[RFC 5/7] Add commands for linux-kernel target

Philipp Rudo
2017-01-12T11:32:36Z

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.
(COMMON_OBS): Add lk-cmds.o.
---
gdb/Makefile.in | 4 +
gdb/lk-cmds.c | 248 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
gdb/lk-cmds.h | 25 ++++++
gdb/lk-low.c | 3 +
gdb/typeprint.c | 8 +-
gdb/typeprint.h | 2 +
6 files changed, 283 insertions(+), 7 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 be8a91d..10dce6a 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -1092,6 +1092,7 @@ SFILES = \
jit.c \
language.c \
linespec.c \
+ lk-cmds.c \
lk-lists.c \
lk-low.c \
lk-modules.c \
@@ -1341,6 +1342,7 @@ HFILES_NO_SRCDIR = \
linux-nat.h \
linux-record.h \
linux-tdep.h \
+ lk-cmds.h \
lk-lists.h \
lk-low.h \
lk-modules.h \
@@ -1702,6 +1704,7 @@ COMMON_OBS = $(DEPFILES) $(CONFIG_OBS) $(YYOBJ) \
jit.o \
language.o \
linespec.o \
+ lk-cmds.o \
lk-lists.o \
lk-modules.o \
location.o \
@@ -2535,6 +2538,7 @@ ALLDEPFILES = \
linux-fork.c \
linux-record.c \
linux-tdep.c \
+ lk-cmds.c \
lk-lists.c \
lk-low.c \
lk-modules.c \
diff --git a/gdb/lk-cmds.c b/gdb/lk-cmds.c
new file mode 100644
index 0000000..a47aad9
--- /dev/null
+++ b/gdb/lk-cmds.c
@@ -0,0 +1,248 @@
+/* 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 "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++;
+ }
+ /* Remove trailing comma. */
+ src_list [list_len - 2] = '\0';
+
+ ui_chain = make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
+
+ uiout->field_fmt ("addr", "%#lx", mod);
+ 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> \n\n\
+Print content of field <field> in structure <struct> for structure located\n\
+at address . If no field is given prints entire content of\n\
+<struct>. If neither <field> nor 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 0000000..63e4246
--- /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 81ff61c..4211825 100644
--- a/gdb/lk-low.c
+++ b/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"
@@ -825,6 +826,8 @@ 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);
}

diff --git a/gdb/typeprint.c b/gdb/typeprint.c
index 56e993e..f30f5dc 100644
--- a/gdb/typeprint.c
+++ b/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 */
@@ -396,7 +390,7 @@ 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;
diff --git a/gdb/typeprint.h b/gdb/typeprint.h
index 72da7f4..4cbe189 100644
--- a/gdb/typeprint.h
+++ b/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
--
2.8.4