From eaa9088d568c84afd72fa32dbe01833aef861d0d Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 27 Oct 2025 09:45:05 +0100 Subject: [PATCH] rseq: Use static branch for syscall exit debug when GENERIC_IRQ_ENTRY=y Make the syscall exit debug mechanism available via the static branch on architectures which utilize the generic entry code. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Mathieu Desnoyers Link: https://patch.msgid.link/20251027084307.333440475@linutronix.de --- include/linux/entry-common.h | 2 +- include/linux/rseq_entry.h | 9 +++++++++ kernel/rseq.c | 10 ++++++++-- 3 files changed, 18 insertions(+), 3 deletions(-) diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index 75b194c34e18d..d967184ae08fc 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -146,7 +146,7 @@ static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs) local_irq_enable(); } - rseq_syscall(regs); + rseq_debug_syscall_return(regs); /* * Do one-time syscall specific work. If these work items are diff --git a/include/linux/rseq_entry.h b/include/linux/rseq_entry.h index 5bdcf5b5f5958..fb53a6ff05d7f 100644 --- a/include/linux/rseq_entry.h +++ b/include/linux/rseq_entry.h @@ -296,9 +296,18 @@ static __always_inline void rseq_exit_to_user_mode(void) ev->events = 0; } +void __rseq_debug_syscall_return(struct pt_regs *regs); + +static inline void rseq_debug_syscall_return(struct pt_regs *regs) +{ + if (static_branch_unlikely(&rseq_debug_enabled)) + __rseq_debug_syscall_return(regs); +} + #else /* CONFIG_RSEQ */ static inline void rseq_note_user_irq_entry(void) { } static inline void rseq_exit_to_user_mode(void) { } +static inline void rseq_debug_syscall_return(struct pt_regs *regs) { } #endif /* !CONFIG_RSEQ */ #endif /* _LINUX_RSEQ_ENTRY_H */ diff --git a/kernel/rseq.c b/kernel/rseq.c index abd6bfadbcc66..97631554ae962 100644 --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -473,12 +473,11 @@ error: force_sigsegv(sig); } -#ifdef CONFIG_DEBUG_RSEQ /* * Terminate the process if a syscall is issued within a restartable * sequence. */ -void rseq_syscall(struct pt_regs *regs) +void __rseq_debug_syscall_return(struct pt_regs *regs) { struct task_struct *t = current; u64 csaddr; @@ -496,6 +495,13 @@ void rseq_syscall(struct pt_regs *regs) fail: force_sig(SIGSEGV); } + +#ifdef CONFIG_DEBUG_RSEQ +/* Kept around to keep GENERIC_ENTRY=n architectures supported. */ +void rseq_syscall(struct pt_regs *regs) +{ + __rseq_debug_syscall_return(regs); +} #endif /* -- 2.47.3