old sigsuspend variants in kernel/signal.c

conditional on OLD_SIGSUSPEND/OLD_SIGSUSPEND3, depending on which
variety of that fossil is needed.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/Kconfig

@@ -387,4 +387,14 @@ config ODD_RT_SIGACTION
 	help
 	  Architecture has unusual rt_sigaction(2) arguments
 
+config OLD_SIGSUSPEND
+	bool
+	help
+	  Architecture has old sigsuspend(2) syscall, of one-argument variety
+
+config OLD_SIGSUSPEND3
+	bool
+	help
+	  Even weirder antique ABI - three-argument sigsuspend(2)
+
 source "kernel/gcov/Kconfig"

include/linux/syscalls.h

@@ -377,6 +377,14 @@ asmlinkage long sys_init_module(void __user *umod, unsigned long len,
 asmlinkage long sys_delete_module(const char __user *name_user,
 				unsigned int flags);
 
+#ifdef CONFIG_OLD_SIGSUSPEND
+asmlinkage long sys_sigsuspend(old_sigset_t mask);
+#endif
+
+#ifdef CONFIG_OLD_SIGSUSPEND3
+asmlinkage long sys_sigsuspend(int unused1, int unused2, old_sigset_t mask);
+#endif
+
 #ifndef CONFIG_ODD_RT_SIGACTION
 asmlinkage long sys_rt_sigaction(int,
 				 const struct sigaction __user *,

kernel/signal.c

@@ -3454,6 +3454,23 @@ COMPAT_SYSCALL_DEFINE2(rt_sigsuspend, compat_sigset_t __user *, unewset, compat_
 #endif
 #endif
 
+#ifdef CONFIG_OLD_SIGSUSPEND
+SYSCALL_DEFINE1(sigsuspend, old_sigset_t, mask)
+{
+	sigset_t blocked;
+	siginitset(&blocked, mask);
+	return sigsuspend(&blocked);
+}
+#endif
+#ifdef CONFIG_OLD_SIGSUSPEND3
+SYSCALL_DEFINE3(sigsuspend, int, unused1, int, unused2, old_sigset_t, mask)
+{
+	sigset_t blocked;
+	siginitset(&blocked, mask);
+	return sigsuspend(&blocked);
+}
+#endif
+
 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
 {
 	return NULL;