linux-user: Properly handle sigset arg to epoll_pwait

Unblocked signals are never delivered, because we
didn't record the new mask for process_pending_signals.
Handle this with the same mechanism as sigsuspend.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20220315084308.433109-5-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

linux-user/syscall.c

@@ -12694,29 +12694,21 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
 #if defined(TARGET_NR_epoll_pwait)
         case TARGET_NR_epoll_pwait:
         {
-            target_sigset_t *target_set;
-            sigset_t _set, *set = &_set;
+            sigset_t *set = NULL;
 
             if (arg5) {
-                if (arg6 != sizeof(target_sigset_t)) {
-                    ret = -TARGET_EINVAL;
-                    break;
-                }
-
-                target_set = lock_user(VERIFY_READ, arg5,
-                                       sizeof(target_sigset_t), 1);
-                if (!target_set) {
-                    ret = -TARGET_EFAULT;
+                ret = process_sigsuspend_mask(&set, arg5, arg6);
+                if (ret != 0) {
                     break;
                 }
-                target_to_host_sigset(set, target_set);
-                unlock_user(target_set, arg5, 0);
-            } else {
-                set = NULL;
             }
 
             ret = get_errno(safe_epoll_pwait(epfd, ep, maxevents, timeout,
                                              set, SIGSET_T_SIZE));
+
+            if (set) {
+                finish_sigsuspend_mask(ret);
+            }
             break;
         }
 #endif