Introduce _TIF_SYSCALL_EXIT_WORK to filter out entry-only flags during the syscall exit path. This aligns arm64 with the generic entry framework's SYSCALL_WORK_EXIT semantics.
[Rationale] The current syscall exit path uses _TIF_SYSCALL_WORK to decide whether to invoke syscall_exit_work(). However, _TIF_SYSCALL_WORK includes flags that are only relevant during syscall entry: 1. _TIF_SECCOMP: Seccomp filtering (__secure_computing) only runs on entry. There is no seccomp callback for syscall exit. 2. _TIF_SYSCALL_EMU: In PTRACE_SYSEMU mode, the syscall is intercepted and skipped on entry. Since the syscall is never executed, reporting a syscall exit stop is unnecessary. [Changes] - Define _TIF_SYSCALL_EXIT_WORK: A new mask containing only flags requiring exit processing: _TIF_SYSCALL_TRACE, _TIF_SYSCALL_AUDIT, and _TIF_SYSCALL_TRACEPOINT. - Update exit path: Use _TIF_SYSCALL_EXIT_WORK in syscall_exit_to_user_mode_work() to avoid redundant calls to audit and ptrace reporting when only entry-flags are set. - Cleanup: Remove the has_syscall_work() helper as it is no longer needed. Direct flag comparison is now used to distinguish between entry and exit work requirements. [Impact] audit_syscall_exit() and report_syscall_exit() will no longer be triggered for seccomp-only or emu-only syscalls. This matches the generic entry behavior and improves efficiency by skipping unnecessary exit processing. Cc: Will Deacon <[email protected]> Cc: Catalin Marinas <[email protected]> Signed-off-by: Jinjie Ruan <[email protected]> --- arch/arm64/include/asm/syscall.h | 5 ----- arch/arm64/include/asm/thread_info.h | 3 +++ arch/arm64/kernel/ptrace.c | 2 +- arch/arm64/kernel/syscall.c | 2 +- 4 files changed, 5 insertions(+), 7 deletions(-) diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h index c469d09a7964..dea392c081ca 100644 --- a/arch/arm64/include/asm/syscall.h +++ b/arch/arm64/include/asm/syscall.h @@ -120,11 +120,6 @@ static inline int syscall_get_arch(struct task_struct *task) return AUDIT_ARCH_AARCH64; } -static inline bool has_syscall_work(unsigned long flags) -{ - return unlikely(flags & _TIF_SYSCALL_WORK); -} - int syscall_trace_enter(struct pt_regs *regs, unsigned long flags); void syscall_exit_to_user_mode_work(struct pt_regs *regs); diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index 7942478e4065..4ae83cb620bb 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h @@ -109,6 +109,9 @@ void arch_setup_new_exec(void); _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \ _TIF_SYSCALL_EMU) +#define _TIF_SYSCALL_EXIT_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \ + _TIF_SYSCALL_TRACEPOINT) + #ifdef CONFIG_SHADOW_CALL_STACK #define INIT_SCS \ .scs_base = init_shadow_call_stack, \ diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 35efa2062408..3cac9668aaa8 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -2471,7 +2471,7 @@ void syscall_exit_to_user_mode_work(struct pt_regs *regs) rseq_syscall(regs); - if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP) + if (unlikely(flags & _TIF_SYSCALL_EXIT_WORK) || flags & _TIF_SINGLESTEP) syscall_exit_work(regs, flags); } diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c index 66d4da641d97..ec478fc37a9f 100644 --- a/arch/arm64/kernel/syscall.c +++ b/arch/arm64/kernel/syscall.c @@ -101,7 +101,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, return; } - if (has_syscall_work(flags)) { + if (unlikely(flags & _TIF_SYSCALL_WORK)) { /* * The de-facto standard way to skip a system call using ptrace * is to set the system call to -1 (NO_SYSCALL) and set x0 to a -- 2.34.1
