[PATCH v8 07/22] scripts/gdb: Add automatic symbol reloading on module insertion

From: Jan Kiszka
Date: Fri Jun 06 2014 - 13:24:16 EST


This installs a silent breakpoint on the do_init_module function. The
breakpoint handler will try to load symbols from the module files found
during lx-symbols execution. This way, breakpoints can be set to module
initialization functions, and there is no need to explicitly call
lx-symbols after (re-)loading a module.

Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
---
scripts/gdb/linux/symbols.py | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)

diff --git a/scripts/gdb/linux/symbols.py b/scripts/gdb/linux/symbols.py
index bd21a96..139841f 100644
--- a/scripts/gdb/linux/symbols.py
+++ b/scripts/gdb/linux/symbols.py
@@ -19,6 +19,30 @@ import string
from linux import modules, utils


+if hasattr(gdb, 'Breakpoint'):
+ class LoadModuleBreakpoint(gdb.Breakpoint):
+ def __init__(self, spec, gdb_command):
+ super(LoadModuleBreakpoint, self).__init__(spec, internal=True)
+ self.silent = True
+ self.gdb_command = gdb_command
+
+ def stop(self):
+ module = gdb.parse_and_eval("mod")
+ module_name = module['name'].string()
+ cmd = self.gdb_command
+
+ # enforce update if object file is not found
+ cmd.module_files_updated = False
+
+ if module_name in cmd.loaded_modules:
+ gdb.write("refreshing all symbols to reload module "
+ "'{0}'\n".format(module_name))
+ cmd.load_all_symbols()
+ else:
+ cmd.load_module_symbols(module)
+ return False
+
+
class LxSymbols(gdb.Command):
"""(Re-)load symbols of Linux kernel and currently loaded modules.

@@ -30,6 +54,8 @@ lx-symbols command."""
module_paths = []
module_files = []
module_files_updated = False
+ loaded_modules = []
+ breakpoint = None

def __init__(self):
super(LxSymbols, self).__init__("lx-symbols", gdb.COMMAND_FILES,
@@ -87,6 +113,8 @@ lx-symbols command."""
addr=module_addr,
sections=self._section_arguments(module))
gdb.execute(cmdline, to_string=True)
+ if not module_name in self.loaded_modules:
+ self.loaded_modules.append(module_name)
else:
gdb.write("no module object found for '{0}'\n".format(module_name))

@@ -104,6 +132,7 @@ lx-symbols command."""
gdb.execute("symbol-file", to_string=True)
gdb.execute("symbol-file vmlinux")

+ self.loaded_modules = []
module_list = modules.ModuleList()
if not module_list:
gdb.write("no modules found\n")
@@ -123,5 +152,15 @@ lx-symbols command."""

self.load_all_symbols()

+ if hasattr(gdb, 'Breakpoint'):
+ if not self.breakpoint is None:
+ self.breakpoint.delete()
+ self.breakpoint = None
+ self.breakpoint = LoadModuleBreakpoint(
+ "kernel/module.c:do_init_module", self)
+ else:
+ gdb.write("Note: symbol update on module loading not supported "
+ "with this gdb version\n")
+

LxSymbols()
--
1.8.1.1.298.ge7eed54

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