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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45A0DC43334 for ; Sun, 26 Jun 2022 06:24:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233935AbiFZGYC (ORCPT ); Sun, 26 Jun 2022 02:24:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58474 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232885AbiFZGYB (ORCPT ); Sun, 26 Jun 2022 02:24:01 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8047B101D3; Sat, 25 Jun 2022 23:24:00 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 365E3B80CF6; Sun, 26 Jun 2022 06:23:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85530C34114; Sun, 26 Jun 2022 06:23:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1656224637; bh=WB3vT3WVZkW9Hgvvw424FD+cwJ0iWOXgy3acAWvUG30=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=gabpwz7T+5T0u402eXby2IHjeNtClSYoG5fcgx8p805kmn9Rb0+USot1IaXqwlczV QRtb8J5D36Go2xZO6rGb3NVrdNUDAV91/W5pqMuwjEcCbXfMJiKkOlUHZEMv0KocI0 h/9Dj/gTS8Gt3iPGx18MItiQrKHykwRLHXbhG16zxgT49YD8H5OfDrcCp+ahJZFXzu Sd2h3yigdxIOMGXPNDTfiru6OqTqLMaB5bEbqGRmYGF8gDl+cF6xyYXkEM12XXnZTT T/GfsEacPsEdMkzl49ayZ4zPG4RQJDuHzuvnYzeC+JQL7RRvNo+1TWZE5QBX6QKW0V nsJsMnPFGAqNA== Date: Sun, 26 Jun 2022 09:23:54 +0300 From: Jarkko Sakkinen To: Lino Sanfilippo Cc: peterhuewe@gmx.de, jgg@ziepe.ca, stefanb@linux.vnet.ibm.com, linux@mniewoehner.de, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, l.sanfilippo@kunbus.com, lukas@wunner.de, p.rosenberger@kunbus.com Subject: Re: [PATCH v6 1/9] tpm, tpm_tis: Avoid cache incoherency in test for interrupts Message-ID: References: <20220621132447.16281-1-LinoSanfilippo@gmx.de> <20220621132447.16281-2-LinoSanfilippo@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220621132447.16281-2-LinoSanfilippo@gmx.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 21, 2022 at 03:24:39PM +0200, Lino Sanfilippo wrote: > From: Lino Sanfilippo > > The interrupt handler that sets the boolean variable irq_tested may run on > another CPU as the thread that checks irq_tested as part of the irq test in > tmp_tis_send(). > > Since nothing guarantees cache coherency between CPUs for unsynchronized > accesses to boolean variables the testing thread might not perceive the > value change done in the interrupt handler. > > Avoid this issue by setting the bit TPM_TIS_IRQ_TESTED in the flags field > of the tpm_tis_data struct and by accessing this field with the bit > manipulating functions that provide cache coherency. > > Also convert all other existing sites to use the proper macros when > accessing this bitfield. > > Signed-off-by: Lino Sanfilippo > --- > drivers/char/tpm/tpm_tis.c | 2 +- > drivers/char/tpm/tpm_tis_core.c | 21 +++++++++++---------- > drivers/char/tpm/tpm_tis_core.h | 2 +- > 3 files changed, 13 insertions(+), 12 deletions(-) > > diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c > index bcff6429e0b4..ce43412eb398 100644 > --- a/drivers/char/tpm/tpm_tis.c > +++ b/drivers/char/tpm/tpm_tis.c > @@ -226,7 +226,7 @@ static int tpm_tis_init(struct device *dev, struct tpm_info *tpm_info) > irq = tpm_info->irq; > > if (itpm || is_itpm(ACPI_COMPANION(dev))) > - phy->priv.flags |= TPM_TIS_ITPM_WORKAROUND; > + set_bit(TPM_TIS_ITPM_WORKAROUND, &phy->priv.flags); > > return tpm_tis_core_init(dev, &phy->priv, irq, &tpm_tcg, > ACPI_HANDLE(dev)); > diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c > index dc56b976d816..b5fd4ff46666 100644 > --- a/drivers/char/tpm/tpm_tis_core.c > +++ b/drivers/char/tpm/tpm_tis_core.c > @@ -343,7 +343,7 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len) > struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev); > int rc, status, burstcnt; > size_t count = 0; > - bool itpm = priv->flags & TPM_TIS_ITPM_WORKAROUND; > + bool itpm = test_bit(TPM_TIS_ITPM_WORKAROUND, &priv->flags); > > status = tpm_tis_status(chip); > if ((status & TPM_STS_COMMAND_READY) == 0) { > @@ -470,7 +470,8 @@ static int tpm_tis_send(struct tpm_chip *chip, u8 *buf, size_t len) > int rc, irq; > struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev); > > - if (!(chip->flags & TPM_CHIP_FLAG_IRQ) || priv->irq_tested) > + if (!(chip->flags & TPM_CHIP_FLAG_IRQ) || > + test_bit(TPM_TIS_IRQ_TESTED, &priv->flags)) > return tpm_tis_send_main(chip, buf, len); > > /* Verify receipt of the expected IRQ */ > @@ -480,11 +481,11 @@ static int tpm_tis_send(struct tpm_chip *chip, u8 *buf, size_t len) > rc = tpm_tis_send_main(chip, buf, len); > priv->irq = irq; > chip->flags |= TPM_CHIP_FLAG_IRQ; > - if (!priv->irq_tested) > + if (!test_bit(TPM_TIS_IRQ_TESTED, &priv->flags)) > tpm_msleep(1); > - if (!priv->irq_tested) > + if (!test_bit(TPM_TIS_IRQ_TESTED, &priv->flags)) > disable_interrupts(chip); > - priv->irq_tested = true; > + set_bit(TPM_TIS_IRQ_TESTED, &priv->flags); > return rc; > } > > @@ -627,7 +628,7 @@ static int probe_itpm(struct tpm_chip *chip) > size_t len = sizeof(cmd_getticks); > u16 vendor; > > - if (priv->flags & TPM_TIS_ITPM_WORKAROUND) > + if (test_bit(TPM_TIS_ITPM_WORKAROUND, &priv->flags)) > return 0; > > rc = tpm_tis_read16(priv, TPM_DID_VID(0), &vendor); > @@ -647,13 +648,13 @@ static int probe_itpm(struct tpm_chip *chip) > > tpm_tis_ready(chip); > > - priv->flags |= TPM_TIS_ITPM_WORKAROUND; > + set_bit(TPM_TIS_ITPM_WORKAROUND, &priv->flags); > > rc = tpm_tis_send_data(chip, cmd_getticks, len); > if (rc == 0) > dev_info(&chip->dev, "Detected an iTPM.\n"); > else { > - priv->flags &= ~TPM_TIS_ITPM_WORKAROUND; > + clear_bit(TPM_TIS_ITPM_WORKAROUND, &priv->flags); > rc = -EFAULT; > } > > @@ -693,7 +694,7 @@ static irqreturn_t tis_int_handler(int dummy, void *dev_id) > if (interrupt == 0) > return IRQ_NONE; > > - priv->irq_tested = true; > + set_bit(TPM_TIS_IRQ_TESTED, &priv->flags); > if (interrupt & TPM_INTF_DATA_AVAIL_INT) > wake_up_interruptible(&priv->read_queue); > if (interrupt & TPM_INTF_LOCALITY_CHANGE_INT) > @@ -779,7 +780,7 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip, u32 intmask, > if (rc < 0) > return rc; > > - priv->irq_tested = false; > + clear_bit(TPM_TIS_IRQ_TESTED, &priv->flags); > > /* Generate an interrupt by having the core call through to > * tpm_tis_send > diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h > index 6c203f36b8a1..bf07379dea42 100644 > --- a/drivers/char/tpm/tpm_tis_core.h > +++ b/drivers/char/tpm/tpm_tis_core.h > @@ -86,13 +86,13 @@ enum tis_defaults { > enum tpm_tis_flags { > TPM_TIS_ITPM_WORKAROUND = BIT(0), > TPM_TIS_INVALID_STATUS = BIT(1), > + TPM_TIS_IRQ_TESTED = BIT(2), > }; > > struct tpm_tis_data { > u16 manufacturer_id; > int locality; > int irq; > - bool irq_tested; > unsigned long flags; > void __iomem *ilb_base_addr; > u16 clkrun_enabled; > -- > 2.36.1 > Reviewed-by: Jarkko Sakkinen BR, Jarkko