[PATCH v16 02/18] syscall_user_dispatch: Introduce a weak fallback for arch_syscall_is_vdso_sigreturn()
From: Jinjie Ruan <hidden>
Date: 2026-06-29 13:06:50
Also in:
linux-alpha, linux-m68k, linux-mips, linux-mm, linux-riscv, linux-s390, linux-sh, linux-um, lkml, loongarch
Subsystem:
generic entry code, linux for powerpc (32-bit and 64-bit), loongarch, risc-v architecture, s390 architecture, the rest · Maintainers:
Thomas Gleixner, Peter Zijlstra, Andy Lutomirski, Madhavan Srinivasan, Michael Ellerman, Huacai Chen, Paul Walmsley, Palmer Dabbelt, Albert Ou, Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds
Currently, multiple architectures (LoongArch, RISC-V, S390, Powerpc) provide identical stubs for arch_syscall_is_vdso_sigreturn() that simply return false. This results in redundant boilerplate code across the tree. Introduce a default __weak implementation of arch_syscall_is_vdso_sigreturn() directly in syscall_user_dispatch.c that returns false. This allows architectures that do not utilize a vDSO sigreturn to entirely drop their redundant inline definitions. Architectures requiring a specialized check (such as x86) will continue to override this fallback with their strong symbol definitions. Clean up the redundant implementations in loongarch, riscv, s390 and powerpc. Cc: Thomas Gleixner <tglx@kernel.org> Signed-off-by: Jinjie Ruan <redacted> --- arch/loongarch/include/asm/syscall.h | 5 ----- arch/powerpc/include/asm/syscall.h | 5 ----- arch/riscv/include/asm/syscall.h | 5 ----- arch/s390/include/asm/syscall.h | 5 ----- include/linux/syscall_user_dispatch.h | 1 + kernel/entry/syscall_user_dispatch.c | 5 +++++ 6 files changed, 6 insertions(+), 20 deletions(-)
diff --git a/arch/loongarch/include/asm/syscall.h b/arch/loongarch/include/asm/syscall.h
index df8ea223c77b..946886794ced 100644
--- a/arch/loongarch/include/asm/syscall.h
+++ b/arch/loongarch/include/asm/syscall.h@@ -85,9 +85,4 @@ static inline int syscall_get_arch(struct task_struct *task) #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/include/linux/syscall_user_dispatch.h b/include/linux/syscall_user_dispatch.h
index 3858a6ffdd5c..73d69e02807d 100644
--- a/include/linux/syscall_user_dispatch.h
+++ b/include/linux/syscall_user_dispatch.h@@ -10,6 +10,7 @@ #ifdef CONFIG_GENERIC_ENTRY +bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs); int set_syscall_user_dispatch(unsigned long mode, unsigned long offset, unsigned long len, char __user *selector);
diff --git a/kernel/entry/syscall_user_dispatch.c b/kernel/entry/syscall_user_dispatch.c
index d89dffcc2d64..acf545774d37 100644
--- a/kernel/entry/syscall_user_dispatch.c
+++ b/kernel/entry/syscall_user_dispatch.c@@ -32,6 +32,11 @@ static void trigger_sigsys(struct pt_regs *regs) force_sig_info(&info); } +bool __weak arch_syscall_is_vdso_sigreturn(struct pt_regs *regs) +{ + return false; +} + bool syscall_user_dispatch(struct pt_regs *regs) { struct syscall_user_dispatch *sd = ¤t->syscall_dispatch;
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2.34.1