On Thu, Sep 18, 2014 at 12:19:08PM -0700, Kees Cook wrote:
> @@ -1373,13 +1373,24 @@ static void __init map_lowmem(void)
> if (start >= end)
> break;
>
> - if (end < kernel_x_start || start >= kernel_x_end) {
> + if (end < kernel_x_start) {
> map.pfn = __phys_to_pfn(start);
> map.virtual = __phys_to_virt(start);
> map.length = end - start;
> map.type = MT_MEMORY_RWX;
>
> create_mapping(&map);
> + } else if (start >= kernel_x_end) {
> + map.pfn = __phys_to_pfn(start);
> + map.virtual = __phys_to_virt(start);
> + map.length = end - start;
> +#ifdef CONFIG_ARM_KERNMEM_PERMS
> + map.type = MT_MEMORY_RW;
> +#else
> + map.type = MT_MEMORY_RWX;
> +#endif
> +
> + create_mapping(&map);
I'm looking at this, and wondering two things. Firstly, why isn't it
MT_MEMORY_RW in the first place. Secondly, why do you need to make
this depend on CONFIG_ARM_KERNMEM_PERMS at all?
I think the first is an oversight by me (and is a case which never came
up in my testing, because most of my platforms don't have segmented
memory layouts.)
The second I think is not necessary - the memory region being considered
is not part of the kernel at all, and so should not be executable in any
shape or form.
--
FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up
according to speedtest.net.
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