signal/timer/event: signalfd compat code

This patch implements the necessary compat code for the signalfd system call.
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/compat.c

@@ -46,6 +46,7 @@
 #include <linux/tsacct_kern.h>
 #include <linux/security.h>
 #include <linux/highmem.h>
+#include <linux/signal.h>
 #include <linux/poll.h>
 #include <linux/mm.h>
 #include <linux/eventpoll.h>
@@ -2199,3 +2200,28 @@ asmlinkage long compat_sys_epoll_pwait(int epfd,
 #endif /* TIF_RESTORE_SIGMASK */
 
 #endif /* CONFIG_EPOLL */
+
+#ifdef CONFIG_SIGNALFD
+
+asmlinkage long compat_sys_signalfd(int ufd,
+				    const compat_sigset_t __user *sigmask,
+				    compat_size_t sigsetsize)
+{
+	compat_sigset_t ss32;
+	sigset_t tmp;
+	sigset_t __user *ksigmask;
+
+	if (sigsetsize != sizeof(compat_sigset_t))
+		return -EINVAL;
+	if (copy_from_user(&ss32, sigmask, sizeof(ss32)))
+		return -EFAULT;
+	sigset_from_compat(&tmp, &ss32);
+	ksigmask = compat_alloc_user_space(sizeof(sigset_t));
+	if (copy_to_user(ksigmask, &tmp, sizeof(sigset_t)))
+		return -EFAULT;
+
+	return sys_signalfd(ufd, ksigmask, sizeof(sigset_t));
+}
+
+#endif /* CONFIG_SIGNALFD */
+