From f872f5400cc01373d8e29d9c7a5296ccfaf4ccf3 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Tue, 29 Dec 2015 20:12:19 -0800 Subject: mm: Add a vm_special_mapping.fault() method Requiring special mappings to give a list of struct pages is inflexible: it prevents sane use of IO memory in a special mapping, it's inefficient (it requires arch code to initialize a list of struct pages, and it requires the mm core to walk the entire list just to figure out how long it is), and it prevents arch code from doing anything fancy when a special mapping fault occurs. Add a .fault method as an alternative to filling in a .pages array. Looks-OK-to: Andrew Morton Signed-off-by: Andy Lutomirski Reviewed-by: Kees Cook Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: Fenghua Yu Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Quentin Casasnovas Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/a26d1677c0bc7e774c33f469451a78ca31e9e6af.1451446564.git.luto@kernel.org Signed-off-by: Ingo Molnar --- include/linux/mm_types.h | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) (limited to 'include') diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index f8d1492a114f..c88e48a3c155 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -568,10 +568,26 @@ static inline void clear_tlb_flush_pending(struct mm_struct *mm) } #endif -struct vm_special_mapping -{ - const char *name; +struct vm_fault; + +struct vm_special_mapping { + const char *name; /* The name, e.g. "[vdso]". */ + + /* + * If .fault is not provided, this points to a + * NULL-terminated array of pages that back the special mapping. + * + * This must not be NULL unless .fault is provided. + */ struct page **pages; + + /* + * If non-NULL, then this is called to resolve page faults + * on the special mapping. If used, .pages is not checked. + */ + int (*fault)(const struct vm_special_mapping *sm, + struct vm_area_struct *vma, + struct vm_fault *vmf); }; enum tlb_flush_reason { -- cgit v1.2.3 From 1745cbc5d0dee0749a6bc0ea8e872c5db0074061 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Tue, 29 Dec 2015 20:12:20 -0800 Subject: mm: Add vm_insert_pfn_prot() The x86 vvar vma contains pages with differing cacheability flags. x86 currently implements this by manually inserting all the ptes using (io_)remap_pfn_range when the vma is set up. x86 wants to move to using .fault with VM_FAULT_NOPAGE to set up the mappings as needed. The correct API to use to insert a pfn in .fault is vm_insert_pfn(), but vm_insert_pfn() can't override the vma's cache mode, and the HPET page in particular needs to be uncached despite the fact that the rest of the VMA is cached. Add vm_insert_pfn_prot() to support varying cacheability within the same non-COW VMA in a more sane manner. x86 could alternatively use multiple VMAs, but that's messy, would break CRIU, and would create unnecessary VMAs that would waste memory. Signed-off-by: Andy Lutomirski Reviewed-by: Kees Cook Acked-by: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: Fenghua Yu Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Quentin Casasnovas Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/d2938d1eb37be7a5e4f86182db646551f11e45aa.1451446564.git.luto@kernel.org Signed-off-by: Ingo Molnar --- include/linux/mm.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/linux/mm.h b/include/linux/mm.h index 00bad7793788..87ef1d7730ba 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2080,6 +2080,8 @@ int remap_pfn_range(struct vm_area_struct *, unsigned long addr, int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *); int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, unsigned long pfn); +int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, + unsigned long pfn, pgprot_t pgprot); int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, unsigned long pfn); int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len); -- cgit v1.2.3