From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 25F1DC28CC0 for ; Thu, 30 May 2019 11:08:08 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 67A3C257C9 for ; Thu, 30 May 2019 11:08:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="KW9gnXpS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 67A3C257C9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 45F4Yw4YwlzDqXN for ; Thu, 30 May 2019 21:08:04 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=infradead.org (client-ip=2607:7c80:54:e::133; helo=bombadil.infradead.org; envelope-from=willy@infradead.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=infradead.org header.i=@infradead.org header.b="KW9gnXpS"; dkim-atps=neutral Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) (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 45F4XW0LBnzDqTl for ; Thu, 30 May 2019 21:06:46 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=XWSZAD9Y6uBVo7L5n2t8Ehyy7C5gbqMnRx8yZh9FlDg=; b=KW9gnXpShROlZkddwXNzmFYlO fmIqAbGM2SAjmXl9zY3TDwFtQnfiDLggLdshi5XIGPQxS3N2b9fI8eNDGA5CdBld4QgdGWer5Q9Ir 58plIdYsqK7CE2ULlzaf6e3ndrG50anFfSpiL1RUGymu0dFCqQYpDTA9rKtBgtDQFojobJPChdzfh MzHtjhsFqDNt+GjziZ1c5QrQMMbip4vZ+Zfak6M+Hs4u1QJVcpRPLOPMswU88cCWHQw/XIU3x1t9u QHvDrd9yzlNEjQ5Cs6u2sQB4QLtEFYrUHNmUW7XL7WXMfwfRqZkB5YqUhHS/1U//ulgnX74EIJ6o3 ZQ2g4WdDw==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1hWItL-0006m3-ND; Thu, 30 May 2019 11:06:39 +0000 Date: Thu, 30 May 2019 04:06:39 -0700 From: Matthew Wilcox To: Anshuman Khandual Subject: Re: [RFC] mm: Generalize notify_page_fault() Message-ID: <20190530110639.GC23461@bombadil.infradead.org> References: <1559195713-6956-1-git-send-email-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1559195713-6956-1-git-send-email-anshuman.khandual@arm.com> User-Agent: Mutt/1.9.2 (2017-12-15) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Michal Hocko , linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Catalin Marinas , Will Deacon , linux-mm@kvack.org, Paul Mackerras , sparclinux@vger.kernel.org, linux-s390@vger.kernel.org, Yoshinori Sato , Russell King , Fenghua Yu , Stephen Rothwell , Andrey Konovalov , linux-arm-kernel@lists.infradead.org, Tony Luck , Heiko Carstens , linux-kernel@vger.kernel.org, Martin Schwidefsky , Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, May 30, 2019 at 11:25:13AM +0530, Anshuman Khandual wrote: > Similar notify_page_fault() definitions are being used by architectures > duplicating much of the same code. This attempts to unify them into a > single implementation, generalize it and then move it to a common place. > kprobes_built_in() can detect CONFIG_KPROBES, hence notify_page_fault() > must not be wrapped again within CONFIG_KPROBES. Trap number argument can This is a funny quirk of the English language. "must not" means "is not allowed to be", not "does not have to be". > @@ -141,6 +142,19 @@ static int __init init_zero_pfn(void) > core_initcall(init_zero_pfn); > > > +int __kprobes notify_page_fault(struct pt_regs *regs, unsigned int trap) > +{ > + int ret = 0; > + > + if (kprobes_built_in() && !user_mode(regs)) { > + preempt_disable(); > + if (kprobe_running() && kprobe_fault_handler(regs, trap)) > + ret = 1; > + preempt_enable(); > + } > + return ret; > +} > + > #if defined(SPLIT_RSS_COUNTING) Comparing this to the canonical implementation (ie x86), it looks similar. static nokprobe_inline int kprobes_fault(struct pt_regs *regs) { if (!kprobes_built_in()) return 0; if (user_mode(regs)) return 0; /* * To be potentially processing a kprobe fault and to be allowed to call * kprobe_running(), we have to be non-preemptible. */ if (preemptible()) return 0; if (!kprobe_running()) return 0; return kprobe_fault_handler(regs, X86_TRAP_PF); } The two handle preemption differently. Why is x86 wrong and this one correct?