On Tue, Mar 17, 2026 at 9:20 AM Jinjie Ruan <[email protected]> wrote:
> Implement the generic entry framework for arm64 to handle system call > entry and exit. This follows the migration of x86, RISC-V, and LoongArch, > consolidating architecture-specific syscall tracing and auditing into > the common kernel entry infrastructure. > > [Background] > Arm64 has already adopted generic IRQ entry. Completing the conversion > to the generic syscall entry framework reduces architectural divergence, > simplifies maintenance, and allows arm64 to automatically benefit from > improvements in the common entry code. > > [Changes] > > 1. Kconfig and Infrastructure: > - Select GENERIC_ENTRY and remove GENERIC_IRQ_ENTRY (now implied). > > - Migrate struct thread_info to use the syscall_work field instead > of TIF flags for syscall-related tasks. > > 2. Thread Info and Flags: > - Remove definitions for TIF_SYSCALL_TRACE, TIF_SYSCALL_AUDIT, > TIF_SYSCALL_TRACEPOINT, TIF_SECCOMP, and TIF_SYSCALL_EMU. > > - Replace _TIF_SYSCALL_WORK and _TIF_SYSCALL_EXIT_WORK with the > generic SYSCALL_WORK bitmask. > > - Map single-step state to SYSCALL_EXIT_TRAP in debug-monitors.c. > > 3. Architecture-Specific Hooks (asm/entry-common.h): > - Implement arch_ptrace_report_syscall_entry() and _exit() by > porting the existing arm64 logic to the generic interface. > > - Add arch_syscall_is_vdso_sigreturn() to asm/syscall.h to > support Syscall User Dispatch (SUD). > > 4. Differentiate between syscall and interrupt entry/exit paths to handle > RSEQ slice extensions correctly. > - For irq/exception entry/exit: use irqentry_enter_from_user_mode() and > irqentry_exit_to_user_mode_prepare(). > - For syscall entry/exit: use enter_from_user_mode() and > syscall_exit_to_user_mode_prepare(). > - Remove exit_to_user_mode_prepare_legacy() which is no longer necessary. > > 5. rseq_syscall() will be replaced with the static key version, that is > "rseq_debug_syscall_return()" > > 6. Cleanup and Refactoring: > - Remove redundant arm64-specific syscall tracing functions from > ptrace.c, including syscall_trace_enter(), syscall_exit_work(), > and related audit/step helpers. > > - Update el0_svc_common() in syscall.c to use the generic > syscall_work checks and entry/exit call sites. > > [Why this matters] > - Unified Interface: Aligns arm64 with the modern kernel entry standard. > > - Improved Maintainability: Bug fixes in kernel/entry/common.c now > apply to arm64 automatically. > > - Feature Readiness: Simplifies the implementation of future > cross-architecture syscall features. > > [Compatibility] > This conversion maintains full ABI compatibility with existing > userspace. The ptrace register-saving behavior, seccomp filtering, and > syscall tracing semantics remain identical to the previous implementation. > > Cc: Will Deacon <[email protected]> > Cc: Catalin Marinas <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Reviewed-by: Kevin Brodsky <[email protected]> > Suggested-by: Kevin Brodsky <[email protected]> > Suggested-by: Mark Rutland <[email protected]> > Signed-off-by: Jinjie Ruan <[email protected]> This looks really neat. Reviewed-by: Linus Walleij <[email protected]> Yours, Linus Walleij
