Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 0bb8aeee authored by Borislav Petkov's avatar Borislav Petkov Committed by Matt Fleming
Browse files

x86/mm/pageattr: Add a PUD error unwinding path 



In case we encounter an error during the mapping of a region, we want to
unwind what we've established so far exactly the way we did the mapping.
This is the PUD part kept deliberately small for easier review.

Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
parent c6b6f363

arch/x86/mm/pageattr.c

+58 −2
Original line number Diff line number Diff line
@@ -666,6 +666,51 @@ 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 void unmap_pud_range(pgd_t *pgd, unsigned long start, unsigned long end)

{

	pud_t *pud = pud_offset(pgd, start);



	/*

	 * Not on a GB page boundary?

	 */

	if (start & (PUD_SIZE - 1)) {

		unsigned long next_page = (start + PUD_SIZE) & PUD_MASK;

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



		unmap_pmd_range(pud, start, pre_end);



		start = pre_end;

		pud++;

	}



	/*

	 * Try to unmap in 1G chunks?

	 */

	while (end - start >= PUD_SIZE) {



		if (pud_large(*pud))

			pud_clear(pud);

		else

			unmap_pmd_range(pud, start, start + PUD_SIZE);



		start += PUD_SIZE;

		pud++;

	}



	/*

	 * 2M leftovers?

	 */

	if (start < end)

		unmap_pmd_range(pud, start, end);



	/*

	 * No need to try to free the PUD page because we'll free it in

	 * populate_pgd's error path

	 */

}



static int alloc_pte_page(pmd_t *pmd)

{

	pte_t *pte = (pte_t *)get_zeroed_page(GFP_KERNEL | __GFP_NOTRACK);
@@ -883,9 +928,20 @@ static int populate_pgd(struct cpa_data *cpa, unsigned long addr) 
	pgprot_val(pgprot) |=  pgprot_val(cpa->mask_set);



	ret = populate_pud(cpa, addr, pgd_entry, pgprot);

	if (ret < 0)

		return ret;

	if (ret < 0) {

		unmap_pud_range(pgd_entry, addr,

				addr + (cpa->numpages << PAGE_SHIFT));



		if (allocd_pgd) {

			/*

			 * If I allocated this PUD page, I can just as well

			 * free it in this error path.

			 */

			pgd_clear(pgd_entry);

			free_page((unsigned long)pud);

		}

		return ret;

	}

	cpa->numpages = ret;

	return 0;

}