From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751765Ab2LaRwo (ORCPT ); Mon, 31 Dec 2012 12:52:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:61262 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751654Ab2LaRwi (ORCPT ); Mon, 31 Dec 2012 12:52:38 -0500 Date: Mon, 31 Dec 2012 18:52:23 +0100 From: Oleg Nesterov To: Ingo Molnar , Peter Zijlstra , Srikar Dronamraju Cc: Ananth N Mavinakayanahalli , Anton Arapov , Frank Eigler , Josh Stone , "Suzuki K. Poulose" , linux-kernel@vger.kernel.org Subject: [PATCH 4/7] uprobes: Do not play with utask in xol_get_insn_slot() Message-ID: <20121231175223.GA32101@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121231175150.GA32066@redhat.com> 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 pre_ssout()->xol_get_insn_slot() path is confusing and buggy. This patch cleanups the code, the next one fixes the bug. Change xol_get_insn_slot() to only allocate the slot and do nothing more, move the initialization of utask->xol_vaddr/vaddr into pre_ssout(). Signed-off-by: Oleg Nesterov --- kernel/events/uprobes.c | 37 +++++++++++++++++++++---------------- 1 files changed, 21 insertions(+), 16 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index b09b3ba..2ed6239 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1176,30 +1176,26 @@ static unsigned long xol_take_insn_slot(struct xol_area *area) } /* - * xol_get_insn_slot - If was not allocated a slot, then - * allocate a slot. + * xol_get_insn_slot - allocate a slot for xol. * Returns the allocated slot address or 0. */ -static unsigned long xol_get_insn_slot(struct uprobe *uprobe, unsigned long slot_addr) +static unsigned long xol_get_insn_slot(struct uprobe *uprobe) { struct xol_area *area; unsigned long offset; + unsigned long xol_vaddr; void *vaddr; area = get_xol_area(); if (!area) return 0; - current->utask->xol_vaddr = xol_take_insn_slot(area); - /* - * Initialize the slot if xol_vaddr points to valid - * instruction slot. - */ - if (unlikely(!current->utask->xol_vaddr)) + xol_vaddr = xol_take_insn_slot(area); + if (unlikely(!xol_vaddr)) return 0; - current->utask->vaddr = slot_addr; - offset = current->utask->xol_vaddr & ~PAGE_MASK; + /* Initialize the slot */ + offset = xol_vaddr & ~PAGE_MASK; vaddr = kmap_atomic(area->page); memcpy(vaddr + offset, uprobe->arch.insn, MAX_UINSN_BYTES); kunmap_atomic(vaddr); @@ -1209,7 +1205,7 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe, unsigned long slot */ flush_dcache_page(area->page); - return current->utask->xol_vaddr; + return xol_vaddr; } /* @@ -1306,12 +1302,21 @@ static struct uprobe_task *get_utask(void) /* Prepare to single-step probed instruction out of line. */ static int -pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long vaddr) +pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr) { - if (xol_get_insn_slot(uprobe, vaddr) && !arch_uprobe_pre_xol(&uprobe->arch, regs)) - return 0; + struct uprobe_task *utask; + unsigned long xol_vaddr; + + utask = current->utask; + + xol_vaddr = xol_get_insn_slot(uprobe); + if (!xol_vaddr) + return -ENOMEM; + + utask->xol_vaddr = xol_vaddr; + utask->vaddr = bp_vaddr; - return -EFAULT; + return arch_uprobe_pre_xol(&uprobe->arch, regs); } /* -- 1.5.5.1