| Message ID | 1447207057-11323-2-git-send-email-labbott@fedoraproject.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 11 November 2015 at 02:57, Laura Abbott <labbott@fedoraproject.org> wrote: > Rather than always putting the least restrictived permissions > (PAGE_KERNEL_EXEC) when spliting a pmd into pages, use > the existing permissions from the pmd for the page. > > Signed-off-by: Laura Abbott <labbott@fedoraproject.org> > --- > v2: Typo and typechecking fixed > > I chose not to add the Reviewed-by from Ard here because of the addition of > the contiguous bit in split_pmd. Not sure if I should be explicitly carrying > it over. Yes, you should. A PMD will be split into more than one contiguous range, e.g., 32 x 64 KB on 4 KB pages, and the PTE manipulation code is responsible for clearing the PTE_CONT bit on any PTE that is part of a range that is no longer mapped contiguously. > --- > arch/arm64/mm/mmu.c | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index c2fa6b5..496c3fd 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -76,15 +76,13 @@ static void __init *early_alloc(unsigned long sz) > static void split_pmd(pmd_t *pmd, pte_t *pte) > { > unsigned long pfn = pmd_pfn(*pmd); > + unsigned long addr = pfn << PAGE_SHIFT; > + pgprot_t prot = __pgprot((pmd_val(*pmd) ^ addr) | PTE_TYPE_PAGE); > + > int i = 0; > > do { > - /* > - * Need to have the least restrictive permissions available > - * permissions will be fixed up later. Default the new page > - * range as contiguous ptes. > - */ > - set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC_CONT)); > + set_pte(pte, pfn_pte(pfn, prot)); > pfn++; > } while (pte++, i++, i < PTRS_PER_PTE); > } > -- > 2.5.0 >
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index c2fa6b5..496c3fd 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -76,15 +76,13 @@ static void __init *early_alloc(unsigned long sz) static void split_pmd(pmd_t *pmd, pte_t *pte) { unsigned long pfn = pmd_pfn(*pmd); + unsigned long addr = pfn << PAGE_SHIFT; + pgprot_t prot = __pgprot((pmd_val(*pmd) ^ addr) | PTE_TYPE_PAGE); + int i = 0; do { - /* - * Need to have the least restrictive permissions available - * permissions will be fixed up later. Default the new page - * range as contiguous ptes. - */ - set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC_CONT)); + set_pte(pte, pfn_pte(pfn, prot)); pfn++; } while (pte++, i++, i < PTRS_PER_PTE); }
Rather than always putting the least restrictived permissions (PAGE_KERNEL_EXEC) when spliting a pmd into pages, use the existing permissions from the pmd for the page. Signed-off-by: Laura Abbott <labbott@fedoraproject.org> --- v2: Typo and typechecking fixed I chose not to add the Reviewed-by from Ard here because of the addition of the contiguous bit in split_pmd. Not sure if I should be explicitly carrying it over. --- arch/arm64/mm/mmu.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-)