Messages in this thread Patch in this message | | | From | Jan Kiszka <> | Subject | [PATCH 02/13] scripts/gdb: Add container_of helper and convenience function | Date | Mon, 5 Nov 2012 17:08:55 +0100 |
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Provide an internal helper with container_of semantics. As type lookups are very slow in gdb-python and we need a type "long" for this, cache the reference to this type object. Then export the helper also as a convenience function form use at the gdb command line.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> --- scripts/gdb/utils.py | 55 ++++++++++++++++++++++++++++++++++++++++++++ scripts/gdb/vmlinux-gdb.py | 2 + 2 files changed, 57 insertions(+), 0 deletions(-) create mode 100644 scripts/gdb/utils.py
diff --git a/scripts/gdb/utils.py b/scripts/gdb/utils.py new file mode 100644 index 0000000..74682c3 --- /dev/null +++ b/scripts/gdb/utils.py @@ -0,0 +1,55 @@ +# +# gdb helper commands and functions for Linux kernel debugging +# +# common utilities +# +# Copyright (c) 2011, 2012 Siemens AG +# +# Authors: +# Jan Kiszka <jan.kiszka@siemens.com> +# +# This work is licensed under the terms of the GNU GPL version 2. +# + +import gdb + +long_type = None + +def get_type(type_name): + t = gdb.lookup_type(type_name) + if t == None: + raise gdb.GdbError("cannot resolve type '%s'" % type_name) + return t + +def get_long_type(): + global long_type + if long_type == None: + long_type = get_type("long") + return long_type + + +def offset_of(typeobj, field): + element = gdb.Value(0).cast(typeobj) + return int(str(element[field].address).split()[0], 16) + +def container_of(ptr, typeobj, member): + return (ptr.cast(get_long_type()) - + offset_of(typeobj, member)).cast(typeobj) + + +class ContainerOf(gdb.Function): + __doc__ = "Return pointer to containing data structure.\n" \ + "\n" \ + "$container_of(PTR, \"TYPE\", \"ELEMENT\"): Given PTR, return a pointer to the\n" \ + "data structure of the type TYPE in which PTR is the address of ELEMENT.\n" \ + "Note that TYPE and ELEMENT have to be quoted as strings." + + def __init__(self): + super(ContainerOf, self).__init__("container_of") + + def invoke(self, ptr, typename, elementname): + return container_of(ptr, + gdb.lookup_type(typename.string()).pointer(), + elementname.string()) + +ContainerOf() diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py index 00df617..62c30b8 100644 --- a/scripts/gdb/vmlinux-gdb.py +++ b/scripts/gdb/vmlinux-gdb.py @@ -18,3 +18,5 @@ sys.path = [ os.path.dirname(__file__) + "/scripts/gdb" ] + sys.path if not gdb.VERSION >= "7.1": print "NOTE: gdb 7.1 or later required for Linux helper scripts " \ "to work." +else: + import utils -- 1.7.3.4
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