Re: [PATCH] riscv: Mark __se_sys_* functions __used

[Conor Dooley]

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:
> 
>    mm/oom_kill.c:1195:1: warning: unused function '___se_sys_process_mrelease' [-Wunused-function]
>     1195 | SYSCALL_DEFINE2(process_mrelease, int, pidfd, unsigned int, flags)
>          | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    include/linux/syscalls.h:221:36: note: expanded from macro 'SYSCALL_DEFINE2'
>      221 | #define SYSCALL_DEFINE2(name, ...) SYSCALL_DEFINEx(2, _##name, __VA_ARGS__)
>          |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    include/linux/syscalls.h:231:2: note: expanded from macro 'SYSCALL_DEFINEx'
>      231 |         __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
>          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    arch/riscv/include/asm/syscall_wrapper.h:81:2: note: expanded from macro '__SYSCALL_DEFINEx'
>       81 |         __SYSCALL_SE_DEFINEx(x, sys, name, __VA_ARGS__)                         \
>          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    arch/riscv/include/asm/syscall_wrapper.h:40:14: note: expanded from macro '__SYSCALL_SE_DEFINEx'
>       40 |         static long ___se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__))
>          |                     ^~~~~~~~~~~~~~~~~~~~
>    <scratch space>:30:1: note: expanded from here
>       30 | ___se_sys_process_mrelease
>          | ^~~~~~~~~~~~~~~~~~~~~~~~~~
>    1 warning generated.
> 
> Mark the functions __used explicitly to fix the Clang warnings.
> 
> Fixes: a9ad73295cc1 ("riscv: Fix syscall wrapper for >word-size arguments")
> Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
> Tested-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>
> Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>

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

Thanks,
Conor.

> ---
>  arch/riscv/include/asm/syscall_wrapper.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/include/asm/syscall_wrapper.h b/arch/riscv/include/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__))
>  
>  #define SC_RISCV_REGS_TO_ARGS(x, ...) \
> 
> base-commit: 4cece764965020c22cff7665b18a012006359095
> -- 
> 2.44.0.396.g6e790dbe36-goog
> 
> 
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