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In-Reply-To: <20171114092910.20399-2-kamalesh@linux.vnet.ibm.com>
To: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
From: Michael Ellerman <patch-notifications@ellerman.id.au>
Cc: Aravinda Prasad <aravinda@linux.vnet.ibm.com>, Jessica Yu <jeyu@kernel.org>,
 linux-kernel@vger.kernel.org, Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
 Torsten Duwe <duwe@lst.de>, Josh Poimboeuf <jpoimboe@redhat.com>,
 live-patching@vger.kernel.org,
 "Naveen N . Rao" <naveen.n.rao@linux.vnet.ibm.com>,
 linuxppc-dev@lists.ozlabs.org
Subject: Re: [v4,
 1/3] kernel/modules: Add REL24 relocation support of livepatch symbols
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Date: Tue, 12 Dec 2017 22:39:26 +1100 (AEDT)
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On Tue, 2017-11-14 at 09:29:08 UTC, Kamalesh Babulal wrote:
> Livepatch re-uses module loader function apply_relocate_add() to write
> relocations, instead of managing them by arch-dependent
> klp_write_module_reloc() function.
> 
> apply_relocate_add() doesn't understand livepatch symbols (marked with
> SHN_LIVEPATCH symbol section index) and assumes them to be local symbols
> by default for R_PPC64_REL24 relocation type. It fails with an error,
> when trying to calculate offset with local_entry_offset():
> 
>  module_64: kpatch_meminfo: REL24 -1152921504897399800 out of range!
> 
> Whereas livepatch symbols are essentially SHN_UNDEF, should be
> called via stub used for global calls. This issue can be fixed by
> teaching apply_relocate_add() to handle both SHN_UNDEF/SHN_LIVEPATCH
> symbols via the same stub. This patch extends SHN_UNDEF code to handle
> livepatch symbols too.
> 
> Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
> CC: Balbir Singh <bsingharora@gmail.com>
> Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
> Cc: Josh Poimboeuf <jpoimboe@redhat.com>
> Cc: Jessica Yu <jeyu@kernel.org>
> Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
> Cc: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
> Cc: Torsten Duwe <duwe@lst.de>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/a443bf6e8a7674b86221f4922cae82

cheers