riscv: Mark __se_sys_* functions __used

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>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240326153712.1839482-2-samitolvanen@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/include/asm/syscall_wrapper.h b/arch/riscv/include/asm/syscall_wrapper.h
index 980094c2e9761d19b562d4dd8f9f707fd13480ae..ac80216549ffa6fce76ffe1759ad4e0da4609f9f 100644 (file)
--- 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, ...) \