Support strange discontiguous PFN remappings (238f58d8) · Commits · 戴 / test

include/linux/mm.h

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -163,6 +163,7 @@ extern unsigned int kobjsize(const void *objp);
	#define VM_HUGETLB 0x00400000 /* Huge TLB Page VM */		#define VM_HUGETLB 0x00400000 /* Huge TLB Page VM */
	#define VM_NONLINEAR 0x00800000 /* Is non-linear (remap_file_pages) */		#define VM_NONLINEAR 0x00800000 /* Is non-linear (remap_file_pages) */
	#define VM_MAPPED_COPY 0x01000000 /* T if mapped copy of data (nommu mmap) */		#define VM_MAPPED_COPY 0x01000000 /* T if mapped copy of data (nommu mmap) */
			#define VM_INCOMPLETE 0x02000000 /* Strange partial PFN mapping marker */

	#ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */		#ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */
	#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS		#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS

mm/memory.c

+92 −0

Original line number	Original line	Diff line number	Diff line
	@@ -1146,6 +1146,95 @@ int zeromap_page_range(struct vm_area_struct *vma,
	return err;		return err;
	}		}

			/*
			* This is the old fallback for page remapping.
			*
			* For historical reasons, it only allows reserved pages. Only
			* old drivers should use this, and they needed to mark their
			* pages reserved for the old functions anyway.
			*/
			static int insert_page(struct mm_struct mm, unsigned long addr, struct page page, pgprot_t prot)
			{
			int retval;
			pgd_t * pgd;
			pud_t * pud;
			pmd_t * pmd;
			pte_t * pte;
			spinlock_t *ptl;

			retval = -EINVAL;
			if (PageAnon(page) \|\| !PageReserved(page))
			goto out;
			retval = -ENOMEM;
			flush_dcache_page(page);
			pgd = pgd_offset(mm, addr);
			pud = pud_alloc(mm, pgd, addr);
			if (!pud)
			goto out;
			pmd = pmd_alloc(mm, pud, addr);
			if (!pmd)
			goto out;
			pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
			if (!pte)
			goto out;
			retval = -EBUSY;
			if (!pte_none(*pte))
			goto out_unlock;

			/* Ok, finally just insert the thing.. */
			get_page(page);
			inc_mm_counter(mm, file_rss);
			page_add_file_rmap(page);
			set_pte_at(mm, addr, pte, mk_pte(page, prot));

			retval = 0;
			out_unlock:
			pte_unmap_unlock(pte, ptl);
			out:
			return retval;
			}

			/*
			* Somebody does a pfn remapping that doesn't actually work as a vma.
			*
			* Do it as individual pages instead, and warn about it. It's bad form,
			* and very inefficient.
			*/
			static int incomplete_pfn_remap(struct vm_area_struct *vma,
			unsigned long start, unsigned long end,
			unsigned long pfn, pgprot_t prot)
			{
			static int warn = 10;
			struct page *page;
			int retval;

			if (!(vma->vm_flags & VM_INCOMPLETE)) {
			if (warn) {
			warn--;
			printk("%s does an incomplete pfn remapping", current->comm);
			dump_stack();
			}
			}
			vma->vm_flags \|= VM_INCOMPLETE \| VM_IO \| VM_RESERVED;

			if (start < vma->vm_start \|\| end > vma->vm_end)
			return -EINVAL;

			if (!pfn_valid(pfn))
			return -EINVAL;

			retval = 0;
			page = pfn_to_page(pfn);
			while (start < end) {
			retval = insert_page(vma->vm_mm, start, page, prot);
			if (retval < 0)
			break;
			start += PAGE_SIZE;
			page++;
			}
			return retval;
			}

	/*		/*
	* maps a range of physical memory into the requested pages. the old		* maps a range of physical memory into the requested pages. the old
	* mappings are removed. any references to nonexistent pages results		* mappings are removed. any references to nonexistent pages results
	@@ -1220,6 +1309,9 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
	struct mm_struct *mm = vma->vm_mm;		struct mm_struct *mm = vma->vm_mm;
	int err;		int err;

			if (addr != vma->vm_start \|\| end != vma->vm_end)
			return incomplete_pfn_remap(vma, addr, end, pfn, prot);

	/*		/*
	* Physically remapped pages are special. Tell the		* Physically remapped pages are special. Tell the
	* rest of the world about it:		* rest of the world about it:

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