From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C1190C4743C for ; Wed, 23 Jun 2021 05:23:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9BC71610A0 for ; Wed, 23 Jun 2021 05:23:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229913AbhFWFZv (ORCPT ); Wed, 23 Jun 2021 01:25:51 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:50665 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229665AbhFWFZu (ORCPT ); Wed, 23 Jun 2021 01:25:50 -0400 Received: from localhost (mailhub3.si.c-s.fr [192.168.12.233]) by localhost (Postfix) with ESMTP id 4G8s9w0JgnzBDb3; Wed, 23 Jun 2021 07:23:32 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id bYOMyFCcoABL; Wed, 23 Jun 2021 07:23:31 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4G8s9v59R8zBDZK; Wed, 23 Jun 2021 07:23:31 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id A36AE8B7C1; Wed, 23 Jun 2021 07:23:31 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id JK5fSF0_49QA; Wed, 23 Jun 2021 07:23:31 +0200 (CEST) Received: from po9473vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 5C1578B767; Wed, 23 Jun 2021 07:23:31 +0200 (CEST) Received: by po9473vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 1BA1B6630E; Wed, 23 Jun 2021 05:23:30 +0000 (UTC) Message-Id: <5bdc8cbc9a95d0779e27c9ddbf42b40f51f883c0.1624425798.git.christophe.leroy@csgroup.eu> From: Christophe Leroy Subject: [PATCH v2] powerpc/kprobes: Fix Oops by passing ppc_inst as a pointer to emulate_step() on ppc32 To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Date: Wed, 23 Jun 2021 05:23:30 +0000 (UTC) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Naveen N. Rao Trying to use a kprobe on ppc32 results in the below splat: BUG: Unable to handle kernel data access on read at 0x7c0802a6 Faulting instruction address: 0xc002e9f0 Oops: Kernel access of bad area, sig: 11 [#1] BE PAGE_SIZE=4K PowerPC 44x Platform Modules linked in: CPU: 0 PID: 89 Comm: sh Not tainted 5.13.0-rc1-01824-g3a81c0495fdb #7 NIP: c002e9f0 LR: c0011858 CTR: 00008a47 REGS: c292fd50 TRAP: 0300 Not tainted (5.13.0-rc1-01824-g3a81c0495fdb) MSR: 00009000 CR: 24002002 XER: 20000000 DEAR: 7c0802a6 ESR: 00000000 NIP [c002e9f0] emulate_step+0x28/0x324 LR [c0011858] optinsn_slot+0x128/0x10000 Call Trace: opt_pre_handler+0x7c/0xb4 (unreliable) optinsn_slot+0x128/0x10000 ret_from_syscall+0x0/0x28 The offending instruction is: 81 24 00 00 lwz r9,0(r4) Here, we are trying to load the second argument to emulate_step(): struct ppc_inst, which is the instruction to be emulated. On ppc64, structures are passed in registers when passed by value. However, per the ppc32 ABI, structures are always passed to functions as pointers. This isn't being adhered to when setting up the call to emulate_step() in the optprobe trampoline. Fix the same. Fixes: eacf4c0202654a ("powerpc: Enable OPTPROBES on PPC32") Cc: stable@vger.kernel.org Signed-off-by: Naveen N. Rao --- v2: Rebased on powerpc/merge 7f030e9d57b8 Signed-off-by: Christophe Leroy --- arch/powerpc/kernel/optprobes.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c index 2b8fe40069ad..53facb4b377f 100644 --- a/arch/powerpc/kernel/optprobes.c +++ b/arch/powerpc/kernel/optprobes.c @@ -228,8 +228,12 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p) /* * 3. load instruction to be emulated into relevant register, and */ - temp = ppc_inst_read(p->ainsn.insn); - patch_imm_load_insns(ppc_inst_as_ulong(temp), 4, buff + TMPL_INSN_IDX); + if (IS_ENABLED(CONFIG_PPC64)) { + temp = ppc_inst_read(p->ainsn.insn); + patch_imm_load_insns(ppc_inst_as_ulong(temp), 4, buff + TMPL_INSN_IDX); + } else { + patch_imm_load_insns((unsigned long)p->ainsn.insn, 4, buff + TMPL_INSN_IDX); + } /* * 4. branch back from trampoline -- 2.25.0