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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 C25F9C433E0 for ; Thu, 9 Jul 2020 12:18:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9AFE02074B for ; Thu, 9 Jul 2020 12:18:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594297109; bh=0d67Y8UvYLgaPIhr1Hlc+Z6U3OE3Kp6d4ia4b+j8cEc=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=jeEBZHuGqf5Gjgv0TnfJiOBk0JgYwWw6rIrJHLbNppdK7DYiNYy8bn41E7sm4cfVX xwt597K6aY+ZhnLyMaeWmPgxdID0DpSw4BGEEqA1bkMTJnmk9USKcBypXBEWS02NbL UOYblBy3WJY1CdacSePK4JMleYNhKtLAakxXPmWI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726836AbgGIMS0 (ORCPT ); Thu, 9 Jul 2020 08:18:26 -0400 Received: from mail-oi1-f194.google.com ([209.85.167.194]:43278 "EHLO mail-oi1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726327AbgGIMS0 (ORCPT ); Thu, 9 Jul 2020 08:18:26 -0400 Received: by mail-oi1-f194.google.com with SMTP id x83so1671643oif.10; Thu, 09 Jul 2020 05:18:25 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=BHVNxL+/4Dut3OSZTR+rYs7XqFLN3i0nnfmN8u7+xOA=; b=HsPvqGX/GQ4OR4PD8qcCtxVGfclDRun1lAmESdkuU5btq7AutoGcvN2+yohnLpnadd tO60+9ABX4LJe7VCGmwf3pMI0Wt1N8tamr/dvrWsGebqc3FP3mb9sonTbgnWOl2SQJlL XrMcCPoWHbBo1ReQEkC5cDiVhkDhg/amdZE7fFBqo6gU3bkQKQ/Af52flG6sJY2c8EI7 d8f/IOU/hs3D5OqeNUDtC5WOWMs620lKXhe0IQgsWQZWUMi/uGVUYieMxucFV7xyzYcs EzH+gn1USAQ2/QGft1FL1b4AIs4vs8pz6/nhGibMmQkjTqmyS7KOxkq3mjRBGnsYvNiJ HYeQ== X-Gm-Message-State: AOAM532wTK2f2HpwOkCilCgt7dQ/Nsva5wPIK2qVvOttSL6JD3fYtrE9 5NR/R1T7hZM+PT3ikdyQUQB0WiT8/B8serd8Okc= X-Google-Smtp-Source: ABdhPJxtj1vjB44EgNVrKbINxMf3MLBQQVOimbtqX57PoimFmHD9A3C9Fv4wq87LSAfsDKch7XlhTuenX5e7j0W2xjI= X-Received: by 2002:aca:4a89:: with SMTP id x131mr11420648oia.103.1594297104569; Thu, 09 Jul 2020 05:18:24 -0700 (PDT) MIME-Version: 1.0 References: <1594005196-16327-1-git-send-email-neal.liu@mediatek.com> <1594005196-16327-2-git-send-email-neal.liu@mediatek.com> In-Reply-To: <1594005196-16327-2-git-send-email-neal.liu@mediatek.com> From: "Rafael J. Wysocki" Date: Thu, 9 Jul 2020 14:18:13 +0200 Message-ID: Subject: Re: [PATCH v2] cpuidle: change enter_s2idle() prototype To: Neal Liu Cc: "Rafael J. Wysocki" , Len Brown , Daniel Lezcano , Thierry Reding , Jonathan Hunter , Jacob Pan , Matthias Brugger , Sami Tolvanen , ACPI Devel Maling List , Linux PM , linux-tegra , Linux ARM , "moderated list:ARM/Mediatek SoC..." , lkml , wsd_upstream@mediatek.com Content-Type: text/plain; charset="UTF-8" Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Mon, Jul 6, 2020 at 5:13 AM Neal Liu wrote: > > Control Flow Integrity(CFI) is a security mechanism that disallows > changes to the original control flow graph of a compiled binary, > making it significantly harder to perform such attacks. > > init_state_node() assign same function callback to different > function pointer declarations. > > static int init_state_node(struct cpuidle_state *idle_state, > const struct of_device_id *matches, > struct device_node *state_node) { ... > idle_state->enter = match_id->data; ... > idle_state->enter_s2idle = match_id->data; } > > Function declarations: > > struct cpuidle_state { ... > int (*enter) (struct cpuidle_device *dev, > struct cpuidle_driver *drv, > int index); > > void (*enter_s2idle) (struct cpuidle_device *dev, > struct cpuidle_driver *drv, > int index); }; > > In this case, either enter() or enter_s2idle() would cause CFI check > failed since they use same callee. Can you please explain this in a bit more detail? As it stands, I don't understand the problem statement enough to apply the patch. > Align function prototype of enter() since it needs return value for > some use cases. The return value of enter_s2idle() is no > need currently. So last time I requested you to document why ->enter_s2idle needs to return an int in the code, which has not been done. Please do that. > Signed-off-by: Neal Liu > --- > drivers/acpi/processor_idle.c | 6 ++++-- > drivers/cpuidle/cpuidle-tegra.c | 8 +++++--- > drivers/idle/intel_idle.c | 6 ++++-- > include/linux/cpuidle.h | 6 +++--- > 4 files changed, 16 insertions(+), 10 deletions(-) > > diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c > index 75534c5..6ffb6c9 100644 > --- a/drivers/acpi/processor_idle.c > +++ b/drivers/acpi/processor_idle.c > @@ -655,8 +655,8 @@ static int acpi_idle_enter(struct cpuidle_device *dev, > return index; > } > > -static void acpi_idle_enter_s2idle(struct cpuidle_device *dev, > - struct cpuidle_driver *drv, int index) > +static int acpi_idle_enter_s2idle(struct cpuidle_device *dev, > + struct cpuidle_driver *drv, int index) > { > struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu); > > @@ -674,6 +674,8 @@ static void acpi_idle_enter_s2idle(struct cpuidle_device *dev, > } > } > acpi_idle_do_entry(cx); > + > + return 0; > } > > static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr, > diff --git a/drivers/cpuidle/cpuidle-tegra.c b/drivers/cpuidle/cpuidle-tegra.c > index 1500458..a12fb14 100644 > --- a/drivers/cpuidle/cpuidle-tegra.c > +++ b/drivers/cpuidle/cpuidle-tegra.c > @@ -253,11 +253,13 @@ static int tegra_cpuidle_enter(struct cpuidle_device *dev, > return err ? -1 : index; > } > > -static void tegra114_enter_s2idle(struct cpuidle_device *dev, > - struct cpuidle_driver *drv, > - int index) > +static int tegra114_enter_s2idle(struct cpuidle_device *dev, > + struct cpuidle_driver *drv, > + int index) > { > tegra_cpuidle_enter(dev, drv, index); > + > + return 0; > } > > /* > diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c > index f449584..b178da3 100644 > --- a/drivers/idle/intel_idle.c > +++ b/drivers/idle/intel_idle.c > @@ -175,13 +175,15 @@ static __cpuidle int intel_idle(struct cpuidle_device *dev, > * Invoked as a suspend-to-idle callback routine with frozen user space, frozen > * scheduler tick and suspended scheduler clock on the target CPU. > */ > -static __cpuidle void intel_idle_s2idle(struct cpuidle_device *dev, > - struct cpuidle_driver *drv, int index) > +static __cpuidle int intel_idle_s2idle(struct cpuidle_device *dev, > + struct cpuidle_driver *drv, int index) > { > unsigned long eax = flg2MWAIT(drv->states[index].flags); > unsigned long ecx = 1; /* break on interrupt flag */ > > mwait_idle_with_hints(eax, ecx); > + > + return 0; > } > > /* > diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h > index ec2ef63..bee10c0 100644 > --- a/include/linux/cpuidle.h > +++ b/include/linux/cpuidle.h > @@ -66,9 +66,9 @@ struct cpuidle_state { > * suspended, so it must not re-enable interrupts at any point (even > * temporarily) or attempt to change states of clock event devices. > */ > - void (*enter_s2idle) (struct cpuidle_device *dev, > - struct cpuidle_driver *drv, > - int index); > + int (*enter_s2idle)(struct cpuidle_device *dev, > + struct cpuidle_driver *drv, > + int index); > }; > > /* Idle State Flags */ > -- > 1.7.9.5