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, 231 insertions, 0 deletions

diff --git a/linux-user/nios2/signal.c b/linux-user/nios2/signal.c
new file mode 100644
index 000000000..a77e8a40f
--- /dev/null
+++ b/linux-user/nios2/signal.c
@@ -0,0 +1,231 @@
+/*
+ *  Emulation of Linux signals
+ *
+ *  Copyright (c) 2003 Fabrice Bellard
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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 General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+#include "qemu/osdep.h"
+#include "qemu.h"
+#include "user-internals.h"
+#include "signal-common.h"
+#include "linux-user/trace.h"
+
+#define MCONTEXT_VERSION 2
+
+struct target_sigcontext {
+    int version;
+    unsigned long gregs[32];
+};
+
+struct target_ucontext {
+    abi_ulong tuc_flags;
+    abi_ulong tuc_link;
+    target_stack_t tuc_stack;
+    struct target_sigcontext tuc_mcontext;
+    target_sigset_t tuc_sigmask;   /* mask last for extensibility */
+};
+
+struct target_rt_sigframe {
+    struct target_siginfo info;
+    struct target_ucontext uc;
+};
+
+static int rt_setup_ucontext(struct target_ucontext *uc, CPUNios2State *env)
+{
+    unsigned long *gregs = uc->tuc_mcontext.gregs;
+
+    __put_user(MCONTEXT_VERSION, &uc->tuc_mcontext.version);
+    __put_user(env->regs[1], &gregs[0]);
+    __put_user(env->regs[2], &gregs[1]);
+    __put_user(env->regs[3], &gregs[2]);
+    __put_user(env->regs[4], &gregs[3]);
+    __put_user(env->regs[5], &gregs[4]);
+    __put_user(env->regs[6], &gregs[5]);
+    __put_user(env->regs[7], &gregs[6]);
+    __put_user(env->regs[8], &gregs[7]);
+    __put_user(env->regs[9], &gregs[8]);
+    __put_user(env->regs[10], &gregs[9]);
+    __put_user(env->regs[11], &gregs[10]);
+    __put_user(env->regs[12], &gregs[11]);
+    __put_user(env->regs[13], &gregs[12]);
+    __put_user(env->regs[14], &gregs[13]);
+    __put_user(env->regs[15], &gregs[14]);
+    __put_user(env->regs[16], &gregs[15]);
+    __put_user(env->regs[17], &gregs[16]);
+    __put_user(env->regs[18], &gregs[17]);
+    __put_user(env->regs[19], &gregs[18]);
+    __put_user(env->regs[20], &gregs[19]);
+    __put_user(env->regs[21], &gregs[20]);
+    __put_user(env->regs[22], &gregs[21]);
+    __put_user(env->regs[23], &gregs[22]);
+    __put_user(env->regs[R_RA], &gregs[23]);
+    __put_user(env->regs[R_FP], &gregs[24]);
+    __put_user(env->regs[R_GP], &gregs[25]);
+    __put_user(env->regs[R_EA], &gregs[27]);
+    __put_user(env->regs[R_SP], &gregs[28]);
+
+    return 0;
+}
+
+static int rt_restore_ucontext(CPUNios2State *env, struct target_ucontext *uc,
+                               int *pr2)
+{
+    int temp;
+    unsigned long *gregs = uc->tuc_mcontext.gregs;
+
+    /* Always make any pending restarted system calls return -EINTR */
+    /* current->restart_block.fn = do_no_restart_syscall; */
+
+    __get_user(temp, &uc->tuc_mcontext.version);
+    if (temp != MCONTEXT_VERSION) {
+        return 1;
+    }
+
+    /* restore passed registers */
+    __get_user(env->regs[1], &gregs[0]);
+    __get_user(env->regs[2], &gregs[1]);
+    __get_user(env->regs[3], &gregs[2]);
+    __get_user(env->regs[4], &gregs[3]);
+    __get_user(env->regs[5], &gregs[4]);
+    __get_user(env->regs[6], &gregs[5]);
+    __get_user(env->regs[7], &gregs[6]);
+    __get_user(env->regs[8], &gregs[7]);
+    __get_user(env->regs[9], &gregs[8]);
+    __get_user(env->regs[10], &gregs[9]);
+    __get_user(env->regs[11], &gregs[10]);
+    __get_user(env->regs[12], &gregs[11]);
+    __get_user(env->regs[13], &gregs[12]);
+    __get_user(env->regs[14], &gregs[13]);
+    __get_user(env->regs[15], &gregs[14]);
+    __get_user(env->regs[16], &gregs[15]);
+    __get_user(env->regs[17], &gregs[16]);
+    __get_user(env->regs[18], &gregs[17]);
+    __get_user(env->regs[19], &gregs[18]);
+    __get_user(env->regs[20], &gregs[19]);
+    __get_user(env->regs[21], &gregs[20]);
+    __get_user(env->regs[22], &gregs[21]);
+    __get_user(env->regs[23], &gregs[22]);
+    /* gregs[23] is handled below */
+    /* Verify, should this be settable */
+    __get_user(env->regs[R_FP], &gregs[24]);
+    /* Verify, should this be settable */
+    __get_user(env->regs[R_GP], &gregs[25]);
+    /* Not really necessary no user settable bits */
+    __get_user(temp, &gregs[26]);
+    __get_user(env->regs[R_EA], &gregs[27]);
+
+    __get_user(env->regs[R_RA], &gregs[23]);
+    __get_user(env->regs[R_SP], &gregs[28]);
+
+    target_restore_altstack(&uc->tuc_stack, env);
+
+    *pr2 = env->regs[2];
+    return 0;
+}
+
+static void *get_sigframe(struct target_sigaction *ka, CPUNios2State *env,
+                          size_t frame_size)
+{
+    unsigned long usp;
+
+    /* This is the X/Open sanctioned signal stack switching.  */
+    usp = target_sigsp(get_sp_from_cpustate(env), ka);
+
+    /* Verify, is it 32 or 64 bit aligned */
+    return (void *)((usp - frame_size) & -8UL);
+}
+
+void setup_rt_frame(int sig, struct target_sigaction *ka,
+                    target_siginfo_t *info,
+                    target_sigset_t *set,
+                    CPUNios2State *env)
+{
+    struct target_rt_sigframe *frame;
+    int i, err = 0;
+
+    frame = get_sigframe(ka, env, sizeof(*frame));
+
+    if (ka->sa_flags & SA_SIGINFO) {
+        tswap_siginfo(&frame->info, info);
+    }
+
+    /* Create the ucontext.  */
+    __put_user(0, &frame->uc.tuc_flags);
+    __put_user(0, &frame->uc.tuc_link);
+    target_save_altstack(&frame->uc.tuc_stack, env);
+    err |= rt_setup_ucontext(&frame->uc, env);
+    for (i = 0; i < TARGET_NSIG_WORDS; i++) {
+        __put_user((abi_ulong)set->sig[i],
+            (abi_ulong *)&frame->uc.tuc_sigmask.sig[i]);
+    }
+
+    if (err) {
+        goto give_sigsegv;
+    }
+
+    /* Set up to return from userspace; jump to fixed address sigreturn
+       trampoline on kuser page.  */
+    env->regs[R_RA] = (unsigned long) (0x1044);
+
+    /* Set up registers for signal handler */
+    env->regs[R_SP] = (unsigned long) frame;
+    env->regs[4] = (unsigned long) sig;
+    env->regs[5] = (unsigned long) &frame->info;
+    env->regs[6] = (unsigned long) &frame->uc;
+    env->regs[R_EA] = (unsigned long) ka->_sa_handler;
+    return;
+
+give_sigsegv:
+    if (sig == TARGET_SIGSEGV) {
+        ka->_sa_handler = TARGET_SIG_DFL;
+    }
+    force_sigsegv(sig);
+    return;
+}
+
+long do_sigreturn(CPUNios2State *env)
+{
+    trace_user_do_sigreturn(env, 0);
+    qemu_log_mask(LOG_UNIMP, "do_sigreturn: not implemented\n");
+    return -TARGET_ENOSYS;
+}
+
+long do_rt_sigreturn(CPUNios2State *env)
+{
+    /* Verify, can we follow the stack back */
+    abi_ulong frame_addr = env->regs[R_SP];
+    struct target_rt_sigframe *frame;
+    sigset_t set;
+    int rval;
+
+    if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
+        goto badframe;
+    }
+
+    target_to_host_sigset(&set, &frame->uc.tuc_sigmask);
+    do_sigprocmask(SIG_SETMASK, &set, NULL);
+
+    if (rt_restore_ucontext(env, &frame->uc, &rval)) {
+        goto badframe;
+    }
+
+    unlock_user_struct(frame, frame_addr, 0);
+    return rval;
+
+badframe:
+    unlock_user_struct(frame, frame_addr, 0);
+    force_sig(TARGET_SIGSEGV);
+    return 0;
+}