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arm64: Make sure permission updates happen for pmd/pud

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Commit 15122ee2c5 ("arm64: Enforce BBM for huge IO/VMAP mappings")
disallowed block mappings for ioremap since that code does not honor
break-before-make. The same APIs are also used for permission updating
though and the extra checks prevent the permission updates from happening,
even though this should be permitted. This results in read-only permissions
not being fully applied. Visibly, this can occasionaly be seen as a failure
on the built in rodata test when the test data ends up in a section or
as an odd RW gap on the page table dump. Fix this by using
pgattr_change_is_safe instead of p*d_present for determining if the
change is permitted.

Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Peter Robinson <pbrobinson@gmail.com>
Reported-by: Peter Robinson <pbrobinson@gmail.com>
Fixes: 15122ee2c5 ("arm64: Enforce BBM for huge IO/VMAP mappings")
Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Laura Abbott 2018-05-23 11:43:46 -07:00 committed by Will Deacon
parent cc19846079
commit 82034c23fc
1 changed files with 10 additions and 6 deletions
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16
arch/arm64/mm/mmu.c
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@ -933,13 +933,15 @@ int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot)
{
pgprot_t sect_prot = __pgprot(PUD_TYPE_SECT |
pgprot_val(mk_sect_prot(prot)));
pud_t new_pud = pfn_pud(__phys_to_pfn(phys), sect_prot);
/* ioremap_page_range doesn't honour BBM */
if (pud_present(READ_ONCE(*pudp)))
/* Only allow permission changes for now */
if (!pgattr_change_is_safe(READ_ONCE(pud_val(*pudp)),
pud_val(new_pud)))
return 0;
BUG_ON(phys & ~PUD_MASK);
set_pud(pudp, pfn_pud(__phys_to_pfn(phys), sect_prot));
set_pud(pudp, new_pud);
return 1;
}
@ -947,13 +949,15 @@ int pmd_set_huge(pmd_t *pmdp, phys_addr_t phys, pgprot_t prot)
{
pgprot_t sect_prot = __pgprot(PMD_TYPE_SECT |
pgprot_val(mk_sect_prot(prot)));
pmd_t new_pmd = pfn_pmd(__phys_to_pfn(phys), sect_prot);
/* ioremap_page_range doesn't honour BBM */
if (pmd_present(READ_ONCE(*pmdp)))
/* Only allow permission changes for now */
if (!pgattr_change_is_safe(READ_ONCE(pmd_val(*pmdp)),
pmd_val(new_pmd)))
return 0;
BUG_ON(phys & ~PMD_MASK);
set_pmd(pmdp, pfn_pmd(__phys_to_pfn(phys), sect_prot));
set_pmd(pmdp, new_pmd);
return 1;
}