syscall: Add __NR_rt_sigreturn

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

include/syscall-codes.h

@@ -12,6 +12,7 @@
 #define __NR_mprotect		10
 #define __NR_munmap		11
 #define __NR_brk		12
+#define __NR_rt_sigreturn	15
 #define __NR_mincore		27
 #define __NR_dup		32
 #define __NR_dup2		33

include/syscall.h

@@ -156,6 +156,15 @@ static long sys_read(unsigned long fd, void *buf, unsigned long count)
 	return syscall3(__NR_read, fd, (unsigned long)buf, count);
 }
 
+/*
+ * Note this call expects a signal frame on stack
+ * (regs->sp) so be very carefull here!
+ */
+static long sys_rt_sigreturn(void)
+{
+	return syscall0(__NR_rt_sigreturn);
+}
+
 #else /* CONFIG_X86_64 */
 # error x86-32 bit mode not yet implemented
 #endif /* CONFIG_X86_64 */