In subject: s/refator/refactor/
Also nit: this is less about ptrace than about syscall entry, so maybe "arm64/syscall:"?
On 17/11/2025 14:30, Jinjie Ruan wrote:
Compared to the generic entry code, arm64 terminate the process
s/terminate/terminates/ (similar observation for other commit messages)
after report_syscall_exit() if the syscall is issued within a restartable sequence.
Presumably this implies that forcing SIGSEGV before or after calling the tracing handlers makes no difference, if so it should be clarified.
In preparation for moving arm64 over to the generic entry code, refactor el0_svc_common() as below:
Extract syscall_exit_to_user_mode_prepare() to replace the the combination of read_thread_flags() and syscall_trace_exit(), also move the syscall exit check logic into it.
Move rseq_syscall() ahead, so the CONFIG_DEBUG_RSEQ check is not needed.
Move has_syscall_work() helper into asm/syscall.h, which will be reused by ptrace.c.
Signed-off-by: Jinjie Ruan ruanjinjie@huawei.com
arch/arm64/include/asm/syscall.h | 7 ++++++- arch/arm64/kernel/ptrace.c | 10 +++++++++- arch/arm64/kernel/syscall.c | 26 +++++--------------------- 3 files changed, 20 insertions(+), 23 deletions(-)
diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h index d69f590a989b..6225981fbbdb 100644 --- a/arch/arm64/include/asm/syscall.h +++ b/arch/arm64/include/asm/syscall.h @@ -114,7 +114,12 @@ 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, long syscall, unsigned long flags); -void syscall_trace_exit(struct pt_regs *regs, unsigned long flags); +void syscall_exit_to_user_mode_prepare(struct pt_regs *regs); #endif /* __ASM_SYSCALL_H */ diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index bbb868f6b292..95984bbf53db 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -2403,7 +2403,7 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags) return regs->syscallno; } -void syscall_trace_exit(struct pt_regs *regs, unsigned long flags) +static void syscall_trace_exit(struct pt_regs *regs, unsigned long flags) { audit_syscall_exit(regs); @@ -2412,8 +2412,16 @@ void syscall_trace_exit(struct pt_regs *regs, unsigned long flags) if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP)) report_syscall_exit(regs); +}
+void syscall_exit_to_user_mode_prepare(struct pt_regs *regs) +{
- unsigned long flags = read_thread_flags();
rseq_syscall(regs);
- if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP)
syscall_trace_exit(regs, flags);
Since we're trying to align as much with the generic code as possible, we might as well rename this function to syscall_exit_work() as well.
} /* diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c index 6e3fe760e0bb..9713b038d750 100644 --- a/arch/arm64/kernel/syscall.c +++ b/arch/arm64/kernel/syscall.c @@ -65,11 +65,6 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno, choose_random_kstack_offset(get_random_u16()); } -static inline bool has_syscall_work(unsigned long flags) -{
- return unlikely(flags & _TIF_SYSCALL_WORK);
-}
static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, const syscall_fn_t syscall_table[]) { @@ -125,26 +120,15 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, if (scno == NO_SYSCALL) syscall_set_return_value(current, regs, -ENOSYS, 0); scno = syscall_trace_enter(regs, regs->syscallno, flags);
if (scno == NO_SYSCALL)goto trace_exit;
Why not keep the goto instead of duplicating the call? It could be renamed if necessary.
- Kevin
if (scno == NO_SYSCALL) {syscall_exit_to_user_mode_prepare(regs);return;}invoke_syscall(regs, scno, sc_nr, syscall_table);
- /*
* The tracing status may have changed under our feet, so we have to* check again. However, if we were tracing entry, then we always trace* exit regardless, as the old entry assembly did.*/- if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
flags = read_thread_flags();if (!has_syscall_work(flags) && !(flags & _TIF_SINGLESTEP))return;- }
-trace_exit:
- flags = read_thread_flags();
- syscall_trace_exit(regs, flags);
- syscall_exit_to_user_mode_prepare(regs);
} void do_el0_svc(struct pt_regs *regs)