Files
linux/arch/riscv/include/asm/syscall_wrapper.h
Nathan Chancellor 175db11786 Disable -Wattribute-alias for clang-23 and newer
Clang recently added support for -Wattribute-alias [1], which results in
the same warnings that necessitated commit bee2003177 ("disable
-Wattribute-alias warning for SYSCALL_DEFINEx()") for GCC.

  kernel/time/itimer.c:325:1: error: alias and aliasee have different types 'long (unsigned int)' and 'long (typeof (__builtin_choose_expr((__builtin_types_compatible_p(typeof ((unsigned int)0), typeof (0LL)) || __builtin_types_compatible_p(typeof ((unsigned int)0), typeof (0ULL))), 0LL, 0L)))' (aka 'long (long)') [-Werror,-Wattribute-alias]
    325 | SYSCALL_DEFINE1(alarm, unsigned int, seconds)
        | ^
  include/linux/syscalls.h:225:36: note: expanded from macro 'SYSCALL_DEFINE1'
    225 | #define SYSCALL_DEFINE1(name, ...) SYSCALL_DEFINEx(1, _##name, __VA_ARGS__)
        |                                    ^
  include/linux/syscalls.h:236:2: note: expanded from macro 'SYSCALL_DEFINEx'
    236 |         __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
        |         ^
  include/linux/syscalls.h:251:18: note: expanded from macro '__SYSCALL_DEFINEx'
    251 |                 __attribute__((alias(__stringify(__se_sys##name))));    \
        |                                ^
  kernel/time/itimer.c:325:1: note: aliasee is declared here
  include/linux/syscalls.h:225:36: note: expanded from macro 'SYSCALL_DEFINE1'
    225 | #define SYSCALL_DEFINE1(name, ...) SYSCALL_DEFINEx(1, _##name, __VA_ARGS__)
        |                                    ^
  include/linux/syscalls.h:236:2: note: expanded from macro 'SYSCALL_DEFINEx'
    236 |         __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
        |         ^
  include/linux/syscalls.h:255:18: note: expanded from macro '__SYSCALL_DEFINEx'
    255 |         asmlinkage long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))  \
        |                         ^
  <scratch space>:16:1: note: expanded from here
     16 | __se_sys_alarm
        | ^

Disable the warnings in the same way for clang-23 and newer. Disable the
warning about unknown warning options to avoid breaking the build for
versions of clang-23 that do not have -Wattribute-alias, such as ones
deployed by vendors like Android or CI systems or when bisecting LLVM
between llvmorg-23-init and release/23.x.

Cc: stable@vger.kernel.org
Closes: https://github.com/ClangBuiltLinux/linux/issues/2163
Link: 40da6920a0 [1]
Link: https://patch.msgid.link/20260515-syscall-disable-attribute-alias-for-clang-v1-1-9a9d95d41df6@kernel.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
2026-05-28 06:51:30 -07:00

113 lines
4.2 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
/*
* syscall_wrapper.h - riscv specific wrappers to syscall definitions
*
* Based on arch/arm64/include/syscall_wrapper.h
*/
#ifndef __ASM_SYSCALL_WRAPPER_H
#define __ASM_SYSCALL_WRAPPER_H
#include <asm/ptrace.h>
asmlinkage long __riscv_sys_ni_syscall(const struct pt_regs *);
#ifdef CONFIG_64BIT
#define __SYSCALL_SE_DEFINEx(x, prefix, name, ...) \
static long __se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
static long __se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__))
#define SC_RISCV_REGS_TO_ARGS(x, ...) \
__MAP(x,__SC_ARGS \
,,regs->orig_a0,,regs->a1,,regs->a2 \
,,regs->a3,,regs->a4,,regs->a5,,regs->a6)
#else
/*
* Use type aliasing to ensure registers a0-a6 are correctly passed to the syscall
* implementation when >word-size arguments are used.
*/
#define __SYSCALL_SE_DEFINEx(x, prefix, name, ...) \
__diag_push(); \
__diag_ignore(GCC, 8, "-Wattribute-alias", \
"Type aliasing is used to sanitize syscall arguments"); \
__diag_ignore(clang, 23, "-Wunknown-warning-option", \
"Avoid breaking versions without -Wattribute-alias"); \
__diag_ignore(clang, 23, "-Wattribute-alias", \
"Type aliasing is used to sanitize syscall arguments"); \
static long __se_##prefix##name(ulong, ulong, ulong, ulong, ulong, ulong, \
ulong) \
__attribute__((alias(__stringify(___se_##prefix##name)))); \
__diag_pop(); \
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, ...) \
regs->orig_a0,regs->a1,regs->a2,regs->a3,regs->a4,regs->a5,regs->a6
#endif /* CONFIG_64BIT */
#ifdef CONFIG_COMPAT
#define COMPAT_SYSCALL_DEFINEx(x, name, ...) \
asmlinkage long __riscv_compat_sys##name(const struct pt_regs *regs); \
ALLOW_ERROR_INJECTION(__riscv_compat_sys##name, ERRNO); \
static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \
__SYSCALL_SE_DEFINEx(x, compat_sys, name, __VA_ARGS__) \
{ \
return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__)); \
} \
asmlinkage long __riscv_compat_sys##name(const struct pt_regs *regs) \
{ \
return __se_compat_sys##name(SC_RISCV_REGS_TO_ARGS(x,__VA_ARGS__)); \
} \
static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
#define COMPAT_SYSCALL_DEFINE0(sname) \
asmlinkage long __riscv_compat_sys_##sname(const struct pt_regs *__unused); \
ALLOW_ERROR_INJECTION(__riscv_compat_sys_##sname, ERRNO); \
asmlinkage long __riscv_compat_sys_##sname(const struct pt_regs *__unused)
#define COND_SYSCALL_COMPAT(name) \
asmlinkage long __weak __riscv_compat_sys_##name(const struct pt_regs *regs); \
asmlinkage long __weak __riscv_compat_sys_##name(const struct pt_regs *regs) \
{ \
return sys_ni_syscall(); \
}
#endif /* CONFIG_COMPAT */
#define __SYSCALL_DEFINEx(x, name, ...) \
asmlinkage long __riscv_sys##name(const struct pt_regs *regs); \
ALLOW_ERROR_INJECTION(__riscv_sys##name, ERRNO); \
static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \
__SYSCALL_SE_DEFINEx(x, sys, name, __VA_ARGS__) \
{ \
long ret = __do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__)); \
__MAP(x,__SC_TEST,__VA_ARGS__); \
__PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \
return ret; \
} \
asmlinkage long __riscv_sys##name(const struct pt_regs *regs) \
{ \
return __se_sys##name(SC_RISCV_REGS_TO_ARGS(x,__VA_ARGS__)); \
} \
static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
#define SYSCALL_DEFINE0(sname) \
SYSCALL_METADATA(_##sname, 0); \
asmlinkage long __riscv_sys_##sname(const struct pt_regs *__unused); \
ALLOW_ERROR_INJECTION(__riscv_sys_##sname, ERRNO); \
asmlinkage long __riscv_sys_##sname(const struct pt_regs *__unused)
#define COND_SYSCALL(name) \
asmlinkage long __weak __riscv_sys_##name(const struct pt_regs *regs); \
asmlinkage long __weak __riscv_sys_##name(const struct pt_regs *regs) \
{ \
return sys_ni_syscall(); \
}
#endif /* __ASM_SYSCALL_WRAPPER_H */