mm: consolidate pte_index() and pte_offset_*() definitions

All architectures define pte_index() as

	(address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)

and all architectures define pte_offset_kernel() as an entry in the array
of PTEs indexed by the pte_index().

For the most architectures the pte_offset_kernel() implementation relies
on the availability of pmd_page_vaddr() that converts a PMD entry value to
the virtual address of the page containing PTEs array.

Let's move x86 definitions of the PTE accessors to the generic place in
<linux/pgtable.h> and then simply drop the respective definitions from the
other architectures.

The architectures that didn't provide pmd_page_vaddr() are updated to have
that defined.

The generic implementation of pte_offset_kernel() can be overridden by an
architecture and alpha makes use of this because it has special ordering
requirements for its version of pte_offset_kernel().

[[email protected]: v2]
  Link: http://lkml.kernel.org/r/[email protected]
[[email protected]: update]
  Link: http://lkml.kernel.org/r/[email protected]
[[email protected]: update]
  Link: http://lkml.kernel.org/r/[email protected]
[[email protected]: fix x86 warning]
[[email protected]: fix powerpc build]
  Link: http://lkml.kernel.org/r/[email protected]

Signed-off-by: Mike Rapoport <[email protected]>
Signed-off-by: Stephen Rothwell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Cain <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Chris Zankel <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Greentime Hu <[email protected]>
Cc: Greg Ungerer <[email protected]>
Cc: Guan Xuetao <[email protected]>
Cc: Guo Ren <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Ley Foon Tan <[email protected]>
Cc: Mark Salter <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: Max Filippov <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Nick Hu <[email protected]>
Cc: Paul Walmsley <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Rich Felker <[email protected]>
Cc: Russell King <[email protected]>
Cc: Stafford Horne <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Vincent Chen <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Yoshinori Sato <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 91 insertions, 0 deletions

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index ee85b222d098..90a5d0c78fca 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -29,6 +29,97 @@
 #endif
 
 /*
+ * A page table page can be thought of an array like this: pXd_t[PTRS_PER_PxD]
+ *
+ * The pXx_index() functions return the index of the entry in the page
+ * table page which would control the given virtual address
+ *
+ * As these functions may be used by the same code for different levels of
+ * the page table folding, they are always available, regardless of
+ * CONFIG_PGTABLE_LEVELS value. For the folded levels they simply return 0
+ * because in such cases PTRS_PER_PxD equals 1.
+ */
+
+static inline unsigned long pte_index(unsigned long address)
+{
+	return (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
+}
+
+#ifndef pmd_index
+static inline unsigned long pmd_index(unsigned long address)
+{
+	return (address >> PMD_SHIFT) & (PTRS_PER_PMD - 1);
+}
+#define pmd_index pmd_index
+#endif
+
+#ifndef pud_index
+static inline unsigned long pud_index(unsigned long address)
+{
+	return (address >> PUD_SHIFT) & (PTRS_PER_PUD - 1);
+}
+#define pud_index pud_index
+#endif
+
+#ifndef pgd_index
+/* Must be a compile-time constant, so implement it as a macro */
+#define pgd_index(a)  (((a) >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1))
+#endif
+
+#ifndef pte_offset_kernel
+static inline pte_t *pte_offset_kernel(pmd_t *pmd, unsigned long address)
+{
+	return (pte_t *)pmd_page_vaddr(*pmd) + pte_index(address);
+}
+#define pte_offset_kernel pte_offset_kernel
+#endif
+
+#if defined(CONFIG_HIGHPTE)
+#define pte_offset_map(dir, address)				\
+	((pte_t *)kmap_atomic(pmd_page(*(dir))) +		\
+	 pte_index((address)))
+#define pte_unmap(pte) kunmap_atomic((pte))
+#else
+#define pte_offset_map(dir, address)	pte_offset_kernel((dir), (address))
+#define pte_unmap(pte) ((void)(pte))	/* NOP */
+#endif
+
+/* Find an entry in the second-level page table.. */
+#ifndef pmd_offset
+static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
+{
+	return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(address);
+}
+#define pmd_offset pmd_offset
+#endif
+
+#ifndef pud_offset
+static inline pud_t *pud_offset(p4d_t *p4d, unsigned long address)
+{
+	return (pud_t *)p4d_page_vaddr(*p4d) + pud_index(address);
+}
+#define pud_offset pud_offset
+#endif
+
+static inline pgd_t *pgd_offset_pgd(pgd_t *pgd, unsigned long address)
+{
+	return (pgd + pgd_index(address));
+};
+
+/*
+ * a shortcut to get a pgd_t in a given mm
+ */
+#ifndef pgd_offset
+#define pgd_offset(mm, address)		pgd_offset_pgd((mm)->pgd, (address))
+#endif
+
+/*
+ * a shortcut which implies the use of the kernel's pgd, instead
+ * of a process's
+ */
+#define pgd_offset_k(address)		pgd_offset(&init_mm, (address))
+
+/*
  * In many cases it is known that a virtual address is mapped at PMD or PTE
  * level, so instead of traversing all the page table levels, we can get a
  * pointer to the PMD entry in user or kernel page table or translate a virtual