[PATCH v17 08/15] arm64: ptrace: Extract arm64_syscall_exit_to_user_mode_work() helper

[Jinjie Ruan]

Introduce a helper arm64_syscall_exit_to_user_mode_work() that
encapsulates the re-reading of thread flags and the call to
syscall_trace_exit().  Use it in el0_svc_common() to replace
the open-coded instances, removing the duplicated flags read
and making the control flow simpler.

This aligns the arm64 exit path with the pattern expected by the
generic entry infrastructure, which uses a similar
syscall_exit_to_user_mode_work() callback.

No functional changes intended; this is a preparation step for converting
arm64 to the generic entry infrastructure.

Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Ada Couprie Diaz <ada.coupriediaz@xxxxxxx>
Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
---
 arch/arm64/include/asm/syscall.h | 7 +++++++
 arch/arm64/kernel/syscall.c      | 9 +++------
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index 696739f5a250..3e4672ab4a4f 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -123,4 +123,11 @@ static inline int syscall_get_arch(struct task_struct *task)
 int arm64_syscall_trace_enter(struct pt_regs *regs, unsigned long flags);
 void syscall_trace_exit(struct pt_regs *regs, unsigned long flags);
 
+static __always_inline void arm64_syscall_exit_to_user_mode_work(struct pt_regs *regs)
+{
+	unsigned long flags = read_thread_flags();
+
+	syscall_trace_exit(regs, flags);
+}
+
 #endif	/* __ASM_SYSCALL_H */
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index e778aac6fab9..0061fc63e7ba 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c
@@ -127,16 +127,13 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 	 */
 	if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
 		flags = read_thread_flags();
-		if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP) {
-			flags = read_thread_flags();
-			syscall_trace_exit(regs, flags);
-		}
+		if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP)
+			arm64_syscall_exit_to_user_mode_work(regs);
 		return;
 	}
 
 trace_exit:
-	flags = read_thread_flags();
-	syscall_trace_exit(regs, flags);
+	arm64_syscall_exit_to_user_mode_work(regs);
 }
 
 void do_el0_svc(struct pt_regs *regs)
-- 
2.34.1