These changes are the raw update to linux-4.4.6-rt14. Kernel sources

[kvmfornfv.git] / kernel / tools / testing / selftests / x86 / syscall_nt.c

diff --git a/kernel/tools/testing/selftests/x86/syscall_nt.c b/kernel/tools/testing/selftests/x86/syscall_nt.c
new file mode 100644 (file)
index 0000000..60c06af
--- /dev/null
+++ b/kernel/tools/testing/selftests/x86/syscall_nt.c
@@ -0,0 +1,54 @@
+/*
+ * syscall_nt.c - checks syscalls with NT set
+ * Copyright (c) 2014-2015 Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * Some obscure user-space code requires the ability to make system calls
+ * with FLAGS.NT set.  Make sure it works.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <asm/processor-flags.h>
+
+#ifdef __x86_64__
+# define WIDTH "q"
+#else
+# define WIDTH "l"
+#endif
+
+static unsigned long get_eflags(void)
+{
+       unsigned long eflags;
+       asm volatile ("pushf" WIDTH "\n\tpop" WIDTH " %0" : "=rm" (eflags));
+       return eflags;
+}
+
+static void set_eflags(unsigned long eflags)
+{
+       asm volatile ("push" WIDTH " %0\n\tpopf" WIDTH
+                     : : "rm" (eflags) : "flags");
+}
+
+int main()
+{
+       printf("[RUN]\tSet NT and issue a syscall\n");
+       set_eflags(get_eflags() | X86_EFLAGS_NT);
+       syscall(SYS_getpid);
+       if (get_eflags() & X86_EFLAGS_NT) {
+               printf("[OK]\tThe syscall worked and NT is still set\n");
+               return 0;
+       } else {
+               printf("[FAIL]\tThe syscall worked but NT was cleared\n");
+               return 1;
+       }
+}