powerpc/cell: Fix iommu exception reporting

Currently, we will report a page fault as a segment fault, and report
a segment fault as both a page and segment fault.

Fix the SPF_P definition to be correct according to the iommu docs, and
mask before comparing.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/cell/iommu.c

@@ -74,7 +74,7 @@
 #define IOC_IO_ExcpStat_V		0x8000000000000000ul
 #define IOC_IO_ExcpStat_SPF_Mask	0x6000000000000000ul
 #define IOC_IO_ExcpStat_SPF_S		0x6000000000000000ul
-#define IOC_IO_ExcpStat_SPF_P		0x4000000000000000ul
+#define IOC_IO_ExcpStat_SPF_P		0x2000000000000000ul
 #define IOC_IO_ExcpStat_ADDR_Mask	0x00000007fffff000ul
 #define IOC_IO_ExcpStat_RW_Mask		0x0000000000000800ul
 #define IOC_IO_ExcpStat_IOID_Mask	0x00000000000007fful
@@ -247,17 +247,18 @@ static void tce_free_cell(struct iommu_table *tbl, long index, long npages)
 
 static irqreturn_t ioc_interrupt(int irq, void *data)
 {
-	unsigned long stat;
+	unsigned long stat, spf;
 	struct cbe_iommu *iommu = data;
 
 	stat = in_be64(iommu->xlate_regs + IOC_IO_ExcpStat);
+	spf = stat & IOC_IO_ExcpStat_SPF_Mask;
 
 	/* Might want to rate limit it */
 	printk(KERN_ERR "iommu: DMA exception 0x%016lx\n", stat);
 	printk(KERN_ERR "  V=%d, SPF=[%c%c], RW=%s, IOID=0x%04x\n",
 	       !!(stat & IOC_IO_ExcpStat_V),
-	       (stat & IOC_IO_ExcpStat_SPF_S) ? 'S' : ' ',
-	       (stat & IOC_IO_ExcpStat_SPF_P) ? 'P' : ' ',
+	       (spf == IOC_IO_ExcpStat_SPF_S) ? 'S' : ' ',
+	       (spf == IOC_IO_ExcpStat_SPF_P) ? 'P' : ' ',
 	       (stat & IOC_IO_ExcpStat_RW_Mask) ? "Read" : "Write",
 	       (unsigned int)(stat & IOC_IO_ExcpStat_IOID_Mask));
 	printk(KERN_ERR "  page=0x%016lx\n",