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

Alexandre Ghiti
2024-03-26T18:43:41Z

Hi Sami,

On 26/03/2024 16:37, 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@linaro.org>

Do you have the link of the report? So we can add a Closes tag.

> Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> ---
> 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

You can add:

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>

As the commit fixed here was merged in 6.9, this should go into fixes.

Thanks,

Alex