Re: [PATCH -next V17 1/7] compiler_types.h: Add __noinstr_section() for noinstr

[Lai Jiangshan]

On Wed, Feb 22, 2023 at 11:56 AM <guoren@xxxxxxxxxx> wrote:
>
> From: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx>
>
> Using __noinstr_section() doesn't automatically disable all
> instrumentations on the section. Inhibition for some
> instrumentations requires extra code. I.E. KPROBES explicitly
> avoids instrumenting on .noinstr.text.
>
> Suggested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Reviewed-by: Miguel Ojeda <ojeda@xxxxxxxxxx>
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Reviewed-by: Björn Töpel <bjorn@xxxxxxxxxxxx>
> Tested-by: Jisheng Zhang <jszhang@xxxxxxxxxx>
> Tested-by: Guo Ren <guoren@xxxxxxxxxx>
> Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Guo Ren <guoren@xxxxxxxxxx>

Hello

The change has been made upstream as a part of the commit
2b5a0e425e6e(objtool/idle: Validate __cpuidle code as noinstr).

https://lore.kernel.org/r/20230112195540.373461409@xxxxxxxxxxxxx

Thanks
Lai

> ---
>  include/linux/compiler_types.h | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
> index 7c1afe0f4129..0a2ca5755be7 100644
> --- a/include/linux/compiler_types.h
> +++ b/include/linux/compiler_types.h
> @@ -231,12 +231,19 @@ struct ftrace_likely_data {
>  #define __no_sanitize_or_inline __always_inline
>  #endif
>
> -/* Section for code which can't be instrumented at all */
> -#define noinstr                                                                \
> -       noinline notrace __attribute((__section__(".noinstr.text")))    \
> -       __no_kcsan __no_sanitize_address __no_profile __no_sanitize_coverage \
> +/*
> + * Using __noinstr_section() doesn't automatically disable all instrumentations
> + * on the section.  Inhibition for some instrumentations requires extra code.
> + * I.E. KPROBES explicitly avoids instrumenting on .noinstr.text.
> + */
> +#define __noinstr_section(section)                             \
> +       noinline notrace __section(section) __no_profile        \
> +       __no_kcsan __no_sanitize_address __no_sanitize_coverage \
>         __no_sanitize_memory
>
> +/* Section for code which can't be instrumented at all */
> +#define noinstr __noinstr_section(".noinstr.text")
> +
>  #endif /* __KERNEL__ */
>
>  #endif /* __ASSEMBLY__ */
> --
> 2.36.1
>