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Re: [PATCH][v4] livepatch/ppc: Enable livepatching on powerpc

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Hi Petr,

On Thu, 2016-03-03 at 17:52 +0100, Petr Mladek wrote:

> From: Balbir Singh <bsingharora@gmail.com>
>
> Changelog v4:
> 	1. Renamed klp_matchaddr() to klp_get_ftrace_location()
> 	   and used it just to convert the function address.
> 	2. Synced klp_write_module_reloc() with s390(); made it
> 	   inline, no error message, return -ENOSYS

OK.

> 	3. Added an error message when including
> 	   powerpc/include/asm/livepatch.h without HAVE_LIVEPATCH

I don't know why we want to do that, I don't see how it is helpful. It doesn't
even do what it says:

> +#ifdef CONFIG_LIVEPATCH
...
> +#else /* CONFIG_LIVEPATCH */
> +#error Include linux/livepatch.h, not asm/livepatch.h
> +#endif /* CONFIG_LIVEPATCH */

If I turn on CONFIG_LIVEPATCH then I can quite happily include asm/livepatch.h
and not get an error. So the check doesn't do what the message suggests.

If we *really* want to prevent people from including asm/livepatch.h then it
needs to check for _LINUX_LIVEPATCH_H_. But there's no reason I can see why we
*must* prevent people from including asm/livepatch.h.

And on x86 & s390 it does:

  #else
  #error Live patching support is disabled; check CONFIG_LIVEPATCH
  #endif

Which is also not helpful AFAICS, and just likely to break the build for no
good reason.

> This applies on top of the patches posted by Michael
> https://patchwork.ozlabs.org/patch/589791/
>
> It enables livepatching. This takes patch 6/8 and 7/8 of v8 as the base.
> (See the reference [1] below) and adds logic for checking offset ranges
> in livepatch with ftrace_location_range.
>
> I tested the sample in the livepatch

Thanks.

cheers

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Thread

[PATCH][v4] livepatch/ppc: Enable livepatching on powerpc Petr Mladek <pmladek@suse.com> - 2016-03-03 18:00 +0100
  Re: [PATCH][v4] livepatch/ppc: Enable livepatching on powerpc Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> - 2016-03-04 07:10 +0100
  Re: [PATCH][v4] livepatch/ppc: Enable livepatching on powerpc Michael Ellerman <mpe@ellerman.id.au> - 2016-03-04 09:00 +0100
    Re: [PATCH][v4] livepatch/ppc: Enable livepatching on powerpc Miroslav Benes <mbenes@suse.cz> - 2016-03-04 10:40 +0100
      Re: [PATCH][v4] livepatch/ppc: Enable livepatching on powerpc Michael Ellerman <mpe@ellerman.id.au> - 2016-03-07 04:40 +0100
  How to merge? (was Re: [PATCH][v4] livepatch/ppc: Enable  livepatching on powerpc) Michael Ellerman <mpe@ellerman.id.au> - 2016-03-04 09:10 +0100
    Re: How to merge? (was Re: [PATCH][v4] livepatch/ppc: Enable  livepatching on powerpc) Jiri Kosina <jikos@kernel.org> - 2016-03-04 10:00 +0100
      Re: How to merge? (was Re: [PATCH][v4] livepatch/ppc: Enable  livepatching on powerpc) Michael Ellerman <mpe@ellerman.id.au> - 2016-03-07 11:10 +0100
        Re: How to merge? (was Re: [PATCH][v4] livepatch/ppc: Enable  livepatching on powerpc) Michael Ellerman <mpe@ellerman.id.au> - 2016-03-08 00:30 +0100
          Re: How to merge? (was Re: [PATCH][v4] livepatch/ppc: Enable  livepatching on powerpc) Steven Rostedt <rostedt@goodmis.org> - 2016-03-08 03:00 +0100
        Re: How to merge? (was Re: [PATCH][v4] livepatch/ppc: Enable  livepatching on powerpc) Josh Poimboeuf <jpoimboe@redhat.com> - 2016-03-08 00:30 +0100
        Re: How to merge? (was Re: [PATCH][v4] livepatch/ppc: Enable  livepatching on powerpc) Jiri Kosina <jikos@kernel.org> - 2016-03-08 01:50 +0100
  Re: [PATCH][v4] livepatch/ppc: Enable livepatching on powerpc Torsten Duwe <duwe@lst.de> - 2016-03-04 13:50 +0100
    Re: [PATCH][v4] livepatch/ppc: Enable livepatching on powerpc Petr Mladek <pmladek@suse.com> - 2016-03-04 14:10 +0100
      Re: [PATCH][v4] livepatch/ppc: Enable livepatching on powerpc Torsten Duwe <duwe@lst.de> - 2016-03-04 19:20 +0100
        Re: [PATCH][v4] livepatch/ppc: Enable livepatching on powerpc Torsten Duwe <duwe@lst.de> - 2016-03-04 20:30 +0100
          Re: [PATCH][v4] livepatch/ppc: Enable livepatching on powerpc Torsten Duwe <duwe@lst.de> - 2016-03-08 12:20 +0100
    Re: [PATCH][v4] livepatch/ppc: Enable livepatching on powerpc Balbir Singh <bsingharora@gmail.com> - 2016-03-07 01:00 +0100
  Re: [PATCH][v4] livepatch/ppc: Enable livepatching on powerpc Josh Poimboeuf <jpoimboe@redhat.com> - 2016-03-04 23:00 +0100
  Re: [PATCH][v4] livepatch/ppc: Enable livepatching on powerpc Steven Rostedt <rostedt@goodmis.org> - 2016-03-08 22:50 +0100

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