[RFC PATCH v5 6/9] Add commands for linux-kernel target

[Philipp Rudo <prudo@linux.vnet.ibm.com>]

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   |   3 +
 gdb/configure.tgt |   2 +-
 gdb/lk-cmds.c     | 254 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 gdb/lk-cmds.h     |  25 ++++++
 gdb/lk-low.c      |   3 +
 gdb/typeprint.c   |   2 +-
 gdb/typeprint.h   |   2 +
 7 files changed, 289 insertions(+), 2 deletions(-)
 create mode 100644 gdb/lk-cmds.c
 create mode 100644 gdb/lk-cmds.h

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index afa8039a95..2029c933af 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -715,6 +715,7 @@ ALL_TARGET_OBS = \
 	iq2000-tdep.o \
 	linux-record.o \
 	linux-tdep.o \
+	lk-cmds.o \
 	lk-low.o \
 	lk-modules.o \
 	lm32-tdep.o \
@@ -1278,6 +1279,7 @@ HFILES_NO_SRCDIR = \
 	linux-nat.h \
 	linux-record.h \
 	linux-tdep.h \
+	lk-cmds.h \
 	lk-low.h \
 	lk-modules.h \
 	location.h \
@@ -2260,6 +2262,7 @@ ALLDEPFILES = \
 	linux-fork.c \
 	linux-record.c \
 	linux-tdep.c \
+	lk-cmds.c \
 	lk-low.c \
 	lk-modules.c \
 	lm32-tdep.c \
diff --git a/gdb/configure.tgt b/gdb/configure.tgt
index 39b2144e00..680b3b2e42 100644
--- a/gdb/configure.tgt
+++ b/gdb/configure.tgt
@@ -42,7 +42,7 @@ amd64_tobjs="amd64-tdep.o arch/amd64.o"
 
 # List of objectfiles for Linux kernel support.  To be included into *-linux*
 # targets wich support Linux kernel debugging.
-lk_tobjs="lk-low.o lk-modules.o"
+lk_tobjs="lk-cmds.o lk-low.o lk-modules.o"
 
 # Here are three sections to get a list of target specific object
 # files according to target triplet $TARG.
diff --git a/gdb/lk-cmds.c b/gdb/lk-cmds.c
new file mode 100644
index 0000000000..4046077e2b
--- /dev/null
+++ b/gdb/lk-cmds.c
@@ -0,0 +1,254 @@
+/* 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 "gdbtypes.h"
+#include "inferior.h"
+#include "lk-list.h"
+#include "lk-low.h"
+#include "lk-modules.h"
+#include "typeprint.h"
+#include "valprint.h"
+
+
+static bool
+lk_lsmod_print_name (struct ui_out *uiout, CORE_ADDR mod)
+{
+  char name[LK_MODULE_NAME_LEN + 2];
+  bool loaded;
+
+  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';
+  uiout->field_string ("module", name);
+
+  return loaded;
+}
+
+static void
+lk_lsmod_print_size (struct ui_out *uiout, CORE_ADDR mod)
+{
+  size_t size;
+
+  if (lk_ops->has_field ("module->module_core"))
+    {
+      size = lk_read_uint (mod + lk_offset ("module->init_size"));
+      size += lk_read_uint (mod + lk_offset ("module->core_size"));
+    }
+  else
+    {
+      size = lk_read_uint (mod + lk_offset ("module->init_layout->size"));
+      size += lk_read_uint (mod + lk_offset ("module->core_layout->size"));
+    }
+
+  uiout->field_int ("size", size);
+}
+
+
+static void
+lk_lsmod_print_sources (struct ui_out *uiout, CORE_ADDR mod)
+{
+  CORE_ADDR src_list;
+  int num_sources = 0;
+  std::string sources;
+
+  src_list = mod + lk_offset ("module->source_list");
+  for (CORE_ADDR src : lk_list (src_list, "module_use->source_list", false))
+    {
+      char buf[LK_MODULE_NAME_LEN + 1];
+
+      if (!sources.empty ())
+	sources += ", ";
+
+      src = lk_read_addr (src + lk_offset ("module_use->source"));
+      read_memory_string (src + lk_offset ("module->name"),
+			  buf, LK_MODULE_NAME_LEN);
+
+      sources += buf;
+    }
+
+  uiout->field_int ("src_num", num_sources);
+  uiout->field_string ("src_list", sources.c_str ());
+}
+
+/* Print line for module MOD to UIOUT for lsmod command.  */
+
+static bool
+lk_lsmod_print_single_module (struct ui_out *uiout, CORE_ADDR mod)
+{
+  bool loaded;
+
+  ui_out_emit_tuple tuple_emitter (uiout, NULL);
+
+  uiout->field_fmt ("addr", "0x%s",
+		    phex(mod, lk_builtin_type_size (unsigned_long)));
+  loaded = lk_lsmod_print_name (uiout, mod);
+  lk_lsmod_print_size (uiout, mod);
+  lk_lsmod_print_sources (uiout, mod);
+  uiout->text ("\n");
+
+  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 '*'.  */
+
+static void
+lk_lsmod (const char *args, int from_tty)
+{
+  if (!lk_ifdef (LK_CONFIG_MODULES))
+    {
+      printf_unfiltered (_("Kernel was compiled without module support.\n"));
+      return;
+    }
+
+  struct ui_out *uiout = current_uiout;
+  ui_out_emit_table table_emitter (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 ();
+
+  bool all_loaded = true;
+  for (CORE_ADDR mod : lk_list ("modules", "module->list"))
+      all_loaded &= lk_lsmod_print_single_module (uiout, mod);
+
+  if (!all_loaded)
+    uiout->text ("(*) Missing debug info for module.\n");
+}
+
+static void
+lk_print_struct (const 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);
+}
+
+static void
+lk_print_offset (const 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\
+");
+}
diff --git a/gdb/lk-cmds.h b/gdb/lk-cmds.h
new file mode 100644
index 0000000000..63e424636d
--- /dev/null
+++ b/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__ */
diff --git a/gdb/lk-low.c b/gdb/lk-low.c
index 54d3b6272d..c61361b687 100644
--- a/gdb/lk-low.c
+++ b/gdb/lk-low.c
@@ -28,6 +28,7 @@
 #include "gdbtypes.h"
 #include "inferior.h"
 #include "lk-bitmap.h"
+#include "lk-cmds.h"
 #include "lk-list.h"
 #include "lk-low.h"
 #include "lk-modules.h"
@@ -821,6 +822,8 @@ lk_try_push_target ()
   else
     warning (_("Could not find all symbols for module support.  "
 	       "Module support turned off."));
+
+  lk_init_cmds ();
 }
 
 /* Function for targets to_open hook.  */
diff --git a/gdb/typeprint.c b/gdb/typeprint.c
index c098a3f426..3121fffbf7 100644
--- a/gdb/typeprint.c
+++ b/gdb/typeprint.c
@@ -402,7 +402,7 @@ error_unknown_type (const char *sym_print_name)
 /* Print type of EXP, or last thing in value history if EXP == NULL.
    show is passed to type_print.  */
 
-static void
+void
 whatis_exp (const char *exp, int show)
 {
   struct value *val;
diff --git a/gdb/typeprint.h b/gdb/typeprint.h
index ba9588a118..df96e35a53 100644
--- a/gdb/typeprint.h
+++ b/gdb/typeprint.h
@@ -107,4 +107,6 @@ extern void val_print_not_allocated (struct ui_file *stream);
 
 extern void val_print_not_associated (struct ui_file *stream);
 
+extern void whatis_exp (const char *exp, int show);
+
 #endif
-- 
2.13.5