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SubjectRe: [PATCH 2/5] x86_64 EFI support -v3: EFI boot support
Date

> static unsigned long dma_reserve __initdata;
> +/* Flag indicating EFI runtime executable code area */
> +static int efi_runtime_code_area;

We don't normally use globals to modify function behaviour.

>
> DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
>
> @@ -199,7 +202,7 @@
> static __meminit void unmap_low_page(void *adr)
> {
>
> - if (after_bootmem)
> + if (after_bootmem || efi_runtime_code_area)
> return;
>
> early_iounmap(adr, PAGE_SIZE);
> @@ -259,16 +262,21 @@
> pmd_t *pmd = pmd_page + pmd_index(address);
>
> if (address >= end) {
> - if (!after_bootmem)
> + if (!after_bootmem && !efi_runtime_code_area)


This one seems also weird. Are you sure this doesn't remove _NX from
more than the intended area?

> for (; i < PTRS_PER_PMD; i++, pmd++)
> set_pmd(pmd, __pmd(0));
> break;
> }
>
> - if (pmd_val(*pmd))
> + if (pmd_val(*pmd) && !efi_runtime_code_area)
> continue;
>
> - entry = _PAGE_NX|_PAGE_PSE|_KERNPG_TABLE|_PAGE_GLOBAL|address;
> + if (efi_runtime_code_area) {
> + entry = pmd_val(*pmd);
> + entry &= ~_PAGE_NX;
> + } else
> + entry = _PAGE_NX | _PAGE_PSE | _KERNPG_TABLE | \
> + _PAGE_GLOBAL | address;

This doesn't look correct. PSE/KERNPG/GLOBAL/address surely need to be set
for EFI areas too.

The changes to this file are quite messy.
Perhaps it would be better if you just use change_page_attr() afterwards.
This would make it using 4K pages instead of 2MB, but that wouldn't be a catastrophe.

What exactly are you trying to do here? Just remove _NX for some areas?

-Andi

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