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References: <20230407215406.768464-1-ndesaulniers@google.com> <20230407215824.GA1524475@dev-arch.thelio-3990X>
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From:   Fangrui Song <maskray@google.com>
Date:   Tue, 11 Apr 2023 17:12:24 -0700
Message-ID: <CAFP8O3+YzvwgeSS_GvU3oTtxunyUm8qMaAnV3Mt-ezTsxZ=Q0Q@mail.gmail.com>
Subject: Re: [PATCH] ubsan: remove cc-option test for UBSAN_TRAP
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        linux-hardening@vger.kernel.org, Tom Rix <trix@redhat.com>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Miroslav Benes <mbenes@suse.cz>, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev, linux-kbuild@vger.kernel.org
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On Fri, Apr 7, 2023 at 2:58=E2=80=AFPM Nathan Chancellor <nathan@kernel.org=
> wrote:
>
> On Fri, Apr 07, 2023 at 02:54:06PM -0700, Nick Desaulniers wrote:
> > -fsanitize-undefined-trap-on-error has been supported since GCC 5.1 and
> > Clang 3.2.  The minimum supported version of these according to
> > Documentation/process/changes.rst is 5.1 and 11.0.0 respectively. Drop
> > this cc-option check.
> >
> > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
>
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
>
> As an aside, we should really consider having some standard format of
> comment around cc-option checks so that we can easily remove them when
> they become stale...
>
> > ---
> > Masahiro, Kees: get_maintainer.pl leaves much to be desired for this
> > file. Can one of you please pick this up?
> >
> >  lib/Kconfig.ubsan | 1 -
> >  1 file changed, 1 deletion(-)
> >
> > diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
> > index fd15230a703b..0e7ad0782399 100644
> > --- a/lib/Kconfig.ubsan
> > +++ b/lib/Kconfig.ubsan
> > @@ -15,7 +15,6 @@ if UBSAN
> >  config UBSAN_TRAP
> >       bool "On Sanitizer warnings, abort the running kernel code"
> >       depends on !COMPILE_TEST
> > -     depends on $(cc-option, -fsanitize-undefined-trap-on-error)
> >       help
> >         Building kernels with Sanitizer features enabled tends to grow
> >         the kernel size by around 5%, due to adding all the debugging
> > --
> > 2.40.0.577.gac1e443424-goog
> >
>

-fsanitize-undefined-trap-on-error is a legacy option from 2013 when
-fcatch-undefined-behavior instead of -fsanitize=3Dundefined enabled
UBSan.
On the Clang side, http://reviews.llvm.org/D10464 added
-fsanitize-trap=3D in June 2015.
It's best to use -fsanitize-trap=3Dundefined and avoid uses of
-fsanitize-undefined-trap-on-error.


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