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Date: Tue, 26 Mar 2024 15:37:13 +0000
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Message-ID: <20240326153712.1839482-2-samitolvanen@google.com>
Subject: [PATCH] riscv: Mark __se_sys_* functions __used
From: Sami Tolvanen <samitolvanen@google.com>
To: Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, 
	Albert Ou <aou@eecs.berkeley.edu>
Cc: Kees Cook <keescook@chromium.org>, linux-riscv@lists.infradead.org, 
	llvm@lists.linux.dev, linux-kernel@vger.kernel.org, 
	Sami Tolvanen <samitolvanen@google.com>, Linux Kernel Functional Testing <lkft@linaro.org>
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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>
---
 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