From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752842AbdAZGHU (ORCPT ); Thu, 26 Jan 2017 01:07:20 -0500 Received: from mga02.intel.com ([134.134.136.20]:12061 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752466AbdAZGHT (ORCPT ); Thu, 26 Jan 2017 01:07:19 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,287,1477983600"; d="scan'208";a="1087433520" Message-ID: <1485410836.41148.56.camel@ranerica-desktop> Subject: Re: [v3 PATCH 04/10] x86/insn-kernel: Add a function to obtain register offset in ModRM From: Ricardo Neri To: Masami Hiramatsu Cc: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andy Lutomirski , Borislav Petkov , Peter Zijlstra , Andrew Morton , Brian Gerst , Chris Metcalf , Dave Hansen , Paolo Bonzini , Liang Z Li , Huang Rui , Jiri Slaby , Jonathan Corbet , "Michael S. Tsirkin" , Paul Gortmaker , Vlastimil Babka , Chen Yucong , Alexandre Julliard , Fenghua Yu , Stas Sergeev , "Ravi V. Shankar" , Shuah Khan , linux-kernel@vger.kernel.org, x86@kernel.org, linux-msdos@vger.kernel.org, wine-devel@winehq.org, Adam Buchbinder , Colin Ian King , Lorenzo Stoakes , Qiaowei Ren , Arnaldo Carvalho de Melo , Adrian Hunter , Kees Cook , Thomas Garnier , Dmitry Vyukov Date: Wed, 25 Jan 2017 22:07:16 -0800 In-Reply-To: <20170126111121.2936732c88f1d60fbdc6835a@kernel.org> References: <20170125202353.101059-1-ricardo.neri-calderon@linux.intel.com> <20170125202353.101059-5-ricardo.neri-calderon@linux.intel.com> <20170126111121.2936732c88f1d60fbdc6835a@kernel.org> 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 Hi Masami, On Thu, 2017-01-26 at 11:11 +0900, Masami Hiramatsu wrote: > On Wed, 25 Jan 2017 12:23:47 -0800 > Ricardo Neri wrote: > > > The function insn_get_reg_offset requires a type to indicate whether > > the returned offset is that given by by the ModRM or the SIB byte. > > Callers of this function would need the definition of the type struct. > > This is not needed. Instead, auxiliary functions can be defined for > > this purpose. > > > > When the operand is a register, the emulation code for User-Mode > > Instruction Prevention needs to know the offset of the register indicated > > in the r/m part of the ModRM byte. Thus, start by adding an auxiliary > > function for this purpose. > > Hmm, why wouldn't you just rename it to insn_get_reg_offset() and export it? Do you mean exporting the structure that I mention above? The problem that I am trying to solve is that callers sometimes want to know the offset of the register encoded in the SiB or the ModRM bytes. I could use something insn_get_reg_offset(insn, regs, INSN_TYPE_MODRM) insn_get_reg_offset(insn, regs, INSN_TYPE_SIB) Instead, I opted for insn_get_reg_offset_rm(insn, regs) insn_get_reg_offset_sib(insn, regs) to avoid exposing an enum with the INSN_TYPE_MODRM, INSN_TYPE_SIB. If you feel that the former makes more sense, I can change the implementation. Thanks and BR, Ricardo > > Thank you, > > > > > Cc: Dave Hansen > > Cc: Adam Buchbinder > > Cc: Colin Ian King > > Cc: Lorenzo Stoakes > > Cc: Qiaowei Ren > > Cc: Arnaldo Carvalho de Melo > > Cc: Masami Hiramatsu > > Cc: Adrian Hunter > > Cc: Kees Cook > > Cc: Thomas Garnier > > Cc: Peter Zijlstra > > Cc: Borislav Petkov > > Cc: Dmitry Vyukov > > Cc: Ravi V. Shankar > > Cc: x86@kernel.org > > Signed-off-by: Ricardo Neri > > --- > > arch/x86/include/asm/insn-kernel.h | 1 + > > arch/x86/lib/insn-kernel.c | 5 +++++ > > 2 files changed, 6 insertions(+) > > > > diff --git a/arch/x86/include/asm/insn-kernel.h b/arch/x86/include/asm/insn-kernel.h > > index aef416a..3f34649 100644 > > --- a/arch/x86/include/asm/insn-kernel.h > > +++ b/arch/x86/include/asm/insn-kernel.h > > @@ -12,5 +12,6 @@ > > #include > > > > void __user *insn_get_addr_ref(struct insn *insn, struct pt_regs *regs); > > +int insn_get_reg_offset_rm(struct insn *insn, struct pt_regs *regs); > > > > #endif /* _ASM_X86_INSN_KERNEL_H */ > > diff --git a/arch/x86/lib/insn-kernel.c b/arch/x86/lib/insn-kernel.c > > index 8072abe..267cab4 100644 > > --- a/arch/x86/lib/insn-kernel.c > > +++ b/arch/x86/lib/insn-kernel.c > > @@ -95,6 +95,11 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs, > > return regoff[regno]; > > } > > > > +int insn_get_reg_offset_rm(struct insn *insn, struct pt_regs *regs) > > +{ > > + return get_reg_offset(insn, regs, REG_TYPE_RM); > > +} > > + > > /* > > * return the address being referenced be instruction > > * for rm=3 returning the content of the rm reg > > -- > > 2.9.3 > > > >