1 files changed, 37 insertions, 0 deletions
diff --git a/tests/tcg/i386/test-flags.c b/tests/tcg/i386/test-flags.c
new file mode 100644
index 0000000000..c379e29627
--- /dev/null
+++ b/tests/tcg/i386/test-flags.c
@@ -0,0 +1,37 @@
+#define _GNU_SOURCE
+#include <sys/mman.h>
+#include <signal.h>
+#include <stdio.h>
+#include <assert.h>
+
+volatile unsigned long flags;
+volatile unsigned long flags_after;
+int *addr;
+
+void sigsegv(int sig, siginfo_t *info, ucontext_t *uc)
+{
+    flags = uc->uc_mcontext.gregs[REG_EFL];
+    mprotect(addr, 4096, PROT_READ|PROT_WRITE);
+}
+
+int main()
+{
+    struct sigaction sa = { .sa_handler = (void *)sigsegv, .sa_flags = SA_SIGINFO };
+    sigaction(SIGSEGV, &sa, NULL);
+
+    /* fault in the page then protect it */
+    addr = mmap (NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
+    *addr = 0x1234;
+    mprotect(addr, 4096, PROT_READ);
+
+    asm("# set flags to all ones    \n"
+        "mov $-1, %%eax             \n"
+        "movq addr, %%rdi           \n"
+        "sahf                       \n"
+        "sub %%eax, (%%rdi)         \n"
+        "pushf                      \n"
+        "pop  flags_after(%%rip)    \n" : : : "eax", "edi", "memory");
+
+    /* OF can have any value before the SUB instruction.  */
+    assert((flags & 0xff) == 0xd7 && (flags_after & 0x8ff) == 0x17);
+}