On Thu, 8 May 2025 at 14:23, Marco Elver <elver@xxxxxxxxxx> wrote:
>
> +Cc KCOV maintainers
>
> On Wed, 7 May 2025 at 20:16, Kees Cook <kees@xxxxxxxxxx> wrote:
> >
> > While __noinstr already contained __no_sanitize_coverage, it needs to
> > be added to __init and __head section markings to support the Clang
> > implementation of CONFIG_STACKLEAK. This is to make sure the stack depth
> > tracking callback is not executed in unsupported contexts.
> >
> > The other sanitizer coverage options (trace-pc and trace-cmp) aren't
> > needed in __head nor __init either ("We are interested in code coverage
> > as a function of a syscall inputs"[1]), so this appears safe to disable
> > for them as well.
>
> @ Dmitry, Aleksandr - Will this produce some unwanted side-effects for
> syzbot? I also think it's safe, but just double checking.
I do not see any problems with this.
> > Link: https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/kcov.c?h=v6.14#n179 [1]
> > Signed-off-by: Kees Cook <kees@xxxxxxxxxx>
>
> Acked-by: Marco Elver <elver@xxxxxxxxxx>
>
> > ---
> > Cc: Marco Elver <elver@xxxxxxxxxx>
> > Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
> > Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> > Cc: Borislav Petkov <bp@xxxxxxxxx>
> > Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> > Cc: <x86@xxxxxxxxxx>
> > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> > Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
> > Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> > Cc: Hou Wenlong <houwenlong.hwl@xxxxxxxxxxxx>
> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> > Cc: "Peter Zijlstra (Intel)" <peterz@xxxxxxxxxxxxx>
> > Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx>
> > Cc: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
> > Cc: Arnd Bergmann <arnd@xxxxxxxx>
> > Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> > Cc: <kasan-dev@xxxxxxxxxxxxxxxx>
> > ---
> > arch/x86/include/asm/init.h | 2 +-
> > include/linux/init.h | 4 +++-
> > 2 files changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/init.h b/arch/x86/include/asm/init.h
> > index 8b1b1abcef15..6bfdaeddbae8 100644
> > --- a/arch/x86/include/asm/init.h
> > +++ b/arch/x86/include/asm/init.h
> > @@ -5,7 +5,7 @@
> > #if defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 170000
> > #define __head __section(".head.text") __no_sanitize_undefined __no_stack_protector
> > #else
> > -#define __head __section(".head.text") __no_sanitize_undefined
> > +#define __head __section(".head.text") __no_sanitize_undefined __no_sanitize_coverage
> > #endif
> >
> > struct x86_mapping_info {
> > diff --git a/include/linux/init.h b/include/linux/init.h
> > index ee1309473bc6..c65a050d52a7 100644
> > --- a/include/linux/init.h
> > +++ b/include/linux/init.h
> > @@ -49,7 +49,9 @@
> >
> > /* These are for everybody (although not all archs will actually
> > discard it in modules) */
> > -#define __init __section(".init.text") __cold __latent_entropy __noinitretpoline
> > +#define __init __section(".init.text") __cold __latent_entropy \
> > + __noinitretpoline \
> > + __no_sanitize_coverage
> > #define __initdata __section(".init.data")
> > #define __initconst __section(".init.rodata")
> > #define __exitdata __section(".exit.data")
> > --
> > 2.34.1
> >
