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authorDavid Howells <dhowells@redhat.com>2017-04-04 16:54:22 +0100
committerDavid Howells <dhowells@redhat.com>2017-04-20 12:02:32 +0100
commitcc9c617557cd0442294138188ac8611659768a10 (patch)
treec73fb7154e51b7478ced7387017ff8a6e3a2f1d7 /drivers/clocksource
parent1c37ab5e51792a5419bdc84804aec6379cb43adb (diff)
downloadlinux-next-cc9c617557cd0442294138188ac8611659768a10.tar.gz
Annotate hardware config module parameters in drivers/clocksource/
When the kernel is running in secure boot mode, we lock down the kernel to prevent userspace from modifying the running kernel image. Whilst this includes prohibiting access to things like /dev/mem, it must also prevent access by means of configuring driver modules in such a way as to cause a device to access or modify the kernel image. To this end, annotate module_param* statements that refer to hardware configuration and indicate for future reference what type of parameter they specify. The parameter parser in the core sees this information and can skip such parameters with an error message if the kernel is locked down. The module initialisation then runs as normal, but just sees whatever the default values for those parameters is. Note that we do still need to do the module initialisation because some drivers have viable defaults set in case parameters aren't specified and some drivers support automatic configuration (e.g. PNP or PCI) in addition to manually coded parameters. This patch annotates drivers in drivers/clocksource/. [Note: With regard to cs5535-clockevt.c, Thomas Gleixner asked whether the timer_irq parameter is required for the driver to work on anything other than arbitrary hardware which has it mapped to 0. Jens Rottmann replied that the parameter defaults to 0, which means: 1. autodetect (=keep IRQ BIOS has set up) 2. if that fails use CONFIG_CS5535_MFGPT_DEFAULT_IRQ (see drivers/misc/cs5535-mfgpt.c: cs5535_mfgpt_set_irq()) Jens further noted that there may not be any systems that have CS5535/36 devices that support EFI and secure boot.] Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Signed-off-by: David Howells <dhowells@redhat.com> cc: Daniel Lezcano <daniel.lezcano@linaro.org> cc: Thomas Gleixner <tglx@linutronix.de> cc: Jens Rottmann <Jens.Rottmann@ADLINKtech.com> cc: linux-kernel@vger.kernel.org
Diffstat (limited to 'drivers/clocksource')
-rw-r--r--drivers/clocksource/cs5535-clockevt.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/clocksource/cs5535-clockevt.c b/drivers/clocksource/cs5535-clockevt.c
index 9a7e37cf56b0..a1df588343f2 100644
--- a/drivers/clocksource/cs5535-clockevt.c
+++ b/drivers/clocksource/cs5535-clockevt.c
@@ -22,7 +22,7 @@
#define DRV_NAME "cs5535-clockevt"
static int timer_irq;
-module_param_named(irq, timer_irq, int, 0644);
+module_param_hw_named(irq, timer_irq, int, irq, 0644);
MODULE_PARM_DESC(irq, "Which IRQ to use for the clock source MFGPT ticks.");
/*