From 8383e05af734355ba5cdd348991eaa71f6003e71 Mon Sep 17 00:00:00 2001 From: Jinjie Ruan Date: Mon, 13 Jul 2026 11:54:22 +0800 Subject: [PATCH] syscall_user_dispatch: Introduce ARCH_SUPPORTS_SYSCALL_USER_DISPATCH MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Currently, only x86 genuinely implements and supports Syscall User Dispatch (SUD). Multiple architectures provide a stub arch_syscall_is_vdso_sigreturn() returning 'false' simply to satisfy GENERIC_ENTRY compilation, which creates a false impression of feature support. Introduce ARCH_SUPPORTS_SYSCALL_USER_DISPATCH to decouple this mechanism from GENERIC_ENTRY. Select it exclusively on x86 and remove the redundant stub functions from other architectures. Suggested-by: Mark Rutland Signed-off-by: Jinjie Ruan Signed-off-by: Thomas Gleixner Reviewed-by: Thomas Weißschuh Link: https://patch.msgid.link/20260713035422.582771-1-ruanjinjie@huawei.com --- arch/Kconfig | 4 ++++ arch/loongarch/include/asm/syscall.h | 6 ------ arch/powerpc/include/asm/syscall.h | 5 ----- arch/riscv/include/asm/syscall.h | 5 ----- arch/s390/include/asm/syscall.h | 5 ----- arch/x86/Kconfig | 1 + 6 files changed, 5 insertions(+), 21 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index d2dbed524f15..066263cc44fe 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -114,8 +114,12 @@ config GENERIC_ENTRY select GENERIC_IRQ_ENTRY select GENERIC_SYSCALL +config ARCH_SUPPORTS_SYSCALL_USER_DISPATCH + bool + config SYSCALL_USER_DISPATCH bool "Syscall User Dispatch" + depends on ARCH_SUPPORTS_SYSCALL_USER_DISPATCH depends on GENERIC_ENTRY default y help diff --git a/arch/loongarch/include/asm/syscall.h b/arch/loongarch/include/asm/syscall.h index df8ea223c77b..d9275010f548 100644 --- a/arch/loongarch/include/asm/syscall.h +++ b/arch/loongarch/include/asm/syscall.h @@ -84,10 +84,4 @@ static inline int syscall_get_arch(struct task_struct *task) return AUDIT_ARCH_LOONGARCH64; #endif } - -static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs) -{ - return false; -} - #endif /* __ASM_LOONGARCH_SYSCALL_H */ diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h index 834fcc4f7b54..4b3c52ed6e9d 100644 --- a/arch/powerpc/include/asm/syscall.h +++ b/arch/powerpc/include/asm/syscall.h @@ -139,9 +139,4 @@ static inline int syscall_get_arch(struct task_struct *task) else return AUDIT_ARCH_PPC64; } - -static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs) -{ - return false; -} #endif /* _ASM_SYSCALL_H */ diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h index 8067e666a4ca..987c9a78806f 100644 --- a/arch/riscv/include/asm/syscall.h +++ b/arch/riscv/include/asm/syscall.h @@ -112,11 +112,6 @@ static inline void syscall_handler(struct pt_regs *regs, ulong syscall) regs->a0 = fn(regs); } -static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs) -{ - return false; -} - asmlinkage long sys_riscv_flush_icache(uintptr_t, uintptr_t, uintptr_t); asmlinkage long sys_riscv_hwprobe(struct riscv_hwprobe *, size_t, size_t, diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h index 4271e4169f45..5f310caad1fc 100644 --- a/arch/s390/include/asm/syscall.h +++ b/arch/s390/include/asm/syscall.h @@ -89,11 +89,6 @@ static inline int syscall_get_arch(struct task_struct *task) return AUDIT_ARCH_S390X; } -static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs) -{ - return false; -} - #define SYSCALL_FMT_0 #define SYSCALL_FMT_1 , "0" (r2) #define SYSCALL_FMT_2 , "d" (r3) SYSCALL_FMT_1 diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index bdad90f210e4..f3f8ad107eeb 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -335,6 +335,7 @@ config X86 select SCHED_SMT if SMP select ARCH_SUPPORTS_SCHED_CLUSTER if SMP select ARCH_SUPPORTS_SCHED_MC if SMP + select ARCH_SUPPORTS_SYSCALL_USER_DISPATCH select HAVE_SINGLE_FTRACE_DIRECT_OPS if X86_64 && DYNAMIC_FTRACE_WITH_DIRECT_CALLS config INSTRUCTION_DECODER