Compared to the generic entry code, arm64 terminate the process after report_syscall_exit() if the syscall is issued within a restartable sequence.
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); }
/* 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; + 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)