Add kernel module support for linux-kernel target

This patch implements module support for the new linux-kernel target by
adding a target_so_ops. In addition this patch adds handling for kernel
virtual addresses. This is necessary because kernel modules, unlike
task_structs, live in kernel virtual address space. Thus addresses need
to be translated before they can be read from. We achieve this by adding
an implementation for the targets to_xfer_partial hook, which translates
the addresses before passing them down to the target beneath.

gdb/ChangeLog:

    * lk-modules.h: New file.
    * lk-modules.c: New file.
    * lk-low.h (lk_hook_is_kvaddr, lk_hook_vtop)
    (lk_hook_get_module_text_offset): New arch dependent hooks.
    (sturct lk_private_hooks): Add new hooks.
    (LK_MODULES_NAME_LEN, LK_UTS_NAME_LEN): New define.
    * lk-low.c (lk-modules.h): New include.
    (lk_kvtop, restore_current_target, lk_xfer_partial): New functions.
    (lk_init_private_data): Declare needed debug symbols.
    (lk_try_push_target): Assert for new hooks and set solib_ops.
    (init_linux_kernel_ops): Add implementation for to_xfer_partial.
    * solib.c (get_solib_search_path): New function.
    * solib.h (get_solib_search_path): New export.
    * Makefile.in (SFILES, ALLDEPFILES): Add lk-modules.c.
    (HFILES_NO_SRCDIR): Add lk-modules.h.
    (COMMON_OBS): Add lk-modules.o.

1 files changed, 29 insertions, 0 deletions

diff --git a/gdb/lk-modules.h b/gdb/lk-modules.h
new file mode 100644
index 0000000..47e6dde
--- /dev/null
+++ b/gdb/lk-modules.h
@@ -0,0 +1,29 @@
+/* Handle kernel modules as shared libraries.
+
+   Copyright (C) 2016 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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 3 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/>.  */
+
+#ifndef __LK_MODULES_H__
+#define __LK_MODULES_H__
+
+extern struct target_so_ops *lk_modules_so_ops;
+
+/* Check if debug info for module NAME are loaded.  Needed by lsmod command.  */
+
+extern bool lk_modules_debug_info_loaded (const std::string &name);
+
+#endif /*  __LK_MODULES_H__  */