Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756131Ab1CNRf5 (ORCPT ); Mon, 14 Mar 2011 13:35:57 -0400 Received: from e5.ny.us.ibm.com ([32.97.182.145]:43679 "EHLO e5.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755702Ab1CNRfz (ORCPT ); Mon, 14 Mar 2011 13:35:55 -0400 Date: Mon, 14 Mar 2011 23:00:04 +0530 From: Srikar Dronamraju To: Stephen Wilson Cc: Peter Zijlstra , Ingo Molnar , Steven Rostedt , Linux-mm , Arnaldo Carvalho de Melo , Linus Torvalds , Ananth N Mavinakayanahalli , Christoph Hellwig , Andi Kleen , Masami Hiramatsu , Oleg Nesterov , LKML , Jim Keniston , Roland McGrath , SystemTap , Andrew Morton , "Paul E. McKenney" Subject: Re: [PATCH v2 2.6.38-rc8-tip 3/20] 3: uprobes: Breakground page replacement. Message-ID: <20110314173004.GQ24254@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <20110314133403.27435.7901.sendpatchset@localhost6.localdomain6> <20110314133433.27435.49566.sendpatchset@localhost6.localdomain6> <20110314165818.GA18507@fibrous.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20110314165818.GA18507@fibrous.localdomain> User-Agent: Mutt/1.5.20 (2009-06-14) X-Content-Scanned: Fidelis XPS MAILER Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1902 Lines: 61 * Stephen Wilson [2011-03-14 12:58:18]: > On Mon, Mar 14, 2011 at 07:04:33PM +0530, Srikar Dronamraju wrote: > > +/** > > + * read_opcode - read the opcode at a given virtual address. > > + * @tsk: the probed task. > > + * @vaddr: the virtual address to store the opcode. > > + * @opcode: location to store the read opcode. > > + * > > + * For task @tsk, read the opcode at @vaddr and store it in @opcode. > > + * Return 0 (success) or a negative errno. > > + */ > > +int __weak read_opcode(struct task_struct *tsk, unsigned long vaddr, > > + uprobe_opcode_t *opcode) > > +{ > > + struct vm_area_struct *vma; > > + struct page *page; > > + void *vaddr_new; > > + int ret; > > + > > + ret = get_user_pages(tsk, tsk->mm, vaddr, 1, 0, 0, &page, &vma); > > + if (ret <= 0) > > + return -EFAULT; > > + ret = -EFAULT; > > + > > + /* > > + * check if the page we are interested is read-only mapped > > + * Since we are interested in text pages, Our pages of interest > > + * should be mapped read-only. > > + */ > > + if ((vma->vm_flags & (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)) == > > + (VM_READ|VM_EXEC)) > > + goto put_out; > > + > > + lock_page(page); > > + vaddr_new = kmap_atomic(page, KM_USER0); > > + vaddr &= ~PAGE_MASK; > > + memcpy(&opcode, vaddr_new + vaddr, uprobe_opcode_sz); > > + kunmap_atomic(vaddr_new, KM_USER0); > > + unlock_page(page); > > + ret = uprobe_opcode_sz; > > This looks wrong. We should be setting ret = 0 on success here? Right, I should have set ret = 0 here. > > > + > > +put_out: > > + put_page(page); /* we did a get_page in the beginning */ > > + return ret; > > +} > > -- > steve > -- 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/