[PATCH v16 06/18] arm64: ptrace: Use syscall_get_arguments() helper for audit

Extract syscall_enter_audit() helper and use syscall_get_arguments()
to get syscall arguments, matching the generic entry implementation.

The new code:
- Checks audit_context() first to avoid unnecessary memcpy when audit
  is not active.
- Uses syscall_get_arguments() helper instead of directly accessing
  regs fields.
- Is now exactly equivalent to generic entry's syscall_enter_audit().

No functional changes.

Cc: Mark Rutland <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Catalin Marinas <[email protected]>
Reviewed-by: Ada Couprie Diaz <[email protected]>
Reviewed-by: Linus Walleij <[email protected]>
Reviewed-by: Yeoreum Yun <[email protected]>
Reviewed-by: Kevin Brodsky <[email protected]>
Signed-off-by: Jinjie Ruan <[email protected]>
---
 arch/arm64/kernel/ptrace.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 30df515528e8..ae71cadbd4df 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2408,6 +2408,16 @@ static void report_syscall_exit(struct pt_regs *regs)
 	}
 }
 
+static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
+{
+	if (unlikely(audit_context())) {
+		unsigned long args[6];
+
+		syscall_get_arguments(current, regs, args);
+		audit_syscall_entry(syscall, args[0], args[1], args[2], args[3]);
+	}
+}
+
 int syscall_trace_enter(struct pt_regs *regs, unsigned long flags)
 {
 	long syscall;
@@ -2438,8 +2448,7 @@ int syscall_trace_enter(struct pt_regs *regs, unsigned long flags)
 		 syscall = syscall_get_nr(current, regs);
 	}
 
-	audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1],
-			    regs->regs[2], regs->regs[3]);
+	syscall_enter_audit(regs, syscall);
 
 	return syscall;
 }
-- 
2.34.1