Re: [PATCH x86_64] Live Patching Function on

From: Kyle Moffett
Date: Mon Apr 25 2005 - 06:17:06 EST

On Apr 25, 2005, at 06:39, Takashi Ikebe wrote:
Kyle Moffett wrote:

If you want that exact functionality, do this:

At program start, spawn a new thread:
1) Open a UNIX socket (/var/run/someapp_live_patch.sock)
2) poll() that socket for a connection.
3) When you get a connection, do your own security checks
4) If it's ok, then map the specified file into memory
5) Read a table of crap to patch from the file
6) Do the patching, being careful to avoid the millions of
races involved for each CPU, *especially* regarding the
separate icache and dcache on CPUs like PPC and such.
7) Go back to step 2
Kyle, thank you so much for your detailed information.
If you design completely new software, your suggestion is very useful!

Unfortunately, we carrier have very many exiting software and try to run
on Linux.
We need to seek the way which can apply to exiting software also...

If you notice, the above method has only minimal changes from
your mmap3 stuff, except without needing kernel support. One
thing to remember, though, as there _is_ a very clean method
to do this from userspace, therefore you are not likely to
get much sympathy on this list.

I suggest you try adding a new hotpatch thread to your code,
as above, then use it to implement the mmap3 and other tasks
necessary for live patching instead of in kernel space.

Kyle Moffett

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