From: Michael Ellerman <mpe@ellerman.id.au>
To: Nathan Chancellor <natechancellor@gmail.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Nick Desaulniers <ndesaulniers@google.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
clang-built-linux@googlegroups.com,
Nathan Chancellor <natechancellor@gmail.com>,
stable@vger.kernel.org
Subject: Re: [PATCH] powerpc: Avoid clang warnings around setjmp and longjmp
Date: Wed, 28 Aug 2019 23:43:53 +1000 [thread overview]
Message-ID: <878srdv206.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20190812023214.107817-1-natechancellor@gmail.com>
Nathan Chancellor <natechancellor@gmail.com> writes:
> 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.
>
> Take the same approach as the above commit by disabling the warning for
> the same reason, we provide our own longjmp/setjmp function.
>
> Cc: stable@vger.kernel.org # 4.19+
> Link: https://github.com/ClangBuiltLinux/linux/issues/625
> Link: https://github.com/llvm/llvm-project/commit/3be25e79477db2d31ac46493d97eca8c20592b07
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
>
> It may be worth using -fno-builtin-setjmp and -fno-builtin-longjmp
> instead as it makes it clear to clang that we are not using the builtin
> longjmp and setjmp functions, which I think is why these warnings are
> appearing (at least according to the commit that introduced this waring).
>
> Sample patch:
> https://github.com/ClangBuiltLinux/linux/issues/625#issuecomment-519251372
Couldn't we just add those flags to CFLAGS for the whole kernel? Rather
than making them per-file.
I mean there's no kernel code that wants to use clang's builtin
setjmp/longjmp implementation at all right?
cheers
next prev parent reply other threads:[~2019-08-28 13:44 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-12 2:32 [PATCH] powerpc: Avoid clang warnings around setjmp and longjmp Nathan Chancellor
2019-08-12 5:37 ` Christophe Leroy
2019-08-12 16:55 ` Nathan Chancellor
2019-08-12 17:35 ` Nick Desaulniers
2019-08-27 0:12 ` Nathan Chancellor
2019-08-28 13:43 ` Michael Ellerman [this message]
2019-08-28 17:53 ` Nathan Chancellor
2019-08-28 18:01 ` Nick Desaulniers
2019-08-28 18:45 ` Nathan Chancellor
2019-08-28 22:16 ` Nick Desaulniers
2019-08-29 8:32 ` Segher Boessenkool
[not found] ` <6801a83ed6d54d95b87a41c57ef6e6b0@AcuMS.aculab.com>
2019-09-03 5:55 ` Nathan Chancellor
2019-09-03 19:31 ` Segher Boessenkool
2019-09-04 0:24 ` Nathan Chancellor
[not found] ` <1bcd7086f3d24dfa82eec03980f30fbc@AcuMS.aculab.com>
2019-09-04 13:01 ` Segher Boessenkool
2019-09-04 23:15 ` Nathan Chancellor
2019-09-10 18:30 ` Michael Ellerman
2019-09-10 18:37 ` Nathan Chancellor
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