Hi Nick
2018-08-23 8:37 GMT+09:00 Nick Desaulniers <ndesaulni...@google.com>:
> Commit cafa0010cd51 ("Raise the minimum required gcc version to 4.6")
> recently exposed a brittle part of the build for supporting non-gcc
> compilers.
>
> Both Clang and ICC define __GNUC__, __GNUC_MINOR__, and
> __GNUC_PATCHLEVEL__ for quick compatibility with code bases that haven't
> added compiler specific checks for __clang__ or __INTEL_COMPILER.
>
> This is brittle, as they happened to get compatibility by posing as a
> certain version of GCC. This broke when upgrading the minimal version
> of GCC required to build the kernel, to a version above what ICC and
> Clang claim to be.
>
> Rather than always including compiler-gcc.h then undefining or
> redefining macros in compiler-intel.h or compiler-clang.h, let's
> separate out the compiler specific macro definitions into mutually
> exclusive headers, do more proper compiler detection, and keep shared
> definitions in compiler_types.h.
>
> Reported-by: Masahiro Yamada <yamada.masah...@socionext.com>
> Suggested-by: Eli Friedman <efrie...@codeaurora.org>
> Suggested-by: Joe Perches <j...@perches.com>
> Signed-off-by: Nick Desaulniers <ndesaulni...@google.com>
> ---
> arch/arm/kernel/asm-offsets.c | 13 +-
> drivers/gpu/drm/i915/i915_utils.h | 2 +-
> drivers/watchdog/kempld_wdt.c | 5 -
> include/linux/compiler-clang.h | 20 ++-
> include/linux/compiler-gcc.h | 88 -----------
> include/linux/compiler-intel.h | 13 +-
> include/linux/compiler_types.h | 238 ++++++++++++++----------------
> mm/ksm.c | 4 +-
> mm/migrate.c | 3 +-
> 9 files changed, 133 insertions(+), 253 deletions(-)
If I build ARM linux with Clang,
I see the following error.
arch/arm/firmware/trusted_foundations.c:34:13: error: variable has
incomplete type 'void'
static void __naked tf_generic_smc(u32 type, u32 arg1, u32 arg2)
^
arch/arm/firmware/trusted_foundations.c:34:20: error: expected ';'
after top level declarator
static void __naked tf_generic_smc(u32 type, u32 arg1, u32 arg2)
^
;
arch/arm/firmware/trusted_foundations.c:77:25: error: use of
undeclared identifier 'trusted_foundations_ops'
register_firmware_ops(&trusted_foundations_ops);
^
3 errors generated.
scripts/Makefile.build:307: recipe for target
'arch/arm/firmware/trusted_foundations.o' failed
make[2]: *** [arch/arm/firmware/trusted_foundations.o] Error 1
Makefile:1057: recipe for target 'arch/arm/firmware' failed
make[1]: *** [arch/arm/firmware] Error 2
make[1]: *** Waiting for unfinished jobs....
__naked is defined in <linux/compiler-gcc.h>
It was previous included by all compilers,
but now it is only by _true_ GCC.
Even if I move the __naked definition
to <linux/compiler_types.h>,
I see a different error.
arch/arm/firmware/trusted_foundations.c:47:10: error: parameter
references not allowed in naked functions
: "r" (type), "r" (arg1), "r" (arg2)
^
arch/arm/firmware/trusted_foundations.c:34:13: note: attribute is here
static void __naked tf_generic_smc(u32 type, u32 arg1, u32 arg2)
^
./include/linux/compiler_types.h:277:33: note: expanded from macro '__naked'
#define __naked __attribute__((naked))
^
I do not know what a correct fix is.
--
Best Regards
Masahiro Yamada
