[v2,10/21] kconfig: add 'success' and 'cc-option' macros

Message ID 1522128575-5326-11-git-send-email-yamada.masahiro@socionext.com
State New
Headers show
Series
  • kconfig: move compiler capability tests to Kconfig
Related show

Commit Message

Masahiro Yamada March 27, 2018, 5:29 a.m.
'cc-option' will be the most frequently used macro.  It evaluates to 'y'
if the given argument is supported by the compiler, or 'n' otherwise.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

---

Changes in v2:
  - Implement 'success' as a macro

 init/Kconfig | 6 ++++++
 1 file changed, 6 insertions(+)

-- 
2.7.4

Comments

Kees Cook March 28, 2018, 3:46 a.m. | #1
On Mon, Mar 26, 2018 at 10:29 PM, Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
> 'cc-option' will be the most frequently used macro.  It evaluates to 'y'

> if the given argument is supported by the compiler, or 'n' otherwise.

>

> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>


Reviewed-by: Kees Cook <keescook@chromium.org>


> ---

>

> Changes in v2:

>   - Implement 'success' as a macro

>

>  init/Kconfig | 6 ++++++

>  1 file changed, 6 insertions(+)

>

> diff --git a/init/Kconfig b/init/Kconfig

> index 0d6fe20..c456030 100644

> --- a/init/Kconfig

> +++ b/init/Kconfig

> @@ -8,6 +8,12 @@ config DEFCONFIG_LIST

>         default ARCH_DEFCONFIG

>         default "arch/$ARCH/defconfig"

>

> +# expanded to y if the command exits with 0, n otherwise

> +macro success $(shell ($(1) && echo y) || echo n)

> +

> +# expanded to y if the given compiler flag is supported, n otherwise

> +macro cc-option $(success $CC -Werror $(1) -c -x c /dev/null -o /dev/null)


This should be fine since most cc-option uses are quite simple. The
specialized per-arch and other-flag-dependency checks can just
continue to live in Makefile if we actually need them.

-Kees

-- 
Kees Cook
Pixel Security
Ulf Magnusson April 1, 2018, 6:28 a.m. | #2
On Tue, Mar 27, 2018 at 7:29 AM, Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
> 'cc-option' will be the most frequently used macro.  It evaluates to 'y'

> if the given argument is supported by the compiler, or 'n' otherwise.

>

> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

> ---

>

> Changes in v2:

>   - Implement 'success' as a macro

>

>  init/Kconfig | 6 ++++++

>  1 file changed, 6 insertions(+)

>

> diff --git a/init/Kconfig b/init/Kconfig

> index 0d6fe20..c456030 100644

> --- a/init/Kconfig

> +++ b/init/Kconfig

> @@ -8,6 +8,12 @@ config DEFCONFIG_LIST

>         default ARCH_DEFCONFIG

>         default "arch/$ARCH/defconfig"

>

> +# expanded to y if the command exits with 0, n otherwise

> +macro success $(shell ($(1) && echo y) || echo n)

> +

> +# expanded to y if the given compiler flag is supported, n otherwise

> +macro cc-option $(success $CC -Werror $(1) -c -x c /dev/null -o /dev/null)

> +

>  config CONSTRUCTORS

>         bool

>         depends on !UML

> --

> 2.7.4

>


Reviewed-by: Ulf Magnusson <ulfalizer@gmail.com>


Some other tests (e.g. scripts/*-stack-protector.sh) also pass -S and
-O0 and stuff to speed things up. Feels like that could lead to
gotchas though.

-S does help a bit at least:

    $ time gcc -c -x c /dev/null -o /dev/null
    real 0m0.020s
    user 0m0.013s
    sys 0m0.007s

    $ time gcc -S -x c /dev/null -o /dev/null
    real 0m0.012s
    user 0m0.009s
    sys 0m0.003s

Patch

diff --git a/init/Kconfig b/init/Kconfig
index 0d6fe20..c456030 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -8,6 +8,12 @@  config DEFCONFIG_LIST
 	default ARCH_DEFCONFIG
 	default "arch/$ARCH/defconfig"
 
+# expanded to y if the command exits with 0, n otherwise
+macro success $(shell ($(1) && echo y) || echo n)
+
+# expanded to y if the given compiler flag is supported, n otherwise
+macro cc-option $(success $CC -Werror $(1) -c -x c /dev/null -o /dev/null)
+
 config CONSTRUCTORS
 	bool
 	depends on !UML