1 files changed, 312 insertions, 0 deletions
diff --git a/mm/mincore.c b/mm/mincore.c
new file mode 100644
index 00000000..117ff549
--- /dev/null
+++ b/mm/mincore.c
@@ -0,0 +1,312 @@
+/*
+ *	linux/mm/mincore.c
+ *
+ * Copyright (C) 1994-2006  Linus Torvalds
+ */
+
+/*
+ * The mincore() system call.
+ */
+#include <linux/pagemap.h>
+#include <linux/gfp.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/syscalls.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/hugetlb.h>
+
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+
+static void mincore_hugetlb_page_range(struct vm_area_struct *vma,
+				unsigned long addr, unsigned long end,
+				unsigned char *vec)
+{
+#ifdef CONFIG_HUGETLB_PAGE
+	struct hstate *h;
+
+	h = hstate_vma(vma);
+	while (1) {
+		unsigned char present;
+		pte_t *ptep;
+		/*
+		 * Huge pages are always in RAM for now, but
+		 * theoretically it needs to be checked.
+		 */
+		ptep = huge_pte_offset(current->mm,
+				       addr & huge_page_mask(h));
+		present = ptep && !huge_pte_none(huge_ptep_get(ptep));
+		while (1) {
+			*vec = present;
+			vec++;
+			addr += PAGE_SIZE;
+			if (addr == end)
+				return;
+			/* check hugepage border */
+			if (!(addr & ~huge_page_mask(h)))
+				break;
+		}
+	}
+#else
+	BUG();
+#endif
+}
+
+/*
+ * Later we can get more picky about what "in core" means precisely.
+ * For now, simply check to see if the page is in the page cache,
+ * and is up to date; i.e. that no page-in operation would be required
+ * at this time if an application were to map and access this page.
+ */
+static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
+{
+	unsigned char present = 0;
+	struct page *page;
+
+	/*
+	 * When tmpfs swaps out a page from a file, any process mapping that
+	 * file will not get a swp_entry_t in its pte, but rather it is like
+	 * any other file mapping (ie. marked !present and faulted in with
+	 * tmpfs's .fault). So swapped out tmpfs mappings are tested here.
+	 *
+	 * However when tmpfs moves the page from pagecache and into swapcache,
+	 * it is still in core, but the find_get_page below won't find it.
+	 * No big deal, but make a note of it.
+	 */
+	page = find_get_page(mapping, pgoff);
+	if (page) {
+		present = PageUptodate(page);
+		page_cache_release(page);
+	}
+
+	return present;
+}
+
+static void mincore_unmapped_range(struct vm_area_struct *vma,
+				unsigned long addr, unsigned long end,
+				unsigned char *vec)
+{
+	unsigned long nr = (end - addr) >> PAGE_SHIFT;
+	int i;
+
+	if (vma->vm_file) {
+		pgoff_t pgoff;
+
+		pgoff = linear_page_index(vma, addr);
+		for (i = 0; i < nr; i++, pgoff++)
+			vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
+	} else {
+		for (i = 0; i < nr; i++)
+			vec[i] = 0;
+	}
+}
+
+static void mincore_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
+			unsigned long addr, unsigned long end,
+			unsigned char *vec)
+{
+	unsigned long next;
+	spinlock_t *ptl;
+	pte_t *ptep;
+
+	ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	do {
+		pte_t pte = *ptep;
+		pgoff_t pgoff;
+
+		next = addr + PAGE_SIZE;
+		if (pte_none(pte))
+			mincore_unmapped_range(vma, addr, next, vec);
+		else if (pte_present(pte))
+			*vec = 1;
+		else if (pte_file(pte)) {
+			pgoff = pte_to_pgoff(pte);
+			*vec = mincore_page(vma->vm_file->f_mapping, pgoff);
+		} else { /* pte is a swap entry */
+			swp_entry_t entry = pte_to_swp_entry(pte);
+
+			if (is_migration_entry(entry)) {
+				/* migration entries are always uptodate */
+				*vec = 1;
+			} else {
+#ifdef CONFIG_SWAP
+				pgoff = entry.val;
+				*vec = mincore_page(&swapper_space, pgoff);
+#else
+				WARN_ON(1);
+				*vec = 1;
+#endif
+			}
+		}
+		vec++;
+	} while (ptep++, addr = next, addr != end);
+	pte_unmap_unlock(ptep - 1, ptl);
+}
+
+static void mincore_pmd_range(struct vm_area_struct *vma, pud_t *pud,
+			unsigned long addr, unsigned long end,
+			unsigned char *vec)
+{
+	unsigned long next;
+	pmd_t *pmd;
+
+	pmd = pmd_offset(pud, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+		if (pmd_trans_huge(*pmd)) {
+			if (mincore_huge_pmd(vma, pmd, addr, next, vec)) {
+				vec += (next - addr) >> PAGE_SHIFT;
+				continue;
+			}
+			/* fall through */
+		}
+		if (pmd_none_or_trans_huge_or_clear_bad(pmd))
+			mincore_unmapped_range(vma, addr, next, vec);
+		else
+			mincore_pte_range(vma, pmd, addr, next, vec);
+		vec += (next - addr) >> PAGE_SHIFT;
+	} while (pmd++, addr = next, addr != end);
+}
+
+static void mincore_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
+			unsigned long addr, unsigned long end,
+			unsigned char *vec)
+{
+	unsigned long next;
+	pud_t *pud;
+
+	pud = pud_offset(pgd, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		if (pud_none_or_clear_bad(pud))
+			mincore_unmapped_range(vma, addr, next, vec);
+		else
+			mincore_pmd_range(vma, pud, addr, next, vec);
+		vec += (next - addr) >> PAGE_SHIFT;
+	} while (pud++, addr = next, addr != end);
+}
+
+static void mincore_page_range(struct vm_area_struct *vma,
+			unsigned long addr, unsigned long end,
+			unsigned char *vec)
+{
+	unsigned long next;
+	pgd_t *pgd;
+
+	pgd = pgd_offset(vma->vm_mm, addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		if (pgd_none_or_clear_bad(pgd))
+			mincore_unmapped_range(vma, addr, next, vec);
+		else
+			mincore_pud_range(vma, pgd, addr, next, vec);
+		vec += (next - addr) >> PAGE_SHIFT;
+	} while (pgd++, addr = next, addr != end);
+}
+
+/*
+ * Do a chunk of "sys_mincore()". We've already checked
+ * all the arguments, we hold the mmap semaphore: we should
+ * just return the amount of info we're asked for.
+ */
+static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
+{
+	struct vm_area_struct *vma;
+	unsigned long end;
+
+	vma = find_vma(current->mm, addr);
+	if (!vma || addr < vma->vm_start)
+		return -ENOMEM;
+
+	end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));
+
+	if (is_vm_hugetlb_page(vma)) {
+		mincore_hugetlb_page_range(vma, addr, end, vec);
+		return (end - addr) >> PAGE_SHIFT;
+	}
+
+	end = pmd_addr_end(addr, end);
+
+	if (is_vm_hugetlb_page(vma))
+		mincore_hugetlb_page_range(vma, addr, end, vec);
+	else
+		mincore_page_range(vma, addr, end, vec);
+
+	return (end - addr) >> PAGE_SHIFT;
+}
+
+/*
+ * The mincore(2) system call.
+ *
+ * mincore() returns the memory residency status of the pages in the
+ * current process's address space specified by [addr, addr + len).
+ * The status is returned in a vector of bytes.  The least significant
+ * bit of each byte is 1 if the referenced page is in memory, otherwise
+ * it is zero.
+ *
+ * Because the status of a page can change after mincore() checks it
+ * but before it returns to the application, the returned vector may
+ * contain stale information.  Only locked pages are guaranteed to
+ * remain in memory.
+ *
+ * return values:
+ *  zero    - success
+ *  -EFAULT - vec points to an illegal address
+ *  -EINVAL - addr is not a multiple of PAGE_CACHE_SIZE
+ *  -ENOMEM - Addresses in the range [addr, addr + len] are
+ *		invalid for the address space of this process, or
+ *		specify one or more pages which are not currently
+ *		mapped
+ *  -EAGAIN - A kernel resource was temporarily unavailable.
+ */
+SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
+		unsigned char __user *, vec)
+{
+	long retval;
+	unsigned long pages;
+	unsigned char *tmp;
+
+	/* Check the start address: needs to be page-aligned.. */
+ 	if (start & ~PAGE_CACHE_MASK)
+		return -EINVAL;
+
+	/* ..and we need to be passed a valid user-space range */
+	if (!access_ok(VERIFY_READ, (void __user *) start, len))
+		return -ENOMEM;
+
+	/* This also avoids any overflows on PAGE_CACHE_ALIGN */
+	pages = len >> PAGE_SHIFT;
+	pages += (len & ~PAGE_MASK) != 0;
+
+	if (!access_ok(VERIFY_WRITE, vec, pages))
+		return -EFAULT;
+
+	tmp = (void *) __get_free_page(GFP_USER);
+	if (!tmp)
+		return -EAGAIN;
+
+	retval = 0;
+	while (pages) {
+		/*
+		 * Do at most PAGE_SIZE entries per iteration, due to
+		 * the temporary buffer size.
+		 */
+		down_read(&current->mm->mmap_sem);
+		retval = do_mincore(start, min(pages, PAGE_SIZE), tmp);
+		up_read(&current->mm->mmap_sem);
+
+		if (retval <= 0)
+			break;
+		if (copy_to_user(vec, tmp, retval)) {
+			retval = -EFAULT;
+			break;
+		}
+		pages -= retval;
+		vec += retval;
+		start += retval << PAGE_SHIFT;
+		retval = 0;
+	}
+	free_page((unsigned long) tmp);
+	return retval;
+}