Add commands for linux-kernel target

This patch implements a "lsmod", "struct" and, "offset" command to work with
the new linux-kernel target. The commands are a handy byproduct from
development and crude hacks. I don't expect them to be accepted in the
current state.  Nevertheless there needs to be an discussion on how and
where (see gdb/python scrips in kernel sources) to implement them. So here
is the start for it.

gdb/Changelog:

    * lk-cmds.h: New file.
    * lk-cmds.c: New file.
    * lk-low.c: Include lk-cmds.h.
    (lk_try_push_target): Init commands.
    * typeprint.c: Remove unnecessary forward declarations.
    (whatis_exp): Remove static.
    * typeprint.h (whatis_exp): New export.
    * Makefile.in (SFILES, ALLDEPFILES): Add lk-cmds.c.
    (HFILES_NO_SRCDIR): Add lk-cmds.h.
    (ALL_TARGET_OBS): Add lk-cmds.o.
    * configure.tgt (lk_target_obs): Add lk-cmds.o.

gdb/Makefile.in

@@ -817,6 +817,7 @@ ALL_TARGET_OBS = \
 	iq2000-tdep.o \
 	linux-record.o \
 	linux-tdep.o \
+	lk-cmds.o \
 	lk-lists.o \
 	lk-low.o \
 	lk-modules.o \
@@ -1106,6 +1107,7 @@ SFILES = \
 	jit.c \
 	language.c \
 	linespec.c \
+	lk-cmds.c \
 	lk-lists.c \
 	lk-low.c \
 	lk-modules.c \
@@ -1356,6 +1358,7 @@ HFILES_NO_SRCDIR = \
 	linux-nat.h \
 	linux-record.h \
 	linux-tdep.h \
+	lk-cmds.h \
 	lk-lists.h \
 	lk-low.h \
 	lk-modules.h \
@@ -2556,6 +2559,7 @@ ALLDEPFILES = \
 	linux-fork.c \
 	linux-record.c \
 	linux-tdep.c \
+	lk-cmds.c \
 	lk-lists.c \
 	lk-low.c \
 	lk-modules.c \

gdb/configure.tgt

@@ -36,7 +36,7 @@ esac
 
 # List of objectfiles for Linux kernel support.  To be included into *-linux*
 # targets wich support Linux kernel debugging.
-lk_target_obs="lk-lists.o lk-low.o lk-modules.o"
+lk_target_obs="lk-cmds.o lk-lists.o lk-low.o lk-modules.o"
 
 # map target info into gdb names.
 

gdb/lk-cmds.c

@@ -0,0 +1,253 @@
+/* Commands for Linux kernel target.
+
+   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/>.  */
+
+#include "defs.h"
+
+#include "cli/cli-decode.h"
+#include "gdbcore.h"
+#include "inferior.h"
+#include "lk-lists.h"
+#include "lk-low.h"
+#include "lk-modules.h"
+#include "typeprint.h"
+#include "valprint.h"
+
+
+/* Print line for module MOD to UIOUT for lsmod command.  */
+
+static bool
+lk_lsmod_print_single_module (struct ui_out *uiout, CORE_ADDR mod)
+{
+  char *src_list, name[LK_MODULE_NAME_LEN + 2];
+  CORE_ADDR next, src_list_addr;
+  size_t src_num, src_size, list_len;
+  bool loaded;
+  struct cleanup *ui_chain;
+
+
+  /* Get name.  */
+  read_memory_string (mod + LK_OFFSET (module, name), name + 1,
+		      LK_MODULE_NAME_LEN);
+  loaded = lk_modules_debug_info_loaded (name + 1);
+  name[0] = loaded ? ' ' : '*' ;
+  name[LK_MODULE_NAME_LEN + 1] = '\0';
+
+  /* Get size.  */
+  if (LK_FIELD (module, module_core))
+    {
+      src_size = lk_read_uint (mod + LK_OFFSET (module, init_size));
+      src_size += lk_read_uint (mod + LK_OFFSET (module, core_size));
+    }
+  else
+    {
+      src_size = lk_read_uint (mod + LK_OFFSET (module, init_layout)
+			       + LK_OFFSET (module_layout, size));
+      src_size += lk_read_uint (mod + LK_OFFSET (module, core_layout)
+				+ LK_OFFSET (module_layout, size));
+    }
+
+  /* Get number of sources and list of their names.  */
+  src_num = 0;
+  src_list_addr = mod + LK_OFFSET (module, source_list);
+  src_list = xstrdup ("");
+  list_len = 0;
+
+  lk_list_for_each (next, src_list_addr, module, source_list)
+    {
+      char src_name[LK_MODULE_NAME_LEN + 1];
+      CORE_ADDR src_mod, src_addr;
+
+      src_addr = (LK_CONTAINER_OF (next, module_use, source_list)
+		  + LK_OFFSET (module_use, source));
+      src_mod = lk_read_addr (src_addr);
+      read_memory_string (src_mod + LK_OFFSET (module, name), src_name,
+			  LK_MODULE_NAME_LEN);
+
+      /* 2 = strlen (", ").  */
+      list_len += strlen (src_name) + 2;
+      src_list = reconcat (src_list, src_list, src_name, ", ", NULL);
+
+      src_num++;
+    }
+
+  make_cleanup (xfree, src_list);
+  /* Remove trailing comma.  */
+  if (strlen (src_list) >= 2)
+    src_list [list_len - 2] = '\0';
+
+  ui_chain = make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
+
+  uiout->field_fmt ("addr", "0x%s",
+		    phex(mod, lk_builtin_type_size (unsigned_long)));
+  uiout->field_string ("module", name);
+  uiout->field_int ("size", src_size);
+  uiout->field_int ("src_num", src_num);
+  uiout->field_string ("src_list", src_list);
+  uiout->text ("\n");
+
+  do_cleanups (ui_chain);
+  return loaded;
+}
+
+/* Print information about loaded kernel modules.  Output equivalent to
+   lsmod, but also prints the address of the corrensponfing struct module.
+   Marks modules with missing debug info with an asterix '*'.  */
+
+void
+lk_lsmod (char *args, int from_tty)
+{
+  struct ui_out *uiout;
+  struct cleanup *ui_chain;
+  CORE_ADDR modules, next;
+  bool all_loaded = true;
+
+  uiout = current_uiout;
+  ui_chain = make_cleanup_ui_out_table_begin_end (uiout, 5, -1,
+						  "ModuleTable");
+  uiout->table_header (14, ui_left, "addr", "ADDR");
+  uiout->table_header (20, ui_left, "module", "Module");
+  uiout->table_header (7, ui_right, "size", "Size");
+  uiout->table_header (4, ui_right, "src_num", "");
+  uiout->table_header (40, ui_left, "src_list", "Used by");
+
+  uiout->table_body ();
+
+  modules = LK_ADDR (modules);
+  lk_list_for_each (next, modules, module, list)
+    {
+      CORE_ADDR mod;
+      mod = LK_CONTAINER_OF (next, module, list);
+      all_loaded &= lk_lsmod_print_single_module (uiout, mod);
+    }
+  if (!all_loaded)
+    uiout->text ("(*) Missing debug info for module.\n");
+
+  do_cleanups (ui_chain);
+}
+
+static void
+lk_print_struct (char *args_, int from_tty)
+{
+  struct format_data fmt;
+  size_t pos;
+  print_command_parse_format ((const char **) &args_, "print", &fmt);
+
+  if (!args_)
+    return;
+
+  std::string args (args_);
+  /* No address given default to behave like ptype.  */
+  if ((pos = args.find (" ")) == std::string::npos)
+    {
+      args = "struct " + args;
+      char *tmp = xstrdup (args.c_str ());
+      whatis_exp (tmp, 1);
+      xfree (tmp);
+      return;
+    }
+
+
+  std::string type = args.substr (0, pos);
+  std::string addr = args.substr (args.find_first_not_of (" ", pos));
+
+  if ((pos = type.find ("."))!= std::string::npos)
+    {
+      std::string field = type.substr (pos + 1);
+      type = type.substr (0, pos);
+      args = "((struct " + type + " *) " + addr + ")->" + field;
+    }
+  else if ((pos = type.find ("->"))!= std::string::npos)
+    {
+      std::string field = type.substr (pos + 2);
+      type = type.substr (0, pos);
+      args = "((struct " + type + " *) " + addr + ")->" + field;
+    }
+  else
+    args = "*(struct " + type + " *) " + addr;
+
+  expression_up expr = parse_expression (args.c_str ());
+  struct value *val = evaluate_expression (expr.get ());
+
+  print_value (val, &fmt);
+}
+
+#include "gdbtypes.h"
+void
+lk_print_offset (char *args_, int from_tty)
+{
+  std::string args (args_);
+  std::string type, field;
+  size_t pos;
+
+  if ((pos = args.find ('.')) != std::string::npos)
+    {
+      type = "struct " + args.substr (0, pos);
+      field = args.substr (pos + 1);
+    }
+  else if ((pos = args.find ("->")) != std::string::npos)
+    {
+      type = "struct " + args.substr (0, pos);
+      field = args.substr (pos + 2);
+    }
+  else
+    return;
+
+  expression_up expr = parse_expression (type.c_str ());
+  struct type *tp = value_type (evaluate_type (expr.get ()));
+
+  struct field *first = TYPE_FIELDS (tp);
+  struct field *last = first + TYPE_NFIELDS (tp);
+
+  for (; first != last; first++)
+    if (field.compare (first->name) == 0)
+      break;
+
+  if (first == last)
+    return;
+
+  size_t offset = FIELD_BITPOS (*first);
+
+  if (offset % TARGET_CHAR_BIT)
+    printf_unfiltered ("offset = %lu + %lu\n", offset / 8, offset % TARGET_CHAR_BIT);
+  else
+    printf_unfiltered ("offset = %lu\n", offset / 8);
+}
+
+void
+lk_init_cmds ()
+{
+  add_com ("lsmod", class_vars, lk_lsmod, "\n\
+	lsmod\n\n\
+List kernel modules as known by the kernel.  The address belongs to the \
+corresponding struct module.  \
+");
+
+  add_com ("struct", class_vars, lk_print_struct, "\n\
+	struct <struct>.<field> <address>\n\n\
+Print content of field <field> in structure <struct> for structure located\n\
+at address <address>.  If no field is given prints entire content of\n\
+<struct>.  If neither <field> nor <address> is given prints type definition\n\
+of <struct> (equivalent to ptype).\
+");
+
+  add_com ("offset", class_vars, lk_print_offset, "\n\
+	offset <struct>.<field>\n\n\
+Print offset of field <field> in structure <struct> in byte (+ bit for bit fields).\n\
+");
+}

gdb/lk-cmds.h

@@ -0,0 +1,25 @@
+/* Commands for Linux kernel target.
+
+   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_CMDS_H__
+#define __LK_CMDS_H__
+
+extern void lk_init_cmds ();
+
+#endif /* __LK_CMDS_H__ */

gdb/lk-low.c

@@ -27,6 +27,7 @@
 #include "gdbthread.h"
 #include "gdbtypes.h"
 #include "inferior.h"
+#include "lk-cmds.h"
 #include "lk-lists.h"
 #include "lk-low.h"
 #include "lk-modules.h"
@@ -798,6 +799,8 @@ lk_try_push_target ()
   if (!target_is_pushed (linux_kernel_ops))
     push_target (linux_kernel_ops);
 
+  lk_init_cmds ();
+
   set_solib_ops (gdbarch, lk_modules_so_ops);
 }
 

gdb/typeprint.c

@@ -39,12 +39,6 @@
 
 extern void _initialize_typeprint (void);
 
-static void ptype_command (char *, int);
-
-static void whatis_command (char *, int);
-
-static void whatis_exp (char *, int);
-
 const struct type_print_options type_print_raw_options =
 {
   1,				/* raw */
@@ -389,7 +383,7 @@ type_to_string (struct type *type)
 /* Print type of EXP, or last thing in value history if EXP == NULL.
    show is passed to type_print.  */
 
-static void
+void
 whatis_exp (char *exp, int show)
 {
   struct value *val;

gdb/typeprint.h

@@ -78,4 +78,6 @@ extern void val_print_not_allocated (struct ui_file *stream);
 
 extern void val_print_not_associated (struct ui_file *stream);
 
+extern void whatis_exp (char *exp, int show);
+
 #endif