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Disable -Wattribute-alias for clang-23 and newer

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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>
This commit is contained in:
Nathan Chancellor 2026-05-16 04:34:14 +09:00
parent 5d6919055d
commit 175db11786
No known key found for this signature in database
GPG Key ID: 1D6B269171C01A96
5 changed files with 22 additions and 0 deletions
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4
arch/riscv/include/asm/syscall_wrapper.h
View File

@ -32,6 +32,10 @@ asmlinkage long __riscv_sys_ni_syscall(const struct pt_regs *);
__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)))); \

4
include/linux/compat.h
View File

@ -72,6 +72,10 @@
__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"); \
asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \
__attribute__((alias(__stringify(__se_compat_sys##name)))); \
ALLOW_ERROR_INJECTION(compat_sys##name, ERRNO); \

6
include/linux/compiler-clang.h
View File

@ -131,6 +131,12 @@
#define __diag_str(s) __diag_str1(s)
#define __diag(s) _Pragma(__diag_str(clang diagnostic s))
#if CONFIG_CLANG_VERSION >= 230000
#define __diag_clang_23(s) __diag(s)
#else
#define __diag_clang_23(s)
#endif
#define __diag_clang_13(s) __diag(s)
#define __diag_ignore_all(option, comment) \

4
include/linux/compiler_types.h
View File

@ -711,6 +711,10 @@ struct ftrace_likely_data {
#define __diag_GCC(version, severity, string)
#endif
#ifndef __diag_clang
#define __diag_clang(version, severity, string)
#endif
#define __diag_push() __diag(push)
#define __diag_pop() __diag(pop)

4
include/linux/syscalls.h
View File

@ -247,6 +247,10 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event)
__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");\
asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \
__attribute__((alias(__stringify(__se_sys##name)))); \
ALLOW_ERROR_INJECTION(sys##name, ERRNO); \