Commit 3572bea8 authored Feb 21, 2011 by Nicolas Pitre Committed by Russell King Feb 23, 2011

ARM: 6748/1: ignore mdesc->boot_params if out of range

The initial MMU table created in head.S contains a 1 MB mapping at the
start of memory to let the early kernel boot code access the boot params
specified by mdesc->boot_params.

When using CONFIG_ARM_PATCH_PHYS_VIRT it is possible for the kernel to
have a different idea of where the start of memory is at run time, making
the compile-time determined mdesc->boot_params pointing to a memory area
which is not mapped. Any access to the boot params in that case will
fault and silently hang the kernel at that point. It is therefore a
better idea to simply ignore mdesc->boot_params in that case and give
the kernel a chance to print some diagnostic on the console later.

If the bootloader provides a valid pointer in r2 to the kernel then this
is used instead of mdesc->boot_params, and an explicit mapping is already
created in the initial MMU table for it. It is therefore a good idea to
use that facility when using a relocated kernel.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

parent dce72dd0

arch/arm/kernel/setup.c

+19 −2

Original line number	Diff line number	Diff line
		@@ -839,8 +839,25 @@ void __init setup_arch(char **cmdline_p)

		if (__atags_pointer)
		tags = phys_to_virt(__atags_pointer);
		else if (mdesc->boot_params)
		else if (mdesc->boot_params) {
		#ifdef CONFIG_MMU
		/*
		* We still are executing with a minimal MMU mapping created
		* with the presumption that the machine default for this
		* is located in the first MB of RAM. Anything else will
		* fault and silently hang the kernel at this point.
		*/
		if (mdesc->boot_params < PHYS_OFFSET \|\|
		mdesc->boot_params >= PHYS_OFFSET + SZ_1M) {
		printk(KERN_WARNING
		"Default boot params at physical 0x%08lx out of reach\n",
		mdesc->boot_params);
		} else
		#endif
		{
		tags = phys_to_virt(mdesc->boot_params);
		}
		}

		#if defined(CONFIG_DEPRECATED_PARAM_STRUCT)
		/*

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