Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753281Ab3JSQnm (ORCPT ); Sat, 19 Oct 2013 12:43:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2357 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751549Ab3JSQnl (ORCPT ); Sat, 19 Oct 2013 12:43:41 -0400 Date: Sat, 19 Oct 2013 18:36:27 +0200 From: Oleg Nesterov To: David Long Cc: linux-arm-kernel@lists.infradead.org, Rabin Vincent , "Jon Medhurst (Tixy)" , Srikar Dronamraju , Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 03/13] uprobes: allow arch access to xol slot Message-ID: <20131019163627.GA7837@redhat.com> References: <1381871068-27660-1-git-send-email-dave.long@linaro.org> <1381871068-27660-4-git-send-email-dave.long@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1381871068-27660-4-git-send-email-dave.long@linaro.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1680 Lines: 60 On 10/15, David Long wrote: > > Allow arches to customize how the instruction is filled into the xol > slot. ARM will use this to insert an undefined instruction after the > real instruction in order to simulate a single step of the instruction > without hardware support. OK, but > +void __weak arch_uprobe_xol_copy(struct arch_uprobe *auprobe, void *vaddr) > +{ > + memcpy(vaddr, auprobe->insn, MAX_UINSN_BYTES); > +} > + > /* > * xol_get_insn_slot - allocate a slot for xol. > * Returns the allocated slot address or 0. > @@ -1246,6 +1251,7 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe) > { > struct xol_area *area; > unsigned long xol_vaddr; > + void *kaddr; > > area = get_xol_area(); > if (!area) > @@ -1256,7 +1262,9 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe) > return 0; > > /* Initialize the slot */ > - copy_to_page(area->page, xol_vaddr, uprobe->arch.insn, MAX_UINSN_BYTES); > + kaddr = kmap_atomic(area->page); > + arch_uprobe_xol_copy(&uprobe->arch, kaddr + (xol_vaddr & ~PAGE_MASK)); > + kunmap_atomic(kaddr); This looks a bit strange and defeats the purpose of generic helper... How about void __weak arch_uprobe_xol_copy(...) { copy_to_page(...); } then just - copy_to_page(...); + arch_uprobe_xol_copy(...); ? Or, I am just curious, can't we have an empty "__weak arch_uprobe_xol_copy" if we call it right after copy_to_page() ? Oleg. -- 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/