From mboxrd@z Thu Jan 1 00:00:00 1970 From: Borislav Petkov Subject: Re: [v6 PATCH 11/21] insn/eval: Incorporate segment base in address computation Date: Fri, 21 Apr 2017 16:55:33 +0200 Message-ID: <20170421145533.fg32dcf2af7mksxa@pd.tnic> References: <20170308003254.27833-1-ricardo.neri-calderon@linux.intel.com> <20170308003254.27833-12-ricardo.neri-calderon@linux.intel.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <20170308003254.27833-12-ricardo.neri-calderon@linux.intel.com> Sender: linux-msdos-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="utf-8" To: Ricardo Neri Cc: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Andrew Morton , Brian Gerst , Chris Metcalf , Dave Hansen , Paolo Bonzini , Masami Hiramatsu , Huang Rui , Jiri Slaby , Jonathan Corbet , "Michael S. Tsirkin" , Paul Gortmaker , Vlastimil Babka , Chen Yucong , Alexandre Julliard , Stas Sergeev , Fenghua Yu On Tue, Mar 07, 2017 at 04:32:44PM -0800, Ricardo Neri wrote: > insn_get_addr_ref returns the effective address as defined by the Please end function names with parentheses. > section 3.7.5.1 Vol 1 of the Intel 64 and IA-32 Architectures Software > Developer's Manual. In order to compute the linear address, we must add > to the effective address the segment base address as set in the segment > descriptor. Furthermore, the segment descriptor to use depends on the > register that is used as the base of the effective address. The effective > base address varies depending on whether the operand is a register or a > memory address and on whether a SiB byte is used. > > In most cases, the segment base address will be 0 if the USER_DS/USER32_DS > segment is used or if segmentation is not used. However, the base address > is not necessarily zero if a user programs defines its own segments. This > is possible by using a local descriptor table. > > Since the effective address is a signed quantity, the unsigned segment > base address saved in a separate variable and added to the final effective ".. is saved..." > address. > -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --