From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ricardo Neri Subject: [PATCH v4 10/17] insn/eval: Incorporate segment base in address computation Date: Wed, 22 Feb 2017 22:36:59 -0800 Message-ID: <20170223063706.71554-11-ricardo.neri-calderon@linux.intel.com> References: <20170223063706.71554-1-ricardo.neri-calderon@linux.intel.com> Return-path: In-Reply-To: <20170223063706.71554-1-ricardo.neri-calderon@linux.intel.com> Sender: linux-msdos-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andy Lutomirski , Borislav Petkov Cc: 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 , Alexandre Julliard , Stas Sergeev , Fenghua Yu , "Ravi V. Shankar" , Shuah Khan , linux-kernel@vger.kern insn_get_addr_ref returns the effective address as defined by the section 3.7.5.1 Vol 1 of the Intel 64 and IA-32 Architectures Software Developer's Manual. In order to truly give the linear address, we must add the effective address to the segment base as described by the segment descriptor. In most cases, the base will be 0 if the USER_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. 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/lib/insn-eval.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c index d6525c2..b3a2fe8 100644 --- a/arch/x86/lib/insn-eval.c +++ b/arch/x86/lib/insn-eval.c @@ -523,6 +523,7 @@ static void __user *insn_get_addr_ref(struct insn *insn, struct pt_regs *regs) if (addr_offset < 0) goto out_err; addr = regs_get_register(regs, addr_offset); + addr += insn_get_seg_base(regs, insn, addr_offset); } else { if (insn->sib.nbytes) { /* @@ -551,6 +552,7 @@ static void __user *insn_get_addr_ref(struct insn *insn, struct pt_regs *regs) indx = regs_get_register(regs, indx_offset); addr = base + indx * (1 << X86_SIB_SCALE(sib)); + addr += insn_get_seg_base(regs, insn, base_offset); } else { unsigned char addr_bytes; @@ -575,8 +577,10 @@ static void __user *insn_get_addr_ref(struct insn *insn, struct pt_regs *regs) } else { addr = regs_get_register(regs, addr_offset); } + addr += insn_get_seg_base(regs, insn, addr_offset); } addr += insn->displacement.value; + } return (void __user *)addr; out_err: -- 2.9.3