From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3xz759421WzDsMB for ; Fri, 22 Sep 2017 19:11:25 +1000 (AEST) Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v8M9AxXQ019498 for ; Fri, 22 Sep 2017 05:11:22 -0400 Received: from e23smtp01.au.ibm.com (e23smtp01.au.ibm.com [202.81.31.143]) by mx0a-001b2d01.pphosted.com with ESMTP id 2d4ynp808a-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 22 Sep 2017 05:11:22 -0400 Received: from localhost by e23smtp01.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 22 Sep 2017 19:11:20 +1000 Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay09.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v8M9BHXJ36503728 for ; Fri, 22 Sep 2017 19:11:17 +1000 Received: from d23av02.au.ibm.com (localhost [127.0.0.1]) by d23av02.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v8M9B7vS020832 for ; Fri, 22 Sep 2017 19:11:08 +1000 From: "Naveen N. Rao" To: Michael Ellerman Cc: Kamalesh Babulal , Masami Hiramatsu , Ananth N Mavinakayanahalli , linuxppc-dev@lists.ozlabs.org Subject: [PATCH v2 6/6] powerpc/jprobes: Validate break handler invocation as being due to a jprobe_return() Date: Fri, 22 Sep 2017 14:40:48 +0530 In-Reply-To: <9e98f74834af349564b71bc8443bdad55d6e37c6.1505934128.git.naveen.n.rao@linux.vnet.ibm.com> References: <9e98f74834af349564b71bc8443bdad55d6e37c6.1505934128.git.naveen.n.rao@linux.vnet.ibm.com> In-Reply-To: References: Message-Id: List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Fix a circa 2005 FIXME by implementing a check to ensure that we actually got into the jprobe break handler() due to the trap in jprobe_return(). Acked-by: Masami Hiramatsu Signed-off-by: Naveen N. Rao --- arch/powerpc/kernel/kprobes.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index 48a81614f629..a14c61855705 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -639,24 +639,22 @@ NOKPROBE_SYMBOL(setjmp_pre_handler); void __used jprobe_return(void) { - asm volatile("trap" ::: "memory"); + asm volatile("jprobe_return_trap:\n" + "trap\n" + ::: "memory"); } NOKPROBE_SYMBOL(jprobe_return); -static void __used jprobe_return_end(void) -{ -} -NOKPROBE_SYMBOL(jprobe_return_end); - int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) { struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); - /* - * FIXME - we should ideally be validating that we got here 'cos - * of the "trap" in jprobe_return() above, before restoring the - * saved regs... - */ + if (regs->nip != ppc_kallsyms_lookup_name("jprobe_return_trap")) { + pr_debug("longjmp_break_handler NIP (0x%lx) does not match jprobe_return_trap (0x%lx)\n", + regs->nip, ppc_kallsyms_lookup_name("jprobe_return_trap")); + return 0; + } + memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs)); /* It's OK to start function graph tracing again */ unpause_graph_tracing(); -- 2.14.1