Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750911AbdHaETR (ORCPT ); Thu, 31 Aug 2017 00:19:17 -0400 Received: from mga14.intel.com ([192.55.52.115]:44952 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750747AbdHaETQ (ORCPT ); Thu, 31 Aug 2017 00:19:16 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.41,451,1498546800"; d="scan'208";a="1212813897" Message-ID: <1504153154.51857.15.camel@ranerica-desktop> Subject: Re: [PATCH v8 05/28] x86/mpx: Use signed variables to compute effective addresses From: Ricardo Neri To: Borislav Petkov Cc: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Andrew Morton , Brian Gerst , Chris Metcalf , Dave Hansen , Paolo Bonzini , Liang Z Li , Masami Hiramatsu , Huang Rui , Jiri Slaby , Jonathan Corbet , "Michael S. Tsirkin" , Paul Gortmaker , Vlastimil Babka , Chen Yucong , "Ravi V. Shankar" , Shuah Khan , linux-kernel@vger.kernel.org, x86@kernel.org, Adam Buchbinder , Colin Ian King , Lorenzo Stoakes , Qiaowei Ren , Nathan Howard , Adan Hawthorn , Joe Perches Date: Wed, 30 Aug 2017 21:19:14 -0700 In-Reply-To: <20170829160906.gpenny6yqq5squ6l@pd.tnic> References: <20170819002809.111312-1-ricardo.neri-calderon@linux.intel.com> <20170819002809.111312-6-ricardo.neri-calderon@linux.intel.com> <20170829160906.gpenny6yqq5squ6l@pd.tnic> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3632 Lines: 93 On Tue, 2017-08-29 at 18:09 +0200, Borislav Petkov wrote: > On Fri, Aug 18, 2017 at 05:27:46PM -0700, Ricardo Neri wrote: > > Even though memory addresses are unsigned, the operands used to compute the > > effective address do have a sign. This is true for ModRM.rm, SIB.base, > > SIB.index as well as the displacement bytes. Thus, signed variables shall > > be used when computing the effective address from these operands. Once the > > signed effective address has been computed, it is casted to an unsigned > > long to determine the linear address. > > > > Variables are renamed to better reflect the type of address being > > computed. > > > > Cc: Borislav Petkov > > Cc: Andy Lutomirski > > Cc: Dave Hansen > > Cc: Adam Buchbinder > > Cc: Colin Ian King > > Cc: Lorenzo Stoakes > > Cc: Qiaowei Ren > > Cc: Peter Zijlstra > > Cc: Nathan Howard > > Cc: Adan Hawthorn > > Cc: Joe Perches > > Cc: Ravi V. Shankar > > Cc: x86@kernel.org > > Signed-off-by: Ricardo Neri > > --- > > arch/x86/mm/mpx.c | 20 ++++++++++++++------ > > 1 file changed, 14 insertions(+), 6 deletions(-) > > I think you can simplify this function even more (diff ontop): > > diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c > index 9eec98022510..d0ec5c9b2a57 100644 > --- a/arch/x86/mm/mpx.c > +++ b/arch/x86/mm/mpx.c > @@ -139,7 +139,7 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs, > static void __user *mpx_get_addr_ref(struct insn *insn, struct pt_regs *regs) > { > int addr_offset, base_offset, indx_offset; > - unsigned long linear_addr; > + unsigned long linear_addr = -1; > long eff_addr, base, indx; > insn_byte_t sib; > > @@ -150,18 +150,18 @@ static void __user *mpx_get_addr_ref(struct insn *insn, struct pt_regs *regs) > if (X86_MODRM_MOD(insn->modrm.value) == 3) { > addr_offset = get_reg_offset(insn, regs, REG_TYPE_RM); > if (addr_offset < 0) > - goto out_err; > + goto out; > > eff_addr = regs_get_register(regs, addr_offset); > } else { > if (insn->sib.nbytes) { > base_offset = get_reg_offset(insn, regs, REG_TYPE_BASE); > if (base_offset < 0) > - goto out_err; > + goto out; > This is a good suggestion. This is a good suggestion. > indx_offset = get_reg_offset(insn, regs, REG_TYPE_INDEX); > if (indx_offset < 0) > - goto out_err; > + goto out; > > base = regs_get_register(regs, base_offset); > indx = regs_get_register(regs, indx_offset); > @@ -170,7 +170,7 @@ static void __user *mpx_get_addr_ref(struct insn *insn, struct pt_regs *regs) > } else { > addr_offset = get_reg_offset(insn, regs, REG_TYPE_RM); > if (addr_offset < 0) > - goto out_err; > + goto out; > > eff_addr = regs_get_register(regs, addr_offset); > } > @@ -180,9 +180,8 @@ static void __user *mpx_get_addr_ref(struct insn *insn, struct pt_regs *regs) > > linear_addr = (unsigned long)eff_addr; > > +out: > return (void __user *)linear_addr; > -out_err: > - return (void __user *)-1; This is a good suggestion. I will work on it. By now my series comprises 28 patches. If you plan to review the rest of the series and you don't have major objections, could I work on these updates as increments from my v8 series? I think that with 28 patches in the series is becoming difficult to review. Thanks and BR, Ricardo