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

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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: Borislav Petkov <bp@suse.de>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
This commit is contained in:
Borislav Petkov 2013-10-31 17:25:05 +01:00 committed by Matt Fleming
parent c6b6f363f7
commit 0bb8aeee7b
1 changed files with 58 additions and 2 deletions
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60
arch/x86/mm/pageattr.c
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@ -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;
}