linux-kernel - Re: [PATCH] acpi: add support for extended IRQ to PCI link

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Message-ID: <CAHp75VfHi=p_QTFr-AG06f=7HSH11bPBVvSSHfEnEHqoEvDG5w@mail.gmail.com>
Date:	Thu, 12 Nov 2015 11:56:23 +0200
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	Sinan Kaya <okaya@...eaurora.org>
Cc:	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	Timur Tabi <timur@...eaurora.org>, cov@...eaurora.org,
	jcm@...hat.com, "Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <lenb@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] acpi: add support for extended IRQ to PCI link

On Thu, Nov 12, 2015 at 8:14 AM, Sinan Kaya <okaya@...eaurora.org> wrote:
> The ACPI compiler uses the extended format when used
> interrupt numbers are greater than 256. The PCI link code
> currently only supports simple interrupt format. The IRQ
> numbers are represented using 32 bits when extended IRQ
> syntax. This patch changes the interrupt number type to
> 32 bits and places an upper limit of 1020 as possible
> interrupt id.
>
> 1020 is the maximum interrupt ID that can be assigned to
> an ARM SPI interrupt according to ARM architecture.

I think it worth to put these lines in the code as well.

>
> Additional checks have been placed to prevent out of bounds
> writes.
>
> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
> ---
>  drivers/acpi/pci_link.c | 28 +++++++++++++++++-----------
>  1 file changed, 17 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c
> index 7c8408b..a2becab 100644
> --- a/drivers/acpi/pci_link.c
> +++ b/drivers/acpi/pci_link.c
> @@ -1,6 +1,7 @@
>  /*
>   *  pci_link.c - ACPI PCI Interrupt Link Device Driver ($Revision: 34 $)
>   *
> + *  Copyright (c) 2015, The Linux Foundation. All rights reserved.
>   *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@...el.com>
>   *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@...el.com>
>   *  Copyright (C) 2002       Dominik Brodowski <devel@...do.de>
> @@ -67,12 +68,12 @@ static struct acpi_scan_handler pci_link_handler = {
>   * later even the link is disable. Instead, we just repick the active irq
>   */
>  struct acpi_pci_link_irq {
> -       u8 active;              /* Current IRQ */
> +       u32 active;             /* Current IRQ */
>         u8 triggering;          /* All IRQs */
>         u8 polarity;            /* All IRQs */
>         u8 resource_type;
>         u8 possible_count;
> -       u8 possible[ACPI_PCI_LINK_MAX_POSSIBLE];
> +       u32 possible[ACPI_PCI_LINK_MAX_POSSIBLE];
>         u8 initialized:1;
>         u8 reserved:7;
>  };
> @@ -437,7 +438,7 @@ static int acpi_pci_link_set(struct acpi_pci_link *link, int irq)
>   * enabled system.
>   */
>
> -#define ACPI_MAX_IRQS          256
> +#define ACPI_MAX_IRQS          1020
>  #define ACPI_MAX_ISA_IRQ       16
>
>  #define PIRQ_PENALTY_PCI_AVAILABLE     (0)
> @@ -493,7 +494,8 @@ int __init acpi_irq_penalty_init(void)
>                                             penalty;
>                         }
>
> -               } else if (link->irq.active) {
> +               } else if (link->irq.active &&
> +                       (link->irq.active < ACPI_MAX_IRQS)) {
>                         acpi_irq_penalty[link->irq.active] +=
>                             PIRQ_PENALTY_PCI_POSSIBLE;
>                 }
> @@ -541,14 +543,16 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link)
>         else
>                 irq = link->irq.possible[link->irq.possible_count - 1];
>
> -       if (acpi_irq_balance || !link->irq.active) {
> +       if ((acpi_irq_balance || !link->irq.active) && (irq < ACPI_MAX_IRQS)) {
>                 /*

> -                * Select the best IRQ.  This is done in reverse to promote
> -                * the use of IRQs 9, 10, 11, and >15.
> +                * Select the best IRQ.  This is done in reverse to
> +                * promote the use of IRQs 9, 10, 11, and >15.

What was changed here?

>                  */
> -               for (i = (link->irq.possible_count - 1); i >= 0; i--) {
> -                       if (acpi_irq_penalty[irq] >
> -                           acpi_irq_penalty[link->irq.possible[i]])
> +               i = link->irq.possible_count;
> +               while (--i) {
> +                       if ((link->irq.possible[i] < ACPI_MAX_IRQS) &&
> +                           (acpi_irq_penalty[irq] >
> +                           acpi_irq_penalty[link->irq.possible[i]]))
>                                 irq = link->irq.possible[i];
>                 }
>         }
> @@ -568,7 +572,9 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link)
>                             acpi_device_bid(link->device));
>                 return -ENODEV;
>         } else {
> -               acpi_irq_penalty[link->irq.active] += PIRQ_PENALTY_PCI_USING;
> +               if (link->irq.active < ACPI_MAX_IRQS)
> +                       acpi_irq_penalty[link->irq.active] +=
> +                               PIRQ_PENALTY_PCI_USING;
>                 printk(KERN_WARNING PREFIX "%s [%s] enabled at IRQ %d\n",
>                        acpi_device_name(link->device),
>                        acpi_device_bid(link->device), link->irq.active);


-- 
With Best Regards,
Andy Shevchenko
--
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