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_PASS,USER_AGENT_MUTT autolearn=ham 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 AD51BC43441 for ; Tue, 27 Nov 2018 08:51:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 71C24208E4 for ; Tue, 27 Nov 2018 08:51:10 +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="eLLawHfn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 71C24208E4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729853AbeK0TsS (ORCPT ); Tue, 27 Nov 2018 14:48:18 -0500 Received: from merlin.infradead.org ([205.233.59.134]:48990 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729598AbeK0TsS (ORCPT ); Tue, 27 Nov 2018 14:48:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=2Ek1VtxsmPwT16DbqsD1NAGMF+KfWQlrlR3Nb1jUXBo=; b=eLLawHfn9QaFnpQuRFz3HFFJu PtV7u6FcJ3mNEr+GjKUl8dijwRWLhF+3fZC0khwxaeUNsRKmoAY43QHIVZteLyJejAz6on4T+zdBP TVshWgm0zdgTCcI1KWG7zAkmME2er0+HE7dxg5HSmA/7EkpEz1ZKBycKmHVtDOaqTRb7tukpYcn9x 2XwRBjZJNg463wAzx2Xr0tvpxUhE1Q+cVBa0H/l6sCi7l1ZlPga1Noq8IdcAr9Gc2uNArf23WN/aD NbMBXDZT4bQ15cS+e7VHXORNvl+/m6dqiAAEqbG5piMqSctGRngr4jpRaDT3RjxtKFBa3tniTLH3p S3AtQ1emQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gRZ55-0008VM-Ov; Tue, 27 Nov 2018 08:50:56 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8332A2029FD58; Tue, 27 Nov 2018 09:50:49 +0100 (CET) Date: Tue, 27 Nov 2018 09:50:49 +0100 From: Peter Zijlstra To: Josh Poimboeuf Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Ard Biesheuvel , Andy Lutomirski , Steven Rostedt , Ingo Molnar , Thomas Gleixner , Linus Torvalds , Masami Hiramatsu , Jason Baron , Jiri Kosina , David Laight , Borislav Petkov , Julia Cartwright , Jessica Yu , "H. Peter Anvin" Subject: Re: [PATCH v2 4/4] x86/static_call: Add inline static call implementation for x86-64 Message-ID: <20181127085049.GE2149@hirez.programming.kicks-ass.net> References: <62188c62f6dda49ca2e20629ee8e5a62a6c0b500.1543200841.git.jpoimboe@redhat.com> <20181126160217.GR2113@hirez.programming.kicks-ass.net> <20181126171036.chcbmb35ygpxziub@treble> <20181126175624.bruqfbkngbucpvxr@treble> <20181126200801.GW2113@hirez.programming.kicks-ass.net> <20181126212628.4apztfazichxnt7r@treble> <20181127084330.GX2113@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181127084330.GX2113@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 27, 2018 at 09:43:30AM +0100, Peter Zijlstra wrote: > Now; if I'm not mistaken, the below @site is in fact @regs->ip - 1, no? > > We already patched site with INT3, which is what we just trapped on. So > we could in fact write something like: > > static void static_call_bp_handler(struct pt_regs *regs, void *data) > { > struct static_call_bp_data *scd = data; > > switch (data->type) { > case CALL_INSN: /* emulate CALL instruction */ > regs->sp -= sizeof(unsigned long); > *(unsigned long *)regs->sp = regs->ip + CALL_INSN_SIZE - 1; > regs->ip = data->func; > break; > > case JMP_INSN: /* emulate JMP instruction */ > regs->ip = data->func; > break; > } > } > handler_data = (struct static_call_bp_data){ > .type = IS_ENABLED(CONFIG_HAVE_STATIC_CALL_INLINE) ? CALL_INSN : JMP_INSN, > .func = func, > }; Heck; check this: static void static_call_bp_handler(struct pt_regs *regs, void *data) { #ifdef CONFIG_HAVE_STATIC_CALL_INLINE /* emulate CALL instruction */ regs->sp -= sizeof(unsigned long); *(unsigned long *)regs->sp = regs->ip + CALL_INSN_SIZE - 1; regs->ip = data; #else /* !CONFIG_HAVE_STATIC_CALL_INLINE */ /* emulate JMP instruction */ regs->ip = data; #endif }