From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752342AbWCPKyq (ORCPT ); Thu, 16 Mar 2006 05:54:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752358AbWCPKyq (ORCPT ); Thu, 16 Mar 2006 05:54:46 -0500 Received: from e2.ny.us.ibm.com ([32.97.182.142]:31952 "EHLO e2.ny.us.ibm.com") by vger.kernel.org with ESMTP id S1752341AbWCPKyp (ORCPT ); Thu, 16 Mar 2006 05:54:45 -0500 Date: Thu, 16 Mar 2006 16:25:09 +0530 From: Prasanna S Panchamukhi To: akpm@osdl.org, Andi Kleen , davem@davemloft.net Cc: linux-kernel@vger.kernel.org, ananth@in.ibm.com, anil.s.keshavamurthy@intel.com Subject: Re: [3/5 PATCH] Kprobes-fix-broken-fault-handling-for-powerpc64 Message-ID: <20060316105509.GD16392@in.ibm.com> Reply-To: prasanna@in.ibm.com References: <20060316105236.GB16392@in.ibm.com> <20060316105404.GC16392@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060316105404.GC16392@in.ibm.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This patch fixes the broken kprobes fault handling similar to i386 architecture. Signed-off-by: Prasanna S Panchamukhi arch/powerpc/kernel/kprobes.c | 61 +++++++++++++++++++++++++++++++++++++----- 1 files changed, 54 insertions(+), 7 deletions(-) diff -puN arch/powerpc/kernel/kprobes.c~kprobes-powerpc-pagefault-handling arch/powerpc/kernel/kprobes.c --- linux-2.6.16-rc6-mm1/arch/powerpc/kernel/kprobes.c~kprobes-powerpc-pagefault-handling 2006-03-16 15:58:45.000000000 +0530 +++ linux-2.6.16-rc6-mm1-prasanna/arch/powerpc/kernel/kprobes.c 2006-03-16 15:58:45.000000000 +0530 @@ -30,9 +30,11 @@ #include #include #include +#include #include #include #include +#include DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); @@ -372,17 +374,62 @@ static inline int kprobe_fault_handler(s { struct kprobe *cur = kprobe_running(); struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + const struct exception_table_entry *entry; - if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) - return 1; - - if (kcb->kprobe_status & KPROBE_HIT_SS) { - resume_execution(cur, regs); + switch(kcb->kprobe_status) { + case KPROBE_HIT_SS: + case KPROBE_REENTER: + /* + * We are here because the instruction being single + * stepped caused a page fault. We reset the current + * kprobe and the nip points back to the probe address + * and allow the page fault handler to continue as a + * normal page fault. + */ + regs->nip = (unsigned long)cur->addr; regs->msr &= ~MSR_SE; regs->msr |= kcb->kprobe_saved_msr; - - reset_current_kprobe(); + if (kcb->kprobe_status == KPROBE_REENTER) + restore_previous_kprobe(kcb); + else + reset_current_kprobe(); preempt_enable_no_resched(); + break; + case KPROBE_HIT_ACTIVE: + case KPROBE_HIT_SSDONE: + /* + * We increment the nmissed count for accounting, + * we can also use npre/npostfault count for accouting + * these specific fault cases. + */ + kprobes_inc_nmissed_count(cur); + + /* + * We come here because instructions in the pre/post + * handler caused the page_fault, this could happen + * if handler tries to access user space by + * copy_from_user(), get_user() etc. Let the + * user-specified handler try to fix it first. + */ + if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) + return 1; + + /* + * In case the user-specified fault handler returned + * zero, try to fix up. + */ + if ((entry = search_exception_tables(regs->nip)) != NULL) { + regs->nip = entry->fixup; + return 1; + } + + /* + * fixup_exception() could not handle it, + * Let do_page_fault() fix it. + */ + break; + default: + break; } return 0; } _ -- Prasanna S Panchamukhi Linux Technology Center India Software Labs, IBM Bangalore Email: prasanna@in.ibm.com Ph: 91-80-51776329