From 175db11786bde9061db526bf1ac5107d915f5163 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Sat, 16 May 2026 04:34:14 +0900 Subject: [PATCH] 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 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__)) \ | ^ :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: https://github.com/llvm/llvm-project/commit/40da6920a0d71d49dfa2392b09153600b0759f5e [1] Link: https://patch.msgid.link/20260515-syscall-disable-attribute-alias-for-clang-v1-1-9a9d95d41df6@kernel.org Signed-off-by: Nathan Chancellor --- arch/riscv/include/asm/syscall_wrapper.h | 4 ++++ include/linux/compat.h | 4 ++++ include/linux/compiler-clang.h | 6 ++++++ include/linux/compiler_types.h | 4 ++++ include/linux/syscalls.h | 4 ++++ 5 files changed, 22 insertions(+) diff --git a/arch/riscv/include/asm/syscall_wrapper.h b/arch/riscv/include/asm/syscall_wrapper.h index ac80216549ff..226289c3b5c8 100644 --- a/arch/riscv/include/asm/syscall_wrapper.h +++ b/arch/riscv/include/asm/syscall_wrapper.h @@ -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)))); \ diff --git a/include/linux/compat.h b/include/linux/compat.h index 56cebaff0c91..8da0a15c95f4 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -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); \ 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/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) diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index f5639d5ac331..4fb7291f54b6 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -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); \