From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3ybhzl725pzDqwP for ; Tue, 14 Nov 2017 20:29:39 +1100 (AEDT) Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vAE9TRLj115333 for ; Tue, 14 Nov 2017 04:29:37 -0500 Received: from e06smtp11.uk.ibm.com (e06smtp11.uk.ibm.com [195.75.94.107]) by mx0b-001b2d01.pphosted.com with ESMTP id 2e7vjm476p-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 14 Nov 2017 04:29:37 -0500 Received: from localhost by e06smtp11.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 14 Nov 2017 09:29:35 -0000 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 In-Reply-To: <20171114092910.20399-1-kamalesh@linux.vnet.ibm.com> References: <20171114092910.20399-1-kamalesh@linux.vnet.ibm.com> Message-Id: <20171114092910.20399-2-kamalesh@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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