mm: fault feedback #2

This patch completes Linus's wish that the fault return codes be made into
bit flags, which I agree makes everything nicer.  This requires requires
all handle_mm_fault callers to be modified (possibly the modifications
should go further and do things like fault accounting in handle_mm_fault --
however that would be for another patch).

[akpm@linux-foundation.org: fix alpha build]
[akpm@linux-foundation.org: fix s390 build]
[akpm@linux-foundation.org: fix sparc build]
[akpm@linux-foundation.org: fix sparc64 build]
[akpm@linux-foundation.org: fix ia64 build]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ian Molton <spyro@f2s.com>
Cc: Bryan Wu <bryan.wu@analog.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Greg Ungerer <gerg@uclinux.org>
Cc: Matthew Wilcox <willy@debian.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Richard Curnow <rc@rc0.org.uk>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp>
Cc: Chris Zankel <chris@zankel.net>
Acked-by: Kyle McMartin <kyle@mcmartin.ca>
Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ Still apparently needs some ARM and PPC loving - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 45 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index ff0b884..f8e12b3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -196,25 +196,10 @@ extern pgprot_t protection_map[16];
 #define FAULT_FLAG_NONLINEAR	0x02	/* Fault was via a nonlinear mapping */
 
 
-#define FAULT_RET_NOPAGE	0x0100	/* ->fault did not return a page. This
-					 * can be used if the handler installs
-					 * their own pte.
-					 */
-#define FAULT_RET_LOCKED	0x0200	/* ->fault locked the page, caller must
-					 * unlock after installing the mapping.
-					 * This is used by pagecache in
-					 * particular, where the page lock is
-					 * used to synchronise against truncate
-					 * and invalidate. Mutually exclusive
-					 * with FAULT_RET_NOPAGE.
-					 */
-
 /*
  * vm_fault is filled by the the pagefault handler and passed to the vma's
- * ->fault function. The vma's ->fault is responsible for returning the
- * VM_FAULT_xxx type which occupies the lowest byte of the return code, ORed
- * with FAULT_RET_ flags that occupy the next byte and give details about
- * how the fault was handled.
+ * ->fault function. The vma's ->fault is responsible for returning a bitmask
+ * of VM_FAULT_xxx flags that give details about how the fault was handled.
  *
  * pgoff should be used in favour of virtual_address, if possible. If pgoff
  * is used, one may set VM_CAN_NONLINEAR in the vma->vm_flags to get nonlinear
@@ -226,9 +211,9 @@ struct vm_fault {
 	void __user *virtual_address;	/* Faulting virtual address */
 
 	struct page *page;		/* ->fault handlers should return a
-					 * page here, unless FAULT_RET_NOPAGE
+					 * page here, unless VM_FAULT_NOPAGE
 					 * is set (which is also implied by
-					 * VM_FAULT_OOM or SIGBUS).
+					 * VM_FAULT_ERROR).
 					 */
 };
 
@@ -712,26 +697,17 @@ static inline int page_mapped(struct page *page)
  * just gets major/minor fault counters bumped up.
  */
 
-/*
- * VM_FAULT_ERROR is set for the error cases, to make some tests simpler.
- */
-#define VM_FAULT_ERROR	0x20
+#define VM_FAULT_MINOR	0 /* For backwards compat. Remove me quickly. */
 
-#define VM_FAULT_OOM	(0x00 | VM_FAULT_ERROR)
-#define VM_FAULT_SIGBUS	(0x01 | VM_FAULT_ERROR)
-#define VM_FAULT_MINOR	0x02
-#define VM_FAULT_MAJOR	0x03
+#define VM_FAULT_OOM	0x0001
+#define VM_FAULT_SIGBUS	0x0002
+#define VM_FAULT_MAJOR	0x0004
+#define VM_FAULT_WRITE	0x0008	/* Special case for get_user_pages */
 
-/* 
- * Special case for get_user_pages.
- * Must be in a distinct bit from the above VM_FAULT_ flags.
- */
-#define VM_FAULT_WRITE	0x10
+#define VM_FAULT_NOPAGE	0x0100	/* ->fault installed the pte, not return page */
+#define VM_FAULT_LOCKED	0x0200	/* ->fault locked the returned page */
 
-/*
- * Mask of VM_FAULT_ flags
- */
-#define VM_FAULT_MASK	0xff
+#define VM_FAULT_ERROR	(VM_FAULT_OOM | VM_FAULT_SIGBUS)
 
 #define offset_in_page(p)	((unsigned long)(p) & ~PAGE_MASK)
 
@@ -817,16 +793,8 @@ extern int vmtruncate(struct inode * inode, loff_t offset);
 extern int vmtruncate_range(struct inode * inode, loff_t offset, loff_t end);
 
 #ifdef CONFIG_MMU
-extern int __handle_mm_fault(struct mm_struct *mm,struct vm_area_struct *vma,
+extern int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 			unsigned long address, int write_access);
-
-static inline int handle_mm_fault(struct mm_struct *mm,
-			struct vm_area_struct *vma, unsigned long address,
-			int write_access)
-{
-	return __handle_mm_fault(mm, vma, address, write_access) &
-				(~VM_FAULT_WRITE);
-}
 #else
 static inline int handle_mm_fault(struct mm_struct *mm,
 			struct vm_area_struct *vma, unsigned long address,