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, 167 insertions, 0 deletions

diff --git a/linux-user/linuxload.c b/linux-user/linuxload.c
new file mode 100644
index 000000000..2ed5fc45e
--- /dev/null
+++ b/linux-user/linuxload.c
@@ -0,0 +1,167 @@
+/* Code for loading Linux executables.  Mostly linux kernel code.  */
+
+#include "qemu/osdep.h"
+#include "qemu.h"
+#include "user-internals.h"
+#include "loader.h"
+
+#define NGROUPS 32
+
+/* ??? This should really be somewhere else.  */
+abi_long memcpy_to_target(abi_ulong dest, const void *src, unsigned long len)
+{
+    void *host_ptr;
+
+    host_ptr = lock_user(VERIFY_WRITE, dest, len, 0);
+    if (!host_ptr) {
+        return -TARGET_EFAULT;
+    }
+    memcpy(host_ptr, src, len);
+    unlock_user(host_ptr, dest, 1);
+    return 0;
+}
+
+static int count(char **vec)
+{
+    int i;
+
+    for (i = 0; *vec; i++) {
+        vec++;
+    }
+    return i;
+}
+
+static int prepare_binprm(struct linux_binprm *bprm)
+{
+    struct stat st;
+    int mode;
+    int retval;
+
+    if (fstat(bprm->fd, &st) < 0) {
+        return -errno;
+    }
+
+    mode = st.st_mode;
+    if (!S_ISREG(mode)) {   /* Must be regular file */
+        return -EACCES;
+    }
+    if (!(mode & 0111)) {   /* Must have at least one execute bit set */
+        return -EACCES;
+    }
+
+    bprm->e_uid = geteuid();
+    bprm->e_gid = getegid();
+
+    /* Set-uid? */
+    if (mode & S_ISUID) {
+        bprm->e_uid = st.st_uid;
+    }
+
+    /* Set-gid? */
+    /*
+     * If setgid is set but no group execute bit then this
+     * is a candidate for mandatory locking, not a setgid
+     * executable.
+     */
+    if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
+        bprm->e_gid = st.st_gid;
+    }
+
+    retval = read(bprm->fd, bprm->buf, BPRM_BUF_SIZE);
+    if (retval < 0) {
+        perror("prepare_binprm");
+        exit(-1);
+    }
+    if (retval < BPRM_BUF_SIZE) {
+        /* Make sure the rest of the loader won't read garbage.  */
+        memset(bprm->buf + retval, 0, BPRM_BUF_SIZE - retval);
+    }
+    return retval;
+}
+
+/* Construct the envp and argv tables on the target stack.  */
+abi_ulong loader_build_argptr(int envc, int argc, abi_ulong sp,
+                              abi_ulong stringp, int push_ptr)
+{
+    TaskState *ts = (TaskState *)thread_cpu->opaque;
+    int n = sizeof(abi_ulong);
+    abi_ulong envp;
+    abi_ulong argv;
+
+    sp -= (envc + 1) * n;
+    envp = sp;
+    sp -= (argc + 1) * n;
+    argv = sp;
+    if (push_ptr) {
+        /* FIXME - handle put_user() failures */
+        sp -= n;
+        put_user_ual(envp, sp);
+        sp -= n;
+        put_user_ual(argv, sp);
+    }
+    sp -= n;
+    /* FIXME - handle put_user() failures */
+    put_user_ual(argc, sp);
+    ts->info->arg_start = stringp;
+    while (argc-- > 0) {
+        /* FIXME - handle put_user() failures */
+        put_user_ual(stringp, argv);
+        argv += n;
+        stringp += target_strlen(stringp) + 1;
+    }
+    ts->info->arg_end = stringp;
+    /* FIXME - handle put_user() failures */
+    put_user_ual(0, argv);
+    while (envc-- > 0) {
+        /* FIXME - handle put_user() failures */
+        put_user_ual(stringp, envp);
+        envp += n;
+        stringp += target_strlen(stringp) + 1;
+    }
+    /* FIXME - handle put_user() failures */
+    put_user_ual(0, envp);
+
+    return sp;
+}
+
+int loader_exec(int fdexec, const char *filename, char **argv, char **envp,
+                struct target_pt_regs *regs, struct image_info *infop,
+                struct linux_binprm *bprm)
+{
+    int retval;
+
+    bprm->fd = fdexec;
+    bprm->filename = (char *)filename;
+    bprm->argc = count(argv);
+    bprm->argv = argv;
+    bprm->envc = count(envp);
+    bprm->envp = envp;
+
+    retval = prepare_binprm(bprm);
+
+    if (retval >= 0) {
+        if (bprm->buf[0] == 0x7f
+                && bprm->buf[1] == 'E'
+                && bprm->buf[2] == 'L'
+                && bprm->buf[3] == 'F') {
+            retval = load_elf_binary(bprm, infop);
+#if defined(TARGET_HAS_BFLT)
+        } else if (bprm->buf[0] == 'b'
+                && bprm->buf[1] == 'F'
+                && bprm->buf[2] == 'L'
+                && bprm->buf[3] == 'T') {
+            retval = load_flt_binary(bprm, infop);
+#endif
+        } else {
+            return -ENOEXEC;
+        }
+    }
+
+    if (retval >= 0) {
+        /* success.  Initialize important registers */
+        do_init_thread(regs, infop);
+        return retval;
+    }
+
+    return retval;
+}