Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753654AbaBZTAp (ORCPT ); Wed, 26 Feb 2014 14:00:45 -0500 Received: from mail-vc0-f169.google.com ([209.85.220.169]:58492 "EHLO mail-vc0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750813AbaBZTAo (ORCPT ); Wed, 26 Feb 2014 14:00:44 -0500 MIME-Version: 1.0 In-Reply-To: <5306BD8D.3030606@intel.com> References: <1392230186-16130-1-git-send-email-qiaowei.ren@intel.com> <1392230186-16130-3-git-send-email-qiaowei.ren@intel.com> <52FBD74F.7050203@mit.edu> <5306BD8D.3030606@intel.com> From: Andy Lutomirski Date: Wed, 26 Feb 2014 11:00:21 -0800 Message-ID: Subject: Re: [PATCH v4 2/3] x86, mpx: hook #BR exception handler to allocate bound tables To: Ren Qiaowei Cc: "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , X86 ML , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 20, 2014 at 6:44 PM, Ren Qiaowei wrote: > On 02/13/2014 04:19 AM, Andy Lutomirski wrote: >> >> On 02/12/2014 10:36 AM, Qiaowei Ren wrote: >>> >>> An access to an invalid bound directory entry will cause a #BR >>> exception. This patch hook #BR exception handler to allocate >>> one bound table and bind it with that buond directory entry. >>> >>> This will avoid the need of forwarding the #BR exception >>> to the user space when bound directory has invalid entry. >>> >>> Signed-off-by: Qiaowei Ren >>> --- >>> +void do_mpx_bt_fault(struct xsave_struct *xsave_buf) >>> +{ >>> + unsigned long status; >>> + unsigned long bd_entry, bd_base; >>> + unsigned long bd_size = 1UL << (MPX_L1_BITS+MPX_L1_SHIFT); >>> + >>> + bd_base = xsave_buf->bndcsr.cfg_reg_u & MPX_BNDCFG_ADDR_MASK; >>> + status = xsave_buf->bndcsr.status_reg; >>> + >>> + bd_entry = status & MPX_BNDSTA_ADDR_MASK; >>> + if ((bd_entry >= bd_base) && (bd_entry < bd_base + bd_size)) >>> + allocate_bt(bd_entry); >>> +} >> >> >> This still just loops on failure, right? >> > Seems like that SIGBUS should be raised if the allocation fail. > > if (!do_mpx_bt_fault(xsave_buf)) > force_sig(SIGBUS, tsk); I wonder if this should go through the force_sig_info path. --Andy > > Thanks, > Qiaowei > -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/