From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751336AbdK0IVk (ORCPT <rfc822;w@1wt.eu>);
        Mon, 27 Nov 2017 03:21:40 -0500
Received: from merlin.infradead.org ([205.233.59.134]:47872 "EHLO
        merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751126AbdK0IVj (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Mon, 27 Nov 2017 03:21:39 -0500
Date: Mon, 27 Nov 2017 09:21:28 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>, Andy Lutomirski <luto@amacapital.net>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>, Andy Lutomirski <luto@kernel.org>,
        "H . Peter Anvin" <hpa@zytor.com>, Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>, kasan-dev@googlegroups.com,
        Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [PATCH] x86/mm/kaiser: Fix IRQ entries text section mapping
Message-ID: <20171127082128.vmfl6w66n27iwbwc@hirez.programming.kicks-ass.net>
References: <20171124202237.oytdkqq25s3ak2ul@gmail.com>
 <20171124220934.q7ovq4yzaihevqls@gmail.com>
 <464B14E7-EC38-4A5A-8BF6-B086F437C6D1@amacapital.net>
 <20171124225311.zpbgsejobpzxm7tb@gmail.com>
 <20171125092113.p2shs3hjy6q2mip2@gmail.com>
 <20171125093243.4gmkelmyb4mnhvos@gmail.com>
 <20171125093949.qbnibvj3nej5vidz@gmail.com>
 <20171125111721.p2o3khstk5tawzqt@gmail.com>
 <alpine.DEB.2.20.1711251354550.2316@nanos>
 <20171127081448.27wy6jq2dexa7em5@hirez.programming.kicks-ass.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20171127081448.27wy6jq2dexa7em5@hirez.programming.kicks-ass.net>
User-Agent: NeoMutt/20170609 (1.8.3)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, Nov 27, 2017 at 09:14:48AM +0100, Peter Zijlstra wrote:
> On Sat, Nov 25, 2017 at 05:08:08PM +0100, Thomas Gleixner wrote:
> > On Sat, 25 Nov 2017, Ingo Molnar wrote:
> > >  	kaiser_add_user_map_ptrs_early(__entry_text_start, __entry_text_end,
> > >  				       __PAGE_KERNEL_RX | _PAGE_GLOBAL);
> > > +	kaiser_add_user_map_ptrs_early(__irqentry_text_start, __irqentry_text_end,
> > > +				       __PAGE_KERNEL_RX | _PAGE_GLOBAL);
> > 
> > The bad news is that this maps more stuff than actually needed:
> > 
> > ffffffff81ab1c20 T __irqentry_text_start
> > ffffffff81ab1c20 T apic_timer_interrupt
> > ffffffff81ab1cf0 T x86_platform_ipi
> > ffffffff81ab1dc0 T threshold_interrupt
> > ffffffff81ab1e90 T deferred_error_interrupt
> > ffffffff81ab1f60 T thermal_interrupt
> > ffffffff81ab2030 T call_function_single_interrupt
> > ffffffff81ab2100 T call_function_interrupt
> > ffffffff81ab21d0 T reschedule_interrupt
> > ffffffff81ab22a0 T error_interrupt
> > ffffffff81ab2370 T spurious_interrupt
> > ffffffff81ab2440 T irq_work_interrupt
> 
> I'm confused though; for IDT we have that trampoline Andy did. So the
> interrupt should land on the entry stack, do the switch magic and then
> call the 'real' IDT entry, no?
> 
> So why do these functions need to be mapped at all?

Aah, I see. The switch magic is in the generic macro and thus ends up in
the above functions...