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 <[email protected]> --- scripts/gdb/linux/utils.py | 35 +++++++++++++++++++++++++++++++++++ scripts/gdb/vmlinux-gdb.py | 2 ++ 2 files changed, 37 insertions(+) diff --git a/scripts/gdb/linux/utils.py b/scripts/gdb/linux/utils.py index f883611..c9d705b 100644 --- a/scripts/gdb/linux/utils.py +++ b/scripts/gdb/linux/utils.py @@ -32,3 +32,38 @@ class CachedType: if hasattr(gdb, 'events') and hasattr(gdb.events, 'new_objfile'): gdb.events.new_objfile.connect(self._new_objfile_handler) return self._type + + +long_type = CachedType("long") + + +def get_long_type(): + global long_type + return long_type.get_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): + """Return pointer to containing data structure. + +$container_of(PTR, "TYPE", "ELEMENT"): Given PTR, return a pointer to the +data structure of the type TYPE in which PTR is the address of ELEMENT. +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 c1d90ce..6495841 100644 --- a/scripts/gdb/vmlinux-gdb.py +++ b/scripts/gdb/vmlinux-gdb.py @@ -21,3 +21,5 @@ try: except: gdb.write("NOTE: gdb 7.2 or later required for Linux helper scripts to " "work.\n") +else: + import linux.utils -- 1.8.1.1.298.ge7eed54 ------------------------------------------------------------------------------ November Webinars for C, C++, Fortran Developers Accelerate application performance with scalable programming models. Explore techniques for threading, error checking, porting, and tuning. Get the most from the latest Intel processors and coprocessors. See abstracts and register http://pubads.g.doubleclick.net/gampad/clk?id=60136231&iu=/4140/ostg.clktrk _______________________________________________ Kgdb-bugreport mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/kgdb-bugreport
