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, 16 insertions, 20 deletions

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 75d491448e45..c04124a095cf 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -183,20 +183,20 @@ good_area:
 	 */
 survive:
 	fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, fsr & (1 << 11));
-
-	/*
-	 * Handle the "normal" cases first - successful and sigbus
-	 */
-	switch (fault) {
-	case VM_FAULT_MAJOR:
+	if (unlikely(fault & VM_FAULT_ERROR)) {
+		if (fault & VM_FAULT_OOM)
+			goto out_of_memory;
+		else if (fault & VM_FAULT_SIGBUS)
+			return fault;
+		BUG();
+	}
+	if (fault & VM_FAULT_MAJOR)
 		tsk->maj_flt++;
-		return fault;
-	case VM_FAULT_MINOR:
+	else
 		tsk->min_flt++;
-	case VM_FAULT_SIGBUS:
-		return fault;
-	}
+	return fault;
 
+out_of_memory:
 	if (!is_init(tsk))
 		goto out;
 
@@ -249,7 +249,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	/*
 	 * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
 	 */
-	if (fault >= VM_FAULT_MINOR)
+	if (likely(!(fault & VM_FAULT_ERROR)))
 		return 0;
 
 	/*
@@ -259,8 +259,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	if (!user_mode(regs))
 		goto no_context;
 
-	switch (fault) {
-	case VM_FAULT_OOM:
+	if (fault & VM_FAULT_OOM) {
 		/*
 		 * We ran out of memory, or some other thing
 		 * happened to us that made us unable to handle
@@ -269,17 +268,15 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 		printk("VM: killing process %s\n", tsk->comm);
 		do_exit(SIGKILL);
 		return 0;
-
-	case VM_FAULT_SIGBUS:
+	}
+	if (fault & VM_FAULT_SIGBUS) {
 		/*
 		 * We had some memory, but were unable to
 		 * successfully fix up this page fault.
 		 */
 		sig = SIGBUS;
 		code = BUS_ADRERR;
-		break;
-
-	default:
+	} else {
 		/*
 		 * Something tried to access memory that
 		 * isn't in our memory map..
@@ -287,7 +284,6 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 		sig = SIGSEGV;
 		code = fault == VM_FAULT_BADACCESS ?
 			SEGV_ACCERR : SEGV_MAPERR;
-		break;
 	}
 
 	__do_user_fault(tsk, addr, fsr, sig, code, regs);