From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756034Ab1KJTIE (ORCPT ); Thu, 10 Nov 2011 14:08:04 -0500 Received: from e28smtp08.in.ibm.com ([122.248.162.8]:42142 "EHLO e28smtp08.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753009Ab1KJTH7 (ORCPT ); Thu, 10 Nov 2011 14:07:59 -0500 From: Srikar Dronamraju To: Peter Zijlstra , Linus Torvalds Cc: Oleg Nesterov , Andrew Morton , LKML , Linux-mm , Ingo Molnar , Andi Kleen , Christoph Hellwig , Steven Rostedt , Roland McGrath , Thomas Gleixner , Masami Hiramatsu , Arnaldo Carvalho de Melo , Anton Arapov , Ananth N Mavinakayanahalli , Jim Keniston , Stephen Wilson Date: Fri, 11 Nov 2011 00:12:57 +0530 Message-Id: <20111110184257.11361.74052.sendpatchset@srdronam.in.ibm.com> In-Reply-To: <20111110183725.11361.57827.sendpatchset@srdronam.in.ibm.com> References: <20111110183725.11361.57827.sendpatchset@srdronam.in.ibm.com> Subject: [PATCH v6 3.2-rc1 27/28] uprobes: x86: introduce xol_was_trapped() x-cbid: 11111019-2000-0000-0000-00000121496D Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Postpone the signals until we execute the probed insn. This is simply wrong if xol insn traps and generates the signal itself. Say, SIGILL/SIGSEGV/etc. Adds xol_was_trapped() to detect this case. It assumes that anything like do_page_fault/do_trap/etc sets thread.trap_no != -1. We add uprobe_task_arch_info->saved_trap_no and change pre_xol/post_xol to save/restore thread.trap_no, xol_was_trapped() simply checks that ->trap_no is not equal to UPROBE_TRAP_NO == -1 set by pre_xol(). Original-patch-from: Oleg Nesterov Signed-off-by: Srikar Dronamraju --- arch/x86/include/asm/uprobes.h | 6 +++++- arch/x86/kernel/uprobes.c | 21 +++++++++++++++++++++ 2 files changed, 26 insertions(+), 1 deletions(-) diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h index 99d7d4b..78e0007 100644 --- a/arch/x86/include/asm/uprobes.h +++ b/arch/x86/include/asm/uprobes.h @@ -39,16 +39,20 @@ struct uprobe_arch_info { struct uprobe_task_arch_info { unsigned long saved_scratch_register; + unsigned long saved_trap_no; }; #else struct uprobe_arch_info {}; -struct uprobe_task_arch_info {}; +struct uprobe_task_arch_info { + unsigned long saved_trap_no; +}; #endif struct uprobe; extern int analyze_insn(struct mm_struct *mm, struct uprobe *uprobe); extern void set_instruction_pointer(struct pt_regs *regs, unsigned long vaddr); extern int pre_xol(struct uprobe *uprobe, struct pt_regs *regs); extern int post_xol(struct uprobe *uprobe, struct pt_regs *regs); +extern bool xol_was_trapped(struct task_struct *tsk); extern int uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data); #endif /* _ASM_UPROBES_H */ diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 0792fc8..f5b0841 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -409,6 +409,8 @@ void set_instruction_pointer(struct pt_regs *regs, unsigned long vaddr) regs->ip = vaddr; } +#define UPROBE_TRAP_NO -1ul + /* * pre_xol - prepare to execute out of line. * @uprobe: the probepoint information. @@ -424,6 +426,9 @@ int pre_xol(struct uprobe *uprobe, struct pt_regs *regs) { struct uprobe_task_arch_info *tskinfo = ¤t->utask->tskinfo; + tskinfo->saved_trap_no = current->thread.trap_no; + current->thread.trap_no = UPROBE_TRAP_NO; + regs->ip = current->utask->xol_vaddr; if (uprobe->fixups & UPROBES_FIX_RIP_AX) { tskinfo->saved_scratch_register = regs->ax; @@ -439,6 +444,11 @@ int pre_xol(struct uprobe *uprobe, struct pt_regs *regs) #else int pre_xol(struct uprobe *uprobe, struct pt_regs *regs) { + struct uprobe_task_arch_info *tskinfo = ¤t->utask->tskinfo; + + tskinfo->saved_trap_no = current->thread.trap_no; + current->thread.trap_no = UPROBE_TRAP_NO; + regs->ip = current->utask->xol_vaddr; return 0; } @@ -504,6 +514,14 @@ static void handle_riprel_post_xol(struct uprobe *uprobe, } #endif +bool xol_was_trapped(struct task_struct *tsk) +{ + if (tsk->thread.trap_no != UPROBE_TRAP_NO) + return true; + + return false; +} + /* * Called after single-stepping. To avoid the SMP problems that can * occur when we temporarily put back the original opcode to @@ -534,6 +552,9 @@ int post_xol(struct uprobe *uprobe, struct pt_regs *regs) int result = 0; long correction; + WARN_ON_ONCE(current->thread.trap_no != UPROBE_TRAP_NO); + + current->thread.trap_no = utask->tskinfo.saved_trap_no; correction = (long)(utask->vaddr - utask->xol_vaddr); handle_riprel_post_xol(uprobe, regs, &correction); if (uprobe->fixups & UPROBES_FIX_IP)