From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754001AbdKNJ3w (ORCPT ); Tue, 14 Nov 2017 04:29:52 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:55510 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753865AbdKNJ3h (ORCPT ); Tue, 14 Nov 2017 04:29:37 -0500 From: Kamalesh Babulal To: Michael Ellerman Cc: Kamalesh Babulal , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, live-patching@vger.kernel.org, Josh Poimboeuf , Balbir Singh , "Naveen N . Rao" , Jessica Yu , Ananth N Mavinakayanahalli , Aravinda Prasad , Torsten Duwe Subject: [PATCH v4 1/3] kernel/modules: Add REL24 relocation support of livepatch symbols Date: Tue, 14 Nov 2017 04:29:08 -0500 X-Mailer: git-send-email 2.9.3 In-Reply-To: <20171114092910.20399-1-kamalesh@linux.vnet.ibm.com> References: <20171114092910.20399-1-kamalesh@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17111409-0040-0000-0000-0000040E0AF8 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17111409-0041-0000-0000-000020B0BD51 Message-Id: <20171114092910.20399-2-kamalesh@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-11-14_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1711140129 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 CC: Balbir Singh Cc: Naveen N. Rao Cc: Josh Poimboeuf Cc: Jessica Yu Cc: Ananth N Mavinakayanahalli Cc: Aravinda Prasad Cc: Torsten Duwe --- arch/powerpc/kernel/module_64.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c index 0b0f896..39b01fd 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -613,7 +613,8 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, case R_PPC_REL24: /* FIXME: Handle weak symbols here --RR */ - if (sym->st_shndx == SHN_UNDEF) { + if (sym->st_shndx == SHN_UNDEF || + sym->st_shndx == SHN_LIVEPATCH) { /* External: go via stub */ value = stub_for_addr(sechdrs, value, me); if (!value) -- 2.9.3