[PATCH 6/7] proc: Introduce the /proc/<pid>/dump file

Tejun Heo tj at kernel.org
Sat Jul 23 01:37:11 PDT 2011


Hello,

On Sat, Jul 23, 2011 at 12:11:37PM +0400, Pavel Emelyanov wrote:
> On 07/21/2011 10:44 AM, Tejun Heo wrote:
> > Most of information dumped here is already available
> > through /proc and ptrace and we can add the missing pieces like the
> > suggested proc vma fds.
> 
> Let's start with the simplest things. Can you suggest the best (from you pov)
> way for dumping all the registers, tls and the anonymous pages through the 
> existing interfaces?

Just use ptrace.  Seizing all threads in a process, gather file and
memory map info from /proc, inject a parasite to dump memory pages and
do whatever else.  There's nothing special about TLS, fs/gs base is
already included in ptrace register dump in x86_64.  Dunno how it's
handled in 32bit but if it's not available exporting it isn't a big
deal.  Rebuilding the process image from the captured information
shouldn't be too hard.

There is simply is no need to put CR into kernel at all.  Just add the
missing pieces to export the necessary information and missing APIs
which are required to restore it (e.g. setting TID like you did in
this patchset).  Approaching it that way would make things useful for
other use cases && is highly more likely to get merged.  There doesn't
even need to be one big merge day.  You can just improve things
piecewise until it works.

Thanks.

-- 
tejun


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