[lwp][rv64] riscv: fix potential signal handler infinite loop

Author: eatvector

components/lwp/arch/risc-v/rv64/lwp_gcc.S

@@ -98,6 +98,29 @@ ret_to_user_exit:
     // `RESTORE_ALL` also reset sp to user sp, and setup sscratch
     sret
 
+/**
+ * Signal cleanup exit path - returns to user mode without checking pending signals.
+ * 
+ * This is called after signal handler completion (via arch_signal_quit) to restore
+ * user context. We intentionally skip pending signal checks here to prevent:
+ * 1. Signal handler recursion (e.g. if handler uses sys_tkill to send itself signals)
+ * 
+ * The primary purpose is to break potential infinite loops where a signal handler
+ * keeps triggering new signals. Normal signal delivery will resume on the next
+ * kernel-to-userspace transition.
+ */
+.global arch_signal_quit_to_user
+arch_signal_quit_to_user:
+    call lwp_check_exit_request
+    beqz a0, 1f
+    mv a0, x0
+    call sys_exit
+
+1:
+    mv a0, sp
+    RESTORE_ALL
+    sret
+
 /**
  * Restore user context from exception frame stroraged in ustack
  * And handle pending signals;
@@ -119,7 +142,7 @@ arch_signal_quit:
 
     RESTORE_ALL
     SAVE_ALL
-    j arch_ret_to_user
+    j arch_signal_quit_to_user
 
 /**
  * rt_noreturn