[PATCH] kcov: Unconditionally add -fno-stack-protector to compiler options

[PATCH] kcov: Unconditionally add -fno-stack-protector to compiler options

[Marco Elver]

Unconditionally add -fno-stack-protector to KCOV's compiler options, as
all supported compilers support the option. This saves a compiler
invocation to determine if the option is supported.

Because Clang does not support -fno-conserve-stack, and
-fno-stack-protector was wrapped in the same cc-option, we were missing
-fno-stack-protector with Clang. Unconditionally adding this option
fixes this for Clang.

Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Marco Elver <elver@google.com>
---
Split out from series:
	https://lkml.kernel.org/r/20200605082839.226418-2-elver@google.com
as there is no dependency on the preceding patch (which will be dropped).
---
 kernel/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/Makefile b/kernel/Makefile
index f3218bc5ec69..592cb549dcb8 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -35,7 +35,7 @@ KCOV_INSTRUMENT_stacktrace.o := n
 KCOV_INSTRUMENT_kcov.o := n
 KASAN_SANITIZE_kcov.o := n
 KCSAN_SANITIZE_kcov.o := n
-CFLAGS_kcov.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
+CFLAGS_kcov.o := $(call cc-option, -fno-conserve-stack) -fno-stack-protector
 
 # cond_syscall is currently not LTO compatible
 CFLAGS_sys_ni.o = $(DISABLE_LTO)
-- 
2.27.0.290.gba653c62da-goog

Re: [PATCH] kcov: Unconditionally add -fno-stack-protector to compiler options

[Andrey Konovalov]

On Mon, Jun 15, 2020 at 8:43 PM Marco Elver <elver@google.com> wrote:
>
> Unconditionally add -fno-stack-protector to KCOV's compiler options, as
> all supported compilers support the option. This saves a compiler
> invocation to determine if the option is supported.
>
> Because Clang does not support -fno-conserve-stack, and
> -fno-stack-protector was wrapped in the same cc-option, we were missing
> -fno-stack-protector with Clang. Unconditionally adding this option
> fixes this for Clang.
>
> Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> Signed-off-by: Marco Elver <elver@google.com>
> ---
> Split out from series:
>         https://lkml.kernel.org/r/20200605082839.226418-2-elver@google.com
> as there is no dependency on the preceding patch (which will be dropped).
> ---
>  kernel/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/Makefile b/kernel/Makefile
> index f3218bc5ec69..592cb549dcb8 100644
> --- a/kernel/Makefile
> +++ b/kernel/Makefile
> @@ -35,7 +35,7 @@ KCOV_INSTRUMENT_stacktrace.o := n
>  KCOV_INSTRUMENT_kcov.o := n
>  KASAN_SANITIZE_kcov.o := n
>  KCSAN_SANITIZE_kcov.o := n
> -CFLAGS_kcov.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
> +CFLAGS_kcov.o := $(call cc-option, -fno-conserve-stack) -fno-stack-protector
>
>  # cond_syscall is currently not LTO compatible
>  CFLAGS_sys_ni.o = $(DISABLE_LTO)
> --
> 2.27.0.290.gba653c62da-goog
>

Reviewed-by: Andrey Konovalov <andreyknvl@google.com>