Messages in this thread | | | Subject | Re: [PATCH 1/2] arm64: Get existing page protections in split_pmd | From | Laura Abbott <> | Date | Thu, 5 Nov 2015 17:24:01 -0800 |
| |
On 11/05/2015 02:15 AM, Xishi Qiu wrote: > On 2015/11/4 5:48, Laura Abbott 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> >> --- >> arch/arm64/mm/mmu.c | 9 ++++----- >> 1 file changed, 4 insertions(+), 5 deletions(-) >> >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >> index 9211b85..ff41efa 100644 >> --- a/arch/arm64/mm/mmu.c >> +++ b/arch/arm64/mm/mmu.c >> @@ -75,14 +75,13 @@ 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; >> + > > Hi Laura, > > I'm not quite understand, I find split_pud() doesn't set the flag > PMD_TYPE_TABLE. If we clear xx_TABLE_BIT, does that means the page > is large page?
I'm assuming by large page you mean a block mapping. Yes, without that entry the kernel treats this as a block mapping
> And what is the different from the flag xx_TYPE_SECT?
That would mark it this as a block mapping which is not what we want here.
> > Thanks, > Xishi Qiu >
| |