From 785a3fab4adbf91b2189c928a59ae219c54ba95e Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Mon, 23 Oct 2017 07:20:00 -0700 Subject: mm, dax: introduce pfn_t_special() In support of removing the VM_MIXEDMAP indication from DAX VMAs, introduce pfn_t_special() for drivers to indicate that _PAGE_SPECIAL should be used for DAX ptes. This also helps identify drivers like dccssblk that only want to use DAX in a read-only fashion without get_user_pages() support. Ideally we could delete axonram and dcssblk DAX support, but if we need to keep it better make it explicit that axonram and dcssblk only support a sub-set of DAX due to missing _PAGE_DEVMAP support. Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: Martin Schwidefsky Cc: Heiko Carstens Signed-off-by: Dan Williams --- mm/memory.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) (limited to 'mm/memory.c') diff --git a/mm/memory.c b/mm/memory.c index ca5674cbaff2..46b6c33b7f04 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1897,12 +1897,26 @@ int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, } EXPORT_SYMBOL(vm_insert_pfn_prot); +static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn) +{ + /* these checks mirror the abort conditions in vm_normal_page */ + if (vma->vm_flags & VM_MIXEDMAP) + return true; + if (pfn_t_devmap(pfn)) + return true; + if (pfn_t_special(pfn)) + return true; + if (is_zero_pfn(pfn_t_to_pfn(pfn))) + return true; + return false; +} + static int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, pfn_t pfn, bool mkwrite) { pgprot_t pgprot = vma->vm_page_prot; - BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); + BUG_ON(!vm_mixed_ok(vma, pfn)); if (addr < vma->vm_start || addr >= vma->vm_end) return -EFAULT; -- cgit v1.2.1