On Mon, Jul 30, 2018 at 02:34:12PM -0700, Nick Desaulniers wrote:
> Starting with Clang-7.0, _THIS_IP_ generates -Wreturn-stack-address
> warnings for almost every translation unit. In general, I'd prefer to
> leave this on (returning the address of a stack allocated variable is in
> general a bad idea) and disable it only at whitelisted call sites.
>
> We can't do something like:
> #pragma clang diagnostic push
> #pragma clang diagnostic ignored "-Wreturn-stack-address"
> <code>
> #pragma clang diagnostic pop
>
> in a GNU Statement Expression or macro, hence we use _Pragma, which is
> its raison d'être: https://gcc.gnu.org/onlinedocs/cpp/Pragmas.html
>
> We also can't use compiler specific pragma's without triggering
> -Werror=unknown-pragmas in other compilers, so use __diag.
>
> Cc: sta...@vger.kernel.org # 4.17, 4.14, 4.9, 4.4
> Suggested-by: Nathan Chancellor <natechancel...@gmail.com>
> Signed-off-by: Nick Desaulniers <ndesaulni...@google.com>
Tested-and-reviewed-by: Nathan Chancellor <natechancel...@gmail.com>
> ---
> include/linux/kernel.h | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 941dc0a5a877..909bb771c0ca 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -168,7 +168,15 @@
>
>
> #define _RET_IP_ (unsigned long)__builtin_return_address(0)
> -#define _THIS_IP_ ({ __label__ __here; __here: (unsigned long)&&__here; })
> +#define _THIS_IP_ ( \
> +{ \
> + __label__ __here; \
> + __diag_push() \
> + __diag_ignore(CLANG, 7, "-Wreturn-stack-address", "") \
> +__here: (unsigned long)&&__here; \
> + __diag_pop() \
> +} \
> +)
>
> #ifdef CONFIG_LBDAF
> # include <asm/div64.h>
> --
> 2.18.0.345.g5c9ce644c3-goog
>
