[PATCH] syscall_user_dispatch: Introduce ARCH_SUPPORTS_SYSCALL_USER_DISPATCH
From: Jinjie Ruan <hidden>
Date: 2026-07-09 07:28:21
Also in:
linux-riscv, linux-s390, lkml, loongarch
Subsystem:
linux for powerpc (32-bit and 64-bit), loongarch, risc-v architecture, s390 architecture, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Huacai Chen, Paul Walmsley, Palmer Dabbelt, Albert Ou, Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
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. Link: https://lore.kernel.org/linux-arm-kernel/akZgV0Y4YAmB43_g@J2N7QTR9R3.cambridge.arm.com/ (local) Cc: Thomas Gleixner <tglx@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Ada Couprie Diaz <redacted> Cc: Thomas Weißschuh <redacted> Suggested-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Jinjie Ruan <redacted> --- arch/Kconfig | 1 + 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, 2 insertions(+), 21 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index 0c01521c2f3f..393d0fb75eac 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig@@ -116,6 +116,7 @@ config GENERIC_ENTRY 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
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2.34.1