe your changes" in
Documentation/process/submitting-patches.rst for more details.

> various profiling and sanitizing options. Having these options enabled
> typically will cause dependency on various special symbols exported by
> special libs / stubs used by these frameworks. Since the purgatory is
> special we do not link against these stubs causing missing symbols in
> the purgatory if we do not disable these options.
> 
> This commit syncs the set of disabled profiling and sanitizing options

Avoid having "This patch" or "This commit" in the commit message. It is
tautologically useless.

Also, do

$ git grep 'This patch' Documentation/process

for more details.

Those two review comments apply to patch 2's commit message too, pls fix
them there too.

> with that from drivers/firmware/efi/libstub/Makefile, adding
> -DDISABLE_BRANCH_PROFILING to the CFLAGS and setting:
> 
> GCOV_PROFILE                    := n
> UBSAN_SANITIZE                  := n
> 
> This fixes broken references to ftrace_likely_update when
> CONFIG_TRACE_BRANCH_PROFILING is enabled and to __gcov_init and
> __gcov_exit when CONFIG_GCOV_KERNEL is enabled.
> 
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> ---
> Changes in v5:
> -Not only add -DDISABLE_BRANCH_PROFILING to the CFLAGS but also set:
>  GCOV_PROFILE                    := n
>  UBSAN_SANITIZE                  := n
> 
> Changes in v4:
> -This is a new patch in v4 of this series
> ---
>  arch/x86/purgatory/Makefile | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

$ test-apply.sh -g /tmp/01-x86-purgatory-disable_various_profiling_and_sanitizing_options.patch
checking file arch/x86/purgatory/Makefile
Hunk #1 FAILED at 17.
Hunk #2 succeeded at 27 (offset 2 lines).
1 out of 2 hunks FAILED

This happens because tip/master already has KCSAN merged in and it adds

KCSAN_SANITIZE  := n

there.

Please redo the patches against current tip/master.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette