sh: Fix up legacy PTEA space attribute mapping.

When p3_ioremap() was converted to ioremap_prot() there was some breakage
introduced where the 29-bit segmentation logic would trap the area range
and return an identity mapping without having allowed the area
specification to force mapping through page tables. This wires up a PCC
mask for pgprot verification to work out whether to short-circuit the
identity mapping on legacy parts, restoring the previous behaviour.

Reported-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Cc: stable@kernel.org
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/include/asm/io.h

@@ -290,7 +290,15 @@ __ioremap_29bit(phys_addr_t offset, unsigned long size, pgprot_t prot)
 	 * mapping must be done by the PMB or by using page tables.
 	 */
 	if (likely(PXSEG(offset) < P3SEG && PXSEG(last_addr) < P3SEG)) {
-		if (unlikely(pgprot_val(prot) & _PAGE_CACHABLE))
+		u64 flags = pgprot_val(prot);
+
+		/*
+		 * Anything using the legacy PTEA space attributes needs
+		 * to be kicked down to page table mappings.
+		 */
+		if (unlikely(flags & _PAGE_PCC_MASK))
+			return NULL;
+		if (unlikely(flags & _PAGE_CACHABLE))
 			return (void __iomem *)P1SEGADDR(offset);
 
 		return (void __iomem *)P2SEGADDR(offset);

arch/sh/include/asm/pgtable_32.h

@@ -76,6 +76,10 @@
 /* Wrapper for extended mode pgprot twiddling */
 #define _PAGE_EXT(x)		((unsigned long long)(x) << 32)
 
+#ifdef CONFIG_X2TLB
+#define _PAGE_PCC_MASK	0x00000000	/* No legacy PTEA support */
+#else
+
 /* software: moves to PTEA.TC (Timing Control) */
 #define _PAGE_PCC_AREA5	0x00000000	/* use BSC registers for area5 */
 #define _PAGE_PCC_AREA6	0x80000000	/* use BSC registers for area6 */
@@ -89,7 +93,8 @@
 #define _PAGE_PCC_ATR8	0x60000000	/* Attribute Memory space, 8 bit bus */
 #define _PAGE_PCC_ATR16	0x60000001	/* Attribute Memory space, 6 bit bus */
 
-#ifndef CONFIG_X2TLB
+#define _PAGE_PCC_MASK	0xe0000001
+
 /* copy the ptea attributes */
 static inline unsigned long copy_ptea_attributes(unsigned long x)
 {