[PATCH] powerpc: Don't overwrite flat device tree with kdump kernel

[Kumar Gala]

On Feb 3, 2006, at 2:05 AM, Michael Ellerman wrote:

> It's possible for prom_init to allocate the flat device tree inside  
> the
> kdump crash kernel region. If this happens, when we load the kdump  
> kernel we
> overwrite the flattened device tree, which is bad.
>
> We could make prom_init try and avoid allocating inside the crash  
> kernel
> region, but then we run into issues if the crash kernel region uses  
> all the
> space inside the RMO. The easiest solution is to move the flat  
> device tree
> once we're running in the kernel.
>
> Signed-off-by: Michael Ellerman <michael at ellerman.id.au>

Doesn't setup_32.c need a similar change?

- k

> ---
>
>  arch/powerpc/kernel/prom.c     |   27 +++++++++++++++++++++++++++
>  arch/powerpc/kernel/setup_64.c |    3 +++
>  include/asm-powerpc/prom.h     |    2 ++
>  3 files changed, 32 insertions(+)
>
> Index: kdump/arch/powerpc/kernel/prom.c
> ===================================================================
> --- kdump.orig/arch/powerpc/kernel/prom.c
> +++ kdump/arch/powerpc/kernel/prom.c
> @@ -1913,3 +1913,30 @@ int prom_update_property(struct device_n
>
>  	return 0;
>  }
> +
> +#ifdef CONFIG_KEXEC
> +/* We may have allocated the flat device tree inside the crash  
> kernel region
> + * in prom_init. If so we need to move it out into regular memory. */
> +void kdump_move_device_tree(void)
> +{
> +	unsigned long start, end;
> +	struct boot_param_header *new;
> +
> +	start = __pa((unsigned long)initial_boot_params);
> +	end = start + initial_boot_params->totalsize;
> +
> +	if (end < crashk_res.start || start > crashk_res.end)
> +		return;
> +
> +	new = (struct boot_param_header*)
> +		__va(lmb_alloc(initial_boot_params->totalsize, PAGE_SIZE));
> +
> +	memcpy(new, initial_boot_params, initial_boot_params->totalsize);
> +
> +	initial_boot_params = new;
> +
> +	DBG("Flat device tree blob moved to %p\n", initial_boot_params);
> +
> +	/* XXX should we unreserve the old DT? */
> +}
> +#endif /* CONFIG_KEXEC */
> Index: kdump/arch/powerpc/kernel/setup_64.c
> ===================================================================
> --- kdump.orig/arch/powerpc/kernel/setup_64.c
> +++ kdump/arch/powerpc/kernel/setup_64.c
> @@ -398,6 +398,9 @@ void __init setup_system(void)
>  {
>  	DBG(" -> setup_system()\n");
>
> +#ifdef CONFIG_KEXEC
> +	kdump_move_device_tree();
> +#endif
>  	/*
>  	 * Unflatten the device-tree passed by prom_init or kexec
>  	 */
> Index: kdump/include/asm-powerpc/prom.h
> ===================================================================
> --- kdump.orig/include/asm-powerpc/prom.h
> +++ kdump/include/asm-powerpc/prom.h
> @@ -222,5 +222,7 @@ extern int of_address_to_resource(struct
>  extern int of_pci_address_to_resource(struct device_node *dev, int  
> bar,
>  				      struct resource *r);
>
> +extern void kdump_move_device_tree(void);
> +
>  #endif /* __KERNEL__ */
>  #endif /* _POWERPC_PROM_H */
> _______________________________________________
> Linuxppc64-dev mailing list
> Linuxppc64-dev at ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc64-dev