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Message-ID: <20151124181150.GA27957@localhost>
Date: Tue, 24 Nov 2015 12:11:50 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Sinan Kaya <okaya@...eaurora.org>
Cc: linux-acpi@...r.kernel.org, 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
Subject: Re: [PATCH V4] acpi: add support for extended IRQ to PCI link
Hi Sinan,
On Wed, Nov 18, 2015 at 10:13:38PM -0500, Sinan Kaya 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.
>
> Additional checks have been placed to prevent out of bounds
> writes.
As Andy mentioned, please wrap this text to use more of an 80-column
line. I fill changelogs to 75 columns (vi textwidth=75), which fits
perfectly when "git log" inserts 4 leading spaces.
> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
> ---
> drivers/acpi/pci_link.c | 28 +++++++++++++++++++---------
> 1 file changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c
> index 7c8408b..ec7ec16 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 +438,11 @@ static int acpi_pci_link_set(struct acpi_pci_link *link, int irq)
> * enabled system.
> */
>
> -#define ACPI_MAX_IRQS 256
> +/*
> + * 1020 is the maximum interrupt ID that can be assigned to
> + * an ARM SPI interrupt according to ARM architecture.
> + */
> +#define ACPI_MAX_IRQS 1020
> #define ACPI_MAX_ISA_IRQ 16
>
> #define PIRQ_PENALTY_PCI_AVAILABLE (0)
> @@ -493,7 +498,8 @@ 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 +547,16 @@ 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.
> */
> - 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 >= 0) {
> + 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 +576,9 @@ 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;
These changes are basically all bounds-checking link->irq.possible[i]
and link->irq.active. What if you put that checking at the point
where we *initialize* those fields instead, i.e., in
acpi_pci_link_check_possible() and acpi_pci_link_get_current()? Then
you'd only have to check each field in one place, and you could easily
add a message if we see an ID that's too large.
I think the current code for ACPI_RESOURCE_TYPE_EXTENDED_IRQ is buggy
because it silently truncates IDs to 8 bits.
Bjorn
> printk(KERN_WARNING PREFIX "%s [%s] enabled at IRQ %d\n",
> acpi_device_name(link->device),
> acpi_device_bid(link->device), link->irq.active);
--
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