Allocation/free history

[suresh gumpula]

Hi,
  I am aware of redone(9). I am talking about PC allocation history of
objects.   Do we have something like that ?

Thanks
Suresh


On Mon, Jul 28, 2014 at 3:19 PM, Mateusz Guzik <mjguzik at gmail.com> wrote:

> On Mon, Jul 28, 2014 at 01:40:10PM -0400, suresh gumpula wrote:
> > Hi,
> >    Knowing the PC of an allocation is very usefull in debugging. Having
> the
> > PC hash table and storing the pc hash  either with an object itself( at
> the
> > end) or allocate an exra structure to hold the
> > hash index  help us find out who/where an object was allocated.   We
> > already have something like this in our own operating system and has
> been a
> > useful thing in debugging.
> > BSD allocator uses power of 2, so storing at the end of an object might
> be
> > wasting lot of memory with large objects.
> >
> > It appears we don’t have something like this in current FBSD codeline and
> > would like to work on this ?  Any comments   please?
> >
> >
> > It would be something like below. 8 bytes at the end of each object has
> > fecepost which is usefull in finding overwrites and 2 hash indices to the
> > PC table to track allocation history.
> > (kgdb-amd64-7.4-87) x/40w 0xffffff153728b038
> > 0xffffff153728b038:     0xf6970a05      0x06cb7e0c      0x305a134a
> >  0x831c18bb
> > 0xc0000bed      0x134a2115
> >
> > 0xffffff153728b050:     0x85687ef8      0xffffffff      0x00000001
> >  0x83192201
> >                         0xc0000bed      0x1741143b
> >
>
> See redzone(9).
>
> --
> Mateusz Guzik <mjguzik gmail.com>
>