* [PATCH] Disable -Wattribute-alias for clang-23 and newer
@ 2026-05-15 10:35 Nathan Chancellor
2026-05-15 19:40 ` Nathan Chancellor
0 siblings, 1 reply; 2+ messages in thread
From: Nathan Chancellor @ 2026-05-15 10:35 UTC (permalink / raw)
To: Nathan Chancellor, Bill Wendling, Justin Stitt, Nick Desaulniers
Cc: Arnd Bergmann, Paul Walmsley, Palmer Dabbelt, Albert Ou,
Alexandre Ghiti, linux-riscv, linux-kernel, llvm, stable
Clang recently added support for -Wattribute-alias [1], which results in
the same warnings that necessitated commit bee20031772a ("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.
Cc: stable@vger.kernel.org
Closes: https://github.com/ClangBuiltLinux/linux/issues/2163
Link: https://github.com/llvm/llvm-project/commit/40da6920a0d71d49dfa2392b09153600b0759f5e [1]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
I plan to take this via my clang-fixes tree for 7.1.
---
arch/riscv/include/asm/syscall_wrapper.h | 2 ++
include/linux/compat.h | 2 ++
include/linux/compiler-clang.h | 6 ++++++
include/linux/syscalls.h | 2 ++
4 files changed, 12 insertions(+)
diff --git a/arch/riscv/include/asm/syscall_wrapper.h b/arch/riscv/include/asm/syscall_wrapper.h
index ac80216549ff..366a5354caa5 100644
--- a/arch/riscv/include/asm/syscall_wrapper.h
+++ b/arch/riscv/include/asm/syscall_wrapper.h
@@ -32,6 +32,8 @@ 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, "-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)))); \
diff --git a/include/linux/compat.h b/include/linux/compat.h
index 56cebaff0c91..a1ce6d559db9 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -72,6 +72,8 @@
__diag_push(); \
__diag_ignore(GCC, 8, "-Wattribute-alias", \
"Type aliasing is used to sanitize syscall arguments");\
+ __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); \
diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
index e1123dd28486..527e4e136020 100644
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -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) \
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index f5639d5ac331..97e3411b49d2 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -247,6 +247,8 @@ 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, "-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); \
---
base-commit: 5d6919055dec134de3c40167a490f33c74c12581
change-id: 20260514-syscall-disable-attribute-alias-for-clang-51145bb90086
Best regards,
--
Cheers,
Nathan
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] Disable -Wattribute-alias for clang-23 and newer
2026-05-15 10:35 [PATCH] Disable -Wattribute-alias for clang-23 and newer Nathan Chancellor
@ 2026-05-15 19:40 ` Nathan Chancellor
0 siblings, 0 replies; 2+ messages in thread
From: Nathan Chancellor @ 2026-05-15 19:40 UTC (permalink / raw)
To: Bill Wendling, Justin Stitt, Nick Desaulniers
Cc: Arnd Bergmann, Paul Walmsley, Palmer Dabbelt, Albert Ou,
Alexandre Ghiti, linux-riscv, linux-kernel, llvm, stable
On Fri, May 15, 2026 at 07:35:18PM +0900, Nathan Chancellor wrote:
> Clang recently added support for -Wattribute-alias [1], which results in
> the same warnings that necessitated commit bee20031772a ("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.
>
> Cc: stable@vger.kernel.org
> Closes: https://github.com/ClangBuiltLinux/linux/issues/2163
> Link: https://github.com/llvm/llvm-project/commit/40da6920a0d71d49dfa2392b09153600b0759f5e [1]
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
> I plan to take this via my clang-fixes tree for 7.1.
> ---
> arch/riscv/include/asm/syscall_wrapper.h | 2 ++
> include/linux/compat.h | 2 ++
> include/linux/compiler-clang.h | 6 ++++++
> include/linux/syscalls.h | 2 ++
> 4 files changed, 12 insertions(+)
>
> diff --git a/arch/riscv/include/asm/syscall_wrapper.h b/arch/riscv/include/asm/syscall_wrapper.h
> index ac80216549ff..366a5354caa5 100644
> --- a/arch/riscv/include/asm/syscall_wrapper.h
> +++ b/arch/riscv/include/asm/syscall_wrapper.h
> @@ -32,6 +32,8 @@ 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, "-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)))); \
> diff --git a/include/linux/compat.h b/include/linux/compat.h
> index 56cebaff0c91..a1ce6d559db9 100644
> --- a/include/linux/compat.h
> +++ b/include/linux/compat.h
> @@ -72,6 +72,8 @@
> __diag_push(); \
> __diag_ignore(GCC, 8, "-Wattribute-alias", \
> "Type aliasing is used to sanitize syscall arguments");\
> + __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); \
> diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
> index e1123dd28486..527e4e136020 100644
> --- a/include/linux/compiler-clang.h
> +++ b/include/linux/compiler-clang.h
> @@ -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) \
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index f5639d5ac331..97e3411b49d2 100644
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -247,6 +247,8 @@ 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, "-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); \
The kbuild test robot pointed out that I need
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index e8fd77593b68..369966598a2c 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -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)
--
for this to build properly with GCC, which I will fold in.
--
Cheers,
Nathan
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