powerpc/cell: Move spu_handle_mm_fault() out of cell platform

Currently spu_handle_mm_fault() is in the cell platform.

This code is generically useful for other non-cell co-processors on powerpc.

This patch moves this function out of the cell platform into arch/powerpc/mm so
that others may use it.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/Makefile

@@ -34,3 +34,4 @@ obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += hugepage-hash64.o
 obj-$(CONFIG_PPC_SUBPAGE_PROT)	+= subpage-prot.o
 obj-$(CONFIG_NOT_COHERENT_CACHE) += dma-noncoherent.o
 obj-$(CONFIG_HIGHMEM)		+= highmem.o
+obj-$(CONFIG_PPC_COPRO_BASE)	+= copro_fault.o

arch/powerpc/mm/copro_fault.c

@@ -0,0 +1,92 @@
+/*
+ * CoProcessor (SPU/AFU) mm fault handler
+ *
+ * (C) Copyright IBM Deutschland Entwicklung GmbH 2007
+ *
+ * Author: Arnd Bergmann <arndb@de.ibm.com>
+ * Author: Jeremy Kerr <jk@ozlabs.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/export.h>
+#include <asm/reg.h>
+
+/*
+ * This ought to be kept in sync with the powerpc specific do_page_fault
+ * function. Currently, there are a few corner cases that we haven't had
+ * to handle fortunately.
+ */
+int copro_handle_mm_fault(struct mm_struct *mm, unsigned long ea,
+		unsigned long dsisr, unsigned *flt)
+{
+	struct vm_area_struct *vma;
+	unsigned long is_write;
+	int ret;
+
+	if (mm == NULL)
+		return -EFAULT;
+
+	if (mm->pgd == NULL)
+		return -EFAULT;
+
+	down_read(&mm->mmap_sem);
+	ret = -EFAULT;
+	vma = find_vma(mm, ea);
+	if (!vma)
+		goto out_unlock;
+
+	if (ea < vma->vm_start) {
+		if (!(vma->vm_flags & VM_GROWSDOWN))
+			goto out_unlock;
+		if (expand_stack(vma, ea))
+			goto out_unlock;
+	}
+
+	is_write = dsisr & DSISR_ISSTORE;
+	if (is_write) {
+		if (!(vma->vm_flags & VM_WRITE))
+			goto out_unlock;
+	} else {
+		if (dsisr & DSISR_PROTFAULT)
+			goto out_unlock;
+		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
+			goto out_unlock;
+	}
+
+	ret = 0;
+	*flt = handle_mm_fault(mm, vma, ea, is_write ? FAULT_FLAG_WRITE : 0);
+	if (unlikely(*flt & VM_FAULT_ERROR)) {
+		if (*flt & VM_FAULT_OOM) {
+			ret = -ENOMEM;
+			goto out_unlock;
+		} else if (*flt & VM_FAULT_SIGBUS) {
+			ret = -EFAULT;
+			goto out_unlock;
+		}
+		BUG();
+	}
+
+	if (*flt & VM_FAULT_MAJOR)
+		current->maj_flt++;
+	else
+		current->min_flt++;
+
+out_unlock:
+	up_read(&mm->mmap_sem);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(copro_handle_mm_fault);