From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx150.postini.com [74.125.245.150]) by kanga.kvack.org (Postfix) with SMTP id 4EDC46B00E7 for ; Thu, 5 Apr 2012 18:21:39 -0400 (EDT) Date: Fri, 6 Apr 2012 00:21:06 +0200 From: Oleg Nesterov Subject: [PATCH 2/6] uprobes: introduce is_swbp_at_addr_fast() Message-ID: <20120405222106.GB19166@redhat.com> References: <20120405222024.GA19154@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120405222024.GA19154@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Ingo Molnar , Peter Zijlstra , Srikar Dronamraju Cc: Andrew Morton , Linus Torvalds , Ananth N Mavinakayanahalli , Jim Keniston , LKML , Linux-mm , Andi Kleen , Christoph Hellwig , Steven Rostedt , Arnaldo Carvalho de Melo , Masami Hiramatsu , Thomas Gleixner , Anton Arapov Add the new helper, is_swbp_at_addr_fast(), will be used by find_active_uprobe(). It is almost the same as is_swbp_at_addr(), but since it plays with current->mm it can avoid the slow get_user_pages() in the likely case. --- kernel/events/uprobes.c | 23 +++++++++++++++++++++++ 1 files changed, 23 insertions(+), 0 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 3d0a4d6..2050b1a 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1474,6 +1474,29 @@ static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs) return false; } +int __weak is_swbp_at_addr_fast(unsigned long vaddr) +{ + uprobe_opcode_t opcode; + int fault; + + pagefault_disable(); + fault = __copy_from_user_inatomic(&opcode, (void __user*)vaddr, + sizeof(opcode)); + pagefault_enable(); + + if (unlikely(fault)) { + /* + * XXX: read_opcode() lacks FOLL_FORCE, it can fail if + * we race with another thread which does mprotect(NONE) + * after we hit bp. + */ + if (read_opcode(current->mm, vaddr, &opcode)) + return -EFAULT; + } + + return is_swbp_insn(&opcode); +} + static struct uprobe *find_active_uprobe(unsigned long bp_vaddr) { struct mm_struct *mm = current->mm; -- 1.5.5.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org