From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Mon, 18 May 2015 12:32:16 +0000
Subject: re: x86, mpx: Decode MPX instruction to get bound violation information
Message-Id: <20150518123216.GD32633@mwanda>
List-Id: <kernel-janitors.vger.kernel.org>
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To: kernel-janitors@vger.kernel.org

Hello Dave Hansen,

The patch fcc7ffd67991: "x86, mpx: Decode MPX instruction to get
bound violation information" from Nov 14, 2014, leads to the
following static checker warning:

	arch/x86/mm/mpx.c:147 get_reg_offset()
	warn: masked condition is always false. '((insn->rex_prefix.value) & 2) = 1'

arch/x86/mm/mpx.c
   138          switch (type) {
   139          case REG_TYPE_RM:
   140                  regno = X86_MODRM_RM(insn->modrm.value);
   141                  if (X86_REX_B(insn->rex_prefix.value) = 1)
   142                          regno += 8;
   143                  break;
   144  
   145          case REG_TYPE_INDEX:
   146                  regno = X86_SIB_INDEX(insn->sib.value);
   147                  if (X86_REX_X(insn->rex_prefix.value) = 1)
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Was X86_REX_B() intended?

   148                          regno += 8;
   149                  break;
   150  
   151          case REG_TYPE_BASE:
   152                  regno = X86_SIB_BASE(insn->sib.value);
   153                  if (X86_REX_B(insn->rex_prefix.value) = 1)
   154                          regno += 8;
   155                  break;
   156  
   157          default:
   158                  pr_err("invalid register type");
   159                  BUG();
   160                  break;
   161          }

regards,
dan carpenter