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Commit 52a628fb authored by Borislav Petkov's avatar Borislav Petkov Committed by Matt Fleming
Browse files

x86/mm/pageattr: Add last levels of error path 



We try to free the pagetable pages once we've unmapped our portion.

Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
parent 0bb8aeee

arch/x86/mm/pageattr.c

+93 −1
Original line number Diff line number Diff line
@@ -666,7 +666,99 @@ static int split_large_page(pte_t *kpte, unsigned long address) 
	return 0;

}



#define unmap_pmd_range(pud, start, pre_end)		do {} while (0)

static bool try_to_free_pte_page(pte_t *pte)

{

	int i;



	for (i = 0; i < PTRS_PER_PTE; i++)

		if (!pte_none(pte[i]))

			return false;



	free_page((unsigned long)pte);

	return true;

}



static bool try_to_free_pmd_page(pmd_t *pmd)

{

	int i;



	for (i = 0; i < PTRS_PER_PMD; i++)

		if (!pmd_none(pmd[i]))

			return false;



	free_page((unsigned long)pmd);

	return true;

}



static bool unmap_pte_range(pmd_t *pmd, unsigned long start, unsigned long end)

{

	pte_t *pte = pte_offset_kernel(pmd, start);



	while (start < end) {

		set_pte(pte, __pte(0));



		start += PAGE_SIZE;

		pte++;

	}



	if (try_to_free_pte_page((pte_t *)pmd_page_vaddr(*pmd))) {

		pmd_clear(pmd);

		return true;

	}

	return false;

}



static void __unmap_pmd_range(pud_t *pud, pmd_t *pmd,

			      unsigned long start, unsigned long end)

{

	if (unmap_pte_range(pmd, start, end))

		if (try_to_free_pmd_page((pmd_t *)pud_page_vaddr(*pud)))

			pud_clear(pud);

}



static void unmap_pmd_range(pud_t *pud, unsigned long start, unsigned long end)

{

	pmd_t *pmd = pmd_offset(pud, start);



	/*

	 * Not on a 2MB page boundary?

	 */

	if (start & (PMD_SIZE - 1)) {

		unsigned long next_page = (start + PMD_SIZE) & PMD_MASK;

		unsigned long pre_end = min_t(unsigned long, end, next_page);



		__unmap_pmd_range(pud, pmd, start, pre_end);



		start = pre_end;

		pmd++;

	}



	/*

	 * Try to unmap in 2M chunks.

	 */

	while (end - start >= PMD_SIZE) {

		if (pmd_large(*pmd))

			pmd_clear(pmd);

		else

			__unmap_pmd_range(pud, pmd, start, start + PMD_SIZE);



		start += PMD_SIZE;

		pmd++;

	}



	/*

	 * 4K leftovers?

	 */

	if (start < end)

		return __unmap_pmd_range(pud, pmd, start, end);



	/*

	 * Try again to free the PMD page if haven't succeeded above.

	 */

	if (!pud_none(*pud))

		if (try_to_free_pmd_page((pmd_t *)pud_page_vaddr(*pud)))

			pud_clear(pud);

}



static void unmap_pud_range(pgd_t *pgd, unsigned long start, unsigned long end)

{