Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 50 insertions, 0 deletions

diff --git a/target/i386/tcg/user/excp_helper.c b/target/i386/tcg/user/excp_helper.c
new file mode 100644
index 000000000..cd507e2a1
--- /dev/null
+++ b/target/i386/tcg/user/excp_helper.c
@@ -0,0 +1,50 @@
+/*
+ *  x86 exception helpers - user-mode specific code
+ *
+ *  Copyright (c) 2003 Fabrice Bellard
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "cpu.h"
+#include "exec/exec-all.h"
+#include "tcg/helper-tcg.h"
+
+void x86_cpu_record_sigsegv(CPUState *cs, vaddr addr,
+                            MMUAccessType access_type,
+                            bool maperr, uintptr_t ra)
+{
+    X86CPU *cpu = X86_CPU(cs);
+    CPUX86State *env = &cpu->env;
+
+    /*
+     * The error_code that hw reports as part of the exception frame
+     * is copied to linux sigcontext.err.  The exception_index is
+     * copied to linux sigcontext.trapno.  Short of inventing a new
+     * place to store the trapno, we cannot let our caller raise the
+     * signal and set exception_index to EXCP_INTERRUPT.
+     */
+    env->cr[2] = addr;
+    env->error_code = ((access_type == MMU_DATA_STORE) << PG_ERROR_W_BIT)
+                    | (maperr ? 0 : PG_ERROR_P_MASK)
+                    | PG_ERROR_U_MASK;
+    cs->exception_index = EXCP0E_PAGE;
+
+    /* Disable do_interrupt_user. */
+    env->exception_is_int = 0;
+    env->exception_next_eip = -1;
+
+    cpu_loop_exit_restore(cs, ra);
+}