On Wed, Sep 11, 2019 at 11:21 AM Nathan Chancellor
<natechancellor@xxxxxxxxx> wrote:
>
> Commit aea447141c7e ("powerpc: Disable -Wbuiltin-requires-header when
> setjmp is used") disabled -Wbuiltin-requires-header because of a warning
> about the setjmp and longjmp declarations.
>
> r367387 in clang added another diagnostic around this, complaining that
> there is no jmp_buf declaration.
>
> In file included from ../arch/powerpc/xmon/xmon.c:47:
> ../arch/powerpc/include/asm/setjmp.h:10:13: error: declaration of
> built-in function 'setjmp' requires the declaration of the 'jmp_buf'
> type, commonly provided in the header <setjmp.h>.
> [-Werror,-Wincomplete-setjmp-declaration]
> extern long setjmp(long *);
> ^
> ../arch/powerpc/include/asm/setjmp.h:11:13: error: declaration of
> built-in function 'longjmp' requires the declaration of the 'jmp_buf'
> type, commonly provided in the header <setjmp.h>.
> [-Werror,-Wincomplete-setjmp-declaration]
> extern void longjmp(long *, long);
> ^
> 2 errors generated.
>
> We are not using the standard library's longjmp/setjmp implementations
> for obvious reasons; make this clear to clang by using -ffreestanding
> on these files.
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
https://godbolt.org/z/B2oQnl
>
> Cc: stable@xxxxxxxxxxxxxxx # 4.14+
> Link: https://github.com/ClangBuiltLinux/linux/issues/625
> Link: https://github.com/llvm/llvm-project/commit/3be25e79477db2d31ac46493d97eca8c20592b07
> Suggested-by: Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
> ---
>
> v1 -> v3:
>
> * Use -ffreestanding instead of outright disabling the warning because
> it is legitimate.
>
> I skipped v2 because the first patch in the series already had a v2.
>
> arch/powerpc/kernel/Makefile | 4 ++--
> arch/powerpc/xmon/Makefile | 4 ++--
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index c9cc4b689e60..19f19c8c874b 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -5,8 +5,8 @@
>
> CFLAGS_ptrace.o += -DUTS_MACHINE='"$(UTS_MACHINE)"'
>
> -# Disable clang warning for using setjmp without setjmp.h header
> -CFLAGS_crash.o += $(call cc-disable-warning, builtin-requires-header)
> +# Avoid clang warnings around longjmp/setjmp declarations
> +CFLAGS_crash.o += -ffreestanding
>
> ifdef CONFIG_PPC64
> CFLAGS_prom_init.o += $(NO_MINIMAL_TOC)
> diff --git a/arch/powerpc/xmon/Makefile b/arch/powerpc/xmon/Makefile
> index f142570ad860..c3842dbeb1b7 100644
> --- a/arch/powerpc/xmon/Makefile
> +++ b/arch/powerpc/xmon/Makefile
> @@ -1,8 +1,8 @@
> # SPDX-License-Identifier: GPL-2.0
> # Makefile for xmon
>
> -# Disable clang warning for using setjmp without setjmp.h header
> -subdir-ccflags-y := $(call cc-disable-warning, builtin-requires-header)
> +# Avoid clang warnings around longjmp/setjmp declarations
> +subdir-ccflags-y := -ffreestanding
>
> GCOV_PROFILE := n
> KCOV_INSTRUMENT := n
> --
> 2.23.0
>
--
Thanks,
~Nick Desaulniers
