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SubjectRe: [tip:x86/security] x86: Add NX protection for kernel data
> -	 * .data and .bss should always be writable.
> + * .data and .bss should always be writable, but xen won't like
> + * if we make page table rw (that live in .data or .bss)
> */
> +#ifdef CONFIG_X86_32
> if (within(address, (unsigned long)_sdata, (unsigned long)_edata) ||
> - within(address, (unsigned long)__bss_start, (unsigned long)__bss_stop))
> - pgprot_val(required) |= _PAGE_RW;
> + within(address, (unsigned long)__bss_start, (unsigned long)__bss_stop)) {
> + unsigned int level;
> + if (lookup_address(address, &level) && (level != PG_LEVEL_4K))
> + pgprot_val(forbidden) |= _PAGE_RW;
> + }
> +#endif
>
> #if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
>
> fyi, it does make it boot.

Hold it.. ccache is a wonderful tool but I think I've just "rebuilt" the
binaries with the .bss HPAGE_ALIGN aligment by mistake, so this path got never
taken.


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