Allocation/free history

[suresh gumpula]

I am talking about kernel space Chadd.

Thanks
Suresh


On Mon, Jul 28, 2014 at 3:20 PM, Adrian Chadd <adrian at freebsd.org> wrote:

> Hi!
>
> Are you talking about userland? kernel? both?
>
>
> -a
>
>
> On 28 July 2014 10:40, suresh gumpula <gsuryacse7k at gmail.com> 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
> >
> > Thanks
> > Suresh
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