From 3572bea8cbc57f0bef1e0f4580c01717df7026d8 Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Mon, 21 Feb 2011 06:57:33 +0100 Subject: 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 Signed-off-by: Russell King --- arch/arm/kernel/setup.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) (limited to 'arch/arm/kernel/setup.c') diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c index 6ce80106316e..f43f041a0977 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -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) - tags = phys_to_virt(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) /* -- cgit v1.2.1