+static void describe_addr(struct KBacktraceIterator *kbt,
+ unsigned long address,
+ int have_mmap_sem, char *buf, size_t bufsize)
+{
+ struct vm_area_struct *vma;
+ size_t namelen, remaining;
+ unsigned long size, offset, adjust;
+ char *p, *modname;
+ const char *name;
+ int rc;
+
+ /*
+ * Look one byte back for every caller frame (i.e. those that
+ * aren't a new context) so we look up symbol data for the
+ * call itself, not the following instruction, which may be on
+ * a different line (or in a different function).
+ */
+ adjust = !kbt->new_context;
+ address -= adjust;
+
+ if (address >= PAGE_OFFSET) {
+ /* Handle kernel symbols. */
+ BUG_ON(bufsize < KSYM_NAME_LEN);
+ name = kallsyms_lookup(address, &size, &offset,
+ &modname, buf);
+ if (name == NULL) {
+ buf[0] = '\0';
+ return;
+ }
+ namelen = strlen(buf);
+ remaining = (bufsize - 1) - namelen;
+ p = buf + namelen;
+ rc = snprintf(p, remaining, "+%#lx/%#lx ",
+ offset + adjust, size);
+ if (modname && rc < remaining)
+ snprintf(p + rc, remaining - rc, "[%s] ", modname);
+ buf[bufsize-1] = '\0';
+ return;
+ }
+
+ /* If we don't have the mmap_sem, we can't show any more info. */
+ buf[0] = '\0';
+ if (!have_mmap_sem)
+ return;
+
+ /* Find vma info. */
+ vma = find_vma(kbt->task->mm, address);
+ if (vma == NULL || address < vma->vm_start) {
+ snprintf(buf, bufsize, "[unmapped address] ");
+ return;
+ }
+
+ if (vma->vm_file) {
+ char *s;
+ p = d_path(&vma->vm_file->f_path, buf, bufsize);
+ if (IS_ERR(p))
+ p = "?";
+ s = strrchr(p, '/');
+ if (s)
+ p = s+1;
+ } else {
+ p = "anon";
+ }
+
+ /* Generate a string description of the vma info. */
+ namelen = strlen(p);
+ remaining = (bufsize - 1) - namelen;
+ memmove(buf, p, namelen);
+ snprintf(buf + namelen, remaining, "[%lx+%lx] ",
+ vma->vm_start, vma->vm_end - vma->vm_start);
+}
+