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 248F2C10F03 for ; Thu, 25 Apr 2019 08:19:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CE1D2217FA for ; Thu, 25 Apr 2019 08:19:37 +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="sLoZSC3r" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727438AbfDYITg (ORCPT ); Thu, 25 Apr 2019 04:19:36 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:44402 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725951AbfDYITg (ORCPT ); Thu, 25 Apr 2019 04:19:36 -0400 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=RhfoKhb76TIyHeM5VaQWRBakrv5QI74DngONPZZhv+8=; b=sLoZSC3rt5frxj7EZl681VLmJ cZ2mP0CA97Sez5G4e3jlQEu2QOzH4LNPC2L4UTy2dPeSHFUwrRCnLhhS0T9nk5dS1TynJc0ak/zEw HYi0kev4GyLJDTtcA1gYZdTwOjiE+X7y2CwkrGm9jS5E1XjW202phfEktFp5NTo24fSuK0KxnRQFC cYdyt5onqHf/EWMvh/PT4fXLymesOWG6JII9XoOSE4R/Y+MXek26JunpaC7nSPugv/Wsdp2aG0UvM BYJD+FDFV495WVMBSMpOd/fR4kVsbEpwyPXzYyoxZ+Mozdq/vQdwPxGxDyUIIRwjLgdSEsIW1VdQh esf/OABVw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hJZbR-0007uh-3u; Thu, 25 Apr 2019 08:19:33 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 939D629BA467B; Thu, 25 Apr 2019 10:19:31 +0200 (CEST) Date: Thu, 25 Apr 2019 10:19:31 +0200 From: Peter Zijlstra To: Ingo Molnar Cc: Thomas Gleixner , LKML , x86@kernel.org, Juergen Gross , Andi Kleen Subject: Re: [patch 3/3] x86/paravirt: Replace paravirt patch asm magic Message-ID: <20190425081931.GA14281@hirez.programming.kicks-ass.net> References: <20190424134115.091452807@linutronix.de> <20190424134223.690835713@linutronix.de> <20190425065209.GA89582@gmail.com> <20190425080810.GY11158@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190425080810.GY11158@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 Thu, Apr 25, 2019 at 10:08:10AM +0200, Peter Zijlstra wrote: > On Thu, Apr 25, 2019 at 08:52:09AM +0200, Ingo Molnar wrote: > > > > -# ifdef CONFIG_PARAVIRT_XXL > > > -DEF_NATIVE(irq, irq_disable, "cli"); > > > -DEF_NATIVE(irq, irq_enable, "sti"); > > > -DEF_NATIVE(irq, restore_fl, "push %eax; popf"); > > > -DEF_NATIVE(irq, save_fl, "pushf; pop %eax"); > > > -DEF_NATIVE(cpu, iret, "iret"); > > > -DEF_NATIVE(mmu, read_cr2, "mov %cr2, %eax"); > > > -DEF_NATIVE(mmu, write_cr3, "mov %eax, %cr3"); > > > -DEF_NATIVE(mmu, read_cr3, "mov %cr3, %eax"); > > > > > +static const struct patch_xxl patch_data_xxl = { > > > + .irq_irq_disable = { 0xfa }, // cli > > > + .irq_irq_enable = { 0xfb }, // sti > > > + .irq_save_fl = { 0x9c, 0x58 }, // pushf; pop %[re]ax > > > + .mmu_read_cr2 = { 0x0f, 0x20, 0xd0 }, // mov %cr2, %[re]ax > > > + .mmu_read_cr3 = { 0x0f, 0x20, 0xd8 }, // mov %cr3, %[re]ax > > > +# ifdef CONFIG_X86_64 > > > + .irq_restore_fl = { 0x57, 0x9d }, // push %rdi; popfq > > > + .mmu_write_cr3 = { 0x0f, 0x22, 0xdf }, // mov %rdi, %cr3 > > > + .cpu_wbinvd = { 0x0f, 0x09 }, // wbinvd > > > + .cpu_usergs_sysret64 = { 0x0f, 0x01, 0xf8, > > > + 0x48, 0x0f, 0x07 }, // swapgs; sysretq > > > + .cpu_swapgs = { 0x0f, 0x01, 0xf8 }, // swapgs > > > + .mov64 = { 0x48, 0x89, 0xf8 }, // mov %rdi, %rax > > > +# else > > > + .irq_restore_fl = { 0x50, 0x9d }, // push %eax; popf > > > + .mmu_write_cr3 = { 0x0f, 0x22, 0xd8 }, // mov %eax, %cr3 > > > + .cpu_iret = { 0xcf }, // iret > > > +# endif > > > > I think these open-coded hexa versions are somewhat fragile as well, how > > about putting these into a .S file and controlling the sections in an LTO > > safe manner there? > > > > That will also allow us to write proper asm, and global labels can be > > used to extract the patchlets and their length? > > While I'm not fan either; I think that will be worse still, because it > splits the information over multiple files. > > The advantage of this form is that it is clear how long the instructions > are, which is important for the patching. These immediates have to be > shorter than 5 bytes because they overwrite the CALL/JMP to the paravirt > function. > > /me eyes .cpu_usergs_sysret64 and goes wtf.. OK, my bad, the indirect CALL/JMP is 6 bytes.. phew.