linux-kernel - Re: [PATCH 3/3] efi: Make efi virtual runtime map passing more robust

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Date:	Tue, 17 Dec 2013 12:23:34 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Linux EFI <linux-efi@...r.kernel.org>, X86 ML <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>
Cc:	Borislav Petkov <bp@...e.de>,
	Matt Fleming <matt@...sole-pimps.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	"H. Peter Anvin" <hpa@...or.com>, Dave Young <dyoung@...hat.com>,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	Toshi Kani <toshi.kani@...com>,
	Arjan van de Ven <arjan@...ux.intel.com>
Subject: Re: [PATCH 3/3] efi: Make efi virtual runtime map passing more robust

On Tue, Dec 17, 2013 at 12:36:37AM +0100, Borislav Petkov wrote:
> @@ -880,6 +906,19 @@ void __init efi_enter_virtual_mode(void)
>  
>  	efi_dump_pagetable();
>  
> +	/*
> +	 * It can happen that the physical address of new_memmap lands in memory
> +	 * which is not mapped in the EFI page table. Therefore we need to go
> +	 * and ident-map those pages containing the map before calling
> +	 * phys_efi_set_virtual_address_map().
> +	 */
> +	if (kernel_map_pages_in_pgd(pgd, __pa(new_memmap), __pa(new_memmap),
> +				    1 << new_memmap_shift, _PAGE_NX)) {
> +		pr_err("Error ident-mapping new memmap (0x%lx)!\n",
> +		       __pa(new_memmap));
> +		goto err_out;
> +	}
> +
>  	status = phys_efi_set_virtual_address_map(
>  		memmap.desc_size * count,
>  		memmap.desc_size,
> @@ -916,7 +955,7 @@ void __init efi_enter_virtual_mode(void)
>  	if (efi_enabled(EFI_OLD_MEMMAP) && (__supported_pte_mask & _PAGE_NX))
>  		runtime_code_page_mkexec();
>  
> -	kfree(new_memmap);
> +	__free_pages(new_memmap, new_memmap_shift);

Note to self: carve out the error path of populate_pgd() into a separate
function and call it here to unmap the pages previously mapped above as
we're freeing them here.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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