1 files changed, 42 insertions, 0 deletions
diff --git a/target-i386/seg_helper.c b/target-i386/seg_helper.c
index ba472154e8..31c5508e6c 100644
--- a/target-i386/seg_helper.c
+++ b/target-i386/seg_helper.c
@@ -2469,3 +2469,45 @@ void cpu_x86_load_seg(CPUX86State *env, int seg_reg, int selector)
     }
 }
 #endif
+
+/* check if Port I/O is allowed in TSS */
+static inline void check_io(CPUX86State *env, int addr, int size)
+{
+    int io_offset, val, mask;
+
+    /* TSS must be a valid 32 bit one */
+    if (!(env->tr.flags & DESC_P_MASK) ||
+        ((env->tr.flags >> DESC_TYPE_SHIFT) & 0xf) != 9 ||
+        env->tr.limit < 103) {
+        goto fail;
+    }
+    io_offset = cpu_lduw_kernel(env, env->tr.base + 0x66);
+    io_offset += (addr >> 3);
+    /* Note: the check needs two bytes */
+    if ((io_offset + 1) > env->tr.limit) {
+        goto fail;
+    }
+    val = cpu_lduw_kernel(env, env->tr.base + io_offset);
+    val >>= (addr & 7);
+    mask = (1 << size) - 1;
+    /* all bits must be zero to allow the I/O */
+    if ((val & mask) != 0) {
+    fail:
+        raise_exception_err(env, EXCP0D_GPF, 0);
+    }
+}
+
+void helper_check_iob(CPUX86State *env, uint32_t t0)
+{
+    check_io(env, t0, 1);
+}
+
+void helper_check_iow(CPUX86State *env, uint32_t t0)
+{
+    check_io(env, t0, 2);
+}
+
+void helper_check_iol(CPUX86State *env, uint32_t t0)
+{
+    check_io(env, t0, 4);
+}