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Date: Tue, 26 Mar 2024 18:49:25 +0000
From: Conor Dooley <conor@kernel.org>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Kees Cook <keescook@chromium.org>, linux-riscv@lists.infradead.org,
	llvm@lists.linux.dev, linux-kernel@vger.kernel.org,
	Linux Kernel Functional Testing <lkft@linaro.org>
Subject: Re: [PATCH] riscv: Mark __se_sys_* functions __used
Message-ID: <20240326-proofing-projector-0b8eef253667@spud>
References: <20240326153712.1839482-2-samitolvanen@google.com>
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On Tue, Mar 26, 2024 at 03:37:13PM +0000, Sami Tolvanen wrote:
> Clang doesn't think ___se_sys_* functions used even though they are
> aliased to __se_sys_*, resulting in -Wunused-function warnings when
> building rv32. For example:
>=20
>    mm/oom_kill.c:1195:1: warning: unused function '___se_sys_process_mrel=
ease' [-Wunused-function]
>     1195 | SYSCALL_DEFINE2(process_mrelease, int, pidfd, unsigned int, fl=
ags)
>          | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=
~~~~
>    include/linux/syscalls.h:221:36: note: expanded from macro 'SYSCALL_DE=
FINE2'
>      221 | #define SYSCALL_DEFINE2(name, ...) SYSCALL_DEFINEx(2, _##name,=
 __VA_ARGS__)
>          |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~=
~~~~~~~~~~~~~
>    include/linux/syscalls.h:231:2: note: expanded from macro 'SYSCALL_DEF=
INEx'
>      231 |         __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
>          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    arch/riscv/include/asm/syscall_wrapper.h:81:2: note: expanded from mac=
ro '__SYSCALL_DEFINEx'
>       81 |         __SYSCALL_SE_DEFINEx(x, sys, name, __VA_ARGS__)       =
                  \
>          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    arch/riscv/include/asm/syscall_wrapper.h:40:14: note: expanded from ma=
cro '__SYSCALL_SE_DEFINEx'
>       40 |         static long ___se_##prefix##name(__MAP(x,__SC_LONG,__V=
A_ARGS__))
>          |                     ^~~~~~~~~~~~~~~~~~~~
>    <scratch space>:30:1: note: expanded from here
>       30 | ___se_sys_process_mrelease
>          | ^~~~~~~~~~~~~~~~~~~~~~~~~~
>    1 warning generated.
>=20
> Mark the functions __used explicitly to fix the Clang warnings.
>=20
> Fixes: a9ad73295cc1 ("riscv: Fix syscall wrapper for >word-size arguments=
")
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Oh neat, thanks. This was generating a shed load of noise in CI :)
Tested-by: Conor Dooley <conor.dooley@microchip.com>

Thanks,
Conor.

> ---
>  arch/riscv/include/asm/syscall_wrapper.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>=20
> diff --git a/arch/riscv/include/asm/syscall_wrapper.h b/arch/riscv/includ=
e/asm/syscall_wrapper.h
> index 980094c2e976..ac80216549ff 100644
> --- a/arch/riscv/include/asm/syscall_wrapper.h
> +++ b/arch/riscv/include/asm/syscall_wrapper.h
> @@ -36,7 +36,8 @@ asmlinkage long __riscv_sys_ni_syscall(const struct pt_=
regs *);
>  					ulong)						\
>  			__attribute__((alias(__stringify(___se_##prefix##name))));	\
>  	__diag_pop();									\
> -	static long noinline ___se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__=
));	\
> +	static long noinline ___se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__=
))	\
> +			__used;								\
>  	static long ___se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__))
> =20
>  #define SC_RISCV_REGS_TO_ARGS(x, ...) \
>=20
> base-commit: 4cece764965020c22cff7665b18a012006359095
> --=20
> 2.44.0.396.g6e790dbe36-goog
>=20
>=20
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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